DIYbanter - View Single Post - How to charge battery for electric 12v winch, without tripping fuses

Pete C.

"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+.