Battery price question...

philh wrote:
6V is not about the cost, as two inexpensive 6V still cost more than most 12V batteries. 6V or GC2 batteries take more abuse and have larger power reserves.

This is a "depends" situation.

If you compare 2 Group 24 or Group 27 "RV/Marine" batteries, to two 6V GC2 size batteries on price alone then you are sort of correct.

HOWEVER, 2 group24 or Group 27 "RV/Marine" batteries will not give you not as much Ahr capacity of one pair of 6V GC2 batteries.

Group24 has roughly 60Ahr of capacity, costs about $60 for one, two would be $120 and you get 120Ahr of capacity.

Group 27 has roughly 70Ar of capacity, costs about $70 each, two would be $140 and 140Ahr of capacity.

6V GC2 batteries can be found at Sam's Club or Costco for around $90 each and have roughly 210 Ahr of capacity! 6V batteries when wired in series to get 12V don't add capacity but with 210Ahr that is far more capacity than Group24 or group 27. One PAIR of 6V GC2s costs about $180.

To get near the same Ahr capacity of one pair of GC2s you would need FOUR group 24s ($240) or THREE Group 27s ($210).. Plus lots of additional interconnect cables.

Another issue with group24/27 or any "RV/Marine" battery is they are a "hybrid" between "starting" and "deep cycle", they have "trade offs" which make them not as good for starting and "deep cycle" use..

Group24/27 RV/marine batteries should not be discharged very deep if you want any hopes of getting much life out of them. The shallower discharge, the better life you get from them.. Basically 20%-50% of the capacity is usable..

GC2 batteries on the other hand are designed to be able to withstand as much as 80% of the capacity being used and suffer no harm in life. So you can use GC2 batteries much longer than Group24/27 RV/marine batteries between charges.

As far as OPs question of where to find GC2 batteries, look up your nearest Sam's Club or Costco club, they typically will have them in stock for the lowest prices you are going to find..

Barring that, look up a Batteries Plus store or a NAPA store (although you will pay top dollar at those stores, they will be able to get GC2 batteries for you).

Now, I am sure someone will mention another 12V battery, a Group31, sure you could go that route, but they are insanely priced $240-$300 EACH) and with 135Ahr of capacity it still would take TWO of those to be equivalent to one pair of GC2s in Ahr. Not to mention two group31 would cost a mere $480-$600 and you would have same discharge limitations of the group24/27 RV/marine batteries..

Just because it says "RV/marine" doesn't mean it is a good choice if you need max discharge capacity and max life.