I need to install a 12v winch and a battery next to it, on a trailer.
This winch may need a huge amount of current.

I hope that this auxiliary battery will provide the power needed to
run the winch, however, I want it to be charged from the vehicle's
auxiliary 12v supply.

What concerns me is that when the winch is working, the battery may
demand a lot of current from the vehicle, and blow a fuse. At the same
time, after use, it may also require a lot of current with the same
result.

Ideally, I would like a current limiting device, of some kind, between
the vehicle and the wnich battery, that would limit current to some
low value, like 15 amps, happily supplying any amps under 15, but
automatically limiting the current to 15 amps only.

Is there anything of the sort, that I can purchase off-the-shelf?

I do realize that I can just wire a resistor in series, and I do have
a 1.4 ohm, 290 watt resistor and some others, but I was hoping for
something more elegant.

Thanks

i

An auxillary battery is generally connected to a battery isolator. The
isolator module allows charging of the aux battery while preventing the aux
load (winch) from depleting the vehicle's starting battery.

The wiring to the aux battery is 10ga minimum on a typical RV or other
vehicle, but should be heaver gage for longer runs, and include a fusible
link or circuit breaker at the source (isolator module).
Because a trailer connector is likely to be used, a heavy duty connector
should be installed.

I believe the isolator is generally selected to meet the charging demand of
the aux battery and the output capacity (amps) of the vehicle's alternator.

The output capacity for the load (Ah) may be increased by using two 6V high
capacity golf cart batteries instead of a typical 12V battery.

The most simple method of current limiting is a series LER (light emitting
resistor.. a bulb selected for the desired current level).

--
WB
..........


"Ignoramus17560" wrote in message
...
I need to install a 12v winch and a battery next to it, on a trailer.
This winch may need a huge amount of current.

I hope that this auxiliary battery will provide the power needed to
run the winch, however, I want it to be charged from the vehicle's
auxiliary 12v supply.

What concerns me is that when the winch is working, the battery may
demand a lot of current from the vehicle, and blow a fuse. At the same
time, after use, it may also require a lot of current with the same
result.

Ideally, I would like a current limiting device, of some kind, between
the vehicle and the wnich battery, that would limit current to some
low value, like 15 amps, happily supplying any amps under 15, but
automatically limiting the current to 15 amps only.

Is there anything of the sort, that I can purchase off-the-shelf?

I do realize that I can just wire a resistor in series, and I do have
a 1.4 ohm, 290 watt resistor and some others, but I was hoping for
something more elegant.

Thanks

i

Wild_Bill has brought this to us :
An auxillary battery is generally connected to a battery isolator. The
isolator module allows charging of the aux battery while preventing the aux
load (winch) from depleting the vehicle's starting battery.

The wiring to the aux battery is 10ga minimum on a typical RV or other
vehicle, but should be heaver gage for longer runs, and include a fusible
link or circuit breaker at the source (isolator module).
Because a trailer connector is likely to be used, a heavy duty connector
should be installed.

I believe the isolator is generally selected to meet the charging demand of
the aux battery and the output capacity (amps) of the vehicle's alternator.

The output capacity for the load (Ah) may be increased by using two 6V high
capacity golf cart batteries instead of a typical 12V battery.

The most simple method of current limiting is a series LER (light emitting
resistor.. a bulb selected for the desired current level).

--
WB
.........


"Ignoramus17560" wrote in message
...
I need to install a 12v winch and a battery next to it, on a trailer.
This winch may need a huge amount of current.

I hope that this auxiliary battery will provide the power needed to
run the winch, however, I want it to be charged from the vehicle's
auxiliary 12v supply.

What concerns me is that when the winch is working, the battery may
demand a lot of current from the vehicle, and blow a fuse. At the same
time, after use, it may also require a lot of current with the same
result.

Ideally, I would like a current limiting device, of some kind, between
the vehicle and the wnich battery, that would limit current to some
low value, like 15 amps, happily supplying any amps under 15, but
automatically limiting the current to 15 amps only.

Is there anything of the sort, that I can purchase off-the-shelf?

I do realize that I can just wire a resistor in series, and I do have
a 1.4 ohm, 290 watt resistor and some others, but I was hoping for
something more elegant.

Thanks

i

Try the local Rec Vehicle agents. They do this sort of thing all the
time.

--
John G

Ignoramus17560 fired this volley in
:

I do realize that I can just wire a resistor in series, and I do have
a 1.4 ohm, 290 watt resistor and some others, but I was hoping for
something more elegant.

Thanks

i


You could replace the control contactor with a double-pole affair that
breaks from the charging circuit before making to the motor.

But why? You'd something in the vicinity of a 3A 'slow charge' with that
resistor on a nearly-dead battery.

And what's more 'elegant' than a one-component, no-moving-parts solution?
That resistor is over 20 times larger than necessary, but you can be sure
it won't burn out from overheating!


Lloyd

On Sat, 13 Apr 2013 23:03:57 -0500, Ignoramus17560
wrote:

I need to install a 12v winch and a battery next to it, on a trailer.
This winch may need a huge amount of current.

I hope that this auxiliary battery will provide the power needed to
run the winch, however, I want it to be charged from the vehicle's
auxiliary 12v supply.

What concerns me is that when the winch is working, the battery may
demand a lot of current from the vehicle, and blow a fuse. At the same
time, after use, it may also require a lot of current with the same
result.

Ideally, I would like a current limiting device, of some kind, between
the vehicle and the wnich battery, that would limit current to some
low value, like 15 amps, happily supplying any amps under 15, but
automatically limiting the current to 15 amps only.

Is there anything of the sort, that I can purchase off-the-shelf?

I do realize that I can just wire a resistor in series, and I do have
a 1.4 ohm, 290 watt resistor and some others, but I was hoping for
something more elegant.

Thanks

i

I don't know about your vehicle winch but boats with an electric
anchor winch don't seem to have a problem. Example:
100 lb capacity @62'/min = 25A
400 Lb @ 62'/min = 35A
900 lb @ 80'/min = 70A

Most boats, if they use a winch battery, just have it connected in
parallel to the main house bank and don't run the winch unless the
main engine or the generator is running.

As for restricting battery charging to 15 amps, I would think that
your alternator would likely be capable of producing 60 - 70 amps, and
maybe more, why would you restrict charging to such a low level?




--
Cheers,

John B.

In article ,
Ignoramus17560 wrote:

Is there anything of the sort, that I can purchase off-the-shelf?

A light bulb is one classic approach - the filament resistance varies
with the current. It's not ideal, but it is simple.

