Tuesday, Feb 28, 2012 at 12:15
Question.
What are the advantages of 2 6-volt batteries in series vs two 12 volt batteries in parallel?
Answer
We just attended a seminar on this subject. For house batteries the 12v models just don't have the plate thickness necessary to make them good for a deep-cycle application. As stated above, stick with the 6 volt deep cycle batteries.
The advantage of 6VDC batteries is first of all cost per unit. Second is the fact that 6VDC batteries with very high Amp Hour Ratings can be purchased in pairs for less than one 12VDC battery that comes close in Amp Hours.The 6VDC Batteries will discharge and recharge more times than 12VDC batteries will, so their life span is greater.
WHY 6 VOLT BATTERIES ARE BETTER THAN 12.
For the same ampere hours, if you could get it all in one 12 volt battery, there would be no difference - a 12 volt battery has two 6 volt batteries in series inside it.
BUT for the same ampere hours, if it is going to take two batteries to do it because of size, weight, availability, etc., then rather than two 12 volt in parallel you are better off with two 6 volt in series.
Why is that you ask?
Because batteries in parallel, even if twins from the same manufacturer''s batch, will never be exactly identical, so one will always be a little weaker than the other and when charging ceases, the weaker one will discharge, or steal some of the charge from the stronger one through the parallel connection. This may be minor when they are new but as they age, the problem will get worse.
On the other hand, batteries in series can''t discharge into each other, so for that particular setup, the pair of 6 volt will be better.
FollowupID:
754427