upndair

While winching a Jeep (again) I hit a point where my alternator wasn't able to kick out enough juice to run the winch and my truck and the same time, even with my engine at 3000 RPM.

So, in my V6 94 4Runner, what will give me the most benefit in these situations, a larger alternator or a dual battery setup?

toy283

A second battery, without a doubt. Since your winch can draw 400+ amps, there isn't and alternator out there (without spending serious $$$) that's gonna keep up. It's much better to a have a second pool to draw from. Run the engine off one, the winch off the other.

Churnd

Why not go both? The dual battery setup (with a good isolator) will be a lot more expensive than a bigger alternator. You can get a bigger alternator that's a direct replacement from Mr. Alternator (which is what I have) or you can swap in a GM alt (which is what I'm going to do later). Both can be had for about $230.

If you can only do one, I'd also go with the dual battery setup. The bigger alternator will prevent the batteries from draining as quickly though.

upndair

I happen to have a dual isolate switch for my boat, that I don't really need there, so I guess my challenge is finding a suitable mounting location for the second battery.

MNBOY

I would vote for the second battery, but don't bother with the switch and associated crap. Mine just turned into a headache. Mount the batteries as close together as possible, and wire them together with nice, heavy gauge wire. One positive thing about having extra battery power is that you can use the winch to pull the truck on to the flat bed trailer when it craps out completely and won't run. I'll let you know how well that works in a couple days when I go get my dead truck.

joez

yeah, just get 2 GOOD batteries, and forget the isolator crap. my blazer came from the factory with dual batteries, and there is no isolator, they are just wired together. and mine are on opposite sides of the engine bay. it works fine. it even makes it easier for me to use the readywelder(thanks again MNBOY).

crash

I have been running 2 batts for a # of years with a master battery switch. Don't mess with an isolator setup, too prone to having problems vs. a good marine master battery switch. I also run a gm 100a alt...

upndair

I'll have to see what my setup is in my boat. I do believe that is was an isolater. It seemed simple enough in my boat.

If I wire this with just the switch, what's the wiring pattern?

Churnd

A guy on the pirate board wrote a tech article on doing this exactly:

Dual Battery Setup

Shane

Not really a good idea. If one battery begins to fail it will take the other with it. Even when they're good one will always be lower than the other and they will fight eachother over time until both are drained. You have to have some way to seperate them, either through a switch or an isolator.

joez

well, its been working just fine for 19 years in this truck, and according to the reciept, the battery's are 4 years, 7 months, and 12 days old, and still kicking. i admit that it isnt the best way, but (and im setting myself up here) GM and ford used it on their diesel trucks for a long time, and thats good enough reason for me to keep it the way it is.

Shane

Interesting. If it was a factory job I'd think they would put some sort of isolation device in there. Is it a 12 or 24v system? If it was wired up for 24 it wouldn't need it, the problem only occurs when you wire the +'s and -'s together.

crash

Shane, you ever seen how a diesle is setup? They run 2 batteries in paralell. I have had my setup, with amaster battery switch, for like 3 years now, and yes, I had one battery fail. But once it did, it wasn't hard to figure out... I totaly dissagree running any kind of electrically controlled isolator setup. They are prone to failure, and the way you would have to set the system up, you would not5 be able to use one or the other battery to start the rig, use it for a winch ect (you have to sit down and draw the schematic to show it)...

But what I say comes from 15 years of doing this stuff...(at a profesional level)

joez

crash, what do you have?

and crash explained it all better than i could have. i just know that the diesels need the extra juice running them together to turn against 21:1 compression, and 330 psi.

crash

It has to do with the amperage capability and like you said the flippin high compression ratio's.

My rig has 2 optima's with a marine master battery switch
So, it has setting for
Battery A
Battery B
Battery A&B
Off (and its lockable in the off position)

I always just keep it in the both position, which lets both batterys be constantly charged, and helps with starting/operation of any high amperage electrical parts. And If I was ever in the situation where the motor stalled, turn it to one battery, and have the second fully charged and ready to...

Keep it simple, and I have replaced a # of those blue isolator setups because, well, they are junk...

Shane

Yes, actually. I've seen a small diesel car with a single battery setup, duals like you're talking about, and 24v and larger systems on logging equipment. I was just always taught that having + & +, and - & - connected all the time would drain them over time.


I'm not saying I disagree, I also think the marine battery switch setup is the most robust.

Mad Chemist

I guess I'm confused now. To me, it sounds like Shane is talking about running two batteries together in series, ie. the two +'s connected, and the two -'s connected, with one set of leads running to the alternator. Crash is talking about running the two batteries in parallel, which to me indicates that each battery has a pair of leads running to a marine switch, with one set of leads running from the switch to the alternator. Is this right? Series wiring would give 24V, versus parallel that would still put out 12V total, draw would be split equally between the two batteries? Its been a while since I've done wiring/electricity.

Shane

google is your friend David

http://ourworld.compuserve.com/homep...tt/elect27.htm
http://www.google.com/search?hl=en&i...arallel+series

Mad Chemist

Thanks for the links Shane- it was reassuring that I remembered something right from physics!

Flygtenstein

This has been interesting, and I am curious to find how it ends for those involved.

It appears that you remembered backwards.

Parallel is positive to positive, negative to negative.

Series is positive to negative, positive to negative.