Why not two 12 volt batteries

captpar wrote:
Need to replace my 4 6 volt batteries,was thinking why 4 6 volt and not 2 12 volt. Reasons?

Back on Topic!

The Main Reason is Amphire Hours, you will get more run time, (minutes) out of 4 6 volts than 2 twelve volts in most cases Quality for Quality.

My coach came with 2 12 Volt Deep cycle Group 27 wet cell House Batteries, I replaced them with 12 volt high end AGMs and could not be happier.

If boondocking is not important go with 2 12s less headaches.

timjcarter9 wrote:

owenssailor wrote:
What would happen with 4 12 Volt batteries?

Sorry not allowed. They will automatically self destruct if you hook more than two together. :)

Only takes 2 to self destruct if they are not isolated. Read my previous post.

owenssailor wrote:
What would happen with 4 12 Volt batteries?

You'll have twice the capacity of two 12-volt batteries in parallel, assuming all batteries are the same type and age.

Daveinet wrote:
The problem is that as the batteries age, one battery may be weaker than the other. This means that battery will discharge the other battery to the lower level, which prematurely decreases your over all capacity as the batteries age.

This is, of course, bull.. What happens is the weaker battery can no longer carry it's share of the load, thus pushing a larger and larger share on the good battery so it runs down faster (But they are both, always at exactly the same state of charge)

Also the self discharge rate may be higher in an older battery running them down faster as well.

This, however, does not damage the newer battery unless it is allowed to run down TOO FAR.

The other reason is something I found out the hard way. I used to have 2-12s in parallel, but one of those batteries shorted out. This put a huge load on the other battery which exploded!

Now that... IS fact.. This is the major danger of paralleling batteries. However that said the O/P already has two 12 volt batteries in parallel.. (Each pair of six volt makes one 12 volt) so he already has that potential.

Always keep a box of baking soda handy for such events.

My truck has four 12v in parallel

owenssailor wrote:
What would happen with 4 12 Volt batteries?

Sorry not allowed. They will automatically self destruct if you hook more than two together. :)

What would happen with 4 12 Volt batteries?

Longevity. I just replaced my 7 year old 6 volters. Previously, I only got 4 years out of the pair 12 volters. P.S. I know there is no such word as volter.

OK"four it is, thanks all.

captpar wrote:
Need to replace my 4 6 volt batteries,was thinking why 4 6 volt and not 2 12 volt. Reasons?

Simple, two 12 volt batteries will have approximately 1/2 the amperage capacity of four 6 volt batteries. Remember for batteries connected in series you add the voltage but not the amperage capacity. For batteries connected in parallel you add the amperage capacity but the voltage remains the same.

If you had four 6 volt batteries they were connected in a series-parallel fashion. That is , you had two six volt batteries in series connected in parallel with two more 6 volt batteries that are connected in series. The replacement by only two 12 volt batteries connected in parallel will result in substantially fewer amp-hours available. Yes, with batteries, size matters. Think of each group or "bank" of batteries described above; the four 6's have a lot more bulk than the two 12's.