Battery and alternator charging problem

battery light stay on because there is no output or below voltage out put from the alternator. Check that the battery terminals and posts are shiny clean and tight, if there is a charging circuit fuse (OK). Have the battery load tested . Remove the alternator and have it bench tested by an accredited auto electrician.

What happens is, you have a battery and an alternator. The alternator charges the battery when the engine is running. It can only put out so many amps at 12 volts. A/C compressor runs off the engine, but the clutch for it is electric, and the blower fan is electric. When these are running, unless the car engine is running at above idle RPM's, your alternator may not be actually putting out enough amps to run the A/C AND charge the battery. So it is possible for the battery to go dead, especially if you start the car more than a couple times with out letting the battery charge. It happened to a friend of mine. He delivered newspapers, and it was a hot summer day. His A/C was on, plus, his car had 2 electric fans for the radiator. He was only idling along delivering his papers, and at one point he shut his car off. When he went to re-start, it was dead. He called me and I gave him a jump start, and told him to go for a ride down the expressway, to charge his battery. You see the A/C took say 30 amps, then each cooling fan for his radiator took say 20 amps a piece, then add in the stereo, and the power it takes to fire the spark plugs, and there wasn't enough left to charge the battery. Most cars these days only have 100 amp alternators. Older cars have less

the altinator should be putting out at least 14 volts,so have it checked out,and if its dead after an hour or so,it sounds like the diode,s gone,so the problem does seem to be the altinator.

Voltage regulators are electronic, internal on most units, now days, and not adjustable. Look for failed diodes. Easiest to pull the alternator and bench test it..

Yes ,the alternator,have it checked,or check it yourself with a volt meter connected to the battery,with everything on,ac on high blower,and headlights on,it should be charging 13.65 volts to 14.25 volts,if it is any lower than this,replace the alternator,thank you ,and please rate,if this was helpful,at all.

Did you reset the Inertia Switch in the trunk.

it is a bad idea to disconnect the battery of a running car. If the alternator is working it can destroy virtually any electric component that is on. Alot of shops and some auto parts stores offer free charging/starting system tests.(they sell more baterries and alternators)

your new altinator has a faulty regulater.

you should have 12 volts at battery with engine off.
should have about 14 volts if charging.
what are you getting?

check fuse 20 in power distribution box on left side of engine compartment.

If it is a fuse it should go to the battery side. Only the starter should be on the other terminal