Calculating power draw.

Hi,

I do mainly high horsepower dragracing stuff. One of my customers want to use an 18v Milwaukee M18 Fuel Battery to power his racecar.

I'm fine with that. But I'm trying to figure out if one battery will be enough, or if we will have to run two in paralell.

So I went to calculating power usage using ohms law. I=V/R. But somewhere i must be calculcating incorrectly. Because i'm getting such insane high numbers. While i realize that the injectors are PWM:ed using Peak and Hold drivers. It still seems insanely high.

8x 550Lbs Precision Proinjector 1.8ohm I=18/1.8 10A total 80A

8x 220Lbs Siemens Deka 2.4 ohm I=18/2.4 7.5A total 60A

8x IGN-1A Smart Coils 6A total 48A

Injector Duty Cycle is around 75%

So that would mean a theoretical maximum power draw of 187A. Without even counting the ECU or any of the sensors. Fortunatly these cars use mechanical fuel pumps and have no fans due to running on methanol.

So where am i going wrong?

Sincerely

Anton

I keep thinking about this. Since it is a (8A) peak and (2A)hold driver running the injectors. I suppose the continuous power draw is closer to 2A + some for the peak. So 3A per injector should be more appropriate.

3*16= 48A Which feels like a more realistic maximum power draw for the injectors.

/Anton