--
Cats, coffee, chocolate...vices to live by
Please don't feed the trolls. Killfile and ignore them so they will go away.

On 2013-04-14, J.B.Slocomb wrote:
On Sat, 13 Apr 2013 23:03:57 -0500, Ignoramus17560
wrote:

I need to install a 12v winch and a battery next to it, on a trailer.
This winch may need a huge amount of current.

I hope that this auxiliary battery will provide the power needed to
run the winch, however, I want it to be charged from the vehicle's
auxiliary 12v supply.

What concerns me is that when the winch is working, the battery may
demand a lot of current from the vehicle, and blow a fuse. At the same
time, after use, it may also require a lot of current with the same
result.

Ideally, I would like a current limiting device, of some kind, between
the vehicle and the wnich battery, that would limit current to some
low value, like 15 amps, happily supplying any amps under 15, but
automatically limiting the current to 15 amps only.

Is there anything of the sort, that I can purchase off-the-shelf?

I do realize that I can just wire a resistor in series, and I do have
a 1.4 ohm, 290 watt resistor and some others, but I was hoping for
something more elegant.

Thanks

i

I don't know about your vehicle winch but boats with an electric
anchor winch don't seem to have a problem. Example:
100 lb capacity @62'/min = 25A
400 Lb @ 62'/min = 35A
900 lb @ 80'/min = 70A

Most boats, if they use a winch battery, just have it connected in
parallel to the main house bank and don't run the winch unless the
main engine or the generator is running.

As for restricting battery charging to 15 amps, I would think that
your alternator would likely be capable of producing 60 - 70 amps, and
maybe more, why would you restrict charging to such a low level?

For a semi truck use, and 400A demanded by the winch, it means that I
will need a 40 foot two conductor welding cable, at least 1/0. And the
number one concern is that it will be eventually stolen. I would
rather slowly recharge.

i

On Sun, 14 Apr 2013 08:37:44 -0500, Ignoramus25056
wrote:

On 2013-04-14, J.B.Slocomb wrote:
On Sat, 13 Apr 2013 23:03:57 -0500, Ignoramus17560
wrote:

I need to install a 12v winch and a battery next to it, on a trailer.
This winch may need a huge amount of current.

I hope that this auxiliary battery will provide the power needed to
run the winch, however, I want it to be charged from the vehicle's
auxiliary 12v supply.

What concerns me is that when the winch is working, the battery may
demand a lot of current from the vehicle, and blow a fuse. At the same
time, after use, it may also require a lot of current with the same
result.

Ideally, I would like a current limiting device, of some kind, between
the vehicle and the wnich battery, that would limit current to some
low value, like 15 amps, happily supplying any amps under 15, but
automatically limiting the current to 15 amps only.

Is there anything of the sort, that I can purchase off-the-shelf?

I do realize that I can just wire a resistor in series, and I do have
a 1.4 ohm, 290 watt resistor and some others, but I was hoping for
something more elegant.

Thanks

i

I don't know about your vehicle winch but boats with an electric
anchor winch don't seem to have a problem. Example:
100 lb capacity @62'/min = 25A
400 Lb @ 62'/min = 35A
900 lb @ 80'/min = 70A

Most boats, if they use a winch battery, just have it connected in
parallel to the main house bank and don't run the winch unless the
main engine or the generator is running.

As for restricting battery charging to 15 amps, I would think that
your alternator would likely be capable of producing 60 - 70 amps, and
maybe more, why would you restrict charging to such a low level?

For a semi truck use, and 400A demanded by the winch, it means that I
will need a 40 foot two conductor welding cable, at least 1/0. And the
number one concern is that it will be eventually stolen. I would
rather slowly recharge.

You could plumb most of it through a pipe, providing protection and
theft proofing, and make sheetmetal boxes for the ends.

--
A sound mind in a sound body is a short but full description
of a happy state in this world.
-- John Locke

Ignoramus17560 wrote:

I need to install a 12v winch and a battery next to it, on a trailer.
This winch may need a huge amount of current.

I hope that this auxiliary battery will provide the power needed to
run the winch, however, I want it to be charged from the vehicle's
auxiliary 12v supply.

What concerns me is that when the winch is working, the battery may
demand a lot of current from the vehicle, and blow a fuse. At the same
time, after use, it may also require a lot of current with the same
result.

Ideally, I would like a current limiting device, of some kind, between
the vehicle and the wnich battery, that would limit current to some
low value, like 15 amps, happily supplying any amps under 15, but
automatically limiting the current to 15 amps only.

Is there anything of the sort, that I can purchase off-the-shelf?

I do realize that I can just wire a resistor in series, and I do have
a 1.4 ohm, 290 watt resistor and some others, but I was hoping for
something more elegant.

Thanks

i

Use a standard self resetting automotive circuit breaker, probably a 30A
one since that's the norm for trailer aux power / charge circuits.
Plenty of people have trailers with winches and that how they are
normally connected, with an aux battery on the trailer and just the
vehicles normal 30A trailer charge circuit to top it off.

On my truck I have a receiver mount winch I use periodically that
operates from the truck. I have a forklift style power connector mounted
under the bumper for the winch and it is wired with 1/0 welding cable
back to the battery with a 200A continuous rated contactor near the
battery end which is controlled from an aux switch in the truck. I also
set the truck's battery charge protect mode where the PCM will raise the
engine idle speed as needed to keep up with large electrical loads.

"Ignoramus25056" wrote in
message ...
On 2013-04-14, J.B.Slocomb wrote:
On Sat, 13 Apr 2013 23:03:57 -0500, Ignoramus17560
wrote:


Ideally, I would like a current limiting device, of some kind,
between
the vehicle and the wnich battery, that would limit current to some
low value, like 15 amps, happily supplying any amps under 15, but
automatically limiting the current to 15 amps only.

i

http://en.wikipedia.org/wiki/Thermistor#PTC
http://www.newark.com/ptc-resettable-fuses
jsw

"Ignoramus17560" wrote in message
...

Is there anything of the sort, that I can purchase off-the-shelf?

I do realize that I can just wire a resistor in series, and I do have
a 1.4 ohm, 290 watt resistor and some others, but I was hoping for
something more elegant.

Thanks

i

In the radio control model stuff they have battery chargers that are ran off
of 12VDC.

This charger runs from 12V DC and can charge LiPo, NiMh, NiCd, and Lead Acid
batteries, it limits the charge current to 5A so it shouldn't blow the fuses
from charge power.
http://www.hobbypartz.com/60p-dyc-1004.html

Another idea would be to use an inverter to power a 120VAC battery charger.

