Jeff,
I don't want to discourage anyone from trying, but lets look at those
numbers.
72v x 55ah 20 hour rate=3960watt hours. You'll never get this because you
aren't using them at the 20 hour rate.
Depends on the Peukert's exponent for your batteries but lets be generous and
say real life you'll probably get maybe 40ah from them to 100% DOD at your
discharge rate. Now you don't want to take them to 100% DoD if you want more
than 50 cycles out of them so lets say 80% which is still hard on them. The
omission of these factors I think is the main flaw with the El Ninja/ El
Chopper calculations.,
Now we have 72v (lets ignore the real voltage sag for now) x (40*0.8)=2304
usable watt hours.
Now if you want to go 30 miles would would need to achieve 76.8 watt hours/
miles efficiency. Near identical conversions are getting more like 120wh/m
which would yield less than 20 miles which is at the high end of most
conversions so good well done in my opinion, but if you expect 30 you will be
disappointed. I hate to say it, but on a stock aerodynamics bike, doing
highway speeds breaking 20 miles range with lead in dam hard.
That's why my next conversion is using NiCad. I probably won't go any
greater distance, but I should get better cycle life.
Lithium batteries has the whole ev community in waiting for the real
breakthrough in energy density for what most would consider acceptable range.
The lead range does work for a lot of things though and it's want we can afford
now and the drive-train doesn't care what batteries your using if it makes
sense to change in the future.
-Garret
84 Honda VF500
[[[ My goal 60 mph, 30 mile range commuter ]]]
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