Quote:
Originally Posted by mort
Your math is a little off. But I'm in complete agreement: if 45 is your top speed requirement, 20 hp is plenty.
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I'm sure my math isn't perfect, I'm just estimating in my head to see if what I want to do fits into the laws of physics. I can get more precise if the question is answered in the affirmative:
"Is it sane and possible to shove an F-150 down the road at 55MPH with 21KW @ ~120v?"
Let me get my slightly less crude math on...
Assuming "~120v" is what I'll get when I rectify the gensets... 21,000w/120v = 175a / 3 = 58.333a per gen. Top and bottom of gen head winding are on 30a 120v breakers. So, that's 60A before they pop. Math says China Freight isn't lying. Math says that's sustainable 65+MPH power presuming 30HP = 70MPH. I can peak to 8.5KW each and probably break 75MPH for a short period, which I will never do. They run leisurely at 45 to 50MPH. Could even shut off a gen and go dual.
To say it another way. I can create 180 Battery Amps that aren't Battery Amps with the gens. This occurs at 120V, which is equivalent to 10 12v batteries or 24 6v batteries. If I add in a pack that can non-destructively provide double that capacity, I can burst 540a, which is probably more than I need.
Appears sane and possible. Can someone contradict me?
What battery can give me 360A at 120v? How do I balance the gens' output with it on draw and charge? I almost feel like a static of 9 batteries gives a proper output if rectification gives me 120v even. Charged flooded cells usually top off at 13.4ish, eh? Weird how this works out...
Can someone contradict me in a way other than "that's not LIFePo and A/C drive in a Miata so it's not leet enough to be allowed to exist, I hate it!"
What I need to see is; how fast do other vehicles go while pulling 180 battery amps? Or better; Hey, you! Yeah, you! The guy who already has a working electric car. How fast are you moving when you're done accelerating and have leveled off to a steady 180 battery amps?
I must consider that my CoDA is going to be a mess compared to other EVs. I'll probably be about 25% worse in the Drag department according to how this EV performed when it had batteries in it, compared to the same pack and controller in a smaller truck.
I must also consider that my Revs will be lower with skinny 35in tires. It may be the first EV with a useful 1st gear? :-p