HP Zbook 14 can't properly read batteries? Capacity/charge is unstable

[DutchComputerKid]

Hello!

 

I've gotten a problem with a new-old-stock ZBook 14 from 2014, the CMOS was toast but the internal battery was still good.

Sadly that battery went to another friend cause he also had the same machine and his battery had gone poof.

 

Recently I needed mine again, so I bought a new battery. Only to have this appear:

 

It's highly unstable, voltages and percentages, even capacities go all over the place. Cycling the battery doesn't help, a new CMOS battery did not either.

Charging it makes it randomize faster, when the battery is 'full' and it's being used its a tad more calm but still doesn't report properly.

 

I thought that battery I bought was faulty, so I returned it and bought one with an actual brand, friends recommended GreenCell so that's what turned up today.

Looked fine at first, but now it's the same story all over again. Different chargers didn't change anything and only make the capacities go even more wonky.

Once in a while the laptop wont even turn on, blinking its status lights that says "battery too low to start", but when you start it with the charger attached it goes back to normal?

 

Is the laptop faulty in some way? CMOS replacements, reinstalls of Windows, BIOS resets, nothing helps.

The laptop is also known as an EliteBook 840, which might help.

Tried both 90 watt and 135 watt PSU's, BIOS is on latest from last year, all battery reading tools give the same result.