You might be able to find some kind of constant current regulator with low
drop-out but I'm guessing that may not be much of an "off the shelf"
solution.

RogerN

On Sun, 14 Apr 2013 19:13:26 +0700, J.B.Slocomb
wrote:

On Sat, 13 Apr 2013 23:03:57 -0500, Ignoramus17560
wrote:

I need to install a 12v winch and a battery next to it, on a trailer.
This winch may need a huge amount of current.

I hope that this auxiliary battery will provide the power needed to
run the winch, however, I want it to be charged from the vehicle's
auxiliary 12v supply.

What concerns me is that when the winch is working, the battery may
demand a lot of current from the vehicle, and blow a fuse. At the same
time, after use, it may also require a lot of current with the same
result.

Ideally, I would like a current limiting device, of some kind, between
the vehicle and the wnich battery, that would limit current to some
low value, like 15 amps, happily supplying any amps under 15, but
automatically limiting the current to 15 amps only.

Is there anything of the sort, that I can purchase off-the-shelf?

I do realize that I can just wire a resistor in series, and I do have
a 1.4 ohm, 290 watt resistor and some others, but I was hoping for
something more elegant.

Thanks

i

I don't know about your vehicle winch but boats with an electric
anchor winch don't seem to have a problem. Example:
100 lb capacity @62'/min = 25A
400 Lb @ 62'/min = 35A
900 lb @ 80'/min = 70A

Most boats, if they use a winch battery, just have it connected in
parallel to the main house bank and don't run the winch unless the
main engine or the generator is running.

As for restricting battery charging to 15 amps, I would think that
your alternator would likely be capable of producing 60 - 70 amps, and
maybe more, why would you restrict charging to such a low level?
But the connection between the winch battery and the house battery
is as heavy (at least) as the cable from the winch to the battery.

Ignoramus25056 wrote:

On 2013-04-14, J.B.Slocomb wrote:
On Sat, 13 Apr 2013 23:03:57 -0500, Ignoramus17560
wrote:

I need to install a 12v winch and a battery next to it, on a trailer.
This winch may need a huge amount of current.

I hope that this auxiliary battery will provide the power needed to
run the winch, however, I want it to be charged from the vehicle's
auxiliary 12v supply.

What concerns me is that when the winch is working, the battery may
demand a lot of current from the vehicle, and blow a fuse. At the same
time, after use, it may also require a lot of current with the same
result.

Ideally, I would like a current limiting device, of some kind, between
the vehicle and the wnich battery, that would limit current to some
low value, like 15 amps, happily supplying any amps under 15, but
automatically limiting the current to 15 amps only.

Is there anything of the sort, that I can purchase off-the-shelf?

I do realize that I can just wire a resistor in series, and I do have
a 1.4 ohm, 290 watt resistor and some others, but I was hoping for
something more elegant.

Thanks

i

I don't know about your vehicle winch but boats with an electric
anchor winch don't seem to have a problem. Example:
100 lb capacity @62'/min = 25A
400 Lb @ 62'/min = 35A
900 lb @ 80'/min = 70A

Most boats, if they use a winch battery, just have it connected in
parallel to the main house bank and don't run the winch unless the
main engine or the generator is running.

As for restricting battery charging to 15 amps, I would think that
your alternator would likely be capable of producing 60 - 70 amps, and
maybe more, why would you restrict charging to such a low level?

For a semi truck use, and 400A demanded by the winch, it means that I
will need a 40 foot two conductor welding cable, at least 1/0. And the
number one concern is that it will be eventually stolen. I would
rather slowly recharge.

i

Split the difference, use the local "accumulator" battery on the trailer
to provide the primary winch power. Run your charge circuit through
conduit and use something like 8ga wire with a 50A circuit breaker.

On 2013-04-14, Pete C. wrote:

Ignoramus25056 wrote:

On 2013-04-14, J.B.Slocomb wrote:
On Sat, 13 Apr 2013 23:03:57 -0500, Ignoramus17560
wrote:

I need to install a 12v winch and a battery next to it, on a trailer.
This winch may need a huge amount of current.

I hope that this auxiliary battery will provide the power needed to
run the winch, however, I want it to be charged from the vehicle's
auxiliary 12v supply.

What concerns me is that when the winch is working, the battery may
demand a lot of current from the vehicle, and blow a fuse. At the same
time, after use, it may also require a lot of current with the same
result.

Ideally, I would like a current limiting device, of some kind, between
the vehicle and the wnich battery, that would limit current to some
low value, like 15 amps, happily supplying any amps under 15, but
automatically limiting the current to 15 amps only.

Is there anything of the sort, that I can purchase off-the-shelf?

I do realize that I can just wire a resistor in series, and I do have
a 1.4 ohm, 290 watt resistor and some others, but I was hoping for
something more elegant.

Thanks

i

I don't know about your vehicle winch but boats with an electric
anchor winch don't seem to have a problem. Example:
100 lb capacity @62'/min = 25A
400 Lb @ 62'/min = 35A
900 lb @ 80'/min = 70A

Most boats, if they use a winch battery, just have it connected in
parallel to the main house bank and don't run the winch unless the
main engine or the generator is running.

As for restricting battery charging to 15 amps, I would think that
your alternator would likely be capable of producing 60 - 70 amps, and
maybe more, why would you restrict charging to such a low level?

For a semi truck use, and 400A demanded by the winch, it means that I
will need a 40 foot two conductor welding cable, at least 1/0. And the
number one concern is that it will be eventually stolen. I would
rather slowly recharge.

i

Split the difference, use the local "accumulator" battery on the trailer
to provide the primary winch power. Run your charge circuit through
conduit and use something like 8ga wire with a 50A circuit breaker.

I need that battery without question. But I want to charge it from the
truck and limit the current.

i

Ignoramus25056 wrote:

On 2013-04-14, Pete C. wrote:

Ignoramus25056 wrote:

On 2013-04-14, J.B.Slocomb wrote:
On Sat, 13 Apr 2013 23:03:57 -0500, Ignoramus17560
wrote:

I need to install a 12v winch and a battery next to it, on a trailer.
This winch may need a huge amount of current.

I hope that this auxiliary battery will provide the power needed to
run the winch, however, I want it to be charged from the vehicle's
auxiliary 12v supply.

What concerns me is that when the winch is working, the battery may
demand a lot of current from the vehicle, and blow a fuse. At the same
time, after use, it may also require a lot of current with the same
result.

