My car wasn't running very well tonight at the track. My last 2 passes were 11.69 and 11.63. I was expecting 11.3 and under. My MPH was down to 121 mph. I couldn't figure out why the car wasn't making the power. I noticed the car almost died a couple of times until I gave it some gas. I checked my battery voltage while driving home and the volts were not going above 11.9 volts. (I just replaced the battery a month ago.) I will find out what the problem is but my questions is:

how much effect would the low voltage have on power output?

 

it shouldnt really affect power. the ecu should adjust injector pulsewidths and ignition settings to compensate. if your fuel was maxed out already it could cause a lean condition though.

you should also see at least 14v with the car running otherwise i would suspect the charging system not the battery.

 

your alternator should be putting out over 14volts if its running... even with the battery unplugged it will put out over 14volts if working properly.

 

yes it can have an effect on power if the coils are not getting enough voltage to saturate them well you get weak spark. check the belt and the alt. this is one of those things where voltage does not make power and more of it will not help, but a lack of sufficent voltage will have a negative effect on performance

 

whoever said it doesn't affect power, go back to school

 

The spark should not be affectred as most electronics are engineered to run effectively over a range of voltage. That isn't low enough.

Things with electric motors are affected. That low voltage would reduce fuel pressure and flow capacity. This would lean you out as mentioned earlier.

 

Second week of freshman electronics:

P = V*I

Unless you meant horsepower? That would be lots harder to measure.
-s-

 

Second week? What school did you go to? That was the first day, man.