Alternator bad?

[ineil]

I have been working on this charging problem for some time now. I finally found out that my Optima red is not holding a charge. Last night I removed both Positive and Negative cables when it was at 12.45, this morning it was at 10 and dropping. I charged up an 8+ year old Diehard Gold. It's holding the charge @ 12.45. My issue is when running the volts only show between 12.9 - 13.4. Shouldn't it be higher?

 

[Gary Wells]

Sounds to me more like the battery might have a dead cell, otherwise it should not have dropped voltage like it did with both cables disconnected.
I just lost a 200 amp alternator day before yesterday, front alternator bearings disintegrated allowing about .80 up & down or side to side play at the front end, and it was still charging according to my SC about 13.7-13.9. Replacing the 200 amp with the stock alternator that came on the car took the charge back up to 13.8-14.2 in normal driving conditions.

 

[ineil]

I have already come to the conclusion that the Optima went bad. My question is, how much additional voltage should I expect over the 12.45 with the car running using a 140 amp alternator?

 

[Gary Wells]

I have already come to the conclusion that the Optima went bad. My question is, how much additional voltage should I expect over the 12.45 with the car running using a 140 amp alternator?

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I think that it might be difficuly to assess with a bad battery. I would replace the battery and then give it a while before deciding whether the alternator is working properly. My guess is that it won't take a full charge even monentarily due to the bad battery.

 

[ineil]

As I said in my first post, I was able to fully charge the Diehard to 12.45 and it is holding. I replaced the Optima with the Diehard.

 

[SS/GNX]

I had this SAME problem, and yes, you should have more volts than that.
Your POS optima battery died because your alternator is not charging properly. I call it a POS, because I have killed two of them, NOT due to bad alternators, Optima can blow me.

Anyway, I tightened the post on the back of the alternator and it jumped up to 14 volts all the time. MUCH better. Check to see if yours is loose, if not, find somebody local with one that charges properly and give it a try on your car. You should be getting close to 14 volts. plus or minus .4 or so

 

[turbobose13]

I could Be wrong but i think it depends on how much charge the Battery has, if it is fully charged the voltage will Be lower and vise versa.

 

[salvageV6]

My fully charged new battery always charges at 12.8-13.4 in the GN.

My 9 year old Yellow top in the WE4 is always at 13.6-14.6 in the WE4.

As stated above it depends upon the battery state of charge what the alternator will put out, assuming it's not tricked into thinking it needs to put out more voltage as with using voltbooster device.

 

[TURBOTWIN2]

Look for 1 to 2 volts over Open Circuit voltage-battery voltage with nothing turned on (no loads). Leave your headlights on for about 3 minutes to remove the surface charge, then check with a volt meter, you can get an excellent one at Sears for less than $20. 12.6 volts=fully charged. Start engine and run at about 2,000 rpm. Look for 1 to 2 volts more than your open circuit voltage. You guys know just about every parts store will do a battery/starter/alternator test for free. HTH.

 

[ineil]

Thanks for the info.