The Under the Hood Show
Dear Motor Medics, I have a 1994 Stealth RT without the turbocharged engine. I have gone through two new batteries in a short period of time.
Is it possible that a failing alternator can ruin a battery? If so, I would like to know if there is a way to check if the alternator has actually failed.
Are there specific testing methods that can be used to narrow the cause down?
I listen to your show faithfully. Thanks for your time.
Karen in Fargo
Dear Karen, A failing alternator can ruin a battery in a short period of time. If it’s overcharging or is draining current when off, it will discharge the battery after it sits for extended periods. Even if it does not sit long enough to run completely down, it can cause the battery to fail due to its heavy discharge/ charge cycles.
To check the alternator, you need to have a charging system analysis done with a charging system tester. This will show the internal operation of the alternator, diodes, field and ability to charge at idle and at higher rpm but will not show a drain.
To find a drain they will need to perform a current drain test. Most shops with this type of tool will also have an electronic battery testing tool.
It is possible that you have had a run of bad luck with two bad batteries. It has happened to us in our shop before. Take care, The Motor Medics
- Log in or Subscribe to post comments.