Ideally, I would like a current limiting device, of some kind, between
the vehicle and the wnich battery, that would limit current to some
low value, like 15 amps, happily supplying any amps under 15, but
automatically limiting the current to 15 amps only.

Is there anything of the sort, that I can purchase off-the-shelf?

I do realize that I can just wire a resistor in series, and I do have
a 1.4 ohm, 290 watt resistor and some others, but I was hoping for
something more elegant.

Thanks

i

I don't know about your vehicle winch but boats with an electric
anchor winch don't seem to have a problem. Example:
100 lb capacity @62'/min = 25A
400 Lb @ 62'/min = 35A
900 lb @ 80'/min = 70A

Most boats, if they use a winch battery, just have it connected in
parallel to the main house bank and don't run the winch unless the
main engine or the generator is running.

As for restricting battery charging to 15 amps, I would think that
your alternator would likely be capable of producing 60 - 70 amps, and
maybe more, why would you restrict charging to such a low level?

For a semi truck use, and 400A demanded by the winch, it means that I
will need a 40 foot two conductor welding cable, at least 1/0. And the
number one concern is that it will be eventually stolen. I would
rather slowly recharge.

i

Split the difference, use the local "accumulator" battery on the trailer
to provide the primary winch power. Run your charge circuit through
conduit and use something like 8ga wire with a 50A circuit breaker.

I need that battery without question. But I want to charge it from the
truck and limit the current.

i

Self resetting 30A or 50A automotive circuit breakers = PWM

My large cargo trailer has a winch (3500#) and interior lighting, with a
deep cycle battery on the trailer tongue. It charges from the normal 30A
charge line in the 7RV trailer connector. You should have no issues
doing the same with your semi. Heck, attach an alternator to your
hydraulic setup on the trailer and you can charge independent of the
semi, or find a hydraulic winch.

On Sun, 14 Apr 2013 09:16:20 -0500, "Pete C."
wrote:


Ignoramus17560 wrote:

I need to install a 12v winch and a battery next to it, on a trailer.
This winch may need a huge amount of current.

I hope that this auxiliary battery will provide the power needed to
run the winch, however, I want it to be charged from the vehicle's
auxiliary 12v supply.

What concerns me is that when the winch is working, the battery may
demand a lot of current from the vehicle, and blow a fuse. At the same
time, after use, it may also require a lot of current with the same
result.

Ideally, I would like a current limiting device, of some kind, between
the vehicle and the wnich battery, that would limit current to some
low value, like 15 amps, happily supplying any amps under 15, but
automatically limiting the current to 15 amps only.

Is there anything of the sort, that I can purchase off-the-shelf?

I do realize that I can just wire a resistor in series, and I do have
a 1.4 ohm, 290 watt resistor and some others, but I was hoping for
something more elegant.

Thanks

i

Use a standard self resetting automotive circuit breaker, probably a 30A
one since that's the norm for trailer aux power / charge circuits.
Plenty of people have trailers with winches and that how they are
normally connected, with an aux battery on the trailer and just the
vehicles normal 30A trailer charge circuit to top it off.

On my truck I have a receiver mount winch I use periodically that
operates from the truck. I have a forklift style power connector mounted
under the bumper for the winch and it is wired with 1/0 welding cable
back to the battery with a 200A continuous rated contactor near the
battery end which is controlled from an aux switch in the truck. I also
set the truck's battery charge protect mode where the PCM will raise the
engine idle speed as needed to keep up with large electrical loads.

Or one could simply add an inexpensive generator to the trailer and
use a 110 or 220volt motor and resolve all the bull****.

On 2013-04-14, Pete C. wrote:

Ignoramus25056 wrote:

On 2013-04-14, Pete C. wrote:

Ignoramus25056 wrote:

On 2013-04-14, J.B.Slocomb wrote:
On Sat, 13 Apr 2013 23:03:57 -0500, Ignoramus17560
wrote:

I need to install a 12v winch and a battery next to it, on a trailer.
This winch may need a huge amount of current.

I hope that this auxiliary battery will provide the power needed to
run the winch, however, I want it to be charged from the vehicle's
auxiliary 12v supply.

What concerns me is that when the winch is working, the battery may
demand a lot of current from the vehicle, and blow a fuse. At the same
time, after use, it may also require a lot of current with the same
result.

Ideally, I would like a current limiting device, of some kind, between
the vehicle and the wnich battery, that would limit current to some
low value, like 15 amps, happily supplying any amps under 15, but
automatically limiting the current to 15 amps only.

Is there anything of the sort, that I can purchase off-the-shelf?

I do realize that I can just wire a resistor in series, and I do have
a 1.4 ohm, 290 watt resistor and some others, but I was hoping for
something more elegant.

Thanks

i

I don't know about your vehicle winch but boats with an electric
anchor winch don't seem to have a problem. Example:
100 lb capacity @62'/min = 25A
400 Lb @ 62'/min = 35A
900 lb @ 80'/min = 70A

Most boats, if they use a winch battery, just have it connected in
parallel to the main house bank and don't run the winch unless the
main engine or the generator is running.

As for restricting battery charging to 15 amps, I would think that
your alternator would likely be capable of producing 60 - 70 amps, and
maybe more, why would you restrict charging to such a low level?

For a semi truck use, and 400A demanded by the winch, it means that I
will need a 40 foot two conductor welding cable, at least 1/0. And the
number one concern is that it will be eventually stolen. I would
rather slowly recharge.

i

Split the difference, use the local "accumulator" battery on the trailer
to provide the primary winch power. Run your charge circuit through
conduit and use something like 8ga wire with a 50A circuit breaker.

I need that battery without question. But I want to charge it from the
truck and limit the current.

i

Self resetting 30A or 50A automotive circuit breakers = PWM

My large cargo trailer has a winch (3500#) and interior lighting, with a
deep cycle battery on the trailer tongue. It charges from the normal 30A
charge line in the 7RV trailer connector. You should have no issues
doing the same with your semi. Heck, attach an alternator to your
hydraulic setup on the trailer and you can charge independent of the
semi, or find a hydraulic winch.

I want to move this winch from trailer to trailer. Sometmies it is
really hard to pull a forklift with a front mounted winch, when there
is a pile of scrap metal on the trailer in front of the forklift. An
electric winch would solve this problem nicely.

i

On Sun, 14 Apr 2013 08:37:44 -0500, Ignoramus25056
wrote:

On 2013-04-14, J.B.Slocomb wrote:
On Sat, 13 Apr 2013 23:03:57 -0500, Ignoramus17560
wrote:

I need to install a 12v winch and a battery next to it, on a trailer.
This winch may need a huge amount of current.

