Laptop Battery Loses Charge Quickly

alphaa10

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Nov 20, 2006
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After fully charging and putting aside one of my laptops for two weeks with the battery installed, I attempted to start the laptop and found the machine completely dead.

At first, I suspected the (new) battery might be faulty, so I recharged to 100 percent, removed the battery and put the laptop aside for two days. If the isolated battery held its original 100 percent charge, or even a few points lower, I could not conclude the battery was faulty.

On checking available charge after two days by reinstalling the battery and booting with the power supply, I found the battery at nearly 100 percent.

Next, with the battery still at 100 percent and installed, I again put the laptop aside for two days, and after checking, found the battery had lost significant charge-- down to 75 percent.

Here, I reviewed by findings. Whenever I switch off the laptop with a normal, complete shutdown, with no LEDs of any kind displayed afterward, and with no hard drive or fan noises, my laptop battery still "bleeds" charge at a significant rate. Rather than presume this is normal, I have checked my other laptops and found the same charge decay effect. The charge drops by as much as 10 percent daily.

All this may be industry-normal. For example, cellphone batteries eventually lose charge, especially when the cellphone is actually still ON while on standby status But if the laptop were fully shut down with battery installed, and its status confirmed (no LEDs or whirring fans, anywhere), why should the laptop battery bleed voltage?
 

thx1138v2

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Jun 18, 2011
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This does seem a bit strange. My laptop sometimes sits for months without a problem. There are a few things to check. Turn the radio for your WiFi off before you do the shutdown and see if that helps. If it has a GPS device do the same for its radio. You might also look in the BIOS and see if any of the "resume on..." settings (like resume on LAN, resume on modem, etc) are set. It takes a bit of power to keep those running.

Different types of batteries have different charge/discharge profiles. Lithium Ion need to be kept as fully charged as possible when not in use. Some of the older battery chemistries needed to be fully discharged occasionally and then fully recharged but that does not apply to Li batteries. Because of that limitation you should always use a power cord when available and only use the battery power when necessary. Deeply discharging an Li battery will result in it holding less charge.

Batteries age so it could be a consequence of normal battery degradation if the batteries are old. They can only be charged/discharged a certain number of times. That usually shows up as the battery not charging fully. It may be that the circuitry in the laptop is just saying that the battery has taken as much charge as possible when it reports 100% but that would be strange also.

BTW, a cell phone is still powered when it is turned "fully off". The beacon signal that identifies cell phone towers is still being sent. The only way to fully power down a cell phone is to remove the battery.
 
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alphaa10

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Nov 20, 2006
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In other words, my laptop is still draining its battery because of a setting and/or intrinsic condition. OK, I'll look for that, certainly. And I appreciate your reminder about Li battery care-- even my local battery store may not know the usual NiCad maintenance of deep cycling at least once monthly does not apply to Li batteries.

Yes, it seems counter-intuitive, but the best way to preserve Li battery life is not to use it.