How to test the battery? Is it faulty?

[Garawa]

I had a problem where the PC shut down suddenly and tried to start up (but failed), flashing on and off the power and Caps lock lights in an irregular pattern. I didn't really get an answer as to why this may have happened when I posted this here: https://h30434.www3.hp.com/t5/Notebook-Hardware-and-Upgrade-Questions/PC-completely-dead-but-is-fine...

With fingers firmly crossed, it has worked fine since and has been used on battery and charge for several hours at points! I was advised previously to run some hardware tests which all came back as fine. I originally suspected a failing power supply but now think this may be the battery. After a year of having the laptop, the battery lasted about 4.5 hours from the original 9 from at first use. After just 22 months, it now lasts about 2.5 hours and takes a fraction of the time to fully charge (about 25 minutes). When it charges switched on, it can sometimes get VERY hot and the fans worked really hard when before it was always cool and the fans were silent. If I charge it switched off (not standby) until fully charged and not switch it on, the battery will be fully discharged after 2 days when before it would barely drop past 100%.

Antivirus is fully up to date. BIOS was updated last week and all Windows updates have been installed. As the battery has clearly degraded over time, could this have caused the fault? The HP battery check application showed that the battery was not one on the recall list. The hardware checking application stated that both the battery and the charger were working correctly. Is there another test that could be done? Would they show as OK if they fully charge even if at a lower capacity than when new? What is the best way to replace the battery?

Any thoughts will be fantastic. Thank you.

[Huffer]

Run the HP Battery Check from the HP Support Assistant app and on the results screen there is a link to "show advanced information" or something close to that. Click on it and you get much more data about your battery. Post that and we can help you decipher. I really don't need to see that. I know from your description of how the laptop works it needs a new battery.

Service Manual

Pages 34-42 show "how to" on accessing replacing the battery. 

3-cell, 41-WHr, 3.615-AHr, Li-ion battery 844203-850

https://www.amazon.co.uk/Batterytec%C2%AE-Battery-HP-HSTNN-UB6W-844203-850/dp/B07P6HWM9Y/ref=sr_1_2?...

I have no stake in this battery maker and there are other options. Let us know if you want some other links. 

Post back with any more questions and please accept as solution if this is the info you needed. 

[Garawa]

Apologies for the delay. I thought there must be more to that support app, ha ha. Thank you. I will try that tomorrow and come back to you. It's odd, today it was on 100% after being taken off charge 2 days ago so the battery is good at times or awful. I hope we are both right that it appears to be the battery as it has been playing nicely lately ha ha.

[Garawa]

OK, here is the screenshot of the diagnostics with and without the power attached. As you say, it is likely it will be the battery and I'm (hesitantly) more comfortable it is not the power supply. Hopefully these will confirm it. Could you let me know what this tells me as I suspect this issue will reoccur in the future and it will be good to know. Many thanks.