Split battery bank

[Healeyjet]

We are building a motorhome on a 2015 Dodge Ram 5500 chassis and I have run in to an issue where it may be beneficial to move one of our "house" batteries to another location at the rear of the camper. Will this cause any issues? Right now they are located side by side in a compartment near the front of the truck and less than 2' from the inverter. My question is "are there any issues if I split the battery bank and move 1 of the batteries approx 10' away? We are using 3 - Discover EV8DA 290 Amp hour batteries.

We would be moving the right hand battery in this photo so we can install some different air suspension related components in it's place.


Ward

 

[Healeyjet]

Is there a way to keep the loads in balance? How big a deal is it if they are out of balance?
What will it effect, just battery life?
Ward

 

[DiploStrat]

What is the Voltage of your 12v Battery?

Ward,

Think of it this way - you do not have a 6v battery or a 12v battery, but rather a collection of 2v cells. Put three of them in a case, connected in series, and you have a 6v battery. Put six of them ... you get the idea.

The important thing is to reduce the resistance between cells - that is why modern batteries have connections that go between the cell walls, rather than the old lead bars on time. Again, the idea is the same. So, if you, like me, use a relay to connect the camper/house batteries to the starter batteries, you are really just making one big battery.

So can you physically split up your house/camper battery bank? Of course. The only caveat is to make the connecting cables large enough and short enough to reduce resistance as much as possible.

I agree/disagree with Verkstad. With any bank made up of multiple batteries, it is important to tap into the batteries "diagonally." That is, connect to the positive terminal of one and to the negative terminal of the last battery. Start reading on page 14 of the Lifeline manual: http://lifelineb.wpengine.com/wp-content/uploads/2015/12/manual.pdf

Assuming that the bank is wired correctly, then it will remain balanced. But, and this is where I agree with Verkstad, if your wiring is unbalanced - that is, your positive and negative cables are attached to only one of the batteries in the bank, then extra wiring between the batteries will only make things worse.

Hope this is clear and helpful.

 

[patoz]

Looks like you guys have it covered, but I'll just leave this here for positive reinforcement!

http://www.smartgauge.co.uk/batt_con.html

 

[DiploStrat]

... causes the "close" batteries to work harder than the remote neighbor.

This is not/not a problem if you wire according to the Lifeline manual. (Or the Smartguage site, for that matter.)

Obviously, you may have to extend your main positive and negative cables to assure that you are still tapping the bank correctly. If you merely tap one battery, and daisy chain the others, then you will have a problem as the battery that is tapped will wear faster than the others. (As noted by Verkstad and documented by Chris Gibson of Smartguage.) You could rotate them, but it is much easier to simply wire them correctly the first time. Obviously, the internal resistance of the bank will be a bit higher as some of the wires will be longer, but the batteries will still age equally.

N.B. If you look at the Smartguage diagram, you can see that the physical/wiring distance between the individual batteries can be extended without altering the "balance" of the battery bank. You will have to stay awake if you, like me, have a series/parallel bank, but it is really not that hard to follow.

N.B. 2 The Smartguage link also has a very simple, but good explanation of why "balanced" connection is, in fact, important.