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Charge Control Software

B

Brian Stirling

Diamond Member
I have had laptops that had the battery die within a year or so but the battery in my current work laptop, a Lenovo T61 ThinkPad (2.6 years old), still retains a good portion of the original battery capacity. The differnece as far as I can tell is in the way the ThinkPad handles charging the battery. With many laptops the battery is being charged if the power adapter is plugged in even if the battery is already fully charged and that's not good for battery life. My ThinkPad, however, has a feature that permits you to stop charging at, say, 95% and not to start charging if above, say, 85% so that when plugged in it will run off of AC power without charging the battery so longs as the charge level is above the minimum charge level. When the charge level is below the minimum level it will start charging and continue until reaching the upper cutoff.

Now, my question is ... is there any software that can control the charge of a generic PC running Win 7/Vista? I'm thinking most laptops control the charge action in hardware so software is unlikely but I have to ask...


Brian
 
It is going to vary from laptop to laptop on what you have access to regarding the charging. Most are going to use a charge controller IC on the board and just use the bios to measure voltage and charge state without any way of changing how much it charges. Even while plugged in the AC is not charging an already charged battery. Li-ion batteries can catch fire if over charged.

The best way to extend battery life is not to completely discharge the battery before recharging. Letting the battery drop to below 25% before recharging will shorten the battery life because in Li-ion batteries when they reach a low voltage state they start to form copper inside the cells that will hurt the capacity. Once the battery is damaged from that there is no way to restore it. So charge as often as possible.

Now if the laptop is using NiMh batteries you want to do the opposite. Fully discharge before recharging.
 
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I'm pretty sure you're right that most all current/recent design laptops curtail full charge current for safety reasons but not so sure I buy that they all stop charging entirely. Both the batteries I had for my Dell E1505 laptop (just under 3 years old) have been dead for a couple years -- both of them. I very seldom ran either of them down below 50% and in most cases ran it plugged in. I do the same with my company ThinkPad T61 that's just a few months newer and the single battery I have is still pretty decent.

It is absolutely true that Li-Ion does not like to be overcharged and not just because of the safety issue but also because it shortens the lifespan. It is also true that you do not want to run the battery down all the way very often and that keeping the charge above 50% will significantly extend the life -- so long as you don't overcharge.

My new HP laptops (18.4" dv8t and Mini 210 HD) do not have the options for charge control that the ThinkPad does which is why I asked. I suspected the charge control was by IC but if BIOS can vary the operation than higher level software should be able as well. Again, if I could control the charge so that the battery only charged when below, say 85% and stopped charging at about 95% I would be a happy camper...


Brian
 
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