Voltage issue
Thread Starter
Intermediate
Joined: May 2021
Posts: 49
Likes: 7
Voltage issue
My car seems to have a tendency to run very low voltage with say blower motor on full blast with headlights, fog lights and defroster on. Even with 2 on, the car will run down to 11.9- low 12 range in drive when stopped but shoots up to 13.5-14 when moving or if I put it in drive, neutral or park. Granted that’s what the DIC is saying and that’s not entirely accurate compared to testing correctly. Is this normal? I understand it takes power to run everything but it just seems it’s excessive the way the voltage drops and lights get dim or accessories run slow.
Battery is an optima red top that was installed last year and alternator is a brand new GM unit I put in shortly after.
Car is an auto.
Any input is appreciated.
David
Battery is an optima red top that was installed last year and alternator is a brand new GM unit I put in shortly after.
Car is an auto.
Any input is appreciated.
David
Last edited by Pistol_pete_m9; Mar 5, 2022 at 09:25 AM.
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,309
Likes: 3,924
From: Cape Coral, Florida
May be a faulty alternator or excessive voltage drop in the charging system…do you have a DVOM and know how to use it ??…if so we can show you how to quickly check it. DIC voltage is around .4 to .5 volts lower than the actual battery voltage read AT the battery.
Melting Slicks
Joined: Sep 2008
Posts: 3,117
Likes: 793
From: Espanola New Mexico
Having all the loads you listed on is a lot, there is no way the alternator can supply enough power at idle to not cause low voltage. I would measure voltage across the battery terminals to verify agreement with cars gauge or DIC. You might want to check the cable connections at the starter solenoid making sure they are clean and tight, as this is where the alternator output cable connection is made to the battery.