I hope that this auxiliary battery will provide the power needed to
run the winch, however, I want it to be charged from the vehicle's
auxiliary 12v supply.

What concerns me is that when the winch is working, the battery may
demand a lot of current from the vehicle, and blow a fuse. At the same
time, after use, it may also require a lot of current with the same
result.

Ideally, I would like a current limiting device, of some kind, between
the vehicle and the wnich battery, that would limit current to some
low value, like 15 amps, happily supplying any amps under 15, but
automatically limiting the current to 15 amps only.

Is there anything of the sort, that I can purchase off-the-shelf?

I do realize that I can just wire a resistor in series, and I do have
a 1.4 ohm, 290 watt resistor and some others, but I was hoping for
something more elegant.

Thanks

i

I don't know about your vehicle winch but boats with an electric
anchor winch don't seem to have a problem. Example:
100 lb capacity @62'/min = 25A
400 Lb @ 62'/min = 35A
900 lb @ 80'/min = 70A

Most boats, if they use a winch battery, just have it connected in
parallel to the main house bank and don't run the winch unless the
main engine or the generator is running.

As for restricting battery charging to 15 amps, I would think that
your alternator would likely be capable of producing 60 - 70 amps, and
maybe more, why would you restrict charging to such a low level?

For a semi truck use, and 400A demanded by the winch, it means that I
will need a 40 foot two conductor welding cable, at least 1/0. And the
number one concern is that it will be eventually stolen. I would
rather slowly recharge.

i

Ah well, if you are using a winch that requires 400 amps than you will
have a significantly big battery bank to support it. But still that is
no larger than many cruising yachts use for a "house bank". A "battery
combiner" isn't going to work as it simply isolates the batterys in
discharge mode and not in charge.

The problem is that an alternator putting out say 14 volts, is going
to pump a lot of amps into a mostly discharged 400+ amp battery bank.
I suspect that the easy way is a large resister in the charge line to
the winch batteries. Another alternative might be to build a pulse
width controller but that seems like a lot of work for little benefit.

My limited experience with truck winches is oil field trucks - 50 ton
truck, flat bed, load by winching load up over a tail roller - and
these all had mechanical winches driven off a power take-off, but I
would think that an electric winch drawing 400 amps would be a pretty
large device. A quick look at the catalog shows a 1260 lb. capacity
winch drawing 85 amps so a 400 amp winch may well be a 4 ton winch.

--
Cheers,

John B.

On Sun, 14 Apr 2013 13:52:36 -0400, wrote:

On Sun, 14 Apr 2013 19:13:26 +0700, J.B.Slocomb
wrote:

On Sat, 13 Apr 2013 23:03:57 -0500, Ignoramus17560
wrote:

I need to install a 12v winch and a battery next to it, on a trailer.
This winch may need a huge amount of current.

I hope that this auxiliary battery will provide the power needed to
run the winch, however, I want it to be charged from the vehicle's
auxiliary 12v supply.

What concerns me is that when the winch is working, the battery may
demand a lot of current from the vehicle, and blow a fuse. At the same
time, after use, it may also require a lot of current with the same
result.

Ideally, I would like a current limiting device, of some kind, between
the vehicle and the wnich battery, that would limit current to some
low value, like 15 amps, happily supplying any amps under 15, but
automatically limiting the current to 15 amps only.

Is there anything of the sort, that I can purchase off-the-shelf?

I do realize that I can just wire a resistor in series, and I do have
a 1.4 ohm, 290 watt resistor and some others, but I was hoping for
something more elegant.

Thanks

i

I don't know about your vehicle winch but boats with an electric
anchor winch don't seem to have a problem. Example:
100 lb capacity @62'/min = 25A
400 Lb @ 62'/min = 35A
900 lb @ 80'/min = 70A

Most boats, if they use a winch battery, just have it connected in
parallel to the main house bank and don't run the winch unless the
main engine or the generator is running.

As for restricting battery charging to 15 amps, I would think that
your alternator would likely be capable of producing 60 - 70 amps, and
maybe more, why would you restrict charging to such a low level?
But the connection between the winch battery and the house battery
is as heavy (at least) as the cable from the winch to the battery.

Not really. An alternator that can put out, say 65 amps, doesn't need
the same size wiring as a winch that draws 400 amps.

--
Cheers,

John B.

On 2013-04-15, J.B.Slocomb wrote:
wrote:
For a semi truck use, and 400A demanded by the winch, it means that I
will need a 40 foot two conductor welding cable, at least 1/0. And the
number one concern is that it will be eventually stolen. I would
rather slowly recharge.

Ah well, if you are using a winch that requires 400 amps than you will
have a significantly big battery bank to support it. But still that is
no larger than many cruising yachts use for a "house bank". A "battery
combiner" isn't going to work as it simply isolates the batterys in
discharge mode and not in charge.

The problem is that an alternator putting out say 14 volts, is going
to pump a lot of amps into a mostly discharged 400+ amp battery bank.

This is exactly the problem that I am trying to solve.

I suspect that the easy way is a large resister in the charge line to
the winch batteries. Another alternative might be to build a pulse
width controller but that seems like a lot of work for little benefit.

My limited experience with truck winches is oil field trucks - 50 ton
truck, flat bed, load by winching load up over a tail roller - and
these all had mechanical winches driven off a power take-off, but I
would think that an electric winch drawing 400 amps would be a pretty
large device. A quick look at the catalog shows a 1260 lb. capacity
winch drawing 85 amps so a 400 amp winch may well be a 4 ton winch.


I bought a "12000 lbs rated" Mile Marker winch. It pulls 400+ A at
maxc. load. I think that I will just go with the resistor, it is the
most idiot proof device.

i

On Sun, 14 Apr 2013 08:34:55 -0400, Ecnerwal
wrote:

In article ,
Ignoramus17560 wrote:

Is there anything of the sort, that I can purchase off-the-shelf?

A light bulb is one classic approach - the filament resistance varies
with the current. It's not ideal, but it is simple.

The simple way is an automatic reset thermal circuit breaker sized to
protect the wire under the car and the trailer jumper - 10-GA wire 20A
or 30A, 8-GA 30A to 40A.

Then put a continuous-duty rated solenoid, with the coil from the
Ignition circuit - a control switch on the dash optional. This is
important, a standard "Ford Starter Solenoid" has an Intermittent duty
cycle of like 30 seconds on, 20 minutes off. The Magic Smoke will
escape fast.

