Laptop battery suddenly drop from 35 percent to 7 percent

[PrinceAkai]

I have bought this used HP EliteBook 8470p. I used it about 8 times and out of those 8 times i got this issue 3 times that my laptop battery suddenly dropped to 7 percent from 35 percent. I run battery test through bios, HP power Manager and HWDmonitor and it shows the battery health is excellent.

I think updates were installing in the background when this happened. I don't know if that would be the issue.

I don't know if that is normal or there is something wrong with the battery

[Huffer · Accepted solution]

You need to look at the "advanced" output of the battery test. It will give you specific data on how old the battery is, how many charge/discharge cycles it has had and the remaining ability of each cell to hold a charge. An 8470p is pretty old and if the battery is original, and many years old it explains a lot. The "excellent" health message is not really very informative. You will get that as long as the battery is not physically or electronically damaged and not completely dead. 

Post the advanced readings here and we can help you decipher.