[Ruger95]

When I start my 04 it runs alittle over 14volts then once it warms up will run 13.5ish and drives fine. When I turn my headlight on volts drop high 12s and if im stopped at a light it will drop below 12. Then tonight I was driving around alittle bit with the system going and was steady at 13 while driving and about 11 at idle and I decided to get a car wash system was turned all the way down and i turned off just the headlights and pulled in then all of a sudden I hear a loud whine for the engine compartment and volts drop to around 8 or less car was barely running and I tried to rev it and wouldnt rev so I threw it in neutral, shut off lights and turned off system. Whine stopped volts very slowly went to 13 and stayed. Car wash was over and I put it in drive and dropped to 12 so I let in idle for about 15min then drove home with system off, headlights on at around 13volts driving and would drop very fast to 11 when stopped. Had this problem for about a month but now its getting bad. When I use my multimeter to test battery with car off its always at 11s as soon as I turn the car off. If I dont use it for a day or two the battary wont turn over the car. Sorry for the long post but does this sound like a weak battery or a bad alt? Thanks

[bigjohnstud4200]

Sounds like alternator, you can get both of them tested on the vehicle at the auto parts store.

[RedFury013]

Ya if its not starting after letting it sit it sounds like your battery might be shot. Best bet is to get your battery load tested and have a shop test your charging system. Alternator sounds like its on its way out.

[HighDensity]

If the car stays running, I don't see what the issue would be with the alternator as it is keeping the car running.

I'm thinking it's the battery since the battery can't hold a charge for very long in between starts.

[shanerob34]

with the car running take a voltmeter. take the positive lead and put it on the wire coming from the alternator to battery. and take your negative lead. you should be reading good volts. if you can watch the volts keep dropping until vehicle shuts off its the alternator. But considering you say it stays running. Most likely a batt

[hdrider18]

Check the batt before you start the car. Should be around 13.2'ish. Start the car and the volts should jump to 14'ish. Have someone turn on the lights and the volts should drop down then pick back up. If the volts pick back up it sounds like your batt. If they don't pick up, sounds like the Alt. Also, check all of your connections (Batt, Alt, and the wires going to your starter). Don't forget to check the ground connections..

[maximusneo701]

Turn off car, check battery voltage, let it sit then check it again. If it drops a lot then its the battery. The alternators amperage output is linked to belt speed and therefore engine rpm. So when the car idles and it drops some then that's normal. But it shouldn't drop below 12. If it just drops as it as it heats up then the alternator is most likely bad. I had my alternator tested when I had the battery replaced, they seem to whistle when put under heavy load. So when the alternator heats up and tried to put more power out that would be a significant load. They also will smell; autozone or oriellys do free testing. Voltage drops when more power is drawn but usually the alt will attempt to generate more power and bring the voltage back up.