1. When the battery is new, discharge it completely and charge it completely three times as soon as you can. This is said to 'condition' the battery to enable it to charge to full capacity in future - failure to do so will mean your battery never charges as much as it could.
2. If you're using the laptop on the mains, remove the battery and only reinsert it when you need it. Speaking from bitter experience, my wife failed to do this on her Acer and I failed to do it on my Compaq and in both cases, the batteries are now bricks (and they ain't cheap to replace...)
Batteries in laptops (Li-On type) can not withstand any trickle charging what so ever. The chemistry soesn't support it so when it's fully charged the current is cut off and the battery left to naturally lose charge if it's not used. When the charge falls a percent after a few days it then automatically gets topped back up and the process repeats.
Heat is one killer of batteries... does the laptop run hot and thus heat the battery ?
And use is the other, they only have a limited number of full charge discharge cycles available.
I too have an Acer, a 9301 and that's 4 years old this month, original battery still I would say as good as new. I only use occasionally on battery but do give it a good discharge every 3 or 4 weeks or so.
That doesn't answer the original question but does/did W7 ever have a disable feature... seems odd. Was it a feature included in the manufacturers software that a clean install would have lost.
'you didn't reinstall when you reinstalled Win7?' good point! Seen as the integrated web cam is not working either, it reports a missing driver, but I've had problems logging on to Dell web site (can't find the Tag Code) to try and download them!
Well I've found my service code and it wasn't where the web site it would be. And the web cam and the battery control drivers/utilities have to be installed in the correct order for them to work, so it loooks like a reinstallment!