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.