Inliners International Forums General Discussion Electrical Dual Batteries

Well, I am going to be looking in to getting dual batteries for my TJ Wrangler. I have some extras hooked up to it right now like offroad lights (for when we're stuck into the night :rolleyes: ) and I just got a good deal at Best Buy on a nice sound system for it, so I will have a huge amp hooked to it and I plan on installing a winch on it for spring. I think with all that, I may need extra juice. 4WD parts has this one, but it is a bit much for what I would spend on a battery tray, so I think I can fab something up like it to fit with the AC lines and all http://4wd.com/newsite/shop/productdetail.asp?pid=MGBT01 Can anyone tell me how the right way to have two batteries hooked up is? I know I saw kits somewhere, I have even seen them in my truck and 4x4 mags, but can't find the exact thing I am looking for. It is a switch setup where you can have both running or just have one in reserve so if one is totally dead, I think you just turned the switch and the other comes on. Anything sound familiar or is there an easy way to just do it myself with out the kit? Thanks

You want them hooked up parallel. Positive post to positive post, negative post to negative post, with the far ends connected as usual to the starter ( + ) and ground ( - ). This provides the usual 12 volts but with double the amp hour rating. This won't allow you to disconnect one battery but that can be simply done with a switch like is used on the back end of drag cars for emergency crews to shut them off. You can mount that switch on your dash and run battery cables to the second battery so you can cut it in and out as needed. The switch is a bit big and ugly for a dash but for an off road vehicle that might not be an issue.

Thanks Mike, I was hoping it would be as simple as that since I did find the kit I saw and it was like $180 so the nicely priced kill switch you are talking about will be great and it wont be too ugly for my dash since I have the perfect ugly patch panel to put it in where I think an ashtray would have went? Thanks again. If I wanted to do with out the switch and just have extra juice from two batteries, then I am basically just hooking another battery up to the one I already have post to post as you say...is that correct?

i run 2 batteries in my car for those added extras too., but i bought a battery isolator to link them together. running bateries in series is not going to be real good for the alternator.. need to do somemore research.

oh man guys!!! thanks, I had no clue dual batteries could get tricky like that. It sounded more simple to me. I never thought about how any of that worked. I found the isolator at summit actually, those other sites didn't turn one up in the search which was wierd to me. For the price of one, I may just go the extra few bucks for a regular dual kit, they got a waterproof one which I may look into. Thanks

Recharging 2 batteries will depend on how far down they have been drawn and how much amperage your alternator can produce and how long the time period of the recharge. GM diesel powered cars of the late 70's to mid 80's had a second battery and used a 93 amp alternator without any isolator or recharging problems. Of course few Diesel Toronados came equipped with off road lights and a winch, but the point is a properly selected alternator should keep up with the recharge rate as well as the vehicles electrical load at the same time.

With all this in mind, do you guys think I should just go with a regular dual kit like this one from 4WD Hardware? http://4wd.com/newsite/shop/productdetail.asp?pid=40103&model=tj&cat=10&kid=62&catid=62&mid=n
I like that it is the waterproof kit, but I'm not sure if it is too pricy for what it is, but it is the three way selector like the one I think I saw in the magazine. I don't know if I want to have to change my alternator if it will void any warranty or something, but I like Mike's way too, but with the kit, I can run both at the same time if I want. There been times that a buddy has been stuck so bad and it took over an hour to get him out with tow straps and stuff and it got dark, I figure running those high power lights out in the woods and then running a winch, it will just drain one battery, so two at the same time feels safer. Obviously the Jeep is running when using these things, but it seems like other guys lights get a lot dimmer and stuff for a bit. So I think I want to the option of running two at a time, it doesn't say but do these kits have to change the alternator too? If I get a chance between work, I may call the tech #. Thanks guys.

I did get to call the tech guy and he said that he wasn't sure what alternator I got, but if it is a 110, it may be good enough. They only have a high output one for the I6 and not my I4, but I wanna check since I have a feeling they may be the same and could interchange between the engines. When I get a chance on break, I can go check what alternator I got. This would make a nice little project before I hook a winch up.

John I guess it really comes down to doing your homework and seeing what method best suits your needs. No doubt that a complete kit should do what it claims. It might seem a bit pricey when you dump all the parts out of the box onto the bench, but someone put time and effort into engineering the thing. Not many people like to work for free.

A lot of us Inliners enjoy the satisfaction of coming up with our own way of doing things. For us no electrical fire is too big to kill our desire to succeed.

You are right Mike, I guess I just gotta really sit down and plan this out and do some more hw to see what will be best. I too like to come up with my own way or fab up my own thing. So I guess it comes down to wether I want to pay the extra to have something someone else already engineered or come up with my own. BTW - I always roll with a fire extinguisher by my side Your last comment made me laugh with that. LUCKILY, I have yet to have any problems doing things for the first time since I end up researching things to death before I actually touched anything. You know I made my own wire harness kind of thing for my chevy. For the part and shipping, it was going to cost nearly $100 for the wires that plugsin under the dash and run along the frame to the tailights and for less than $25, almost what the shipping charge would have been I think, I went to NAPA, got rolls of the matching color wire, the little connectors for the ends, taped the wires tightly together every foot or so, plugged it in and done. That is a lot simpler than other things, but point is I made it myself and understand why certain things cost a lot. But THAT, I could not understand why something so easy to make cost $80. LOL, oh well. I will come back to post what I figure out as I continue my research so the other newbies at this stuff like me can benefit from it, but any other opinions, ideas, or comments will definitly be welcome. I'm not so much going for cheapest or easiest way, but practical for my use. Thanks again all.

Summit has the Painless kits; I believe the non-water proof was $99.00. You might check their website.