battery estimate

Here's a quick estimate of battery reqs based on what I've learned about batteries in the last while:

Assume 4 hours of operation at 2HP continuous power consumption.
Assume 75% mechanical/electrical efficiency.

So amperage at 48V = (746x2/48)/0.75 = 41amp. But we have two 48V battery strings, so that's 21amps.

Consider the Trojan 27RV battery.
http://www.absak.com/pdf/trojanspec.pdf

12V 115 Amp-Hrs. 115/21 = approx. 5, so Usage rate is C/5 which is reasonable. They advertise reserve capacity at 25amps as 200min (3hrs 20 min.) So at 21 amps maybe closer to 4 hrs.

This battery is 60 lbs and is $98. We're only running this for a week, so we could probably go with cheaper Costco batteries with somewhat greater capacity.