Battery AMP Question

[dougshipl]

We have to 2 pair of 6 volt deep cell batteries that are connected in seriers, creating 12 volts. Their model is Deka Promaster GC15/115 min. Any idea how to figure the total amp hours available ?

[jarcher]

Originally Posted by dougshipl

We have to 2 pair of 6 volt deep cell batteries that are connected in seriers, creating 12 volts. Their model is Deka Promaster GC15/115 min. Any idea how to figure the total amp hours available ?

Is this it?

http://www.europrospect.com/pdf/ProM...d%20acidEP.pdf

[tager]

Find aH at 6v for an individual battery. Multiply by 2. That gives your aH at 12v.

Approximately.

[tager]

My guess is somewhere around 280aH.

[btrayfors]

NO....you don't multiply AH x 2 when batteries are in series.

You multiply VOLTAGE x 2, as the OP already did. The AH remains the same.

Golf-cart batteries typically are rated between 210 and 225AH. So, two 6-volt golf carts in series will be somewhere between 210 and 225AH @ 12 volts.

Bill

[Maine Sail]

The 20 hour rating on the GC15 is 215 Ah ea. or when in series 215 for 2 or when in fours 430 Ah @ 12v..

[SteveInMD]

But if he has "2 pair" (4 batteries) he's got a total 430Ah. The OP asked how many Ah are available. Which would be 215 from a full charge, since you shouldn't go below 50%. Actually he should only count on 143 Ah from the typical operating range between 80% and 50% charge. You only get to 100% by being on a very long charge i.e. 24 hours.

[btrayfors]

Yes, Steve is right!

Note to self: "2 pair" equals 4 batteries.

Four 215AH golf-cart batteries in series/parallel equals 430AH total capacity.

Thanks, Steve. Too early to figure right :-)

Bill

[dougshipl]

To JARCHER - yes that's the battery.

Ok - so if Im following you guys-

1) it's 430 amp hrs available capacity for the 4 batteries (215 x 2 pair) but not good to run batteries below 60% of the 430.
2) safe to assume at 12.6 volts (on meter/approx) the 4 batteries are charged almost 100%?
3) at 12.2 volts (on meter/approx) I assume I have 60% remaining and have used up my safe max of 172 ah (430x40% usage)...and at that point would need to recharge or risk damage to batteries.
4) to add more nausa - if I bought 2 more 6 volt similiar batteries Id go from 430 ah to 645 ah.... times 40% safe max usage for a total of 258 ah to burn before recharging.

Sound correct?

Doug

[mitiempo]

Correct except voltage is not an accurate way to measure battery capacity unless they have been resting unused and not charging for 12 to 24 hours. Buy a basic battery monitor like the Victron BMV-600 ($175 at Jamestown Dist) and find out what is really happening to your batteries. You won't really know until you do and your batteries will probably last longer.