Factory Dual Battery setup with a Winch

[TC70C10]

I've got the factory dual battery setup in my 81 K5. I just put on my new front bumper and my Warn 9500ti winch 2 weeks ago. I got stuck in a bog on the way down from hunting cabin last Sunday. Winch is run to spare battery and and with engine running it ran down fast. Is the factory spare battery setup more of a trickle charge for running accessories with truck off like a pickup truck with a camper shell? The battery ran down fast under load. I had to run jumpers from the starting battery and then the winch pulled me right out. Factory setup has small wires (10guage?) running from battery to relay, to junction box etc.

[Grim Reaper]

Hell roaring, painless and a few others have a fancy battery set up or you could go low tech and just get a Battery selector switch like you see on boats. Then use 4 gage or maybe even 2 gage throguh the swtich to gang the batteries. Then a $40 40 Amp battery isolator to maintain charge on normal day to day stuff.

Just be sure to leave the batteries jumped togheter till the run down battery pics back up. Also run a 8 gage from alternator to main battery positive. With the existing 8 gage that will let you have about 4 gage of feed between main battery and alternator.

[1tonswb]

Northwest wranglers has a REALLY NICE dual kit. But its also $pendy.

[Mike76251]

I just put in a second battery with the factory diesel second tray and wired the two batteries together with welding cable.
2 years later and it is still going strong.