wire size, 4 6v batteries in series

FIRE UP wrote:
Well Gang,
Our coach, an '04 Itasca Horizon 36GD with the C-7 330HP CAT, came with three, (worthless INTERSTATE) 12V Deep cycle/Marine batteries as house batteries. They were less than a year old when one developed a bad cell and, that caused my inverter/charger to attempt to charge all of them equal. Talk about a rotten egg smell from quite a ways away.

So, I exchanged it, a somewhat high replacement cost for a new one. A month and a half after that issue, one of the other ones developed a bad cell. Well, at that point, I decided to change over to (4) 6V Golf cart batteries from Costco. All four of the new 6V units fit like a glove in the battery box. In fact, I don't even use battery hold down braces. Yeah I know, baring a nuclear bomb going off under that battery tray, they AIN'T going any where!

But, I used the factory 4/0 supply cables to connect all them to the systems but, I used 1/0 for "inter-connect cables". And, since I did/do not have the appropriate crimping tools for such large cable ends like 1/0 through 4/0, all I could do is SOLDER THEM.

So, I cleaned everything like you would normally, and put the lug I a vice, with the cup up. Then, heated it, AND THE TIP OF THE CABLE, at the same time. I had already cut pieces of solder and had them in the cup. When those melted completely, and the tip of the cable was hot enough not to cause a cold solder joint, I quickly inserted the 1/0 cable tip into the hot solder.

It wicked up the cable a tad bit prior to hardening/cooling. That method worked for 6 different wire tip/lug connections over 3 years ago and, none of them as even come close to breaking free. I check them on a regular basis.
Scott

This is a great looking set up! Great job Fire Up.

Most people can get away with #4 wire for the batteries. This is good for 100 amps per wire, and because you have the 4/0 wire for motorhome to battery, that can carry 200+ amps, while the battery to battery would not exceed 100 amps while overall draw is at 200 amps. Yet 99% of the time, amperage will be less than 50 amps total, or 25 amps per battery. Only when running a microwave, you might see 150 amps total, or 75 amps per battery.

What I might suggest changing is that the +12 volt be on the left front battery, while the ground -12 volt be on the rear right battery. This will give one pair of batteries closeness to the + 12 volts, while the other pair is closer to the ground 12 volt wire. It will help provide equal amperage per battery. Not really a big deal with #1 wires running between all of your batteries. So in your case, it probably is not worth changing over now.

When I made my battery lugs, I had plenty of 1/2" copper tubing handy. I cut off 3" and clamped 2" in a vice, flat, then folded it back over itself, giving a double thickness about 1" long. I drilled a 3/8" hole in that, and put the 00 wire in the 1/2" tubing, clamping it in my table wise. No loose connections since 1996, so coming up on 20 years.

I also have run my inverter to run my microwave, but will not do that anymore. It draws about 150 amps from the batteries. But my microwave did not like the MSW power from my Trace M1512 inverter, and never cooked nearly as fast again on shore power. So I had to replace it.

Fred.