wire size, 4 6v batteries in series

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Fellas, I ended up with 4/0 copper wire for the interconnects between the batteries as the welding store only had that wire but the foot. I then went to an electrical shop and they recommended aluminum lugs as shown in the picture. They said copper wire with aluminum lugs was not an issue and suggested an anti-corrosion paste which I bought. Is that set up ok, aluminum lugs and copper wire? Also, now my neg/pos coach wires are a smaller diameter then my battery inter-connects. Is that an issue, nothing has been changed in the coach.
Thanks for any comments
Bill

Hello... he said "I do have an inverter, but it is the portable variety." so maybe 300W or 25 amps and probably a 55 amp converter. 4/0 wire or welding cable...:S
Yes you want to use copper but 4 AWG is big enough.

All four of my batteries are connected by equal lengths of 4/0 copper welding cables crimped and soldered, as is the battery connection to the Magnum inverter/charger. The wiring from the solar panels is #10. It powers everything except the heat pumps and W/D...which I have not tried.

There is no such thing like the wire too thick for application.
Even when #2 wire might not be needed by electrical codes, those codes allow for wires warming up and that means resistance.
Why not spend couple more dollars for bigger size and forget about it for next 20 years, like Fred when he used copper bars (made from pipes) instead of wires with troublesome ends.
Whenever I repair battery connections, I start with buying stainless steel nuts for the terminals.
IMHO the galvanized nuts are used so the manufacturer will sell more batteries when old one will corrode the terminals out
And don't clamp copper connectors to aluminium or galvanized bars.
Those connections will make electrocorossion and will fail in a year or 2.

Fred,
I thank you Sir for your nice comments. I'm not the sharpest tool in the shed so, I'm a tad bit confused about your instructions on the changing of my cables. You see, I have two, 4/0 positive cables. One is on the left rear and, one on the left front. There is a 1/0 connector between the two.

And, I basically have the same setup, on the negative side. One 4/0 on the right rear and, one on the right front. And, a 1/0 connector between the two negative posts.

And of course you see the two "S" cables in the middle, that connect the Pos and Neg of the two sets.

I know that one of those 4/0 sets leads to the inverter. The other set I think leads to either the generator or, directly to the 12VDC distribution center. Not sure. I should know but, just not sure.
Scott

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.

2oldman wrote:
Very nice. Those batteries are immaculate for lead-acids! :)

Laughing, that's because they were just installed and the wiring done when the pictures were taken. There's been a couple of times that one would have thought I was cultivating GREEN MOLD when I forgot about them for a 6 month period. It was UGLY in there. But, I've cleaned them and made sure the water is up to snuff. You gotta keep up on those darn batteries, that's for sure.
Scott

Very nice. Those batteries are immaculate for lead-acids! :)

Very clean and neat job!

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