Voltage drop

[PTmowerMech]

JD D110

Briggs
M# 33R877 0020 G1

Battery was weak when I picked it up, so I put it on slow charge. It took a charge, but load tested weak. I put on a good used battery that tested good. Alternator is charging good. After running the engine for about 20 to 30 minutes, and killing it, the meter read 12.73v last night at 8pm. This morning at 8am, it was 12.54v. Key was off all night.

Question: If the battery is charged up to say the 12.73v, will it drop to a certain level on its own, and stay there? Or should the batter still be a 13.73v after 12hrs?

 

[Hammermechanicman]

When you charge a battery right after you take it off charge it will have what is called a surface charge. Put a load on it for a few minutes or wait a couple hours to get the correct voltage. So. Yes. That is normal. If you want to really test the state of health of a battery you need an internal resistance tester.

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[PTmowerMech]

When you charge a battery right after you take it off charge it will have what is called a surface charge. Put a load on it for a few minutes or wait a couple hours to get the correct voltage. So. Yes. That is normal. If you want to really test the state of health of a battery you need an internal resistance tester.

Amazon.com: Car Battery Tester 12v Car Battery Load Tester on Cranking Charging System, TOPDON AB101 100-2000 CCA Alternator Analyzer Battery Health on Cars/SUVs/Light Trucks with Flooded AGM GEL Types: Automotive

Buy Car Battery Tester 12v Car Battery Load Tester on Cranking Charging System, TOPDON AB101 100-2000 CCA Alternator Analyzer Battery Health on Cars/SUVs/Light Trucks with Flooded AGM GEL Types: Battery Testers - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

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I have a manual load tester. But I'm not opposed to a new tool. Especially a digital one.

LOL.. And here I was thinking that the carb pressure/Vac tester was the last tool I needed to do this job. I have a leak down tester on the way.
Actually I was really looking forward to now buying materials for the aweing. In fact, I was really looking forward to it, since it's about to get really hot.