Is this it?

http://www.europrospect.com/pdf/ProMaster Batteries Lead acidEP.pdf

 

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

Approximately.

 

My guess is somewhere around 280aH.

 

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

 

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..

 

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.

 

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

 

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

 

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

Yes, but 60% is pretty conservative. Most books say going down to 50% charge is acceptable. This is what the term "deep cycle" batteries refers to. They are claiming they can withstand a certain number of deep cycles. I don't know exactly how deep is deep but I would assume they mean below 50%.

If you are away from the dock much, you can really only count on 30% of your total capacity. This is because 50% is your floor and 80% is your practical ceiling. It takes many many hours to charge above the 80%. The closer to 100% the more hours it takes to recharge. While cruising you are looking at operating between 50% and 80% charge unless you really like motoring.

If you add two more batteries you could run a pretty beefy alternator. I'll let someone else jump in here, but I think those batteries have pretty thick plates and could handle a high recharge rate.

If you want to do it right you need a battery monitor. The only way you know what's in your batteries is to start from a full charge and count every amp hour going out and going in. This is what the monitor does. Voltage doesn't really tell you much unless you let the batteries rest with no charging for 24 hours.

 

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.

 

I'd second getting a battery monitor.