Not sure if it's the alternator or battery that's wrong with my electrical system in my ITR. Noticed it over the weekend, the engine would barely be able to crank over.

Did some tests:

1. At idle, 14.2 volts across the battery
2. Car off, 12.4 volts across the battery
3. At idle, with headlights (high and low) on, interior fan on highest and stereo going. The voltage across the battery goes to 14 volts and drops slowly (never returning to 14 volts). If I rev the car, it goes to 14 volts.

What do you think? Do I need a new alternator?

 

Battery, has this ever been replaced on your R? I had the exact sypmtoms and it was alll good once i replaced the battery.

 

Id load test the battery, CCA's may be low. Or check you connections at the terminals, they may be loose. But yeah def sounds like a battery not alternator.

 

batter problem

 

try out a new battery first, if the problem is still here
it may be voltage regulator problem
if voltage regulator is burned, voltage meter would go over 14v execpt under braking w/ accesssories on