Archos 80 Cobalt Battery Issue

[rubberfingers]

Hi there hoping someone can help

I have an issue with my cobalt tablet in that it will sometimes refuse to come out of sleep and I have to reset it (press down power button for 15 seconds). When it starts back up it has lost a LOT of battery all in one go. On one occasion I lost all battery I had overnight. Othertimes I can use the tab and put to to sleep multiple times for over a day with no issues. The sudden battery drop can be as much as 50% in one go

[m600]

I had the problem too look at photos,screen shot 1 just before i went to bed, screen shot 2 in the morning, screen shot 3 open used it dropped down to 16%.

https://www.dropbox.com/sh/449iaojr2t629ea/XCtzfAqIoz

I did use this app below but forgot to check again on the stock rom.

https://play.google.com/store/apps/details?id=com.nema.batterycalibration&feature=related_apps#?t=W251bGwsMSwxLDEwOSwiY29tLm5lbWEuYmF0dGVyeWNhbGlicmF0aW9uIl0.

Now running 900Supersport rom did the same test with wifi off as it was on the other test.
You can see battery now spot on been using it fine not dropping fast at all.