How can I test my alternator-battery?
10-11-2010, 03:41 PM
#1
How can I test my alternator-battery?
Had some weirdness with my 97 C2 the other night. Put the brights on, radio shuts off and comes back on. Think the lights themselves might have blinked once, too (aftermarket HIDs).
Thinking maybe it's a bad battery or alternator-regulator. Both were replaced a couple years ago (rebuilt alternator). Alternator belt feels okay. No other warning lights, etc.
Can that be tested with a regular old multimeter and, if so, can you tell this borderline idiot how to do it in detail?
Thinking maybe it's a bad battery or alternator-regulator. Both were replaced a couple years ago (rebuilt alternator). Alternator belt feels okay. No other warning lights, etc.
Can that be tested with a regular old multimeter and, if so, can you tell this borderline idiot how to do it in detail?
10-11-2010, 08:50 PM
#2
Rennlist Member
Process of elimination. Lets see if the alternator is charging...
Start the car and measure the battery voltage while you put a load on it by turning on anything that draws a healthy current such as high beams, rear window defroster, interior fan on high, etc. With the engine at about 2500 RPM, what voltage do you get across the battery? It is steady, or is it increasing/decreasing very slowly.
Even with the an U/S alternator, the battery if it is in good shape can power your HIDs and other accessories while slowly decreasing in voltage (since it is not being charged). BTW, what is your battery voltage with a few things on and the engine stopped? How quickly is the voltage decreasing?
Start the car and measure the battery voltage while you put a load on it by turning on anything that draws a healthy current such as high beams, rear window defroster, interior fan on high, etc. With the engine at about 2500 RPM, what voltage do you get across the battery? It is steady, or is it increasing/decreasing very slowly.
Even with the an U/S alternator, the battery if it is in good shape can power your HIDs and other accessories while slowly decreasing in voltage (since it is not being charged). BTW, what is your battery voltage with a few things on and the engine stopped? How quickly is the voltage decreasing?
10-11-2010, 11:57 PM
#3
Addicted Specialist
Rennlist Member
Rennlist Member
Garden variety digital meter is fine. You should get around 14v at idle plus/minus around .3 volts maybe. But at 2K RPMs, you should be reading 14-14.4v even with accessories.
If this all test ok, you may want to remove the batt and take it to your local Autozone or PepBoys and put it on a load test. Better yet, take it back to where you bought the battery ...if it's only a yr old, you should be covered under warranty and at the very least, get pro-rated value for a new batt if yours is marginal.
Edward
If this all test ok, you may want to remove the batt and take it to your local Autozone or PepBoys and put it on a load test. Better yet, take it back to where you bought the battery ...if it's only a yr old, you should be covered under warranty and at the very least, get pro-rated value for a new batt if yours is marginal.
Edward
