Sluggish battery is measuring 13.25V while engine is running.

[911obgyn]

I had the same issue over the last couple weeks. Car would start fine if i drove it every day, had to put a trickle charger on it if it sat for over 3 days. Its been discharged several times in the last few years.
Checked voltage resting 12.3v charges at 13.7 with car running. New battery is on its way, 3 months out of warranty. I need to fix dome lights windows roll up with door open.

[darrin]

Originally Posted by 911obgyn

I had the same issue over the last couple weeks. Car would start fine if i drove it every day, had to put a trickle charger on it if it sat for over 3 days. Its been discharged several times in the last few years.
Checked voltage resting 12.3v charges at 13.7 with car running. New battery is on its way, 3 months out of warranty. I need to fix dome lights windows roll up with door open.

911obgyn -- took me around 15 minutes to replace my driver's side switch, be sure not to let the wire attached to the switch drop back behind switch once you've pulled switch out of door jam. Replacing my pin switch both allowed dome light to turn on/off when door opened AND eliminated my battery drain issue

[mysocal911]

Originally Posted by sugarwood

My 2019 AGM battery is dead.
Last 4 years, I have not driven the car much and it mostly sits on a tender

I put it on a trickle charger overnight and still dead.

I removed the battery from the car and hooked up a 12V charger
Once charged, I will take it to FLAPS and load test.
If fail, I will get a new 48 battery for $200 regular or $250 AGM

AGM batteries reguire a higher charging voltage than a regular lead-acid battery.
Late vehicles' alternators (14V+) are designed for use with AGM batteries not early 911s.
Avoid using AGMs, if the vehicle isn't designed for its use!

[sugarwood]

Originally Posted by darrin

sugarwood -- what make/model tender were you using? How frequently do you drive your car? .

Good theory worth exploring

I don't drive it much the last 2 years.
Always on tender.

[sugarwood]

Update:

Left it off the tender the last time I drove it.
Tender could not revive.
I hooked up a 12v charger overnight

Battery now showed 12.65v at rest
14.05v while running

Took it to FLAPS
He attached a device that read 850
(Battery is only rated 765 CCA)
Device said green/OK.

Took it home
Put in car
Went for a drive

Left it off tender
I will see if the car starts on Saturday (3 days)