Battery Voltage 10.38 at WOT??

[peterlocal22]

98 Cobra ysi v-7 supercharger about 550 hp.
Last week my data logs didn't come through but the plugs looked lean.
Fixed the data log problem and ran it down the track twice yesterday and data logged both runs.
First run in the middle of the day, mid 11's but the voltage was min 11.19- Max 12.06.
Second run, at night so needed to have lights on seemed to have lost power at the beginning. Let off throttle then hit WOT again and same thing, lost all power quickly.
Looked at data log and the voltage was now Min 10.38- Max 10.94
Obviously Im mentioning voltage because its really low. Would this be a sign that stock alternator needs to be replaced and what would you recommend for a track/street car?
Could it be another problem? Could low voltage cause a lean condition?
Im lost in the electrical department so any help is appreciated?

thanks,

 

[YJSONLY]

What's the volts with car shut off? at idle? Sounds like a weak battery or going bad alternator.

 

[DSG2003Mach1]

yes, low voltage will cause fuel flow to drop and lean you out, seems to be a common thing with the terminators.

I would guess the alternator is failing. On the dyno mine was starting out in the mid 13s and dropping to mid 12s and you could see the MAF readings falter along with it starting to drift lean

my understanding is with the car running the battery should have nothing to do with it, the alternator isnt putting out enough voltage to run the car properly (although that can hurt the battery too)

 

[YJSONLY]

yes, low voltage will cause fuel flow to drop and lean you out, seems to be a common thing with the terminators.

I would guess the alternator is failing. On the dyno mine was starting out in the mid 13s and dropping to mid 12s and you could see the MAF readings falter along with it starting to drift lean

my understanding is with the car running the battery should have nothing to do with it, the alternator isnt putting out enough voltage to run the car properly (although that can hurt the battery too)

Well I was ruling out a weak battery causing the alternator to overwork and starting to fail from it.

 

[peterlocal22]

When drag racing and going WOT isn't the ignition system and fuel pump running off the battery?

 

[DSG2003Mach1]

no, the car should run from what the alternator puts out, hence race cars with super tiny batteries. They want a battery just big enough to start the car to keep the weight down bc the alternator does the work from there. If its actually draining power from the battery then the alternator isnt keeping up with demand

 

[STAMPEDE3]

90% of older all out drag cars do NOT run an alternator. They run off a battery only. That is why they all have battery chargers in the pits.
Some even going to 16V systems.


And yes, most modern cars can at times use more than the alternator puts out if the battery is in fact weak.
It is possible a weak battery or dead cell can cause low voltage but getting all the way down in the 10V range is crazy.

 

[Cobra285]

Your alternator is not charging. The charging system voltage should be 13.6 to 14.5 volts your running on battery power not charging system power thats why when you add a load to the sytem like lights it drops even lower. Make sure you have 12 volt power to alternator if you do bypass voltage regulator by inserting a large paper clip in the hole provided in the back of the alternator and ground it to the case. If it starts to charge then your regulator is bad if not your alternator is bad.
Auto tech for 36 years