And then your big-ass resistor somewhere it will get cooling air from
the radiator - not buried. It would be tempting to put it on the
fender underneath the Engine ECU, till you consider that heat rises...

A headlamp bulb will work too, might even be better because it's a
Non-Linear Resistance. When the current is low the resistance is low,
and it will allow the full 13.8 - 14.5V through to trickle charge the
battery completely. When the current goes up and the lamp lights,
suddenly the resistance goes up a lot, and the lamp's ratings will
determine the max current on the charge line.

Or put a smaller sealed beam in parallel with the big resistor - the
lamp will pass the trickle charge finishing current.

On Sun, 14 Apr 2013 17:28:29 -0500, Ignoramus25056
wrote:

On 2013-04-14, Pete C. wrote:

Ignoramus25056 wrote:

On 2013-04-14, J.B.Slocomb wrote:
On Sat, 13 Apr 2013 23:03:57 -0500, Ignoramus17560
wrote:

I need to install a 12v winch and a battery next to it, on a trailer.
This winch may need a huge amount of current.

I hope that this auxiliary battery will provide the power needed to
run the winch, however, I want it to be charged from the vehicle's
auxiliary 12v supply.

What concerns me is that when the winch is working, the battery may
demand a lot of current from the vehicle, and blow a fuse. At the same
time, after use, it may also require a lot of current with the same
result.

Ideally, I would like a current limiting device, of some kind, between
the vehicle and the wnich battery, that would limit current to some
low value, like 15 amps, happily supplying any amps under 15, but
automatically limiting the current to 15 amps only.

Is there anything of the sort, that I can purchase off-the-shelf?

I do realize that I can just wire a resistor in series, and I do have
a 1.4 ohm, 290 watt resistor and some others, but I was hoping for
something more elegant.

Thanks

i

I don't know about your vehicle winch but boats with an electric
anchor winch don't seem to have a problem. Example:
100 lb capacity @62'/min = 25A
400 Lb @ 62'/min = 35A
900 lb @ 80'/min = 70A

Most boats, if they use a winch battery, just have it connected in
parallel to the main house bank and don't run the winch unless the
main engine or the generator is running.

As for restricting battery charging to 15 amps, I would think that
your alternator would likely be capable of producing 60 - 70 amps, and
maybe more, why would you restrict charging to such a low level?

For a semi truck use, and 400A demanded by the winch, it means that I
will need a 40 foot two conductor welding cable, at least 1/0. And the
number one concern is that it will be eventually stolen. I would
rather slowly recharge.

i

Split the difference, use the local "accumulator" battery on the trailer
to provide the primary winch power. Run your charge circuit through
conduit and use something like 8ga wire with a 50A circuit breaker.

I need that battery without question. But I want to charge it from the
truck and limit the current.

Don't worry about it. The regulator will limit it (to alternator
capacity) just fine. But with a bigass winch like that, I'd run full
cabling back to tie the winch and its battery directly to the main
battery(ies). It won't cost too much more and will allow all batteries
to provide the enormous power it takes to run it if you lift something
quite heavy. If you're going to use it a whole lot, consider a larger
capacity alternator system, too, Ig. They can be used for onsite
welding, too, if you choose properly.

--
A sound mind in a sound body is a short but full description
of a happy state in this world.
-- John Locke

Larry Jaques submitted this idea :
On Sun, 14 Apr 2013 17:28:29 -0500, Ignoramus25056
wrote:

On 2013-04-14, Pete C. wrote:

Ignoramus25056 wrote:

On 2013-04-14, J.B.Slocomb wrote:
On Sat, 13 Apr 2013 23:03:57 -0500, Ignoramus17560
wrote:

I need to install a 12v winch and a battery next to it, on a trailer.
This winch may need a huge amount of current.

I hope that this auxiliary battery will provide the power needed to
run the winch, however, I want it to be charged from the vehicle's
auxiliary 12v supply.

What concerns me is that when the winch is working, the battery may
demand a lot of current from the vehicle, and blow a fuse. At the same
time, after use, it may also require a lot of current with the same
result.

Ideally, I would like a current limiting device, of some kind, between
the vehicle and the wnich battery, that would limit current to some
low value, like 15 amps, happily supplying any amps under 15, but
automatically limiting the current to 15 amps only.

Is there anything of the sort, that I can purchase off-the-shelf?

I do realize that I can just wire a resistor in series, and I do have
a 1.4 ohm, 290 watt resistor and some others, but I was hoping for
something more elegant.

Thanks

i

I don't know about your vehicle winch but boats with an electric
anchor winch don't seem to have a problem. Example:
100 lb capacity @62'/min = 25A
400 Lb @ 62'/min = 35A
900 lb @ 80'/min = 70A

Most boats, if they use a winch battery, just have it connected in
parallel to the main house bank and don't run the winch unless the
main engine or the generator is running.

As for restricting battery charging to 15 amps, I would think that
your alternator would likely be capable of producing 60 - 70 amps, and
maybe more, why would you restrict charging to such a low level?

For a semi truck use, and 400A demanded by the winch, it means that I
will need a 40 foot two conductor welding cable, at least 1/0. And the
number one concern is that it will be eventually stolen. I would
rather slowly recharge.

i

Split the difference, use the local "accumulator" battery on the trailer
to provide the primary winch power. Run your charge circuit through
conduit and use something like 8ga wire with a 50A circuit breaker.

I need that battery without question. But I want to charge it from the
truck and limit the current.

Don't worry about it. The regulator will limit it (to alternator
capacity) just fine. But with a bigass winch like that, I'd run full
cabling back to tie the winch and its battery directly to the main
battery(ies). It won't cost too much more and will allow all batteries
to provide the enormous power it takes to run it if you lift something
quite heavy. If you're going to use it a whole lot, consider a larger
capacity alternator system, too, Ig. They can be used for onsite
welding, too, if you choose properly.

Remember to enclose and clamp the long cable because you cannot fuse it
and if it rubs thru SOMEWHERE in its lenth the whole show may turn into
a lot of magic smoke. :-?

--
John G

On Mon, 15 Apr 2013 07:15:25 +0700, J.B.Slocomb
wrote:

On Sun, 14 Apr 2013 13:52:36 -0400, wrote:

On Sun, 14 Apr 2013 19:13:26 +0700, J.B.Slocomb
wrote:

On Sat, 13 Apr 2013 23:03:57 -0500, Ignoramus17560
wrote:

I need to install a 12v winch and a battery next to it, on a trailer.
This winch may need a huge amount of current.

I hope that this auxiliary battery will provide the power needed to
run the winch, however, I want it to be charged from the vehicle's
auxiliary 12v supply.

