erratic voltage reading

[spydermangst97]

It started when a light got left on in my car and it drained the battery. Even though I got the car started the alternator would not supply enough voltage to keep the car running and the car would die. I replaced the alternator like a dumbass before testing the one that was on the car. LATER I tested it and it was good. I also replaced the battery, cleaned the connections checked the grounds and all that. after all that the battery gets enough charge to keep the car running and I can drive it around, however all power options move slow. Now the weird part, if i have my foot on the gas under a steady acceleration, the battery light and the brake light will come on, about two seconds after I take my foot off the pedal the lights will go off. If im cruising at a steady speed the lights will flicker. the voltage reading also changes when this happens. It goes from about 10 to 13.5. If ANYONE has any suggestions please respond. Thank you.

 

[91dsmgsx]

check your wiriring harness from your alt. to the battery or run a jumper wire 6ga will work from the output of your alt. straight to the positive of the battery take it for a cruise and see if that shit still happens if not wire in an 80amp fuse between the alt and batt so nothing bad happens some day

 

[spydermangst97]

I was thinking about doing that. But its odd how the voltage changes when I take my foot off the pedal.

 

[Bud92gsx]

The voltage should change when you add throttle.. It should go up..

 

[spydermangst97]

It does go up with rpm, but im talking about it changes when I just touch the pedal

 

[Defiant]

if i have my foot on the gas under a steady acceleration, the battery light and the brake light will come on, about two seconds after I take my foot off the pedal the lights will go off. If im cruising at a steady speed the lights will flicker.

That alternator's dead.

 

[spydermangst97]

Ive tried three of them. Off the car they test out fine but on the car the voltage isnt getting to the battery.I know its not impossibly for them all to be bad units,but its really unlikely.

 

[DSM1G90]

Agree with Defiant:ALT's dead - take them to an ALT/motor shop and have them tested... When you killed the battery and got it going again, the ALT was overtaken with that bad battery which are NOT designed to recharge batteries, but to keep them topped off during operation. (why you buy a battery charger and let them do the deep cycle charging of batteries...).

And, go buy a new battery. If you're popping three ALTS like that, get a new battery.

 

[spydermangst97]

i have a new battery and I have tested all the alts. I work at a shop. Before that I worked at autozone. I used autozones testers on and off the car. On the car it tests the voltage at the battery and its not getting the right voltage all the time.10.5-13.5v(I know 13.5 is good but it hardly will stay there) It randomly jumps around throughout the rpms. Off the car they all test good in all three tests. One more thing I noticed is if it is cold it will start up and everything will work fine but then when I start to drive it will go back to jumping around. It all happened after the old battery got completely drained. Is it possible something was messed up in the computer? It would give me a good excuse to get dsmlink and an eprom

 

[costas14]

bad or cheap alternators, bad or cheap batterys, solution! buy an interstate battery, and dont buy an alternator from autozone, get it from foreign autopart international since you work at a shop you should be able to get parts from them or visit your local mitsu dealership

 

[Defiant]

Worn contact ring brushes in the alternator. It's dead. Let me explain in detail:

The alternator is dead.​

Replace.​

 

[spydermangst97]

Finally after I stopped being stubborn I bought an OEM alternator and it solved all my problems. Rebuilds test fine off the car but still wont work. Thank you defiant for spelling it out for me