Josh, The math is linear assuming you avoid the extremes (really fast or really slow discharge).
2 12ah 12V batteries in series giving you 2.2 hours of runtime: 12 amp-hours / 2.2 hours = 5.45 Amps (per hour) add another set of 2 12AH batteries (the two batteries wired in series to get 24V, and connected in parallel with the existing batteries and the calculation becomes: 24 ah / 5.45 amps = 4.4 hours of runtime Or if you prefer to do it this way: If you want 48 hours of runtime and draw 5.45 Amps per hour you need 261 AH of batteries. That could be 2 12V 260AH batteries, or 4 12V 130AH batteries, or 6 86AH batteries, etc. When paralleling batteries add the AH ratings. When putting them in series use the AH rating for the single unit battery. The one thing you should not do is parallel mixed AH rating batteries - keep them all the same size or you will damage the lower rated batteries when discharging them. Most higher end batteries provide a chart showing the AH rating at various discharge rates and temperatures. At slow discharge rates (over 48 hours) most batteries provide more AH than they are rated and far less at very high discharge rates (under 5 minutes). Mark > On May 2, 2016, at 10:00 AM, Josh Luthman <[email protected]> wrote: > > I have a 24v site that uses two 12v 12ah batteries. I get about 2h 20m of > run time. > > Does it stand to reason if I get eight batteries my run time would be 8+ > hours? Is sizing linear? > > Josh Luthman > Office: 937-552-2340 > Direct: 937-552-2343 > 1100 Wayne St > Suite 1337 > Troy, OH 45373
