Quote:
Originally Posted by thzero
Go for it. Better to be more transparent than the next guy. Formulas, unless wrong, are hard to argue with. Numbers and claims can always be manipulated.
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Each cell is 4.2 volts and if we discharge at 975 amps, we get 4095 watts.
4.2v X 975amps = 4095 watts (Note: this would make a 4S pack, capable of 16,380 watts of power.
1 electric horsepower = 746 watts of power
This would make a single 4S pack capable of producing 21.96 horsepower!
22 electric horsepower would not only start your car, but it would be enough to push a small car fairly well.
The Industrial Lift Trucks I mentioned earlier have a 6.6kw drive motor. That's less than 9 horsepower and the truck weighs almost 10,000lbs. Top Speed of 9.5 mph, but still ALOT of weight.
All Batteries have an amp hour rating or on the smaller types of batteries we use, a mah rating.
Mah rating is amp hours divided by 1000. Since Mili means 1000.
A 6500 mah pack can also be called 6.5 amp hours.
The "hour" term is added to show how much amp draw it can sustain in 1 hour. A 6.5 amp hour pack can hold a 6.5 amp discharge for 1 hour.
As long as we know this, we can play with the numbers and calculate how long the pack can sustain any rate of amperage discharge.
The same pack can sustain a 1 amp discharge for 6.5 hours.... and so on.
Now, how do we calculate how long it can sustain a 975 amp discharge?
6.5 amp hour pack / 975 amp discharge X 60 (discharging minutes) X 60 (discharging seconds) = How long the charge will last at that level of discharge.
6.5 / 975=.006666666666666666666666667 X 60 = 0.4 X 60 = 24 seconds
You can play with this formula any way you like, for any size pack, for any amp draw rate.
So, in conclusion. If the 6500mah of charge ONLY lasts for 24 seconds. This should change the warranty to pretty much an unconditional warranty as far as the discharge rate is concerned.
No more should anyone hear "Well your gearing was wrong and it was too much load on the pack".
Because evidently, if you don't discharge the ENTIRE charge in less than 24 seconds, you are safe within the confines of the discharge rating.
I'm very sure this kind of amperage is enough to smoke and cook every FET from the power board of ANY ESC if the esc fails and the powerboard goes into runaway meltdown.