Battery/Alternator

[450sl4me]

My SL won't start! I'm pretty sure it's my battery, but don't want to lay out the cash until I'm a little more certain. I put a volt meter on the battery while the car is running. It's charging at about 13.8 volts w/ no accesories running, 13.5 w/ ac, stereo, & lights on. It started having trouble starting about three months ago. It did this if I let it sit for 2-3 weeks between starts. Then it was if I let it sit for a week, now it won't start even right after I drive it. What should the voltage be while charging? I always thought you should have 14+. Even if I jump start it, I have to let wait 1-2 minutes before it will start even w/ it hooked up to my truck. What do you think??? ANy help would be greatly appreciated!

Chris

[MB STARS]

Alternator should output more then 13 Volts when engine is running & more then 40 Amps output when use tester to load test alternator some alternator will output to 120 Amps,but for your SL should have 55 to 75 amps (engine number) also load test your battery should not below 10 Volts. Battery drain shold be 0.01 to 0.03 amps. hope this help

Yes, voltage output sounds good. I would place a heavy bet being the battery is the culprit.

Most places that sell batteries will test them for free. Just remove it and haul it into your favorite battery supplier.

Good luck,

[Ferdman]

How old is the battery? I have experienced similar problems when a battey is shot ... it won't hold a charge I agree with Larry ... have it tested.