So I’m normally a fairly sharp guy, but this has me stumped.

I have a Lenovo ideapad 720s with Win 10. 4 years old.

A few days ago after using it on battery for a few hours, I returned home to find it nearly dead. Strange. I connect to power and it is still losing battery percentage. Seemed obvious to me that the battery had failed. Battery diagnostic confirmed it (but then said battery was fine after I charged overnight).

Either way, I order a new battery (cheap Chinese knockoff as there is no longer an OEM). I charge it, which takes a concerning amount of time and today, the battery does the same thing as the old one. Drops from 75% to 5% is under 10 minutes while hooked to my monitors (not even using its own display).

Battery diagnostic tools say the battery is fine, but… something is clearly wrong. What could possibly be draining these batteries within minutes?

Is it possible I had a battery go bad, then got a lemon battery as a replacement? I guess, but the odds seem rather low.

Any ideas appreciated as I am pulling out my hair over here