A couple days ago, I went to start my 93 FD and found the battery was dead. Thinking I had left a light on overnight or something, I jumped it and proceeded to drive around for about half an hour. A matter of seconds after shutting it down, I tried starting it again...and nothing.

The battery is only a few months old, so I immediately suspected the alternator might have gone bad. After searching through a ton of posts regarding this issue, I decided to do some battery voltage tests. It is right at 12.5V with the engine off, and it fluctuated between 14.0V and 14.3V with the engine running. From what I read, this would seem to indicate that the alternator is working properly, yet the battery is obviously not being charged sufficiently.

Can an alternator be bad yet still show correct voltages? Any further info or advice would be much appreciated.

Thanks!

- Jim

 

im guna say its ur battery.......tho it shows 12.5.......see what it does when its loaded(being cranked).....ill bet it drops wayyy below 12.5

 

ya im wit ted..it SHOULD be ur alt. u might not have drivin it long enough to be recharged.

 

im having thos probs too
after driving the car for how ever long.. i turn it off.. and turn the key to make the electricals come on and nothing is on except the fans from the heat and the pfc... after about 2 mins you hear the fans go slower and the dome light dim.. i try to start it and it struggles because of the dead battery

 

I am not inclined to believe that the battery is at fault here. It was just put in a few months ago, and it is unlikely it would have lasted as long as it did if it was bad out the box.

I'm not saying it's impossible that the battery is bad, but I am having trouble believing it at this point. I've seen posters state that voltage readings can be on target but the alternator still be bad. Anyone that can explain why that is?

Thanks!

- Jim

 

This might sound really dumb but I had a similar situation... my terminals were not super clean .. so i cleaned the batt terminals and the terminal connectors.. made sure i had a tight fit.

My symptoms at the time was that car wouldnt start without a jump

i soon realized the clamps from the jumper cables were tightening my connectors onto the terminals.

i used aluminum foil to clean my stuff...

maybe this will help someone else lol

 

take the battery and the alternator ...and get them checked out...

also like said....make sure terminals are clean, i've also seen some weird $#!t happen with corroded terminals....

brad

 

take your car (if possible) or just the alt and batt to get then load tested. a batt when any juice will show 12.5 to most extents due to the number of cells in it. voltage amount is based on number of cells in the batt unit. amperage and storage of amperage is what counts. alt can show 14v charge but when put under load the amperage may dump as well. I.E. charge 14 volt with 20amp charge, car running might need 15amp with no loads, so there's only 5 amp's chargin which would take a dead battery quite a few hours to a full day to fully charge up.

just my .02


Los