Battery or ?

[ADRay]

having a bit of an issue. Last Thursday, I had to jump it in the morning, drove it to work and had to jump it again at the end of the day. Straight to the parts store and got a new battery under warranty. I've been driving it daily since then.

Last night, after having driven it for about 30 minutes, I stopped at Home Depot for 15 minutes. It wouldn't start when I went to leave and luckily someone gave me a jump.

This morning, same thing. It's cranking but not turning over and goes flat pretty fast. Meter is showing 11.75ish. Both red and yellow lights on power.

My question is, do I go back for another battery, or could it be another issue? It's a 82 with a 998 HS4 with zero electrical accessories (radio, heater, charger, etc). New alternator and solenoid last summer. Thanks

[MiniDave]

You need to check your alternator output, sounds to me like it's not working. Do check the cables on the alternator too, I've seen those corrode thru and break. Also carefully check your battery cable connections and the main ground strap between the engine and firewall. Then get it started and see if the alternator is putting out voltage, should be high 13's to low 14's at 1500-2000 rpm. You can measure that at the battery.

At 11.75 clearly the battery is discharged, either from running for a week and not getting charged up or possibly but unlikely a bad battery. Battery fully charged, resting voltage is 12.6