What concerns me is that when the winch is working, the battery may
demand a lot of current from the vehicle, and blow a fuse. At the same
time, after use, it may also require a lot of current with the same
result.

Ideally, I would like a current limiting device, of some kind, between
the vehicle and the wnich battery, that would limit current to some
low value, like 15 amps, happily supplying any amps under 15, but
automatically limiting the current to 15 amps only.

Is there anything of the sort, that I can purchase off-the-shelf?

I do realize that I can just wire a resistor in series, and I do have
a 1.4 ohm, 290 watt resistor and some others, but I was hoping for
something more elegant.

Thanks

i

I don't know about your vehicle winch but boats with an electric
anchor winch don't seem to have a problem. Example:
100 lb capacity @62'/min = 25A
400 Lb @ 62'/min = 35A
900 lb @ 80'/min = 70A

Most boats, if they use a winch battery, just have it connected in
parallel to the main house bank and don't run the winch unless the
main engine or the generator is running.

As for restricting battery charging to 15 amps, I would think that
your alternator would likely be capable of producing 60 - 70 amps, and
maybe more, why would you restrict charging to such a low level?
But the connection between the winch battery and the house battery
is as heavy (at least) as the cable from the winch to the battery.

Not really. An alternator that can put out, say 65 amps, doesn't need
the same size wiring as a winch that draws 400 amps.


Somebody on one of the boat groups just went through a similar
exercise. He had a honking great battery bank and used a lot of
electrical devices so discharged the batteries pretty rapidly. He was
using a 100+amp alternator and the alternator was running pretty much
at max current and he burned out a couple. His solution was to add
cable to the charging circuit which dropped the voltage a bit and
decreased the charging rate enough to keep from cooking his
alternator.

I think that you are being excessively conservative in talking about a
15 amp charging rate into a large battery bank though :-)

--
Cheers,

John B.

John G wrote:

Larry Jaques submitted this idea :
On Sun, 14 Apr 2013 17:28:29 -0500, Ignoramus25056
wrote:

On 2013-04-14, Pete C. wrote:

Ignoramus25056 wrote:

On 2013-04-14, J.B.Slocomb wrote:
On Sat, 13 Apr 2013 23:03:57 -0500, Ignoramus17560
wrote:

I need to install a 12v winch and a battery next to it, on a trailer.
This winch may need a huge amount of current.

I hope that this auxiliary battery will provide the power needed to
run the winch, however, I want it to be charged from the vehicle's
auxiliary 12v supply.

What concerns me is that when the winch is working, the battery may
demand a lot of current from the vehicle, and blow a fuse. At the same
time, after use, it may also require a lot of current with the same
result.

Ideally, I would like a current limiting device, of some kind, between
the vehicle and the wnich battery, that would limit current to some
low value, like 15 amps, happily supplying any amps under 15, but
automatically limiting the current to 15 amps only.

Is there anything of the sort, that I can purchase off-the-shelf?

I do realize that I can just wire a resistor in series, and I do have
a 1.4 ohm, 290 watt resistor and some others, but I was hoping for
something more elegant.

Thanks

i

I don't know about your vehicle winch but boats with an electric
anchor winch don't seem to have a problem. Example:
100 lb capacity @62'/min = 25A
400 Lb @ 62'/min = 35A
900 lb @ 80'/min = 70A

Most boats, if they use a winch battery, just have it connected in
parallel to the main house bank and don't run the winch unless the
main engine or the generator is running.

As for restricting battery charging to 15 amps, I would think that
your alternator would likely be capable of producing 60 - 70 amps, and
maybe more, why would you restrict charging to such a low level?

For a semi truck use, and 400A demanded by the winch, it means that I
will need a 40 foot two conductor welding cable, at least 1/0. And the
number one concern is that it will be eventually stolen. I would
rather slowly recharge.

i

Split the difference, use the local "accumulator" battery on the trailer
to provide the primary winch power. Run your charge circuit through
conduit and use something like 8ga wire with a 50A circuit breaker.

I need that battery without question. But I want to charge it from the
truck and limit the current.

Don't worry about it. The regulator will limit it (to alternator
capacity) just fine. But with a bigass winch like that, I'd run full
cabling back to tie the winch and its battery directly to the main
battery(ies). It won't cost too much more and will allow all batteries
to provide the enormous power it takes to run it if you lift something
quite heavy. If you're going to use it a whole lot, consider a larger
capacity alternator system, too, Ig. They can be used for onsite
welding, too, if you choose properly.

Remember to enclose and clamp the long cable because you cannot fuse it
and if it rubs thru SOMEWHERE in its lenth the whole show may turn into
a lot of magic smoke. :-?

That's one of the reasons I put a large contactor on the aux feed up
front near close to the batteries on my truck. That aux feed is only
powered when I switch it on from the dash switch.

"Pete C." wrote:

John G wrote:

Larry Jaques submitted this idea :
On Sun, 14 Apr 2013 17:28:29 -0500, Ignoramus25056
wrote:

On 2013-04-14, Pete C. wrote:

Ignoramus25056 wrote:

On 2013-04-14, J.B.Slocomb wrote:
On Sat, 13 Apr 2013 23:03:57 -0500, Ignoramus17560
wrote:

I need to install a 12v winch and a battery next to it, on a trailer.
This winch may need a huge amount of current.

I hope that this auxiliary battery will provide the power needed to
run the winch, however, I want it to be charged from the vehicle's
auxiliary 12v supply.

What concerns me is that when the winch is working, the battery may
demand a lot of current from the vehicle, and blow a fuse. At the same
time, after use, it may also require a lot of current with the same
result.

Ideally, I would like a current limiting device, of some kind, between
the vehicle and the wnich battery, that would limit current to some
low value, like 15 amps, happily supplying any amps under 15, but
automatically limiting the current to 15 amps only.

Is there anything of the sort, that I can purchase off-the-shelf?

I do realize that I can just wire a resistor in series, and I do have
a 1.4 ohm, 290 watt resistor and some others, but I was hoping for
something more elegant.

Thanks

i

I don't know about your vehicle winch but boats with an electric
anchor winch don't seem to have a problem. Example:
100 lb capacity @62'/min = 25A
400 Lb @ 62'/min = 35A
900 lb @ 80'/min = 70A

Most boats, if they use a winch battery, just have it connected in
parallel to the main house bank and don't run the winch unless the
main engine or the generator is running.

As for restricting battery charging to 15 amps, I would think that
your alternator would likely be capable of producing 60 - 70 amps, and
maybe more, why would you restrict charging to such a low level?

