Simple battery question, OK maybe not so simple.

[jackfish]

For my application it looks like I will be able to use Group 31 sized batteries. However, the 6 volt Group 31 SunXtender PVX-2560T is designed for stationary PV applications and only warranted for 1 year in mobile applications. Lifeline does not make a comparable 6 volt AGM Group 31 battery intended for RV use. Lifeline AGM RV batteries have a 5 year warranty. I'd have to go with a Lifeline GPL-31XT 125 Ah 12 volt to get that size. Four in parallel would yield 500 Ah, but would lose any advantage of a bank of 6 volts. Is the 6 volt vs 12 volt issue a deal breaker for you?

[markopolo]

It wouldn't be a deal breaker for me.

6 volt battery is comprised of 3 cells. 12 volt battery has 6 cells. If they weigh the same and are all deep cycle batteries then they'll perform about the same.
In the past, 6 volt batteries tended to be true deep cycle batteries. Bigger and heavier. They were compared to lighter marine type batteries.

When it comes to batteries, the biggest and heaviest is often the best! http://www.classbforum.com/phpBB2/vi...=9&t=344&p=602

Looks like the Group 31 SunXtender PVX-2560T weighs 75 lbs and the Lifeline GPL-31XT weighs weighs 74 lbs. I'd expect very similar performance from them.

I'd love to hear opinions on this. I like to learn.

[booster]

Originally Posted by markopolo

It wouldn't be a deal breaker for me.

6 volt battery is comprised of 3 cells. 12 volt battery has 6 cells. If they weigh the same and are all deep cycle batteries then they'll perform about the same.
In the past, 6 volt batteries tended to be true deep cycle batteries. Bigger and heavier. They were compared to lighter marine type batteries.

When it comes to batteries, the biggest and heaviest is often the best! http://www.classbforum.com/phpBB2/vi...=9&t=344&p=602

Looks like the Group 31 SunXtender PVX-2560T weighs 75 lbs and the Lifeline GPL-31XT weighs weighs 74 lbs. I'd expect very similar performance from them.

I'd love to hear opinions on this. I like to learn.

I certainly wouldn't have the 6 volt 12 volt difference be a deal breaker. As Mark says, the guts are pretty similar, and lead mass is the major determination of capacity. I think the only possible exception to this may be if you get into the golf cart 6 volts like a GC2 in wet cells. They are very specifically designed to be bounced around and seem to have bit more water capacity in them, depending on the manufacturer. In any form, the difference is not a huge thing IMO.

[markopolo]

Two six volts have the advantage of being technically simple. Basically six 2volt cells in series to get 12 volts. Very simple.

Each cell of a 75lb 6 volt battery would have more lead than each cell of a 75lb 12volt battery. Roughly double. Common belief is that 6 volt batteries will last longer (more cycles) because of the thicker lead plates. Makes sense to me.

Two 12 volt batteries in parallel is more complicated. You have six 2volt cells in series in each battery. The batteries are then paralleled.

Four 6 volt batteries would be in a series / parallel configuration also so not as technically simple. The advantage left then would be the thicker plates.

I'd still choose the 12v batteries with the 5 year warranty over the 6 volt batteries with the 1 year warranty assuming the total price is similar.

[jackfish]

A couple more questions for you patient responders...

Are AP or automotive post terminals OK for RV house batteries? Are they more prone to loosening than M8 or even Marine Dual terminals?

[markopolo]

I don't know. I haven't read anything about problems with automotive post terminals.
I've used this type of adapter to go from a post to a stud type terminal. They come in two sizes to fit the positive post and the negative post.

[booster]

Originally Posted by markopolo

I don't know. I haven't read anything about problems with automotive post terminals.
I've used this type of adapter to go from a post to a stud type terminal. They come in two sizes to fit the positive post and the negative post.

I think the automotive clamps are used on cars because they need to supply mega amps, with little resistance, for starting. The lead, tapered, clamped connection give a lot contact area.

[jackfish]

Originally Posted by markopolo

markopolo, do you have a source for those adapters? Thanks.

[markopolo]

I think you can find them at most auto parts stores.
Napa link: http://www.napaonline.com/Catalog/Catal ... 0218262230