Originally Posted by mk4gti
240 Wh / mile (per average)
So if I understand the math correctly:
240Wh *35 miles / .8 (safety) = 10.5kw hour pack required.
Sooo considering Lipo is 3.2v and I'd like 120v pack (38 cells):
10.5kwh / 120v = 87.5 ah ??
How can I factor in the loss for running the car in the cold plus using the heater ?
Are you driving 35 miles every day? For a every day figure size the pack so that you are @60% DOD. The 80% is meant to be maximum range. (Although if you bottom balance you can go to 100% in emergencies).
So 240 * 35 / .6 = 14 kWh.
Why the 120 volts?
But yes 14000 / 120 = 120ah. Calb cells come in 100 or 130. Using the 100ah would bump the voltage up to 140.
Running in cold can be mitigated by insulating the battery box and running a low wattage heater while charging. There are a few threads on this on the site.
Sizing for heater is fairly easy. Choose the heater size (not sure maybe 1kw to 2kw - have a look at other threads) then multiply this by your expected run time in hours (how long to drive the 35 miles) then divide by 0.6.
At a guess add 2 or 3 kwh to your pack. So instead of 14 go to 16.
16000 / 120 = 133. A calb 130ah can be got for around $160. So that would be around 6k.