Re: AC Drive Sources?

["VanDerWal, Peter" <vanderwp@fhu.disa.mil>]

>Regarding whether AC system will save you money in a long run compare
>to DC setup - possibly. Depends on how you drive. The only difference
>it makes - it forces you to use high voltage battery pack (At <200 VDC
>pack voltage the drive performance will be really poor). So (for
>for the same performance) currents are lower and (for fixed range) DOD
>of your batteries is also lower. 

That's not true.  Assuming you are using the same weight in batteries, to
use a 240V system vs a 120V system requires you to use 12V batteries instead
of 6V batteries.  Pound for pound 12V have about 1/2 the capacity of 6V
batteries (usually less).

So even if your current draw is only 1/2 that of the lower voltage pack,
it's still will bring the 12V batteries down to the same DOD.  I.e. 80Amps
for 1 hr takes a 100 Ah cell down to the exact same DOD as 160 amps does
with a 200 AH cell.  Furthermore 80 amps on a 100 AHr battery is just as
hard on it as 160 amps is on a 200 AHr battery.

And that's if you use 12V AGM batteries.  The 12V flooded cells don't
perform nearly that well.