12v DC-DC battery charger

[mr.mindless]

I'm planning to upgrade the winch on my trailer, which will also entail putting a full size deep cycle battery onboard. I'm failing at finding high amperage DC battery chargers, just the 800mA units for breakaway batteries. If I draw down this battery winching a dead pile on flat tires 100' and up onto the trailer, I don't want it to take a month to get the battery back up to full power.

Is there something in between the $300-500+ full RV inverter systems that have a ton of features I don't need (like shore power charging, built in inverters, etc) and the $8 throwaway 800mA and less "maintainer" type changers?

--- Update to the previous post...

Figures, I finally find something right after I post. Twice the price I was hoping for, and I'd need to figure out a proper mounting location since these are very much unsealed units, but this is the sort of thing I'm looking for

40a

http://www.wmjmarine.com/33313.html

130a

http://www.wmjmarine.com/33317.html

--- Update to the previous post...

Finally found something close to what I'm after, and probably within the limitations of the "trailer" aux power circuit without having to run additional plugs, nor will it draw down my main batteries when the truck is shut off since it doesn't start charging until 13.1v.

http://www.ctek.com/int/en/chargers/D250S%20DUAL

Couple selles on Ebay for around $200...

[Mopar1973Man]

:shrug:Isn't your 7 pin trailer plug hooked up with the battery lead from the engine? Like my RV has a 40A charge lead from the trailer plug and will charge up the trailer batteries in no time flat. (Pin #4)

[mr.mindless]

Using that 'accessory power' to directly connect to the trailer battery without an isolator of some sort (i.e. dc/dc charger, or at least a diode setup of some sort) would be like having a mismatched battery in any battery plant and lead to all three batteries fighting each other and killing themselves. As that diagram outlines, that's not a charging lead per say, it's just a 40a ignition switched source (whose circuit also happens to run the trailer running lights as well as being the source voltage for the factory installed brake controller, as I found when I had a shorted trailer running light popping that fuse a couple weeks back)

[Mopar1973Man]

Actually its not a switched lead... As I found out the hard way too that is a constant hot lead. You can add a isolator to that (which I should too). Because if I hitch up my travel trailer and leave the trailer plugged into the truck it will bleed the truck batteries dead too. :duh:What I did is hitch up in a cold day and left the trailer plugged in and flipped on the furance. The furance blower was drawing down all 4 batteries... Truck was a bit weak to start... :whistle:As with now my 12V gauge in the trailer I can see the 14.2 Volts from the alternator when the truck is running. I'm sure if you do some wiring you can upgrade that lead to 10 AWG and then use a RV isolator against that and get the charging power you wish from it. But the #4 pin is not key switched...

[mr.mindless]