Dual battery setup

redrazor wrote: Another question then (while I'm reading) If I just have one battery and run two 4g wires from the battery to a distribution block then wouldn't each one carry half the current on them? comments on my previous post would be helpful too. Well back to reading.

Yes , 2 x 4g wires will double the cross-sectional area of the cable carrying current. This will exactly halve the max resistance of the wire from the battery to the amplifiers, thus doubling the maximum current flow.

I = V/R

If R is halved, I is doubled.

chuckstasy - Thank you for your help. These are all things I read and knew or should have known I just couldn't put most of them together until a little while ago. Your posts have just reassured me of the facts. I'm still a little sketchy on why the dual battery setup of having 2 cables coming from the Alternator with 1 going to each battery and then to the distribution block wouldn't cut current it in half but it's a moot point as I will go with the dual 4g setup from one battery. As for the dual battery setup I will continue to read about the dual setup and electricity flow as well because I like to understand why something is thee way it is instead of just saying ok it's that way and go on. I'll make sure to upgrade my alternator, grounding wires and properly fuse everything and be as safe as possible. I may be a stubborn SOB when trying to learn things sometimes but I usually don't give up until I get it correct. Thanks again for everyone’s help.

What about just hooking the 2 battiers up like on a diesel truck!?! They come stock with 2 battiers.

Someone sell me on why not to use an isolator with two batteries. Top Secret, I can tell you but then my wife will kill me.

forbidden wrote: Someone sell me on why not to use an isolator with two batteries.

Here's my argument, Rob... Right or wrong, it's RIGHT... It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

That is quite convincing.Nik

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haemphyst - Thank You for the link to these previous posts. It's very helpful.

forbidden wrote: Someone sell me on why not to use an isolator with two batteries.

There is no simple answer.. it depends on what you're trying to accomplish. As noted, Ford uses dual batteries in parallel in some of their diesel trucks.. Porsche did also in some 911-912 model years.. I've even seen it done on ag tractors. They've determined that one battery wouldn't be enough, so they did two in parallel.. no isolator. 

On the other hand, isolators are widely used in situations where power is being used while the engine is off.. so the starting battery isn't drained. One common configuration I've seen is a starting battery, isolator, and 4 six volt deep cycle golf cart batteries wired in series parallel. While sitting with the engine off power is drawn from the 4x6v battery bank; once the engine is started the isolator connects everything together and charges the battery bank.  

Hope this is helpful..

Jim

This is what I was hoping to see, two possible and logical answers to the same question. It depends on the use of the system entirely. Both methods are correct. The last vehicle I did was basically the same thing. One primary starting battery + isolator + 3 gel-cells. The next one I am doing has no isolator so that both batteries may be used in the system.Top Secret, I can tell you but then my wife will kill me.

forbidden wrote: This is what I was hoping to see, two possible and logical answers to the same question. It depends on the use of the system entirely. Both methods are correct. The last vehicle I did was basically the same thing. One primary starting battery + isolator + 3 gel-cells. The next one I am doing has no isolator so that both batteries may be used in the system.

Hope springs eternal.. eh?..

Jim