Simple battery/alt problem

Its the "end of the day simple question" session. I'm guessing i know the answer already but I thought id throw it to the lions for suggestions. Battery voltage down before firing up (11.8ish volts) and only 12.6 while running (if it starts!). Not alternator fault lights. Am i looking at faulty battery cell or alternator? I'm taking a guess at battery. I can just get her to fire up overnight, run her for 5 minutes, turn off then on again no probs but then strangely drive 5 miles and stop and its as dead as a door nail. It reached the point where it was affecting the ignition last night :(

J
Reply to
Coyoteboy
Loading thread data ...

Check battery voltage when you shut the engine off, and then after sitting overnight. If there is a significant difference, the battery is not holding a charge. On the other hand, the alternator should be putting out in the vicinity of 14.4 volts when running.

Reply to
Ray O

Voltage reg or alternator...a properly working charging system should produce 14.5 volts across a normal battery when at high idle with the headlights off. Your 12.6 is much below spec.

Reply to
Gord Beaman

You got it Ray...hell, I'd say he has a great battery to start while reading less that 12V...it's for sure not being charged...

Reply to
Gord Beaman

My bad, I see that he is only getting 12.6 V when running, yup, I'd start eyeing the alternator/regulator.

Reply to
Ray O

I yup, I'll have to look that over I think. Recently had the alt off so im hoping i just missed a connector somewhere!! Replaced the diode pack and reg module last year so i hope its not that. I was just thinking maybe a shorted cell in the battery could be drawing so much current the reg and alt couldnt keep up. But then it has been run flat twice in the past two weeks while ive been working on it so i wouldnt be too suprised if the extra load has killed the reg.

Ta all ;)

Reply to
Coyoteboy

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.