For a semi truck use, and 400A demanded by the winch, it means that I
will need a 40 foot two conductor welding cable, at least 1/0. And the
number one concern is that it will be eventually stolen. I would
rather slowly recharge.

i

Split the difference, use the local "accumulator" battery on the trailer
to provide the primary winch power. Run your charge circuit through
conduit and use something like 8ga wire with a 50A circuit breaker.

I need that battery without question. But I want to charge it from the
truck and limit the current.

Don't worry about it. The regulator will limit it (to alternator
capacity) just fine. But with a bigass winch like that, I'd run full
cabling back to tie the winch and its battery directly to the main
battery(ies). It won't cost too much more and will allow all batteries
to provide the enormous power it takes to run it if you lift something
quite heavy. If you're going to use it a whole lot, consider a larger
capacity alternator system, too, Ig. They can be used for onsite
welding, too, if you choose properly.

Remember to enclose and clamp the long cable because you cannot fuse it
and if it rubs thru SOMEWHERE in its lenth the whole show may turn into
a lot of magic smoke. :-?

That's one of the reasons I put a large contactor on the aux feed up
front near close to the batteries on my truck. That aux feed is only
powered when I switch it on from the dash switch.

Oh, and you can fuse it just fine if you wanted to spend the $60 or so
on some 500A DC fuses.

"J.B.Slocomb" wrote:

On Mon, 15 Apr 2013 07:15:25 +0700, J.B.Slocomb
wrote:

On Sun, 14 Apr 2013 13:52:36 -0400, wrote:

On Sun, 14 Apr 2013 19:13:26 +0700, J.B.Slocomb
wrote:

On Sat, 13 Apr 2013 23:03:57 -0500, Ignoramus17560
wrote:

I need to install a 12v winch and a battery next to it, on a trailer.
This winch may need a huge amount of current.

I hope that this auxiliary battery will provide the power needed to
run the winch, however, I want it to be charged from the vehicle's
auxiliary 12v supply.

What concerns me is that when the winch is working, the battery may
demand a lot of current from the vehicle, and blow a fuse. At the same
time, after use, it may also require a lot of current with the same
result.

Ideally, I would like a current limiting device, of some kind, between
the vehicle and the wnich battery, that would limit current to some
low value, like 15 amps, happily supplying any amps under 15, but
automatically limiting the current to 15 amps only.

Is there anything of the sort, that I can purchase off-the-shelf?

I do realize that I can just wire a resistor in series, and I do have
a 1.4 ohm, 290 watt resistor and some others, but I was hoping for
something more elegant.

Thanks

i

I don't know about your vehicle winch but boats with an electric
anchor winch don't seem to have a problem. Example:
100 lb capacity @62'/min = 25A
400 Lb @ 62'/min = 35A
900 lb @ 80'/min = 70A

Most boats, if they use a winch battery, just have it connected in
parallel to the main house bank and don't run the winch unless the
main engine or the generator is running.

As for restricting battery charging to 15 amps, I would think that
your alternator would likely be capable of producing 60 - 70 amps, and
maybe more, why would you restrict charging to such a low level?
But the connection between the winch battery and the house battery
is as heavy (at least) as the cable from the winch to the battery.

Not really. An alternator that can put out, say 65 amps, doesn't need
the same size wiring as a winch that draws 400 amps.

Somebody on one of the boat groups just went through a similar
exercise. He had a honking great battery bank and used a lot of
electrical devices so discharged the batteries pretty rapidly. He was
using a 100+amp alternator and the alternator was running pretty much
at max current and he burned out a couple. His solution was to add
cable to the charging circuit which dropped the voltage a bit and
decreased the charging rate enough to keep from cooking his
alternator.

I think that you are being excessively conservative in talking about a
15 amp charging rate into a large battery bank though :-)

Especially from an alternator in a semi which should be good for 200A+.

On Sat, 13 Apr 2013 23:03:57 -0500, Ignoramus17560 wrote:

I need to install a 12v winch and a battery next to it, on a trailer.
This winch may need a huge amount of current.

I hope that this auxiliary battery will provide the power needed to run
the winch, however, I want it to be charged from the vehicle's auxiliary
12v supply.

What concerns me is that when the winch is working, the battery may
demand a lot of current from the vehicle, and blow a fuse. At the same
time, after use, it may also require a lot of current with the same
result.

Ideally, I would like a current limiting device, of some kind, between
the vehicle and the wnich battery, that would limit current to some low
value, like 15 amps, happily supplying any amps under 15, but
automatically limiting the current to 15 amps only.

Is there anything of the sort, that I can purchase off-the-shelf?

I do realize that I can just wire a resistor in series, and I do have a
1.4 ohm, 290 watt resistor and some others, but I was hoping for
something more elegant.

I'd go to an RV store, off-road equipment supplier, or a truck mechanic,
explain your needs, and see if they have a suggestion.

This could all be done fairly easily with one magic electronic gizmo, and
maybe it has -- if it has, one of those above three should have what you
need.

If not, the light bulb idea sounds like a good one.

--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com

On Mon, 15 Apr 2013 09:07:23 -0500, "Pete C."
wrote:

I think that you are being excessively conservative in talking about a
15 amp charging rate into a large battery bank though :-)

Especially from an alternator in a semi which should be good for 200A+.

Doesn't matter how big the alternator on the truck is - 125A to 200A
is normal, but they make 400A truck alternators for specialized
purposes - big honking mothers.

Point being, If the charge line going back to the trailer is only
10-GA wire and you try pumping 400A through it, you'll have it glowing
like a lamp filament - for a few seconds till it grounds out and
blows, and takes any wiring harnesses nearby with it.

Or better yet, melts the nylon air brake lines on the truck and kills
the brakes. Or goes right next to the fuel lines...

The norm for a trailer with a battery and liftgate is 1/0 wire, and
they do make 1-pole and 2-pole trailer connectors and curly-cords for
that. You can charge them at 100A no problem - except most batteries
can't take that much charge current at once. They tend to blow up.

You rig a 500-MCM charge line back to the trailer and get a set of
quick disconnects from the tractor to trailer rated to carry that
much, then you can get the charge feed straight from the 400A
alternator.

Oh, and don't forget a matching ground path good for 400A back from
the trailer battery, or the Fifth Wheel latch assembly and the trailer
Kingpin could get un-annealed and fail - last I checked Semi's don't
have Safety Chains... Or hot enough to light the grease on fire. Or
arcing damage. Gee, wonder which would cause it to fail first...

-- Bruce --