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.