How can I keep battery inside laptop not charging?

I want to keep the battery inside at about 40% as a UPS while using power cord. I want to charge the battery only once a month but always kept inside laptop to serve as a UPS. How can I prevent it being 100% charged?

I have Dell Precision M4300 using Win 7, 64 bit.

Any ideas? Thanks.

 

Does Fn + F2 do anything for you?

 

It does nothing.

 

I don't understand what you are trying to achieve. A UPS works just like a notebook power system. Whilst AC is present (via the power adapter in the case of a notebook), the battery is kept at >98% of full capacity. Since the batteries in both a UPS and a notebook discharge even with no external power draw (due to internal parasitic resistance), your concept of keeping it at 40% would also not work. Notebook power sections are fairly sophisticated and my advice would be to let it do its job....

 

You are right. Fn + F2 stops battery charging from Ex400 series onward, but it does not seem to have been implemented on any D-Series (and related Precisions). I don't know of any other way to do this; your best bet is to move to a newer Latitude or buy a ThinkPad. TP Power Manager has much better control over when and how much to charge the battery.

Also, please do not make multiple threads about the same topic. Your other thread has been deleted.

 

I want to make battery life longer by not being continually charged. And most people recommend to keep the battery 30-50% charged outside for that, but I need the UPS function of battery inside laptop.

 

For the moment my M4300, 2.6 Ghz dual core, 4 gigs ram, 500 Gb hdd, 1920/1200 screen is pretty good for me and the battery it's like new...

 

I'm just saying if you want this functionality, I don't think you can have it with an M4300. Do tell if you figure something out, though, I'd be interested to know as well.

 

I've never heard of the 30-50% charging. Thinking about it logically, 40% or 100%, it doesn't make any difference. There will be no battery discharge whilst AC is connected, apart from parasitic resistance current draw, which is the same regardless of the state of charge, so again, I don't think it matters.