I have a 1996 C180. The car is not holding charge even when driving. The battery and alternator are fine. The light for the battery is showing on the dash. I am completely stumped. Can anyone help me? Thanks

That sounds like an issue with the charging system I _think_ that is part of the alternator. The problem is that intermittent faults are hard to diagnose, especially since you probably don't have OBD2. Although you may just make it. In which case a high level scan tool computer can look at historical freeze frame data.

All cars and light trucks built and sold in the United States after January 1, 1996 were required to be OBD II equipped. In general, this means all 1996 model year cars and light trucks are compliant, even if built in late 1995.

Battery could be faulty....not holding charge! Is alternator charging?

The alternator should be showing at least 15 volts when running! Anything lower would indicate the alternator is at fault, since you say it is showing below 12 volts even for 2 minutes indicates a fault.

there still could be a fault with the battery not holding its charge or something draining the battery like a wire shorting or trunk light staying on that is making the battery go flat!

I will try and answer this. Most responses you will receive will have you looking for a drain in the system. Very well could be that.

But you said when Jumper cables are removed it does not charge. I have not heard of this in your Year of car, but witnessed it myself in a 2004 F150. There is a circuit called a "battery saver". Its job is to disconnect a battery drain to preserve the battery. What can happen is the Alternator uses power to make and generate even more power.

When a battery is not fully charged it needs a higher rate of charge and the Alternator may be viewed as a parasitic drain. The battery saver activates and disconnects the charging circuit. It can cut off at even 70MPH. I have seen F150's charge for about 5 minutes after removing a jumper and then cuts the battery charging circuit.

You need to be sure the battery is 100% charged. You need the car checked for things like the Diodes and starter draw. If you take the Alternator or Starter for a bench check it will not show how the wiring is working in the car. It is best to check the whole car.

Your battery are okay but you may have an alternator/generator problem, it's not charging back electricity to the battery. That's the common interpretation of that battery warning light on the dash...

Hello and welcome to FixYa!

If the battery light is on, I strongly suggest that you have the battery charged. It can be an indication of a weak battery or a faulty alternator. If the battery light still on after charging then the problem will surely be on the alternator itself. If that's the case the alternator should be replaced to resolve the problem.

If the battery won't hold charge even on a new alternator then the problem will be on the battery itself. It surely is in the end of it's service life and replacement will be necessary.

You may try to reset it to by removing the positive battery connector, letting it sit for at least 5mins. then reconnect it again. This will reset the system and can get the battery light off.

Hope this helps and thank you for using FixYa! Have a good one!

SOUND LIKE WEAK BATTERY.CHECK BATTERY CABLES MAKE SURE THEY ARE TIGHT FREE FROM CORROSSION.IF ALL IS GOOD.HAVE BATTERY CHARGED LOAD TESTED OR REPLACED IF BAD.MAKE SURE ALTERNATOR IS CHARGING BATTERY.WITH ENGINE RUNNING VOLTAGE AT THE BATTERY SHOULD BE 13.5 TO 14.5 VOLTS.IF NOT CHECK ALTERNATOR DRIVE BELT MAKE SURE BELT TENSIONER GOOD.CHECK ALTERNATOR B+ WIRE AND FIELD WIRE MAKE SURE THEY ARE NOT LOOSE OR DAMAGED.CHECK FUSE ALSO.ALL IS GOOD ALTERNATOR NOT CHARGING THE BATTERY..

have battery and alt checked battery may not be holding charge or alt may not be putting out charge auto stores such as auto zone and advanced do check for free and can check with them still in car

Its the 175amp megafuse. About $7 at the auto parts store

Hi first check the alternator belt (is it loose...is it there?) if all is ok there then it could be the alternator, have a multimetre put on it it should read around 13.5 if the alternator is doing its job,
Hope this helps

Regards
Steve