4 Six volt vs 4 12 volt?

[paflyboy55]

The four 6 volt Marine deep cycle batteries we installed about 6 years ago are getting weak. Is there any atvantage or disadvantage to replacing with four 12 volt deep cycle batteries? I know the wiring will have to be all in parallel but other than that any other issues? Also, I still have the original battery charger on her, should I be considering a new one that's updated/more efficient?

[Rob Robinson]

In many cases people change from 12V to 6V to increase their available amperage.

[gcyeaw]

The old chargers were brute force single stage chargers. 'Battery Boiler' is the term we use for them. A modern 3 stage charger will extend the life of the batteries. I believe the common thought is that 6 volt deep cycle are a better choice, but 12 volt deep cycle have also been used by Wogers. In the end it is the total amp hour rating that pretty much determines how they will work.

Amp hours for 12 volt batteries in parallel is the sum of the individual batteries. For 6 volt batteries in series/parallel it is the 1/2 the sum of the individual batteries. That doesn't mean you loose amp hours, it is just that when two 6 volts are connected in series they make 1 12 volt battery and the amp/hour rating is done using the 12 volts.

So a 100 amp hour 12 volt battery provides the same total power as two 100 amp hour 6 volt batteries in series producing 12 volts.

[NoGas]

Go with 4 - 6 volt golf cart batteries. In 2008 I changed my SOB over from two 12v marine batts to 4 - 6 volt golf cart batts from Costco and never looked back. They were superior in every way for my situation. Thanks to daily solar charging with a sophisticated Blue Sky controller they are STILL going strong! Search the WOG and you'll find lots of excellent information on the changeover you are contemplating. Good luck with it.

[paflyboy55]

Gardner, trying to decyfer your explanation. Not your fault, I'm a little thick when it comes to amp hours. If four 6 volt 100 amp hour batteries produce 200 amp hours and four 12 volt 100 amp hour batteries produce 400 amp hours isn't the four 12 volt 100 amp hour batteries better?

[Joatha]

Originally Posted by paflyboy55

Gardner, trying to decyfer your explanation. Not your fault, I'm a little thick when it comes to amp hours. If four 6 volt 100 amp hour batteries produce 200 amp hours and four 12 volt 100 amp hour batteries produce 400 amp hours isn't the four 12 volt 100 amp hour batteries better?

His method of calculation is correct. However, the example that was laid out probably isn't a reflection of real world.

Usually, you will have closer to 200Ah (or slightly more) per 6V battery instead of 100Ah that you get with a 12V battery. And really, its more like 200-210Ah (instead of 200Ah). You'll get about 5% extra capacity from 2 6V vs 2 12V. Now, this isn't strictly true for all batteries. But, for comparable batteries, 6V batteries will have a little higher energy density. That is why many folks choose 6V instead of 12V.

So, what you would typically have is 4 6V @ 210Ah each. This is 420Ah. You'd have 4 12V at 100Ah each for a total of 400Ah. That is a better comparison of the capabilities.

The other thing to consider is that 6V batteries have thicker plates and can handle the deep discharge better than 12V batteries. And, the are usually a little cheaper.

[paflyboy55]

Thank you Jonathan. I think I understand a little more now. I don't do much running on just battery power. I use the genny or plug into shore power most of the time, so if four 12 volts don't have as much reserve power it won't make that much difference for me, right?

[Joatha]

Originally Posted by paflyboy55

Thank you Jonathan. I think I understand a little more now. I don't do much running on just battery power. I use the genny or plug into shore power most of the time, so if four 12 volts don't have as much reserve power it won't make that much difference for me, right?

If you don't do much boondocking, then you are correct that it won't matter much. I'd go with whatever is cheapest.

I use my motorhome for tailgating and that means I do boondock a good bit. So, I like to get every bit of extra capacity I can get.

[gcyeaw]

I am old and get confused easily
I used the 100 amp hour value for both 6 and 12 volt batteries to simplify the calculation. I knew, however, that if you go and look at the amp hour ratings and prices (and physical size) when researching 6 and 12 volt batteries, the 6 volt batteries have an advantage.

As noted in the responses, it is not a huge difference, but my experience with the 12 volt ones that were in my coach vs the 6 volt ones I replaced them with, it has been an improvement.

We do boondock a lot (National parks, State parks Walmart, and other venues without power) so I added a third pair of 6 volt batteries.

[giderich]

And of course you need to choose between virgin lead or recycled lead.

http://www.vulcangms.com/2014/03/03/...n-lead-supply/

http://africanenergy.com/products/deep-cycle-batteries/