Six months ago, I purchased two new Dell Inspiron 15R laptops with Windows 7.
- Both laptops have the default Dell power plan selected in the Control Panel power options.
- Both laptops have updated BIOS and Quickset drivers.
- Both laptops are usually used every day, at home plugged in, and rarely need to be used away from home on battery power.
- Two weeks after I started using them, both laptops displayed a message advising that Dell's Desktop mode battery charge should be selected in the power options, and both have had Desktop mode selected since then.
The description of Desktop mode says: "Leaving your computer continuously plugged in may reduce the health of your battery. Should you like to keep your system plugged in continuously for more than 2 weeks, Dell's Desktop mode will protect your battery by moderating the extent to which your battery will charge, resting and protecting your battery when it is not in use.... Battery will only charge between 50% and 100%."
This suggests that the battery will be discharged to 50% and then recharged to 100% automatically and regularly, even while plugged in continuously, although the timing of the cycle is not specified.
My question is: what is the programmed timing of this cycle; i.e., when the computer is plugged in continuously with Desktop mode selected, at what intervals should I see the battery being discharged to 50% and then recharged to 100% automatically?
I need to know this because the battery charge has been varying on my laptops, but not exactly as expected from the description of Desktop mode, and I need to know whether this is because of a possible fault in the battery hardware or because of the way the Desktop mode software is supposed to work, which is unclear from its description.
I read some other posts touching on this question, but they did not answer it.
http://en.community.dell.com/support-forums/laptop/f/3518/p/19460831/20159258.aspx#20159258
http://en.community.dell.com/support-forums/laptop/f/3518/p/19498305/20328924.aspx#20328924
http://en.community.dell.com/support-forums/laptop/f/3518/p/19496518/20321412.aspx#20321412