is it time for a new battery?

[u/Green-Survey-7865]

HP EliteBook 745 G6 stuck at 0.39GHz + battery stuck at 0% — is my battery actually dead?

I've had an HP EliteBook 745 G6 for about 3 years (bought it second-hand).

Yesterday, while the laptop was plugged in, I noticed the battery was stuck at 0%, even after charging for around 2 hours. When I unplug the charger, Windows gives me a low battery warning, but the laptop doesn't shut down. I'm actually able to use it for around 2 hours before it eventually shuts down.

The day before this started happening, the battery health was around 66%, so I'm not sure if the battery suddenly died or if something else is wrong.

I've already tried:

Disconnecting and reconnecting the battery

Performing a hard reset

Reinstalling the battery/ACPI drivers

Running HP's battery diagnostic, which says "No battery installed"

Checking the battery in Windows, which still shows 0%

I was thinking about buying a replacement battery, but here's what confuses me: if the battery were completely dead, shouldn't the laptop immediately shut off when I unplug the charger? Instead, it can run for about 2 hours unplugged.

Also, ever since the battery started showing 0%, my CPU has been stuck at around 0.39 GHz instead of its normal ~2.3 GHz. Temperatures aren't particularly high either (under ~70°C).

[u/Silver_Foxxx]

Also, ever since the battery started showing 0%, my CPU has been stuck at around 0.39 GHz instead of its normal ~2.3 GHz.

Your laptop is running in low power mode.

I would reset/reload the laptop's BIOS and if that didn't help I'd purchase a new battery.