Well I changed the battery in my 740 in april and I bought a new one. It lasted until saturday. The car went dead. Too it out and put it on the charger but also took the alternator and had it tested. It came back as perfectly functioning. So I put the battery back in Sunday morning. It managed to last 7 starts until it died again. Took the battery back today and they said it was only at 46% and wouldnt hold a charge anymore. They warrantied it and gave me a new one.

I checked the engine grounds and they are fine. I also checked the fuses to see if there were any parasitic drains in the system and there were none.

Could the starter be going bad and sucking too much battery power and kill it off quicker? OR are there any other problems that anyone might have an idea about?

 

Did you test the alternator ON the car or bench tested it? It may be ok yet not charge for other reasons...

 

With the new battery installed it happened again. Car was very slow to start and almost didnt so I knew the battery was getting weak and its just a day old. I drove it and had the battery and alternator tested while the car was running and it came back as the car was running on the battery alone. It isnt getting charged. And the alternator is putting out current.

He said it might be a fuseable link that has gone bad I looked in the Haynes manual and couldnt find any in the wiring diagram. Anybody know of any that go bad? to cause the problem? Or any other ideas that it could be?

 

Do your instrument lights work the way they are supposed to? Especially the CHARGE light, the BATTERY symbol? Does it come on when the key is in the II position, then goes off when the car is started?

 

Yup. everything works as is is suppose to. Unless the car wouldnt start you wouldnt that there is any problem with the charging system. Im kind of stumped. I was thinking if the car has an external voltage regulator that went bad but as far as i know the alternator has an internal one. Im just not sure what to think.

 

Here are a couple things to check ...

- verify your connections match what is shown in the attached picture
- With the key on car not running, make sure you have voltage on the small red wire post.
- car running measure the battery voltage, it should be around 14 VDC ... anything much less, but still greater than the car not running would suggest worn brushes.
- car running ... should be less than a volt measured between the alt case and the engine (ground).