Battery, Alternator, or VR?

[phishtaco]

Help me figure out which thing to change.
Dead battery
Jumper cables, let it charge for 5-10
Jumped it
Pulled the cables and let it idle for about 15 minutes
Tested alternator “charging high” loaded 16.22V unloaded 17.4V ripple 41mV
Shut it off and no charge no start

Battery test results after idle and shut down in the picture.

Battery is about 2 years old 2024
Alternator at least 22 years old
VR at least 22 years old.

I feel like it is just the battery but it was replaced in 2022 and 2024. Obviously this is not driven too much. Maybe 1000 miles between August and October of 2025.

 

[igotta40]

What is your amp meter on your gauge panel doing?

 

[Engineer8000]

16-17 v seems kind of high.

 

[phishtaco]

What is your amp meter on your gauge panel doing

Didn’t pay attention.

 

[pb4ugo]

Isn't the v/r adjustable?

 

[cruisermatt]

if you can get 16v then your alternator is perfect.
Your VR should step that down to 13.5V ish.

You can definitely hurt a battery overcharging it and/or letting it sit for extended periods.
Get the battery tested regardless - they can show 12V but have dead/shorted cells and no CCA’s.

On a 50ish year old vehicle wiring you really should be checking every circuit for resistance, corrosion at connectors, etc.

Diag, diag, diag. No guessing or assuming allowed.

 

[charliemeyer007]

I think 14.4 is the high end for charging a lead acid 12 volt battery. Volt meters can very some, almost nothing reasonably priced is actually calibrated. You might be able to adjust the VR. I would invest in a new one and alternator now while you can get them. I also put new 2/0 copper cables for the battery to starter and engine ground - cranks over much stronger now.

Batteries are crap these days. Most die soon after the warranty is up (by design). You let them go flat like 5 times and its dead.
A $50 load tester can be handy.

 

[phishtaco]

I think 14.4 is the high end for charging a lead acid 12 volt battery. Volt meters can very some, almost nothing reasonably priced is actually calibrated. You might be able to adjust the VR. I would invest in a new one and alternator now while you can get them. I also put new 2/0 copper cables for the battery to starter and engine ground - cranks over much stronger now.

Batteries are crap these days. Most die soon after the warranty is up (by design). You let them go flat like 5 times and its dead.
A $50 load tester can be handy.

Actually have an alternator and new VR along with battery cables.