wa8yxm wrote:
3 tons wrote:
Ok, lets cut through ‘my nonsense’ and do the math:
My two 6v Costco GC’s are rated at 210 amp/hrs per (other makes vary a bit)
Two times 210 = 420 - So you and I both agree Sir!!
BUT, once connected in series to arrive at 12v, the 420, is reduced by 1/2, so I’m now at 210 amp/hrs total...To arrive at 12v theres NO SUCH THING AS A FREE LUNCH ...
Now, to arrive at usable amp/hrs lets assume that for longivity’s sake the DOD should not go below about 50% - now were at about 105 usable amp/hrs...
But then again, this is just my opinion...
NO two 210 amp hour GC2' in serie is 210 amp hours. THE VOLTAGE DOUBLE the amp hours remain the same.
Two 130 (G-31) 12 volt batteries in PARALLEL the amp hours double (260) the voltage remains the same.
Battery 101
Now there is one other component where if you put 2 in series the value halves. but I won't even name it because you are already confused. I will only say the value that divides is NOT Voltage. NOR is it current.
Since the overall internal resistance of a given capacity battery bank determines how fast a battery bank can be charged using any given applied charging voltage ... another interesting question is: What battery bank combination of any given amp hour capacity results in the lowest overall battery bank internal resistance (hence fastest to charge) - two 6 volters in series or two 12 volters in parallel?
To help answer the above question, remember that two 6 volt batteries in series make for a 12 volt battery with six 2 volt cells in series ... while two 12 volt batteries in parallel make for a 12 volt battery with six 2 volt cells in series (in one battery) in parallel with another six 2 volt cells in series (the other battery).
Given "ideal" batteries constructed the same way physically and chemically, the answer should be ... "no difference in overall battery bank internal resistance as seen by the charger".
HOWEVER I doubt that - using the commonly available RV batteries in real life - the two different combinations used by RV'ers results in "the same" overall internal resistance. I think I'd put my money on probably two 12 volters in parallel maybe charging a bit faster for most of us - due to an overall lower internal resistance for the combination. :h
