battery not charging when it says it is!

[vivienne61]

I bought a replacement battery for my mid 2010 MacBook and its been working fine up to now, the battery age is only 10 months.Suddenly it is not charging at all.The strange thing is, it says 99% charged both on the menu bar and in the Battery Health app, which also says battery health is good.But if I unplug the power adapter the mac immediately shuts down as though the charge is gone completely.I know the power adapter is fine as it charges my husband's MacBook with no problem.I reset the SMC but this made no difference.Is my battery dead?It was bought off amazon, the make is Simplo and it was well reviewed, not a guarantee i know! Is there a way to find out the true state of the battery?
Also,the battery light indicator just stays on red, never turning green.And it stays on 99% in the menu bar.
Just noticed, the light is green and it now says 100% charged! I will unplug and see what happens
Ok,so I unplugged the power and immediately the MacBook shut itself down.I had to plug power adapter back in and press the power button. so the indicator is saying battery is charged on the menu bar but seemingly it's not.

 

[Raz0rEdge]

That seems to be a very poor battery that is taking the charge, but not holding it. So the charger circuit seems to get the right readings, but it isn't functioning as it should. That's one of the problems with after-market batteries. If you are within some sort of a 1 year warranty or something, you should try to RMA the battery and get a replacement.