Battery report discrepancies

[Sheridan]

Not a big deal, but more of a curiosity - on an HP laptop I ran powercfg /battery report to check the battery state and health. It shows the design capacity of around 50mWh and Full Charged at around 30mWh - fair enough its about 3 years old

 

However I opened the cover to add some ram, and the battery has 41mWh stamped on in several places, and its the original OEM (HP) battery so not a shonky copy

 

Is this normal, I understand the Design/Fully Charged will always differ, but I thought the Design and actual battery should be close?

[Steve21]

It doesn’t need to be - some designs will be at a lower rate but with a higher real option to “extend” how long it’s fully charging for. If I tell you it’ll do 40 for 3 years, it might really mean it’s 50 but will drop to 40 on 3 years etc - yep bizarre branding!

 

Alternatively something like lithium batts could have a higher charge as they’re designed to drop voltage over time and then they become the “designed” level etc

 

Steve

[Sheridan]

It doesn’t need to be - some designs will be at a lower rate but with a higher real option to “extend” how long it’s fully charging for. If I tell you it’ll do 40 for 3 years, it might really mean it’s 50 but will drop to 40 on 3 years etc - yep bizarre branding!

 

Alternatively something like lithium batts could have a higher charge as they’re designed to drop voltage over time and then they become the “designed” level etc

 

Steve

Good point, I guess its possible its a 50mWh battery 'branded' as 41mWh for longevity or user expectations. Never seen it before but I'll be checking every battery now!

[PotNoodleTech]

Generally you don't want to charge and discharge a lithium battery to 100% or 0% so often the battery management will have a built in limiter at the top and bottom so that you effectively only ever discharge to 10% and only ever charge to 90% of the batteries theoretical maximum.

 

So 41 from a 50 sounds about right and down to 30 after a few years sounds about right too!

[Sheridan]

Interestingly (to me!) I had a look in the bios, and there was a battery option for maximising either 'duration' or 'health' - it was set to health

 

Setting it to duration and the Charged capacity has now gone to 36mWh! - which manifests itself in Windows as about another 20%

 

It's not a heavily used device, so I'll leave it with the duration set - that's more use to me and if it knackers the battery its a 3-4 year laptop anyway so its probably past its prime