did i damage my battery?

9150 stays plugged in 24/7. did a full discharge when i first got the machine. this was back in mid-june. it went well and total capacity has exceeded the designed capacity by ~2k mWh till now. been plugged in since. i decided tonight i should do a calibration. from full charge i ran it down to 1% and then plugged in.

i have a feeling this was a very bad idea. i went from 0% wear/~79k mWh TC to now 3.5% wear/~74mWh TC. with my limited knowledge of li-ion batteries, this fails the eyebrow test. please tell me why this was a bad idea and why i should never "calibrate" this way again. is it possible that a full charge will bring the TC back above the DC, or is that just wishful thinking?

 

When you do full discharge it actually just calibrates the battery so it is more accurate in displaying its actual capacity. Many batteries come from the factory with as much as 5% wear, or 5% less than rated capacity. So your battery could have likely been ~ 3% less than actual capacity to begin with.

That being said, it is not a good idea to drain a battery completely dead. I believe there are some safeguards so when it reads 0-1% there's still some safety margin there not shown. But still not a good idea.

In any case. draining to 5-10% is ok. Just rapid discharges can kill a battery (like gaming on battery), but moderate use is ok, that's what it's there for.

 

Do not some batteries come with circuitry to prevent those types of mishaps? In addition, aren't there also "smart" charges that also come with their share of additional safe guards to that end? One of the useful things you pay extra for. I have a "smart" charger. Exactly what was it that I paid extra for?

 

this is a myth from the NiCad era of rechargeable. They had memory issues and regularly required calibration and full discharging to read correctly. Li-ion batteries don't have memory and you actually burn them out faster if you let them die completely. Most laptops prevent this by shutting off at 5%. They only have so many cycles.

On that note, they also don't do well with "trickle charging". That means leaving it on a charge while at full capacity can damage them too. Your best bet is to charge it and then remove it while the laptop is plugged in, then pop it in when you are ready to take it off wall power.

Smart chargers simply shut off charging when the battery reads a certain voltage, which is usually 4.2v on a typical single cell Li-ion. They are rated at 3.7 but can be overcharged to that voltage safely.

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The laptop should be smart enough to stop charging the battery once its fully charged. I recently sold a laptop that was a year and a half old, and spent most of its life shut off, fully plugged in, with the battery inserted. Battery wear was 5% or less when I sold it.

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It is smart enough to stop charging when it's full, but once it drops down a percent it charges it right back up again. That's trickle charging. Some batteries handle it better than others but some batteries die completely even though they have been plugged into a charger 95% of the time.

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Your battery already had 3.5% wear or more calibrating the battery gauge just showed you the correct reading, I like to do a calibrate when i first get a notebook and then every 3 months or so, while it is still in warranty so a can get a replacement, as calibration can cause a battery to fail if it is weak in the first place.

John.

 

That's not trickle charging. Trickle charging is a constant charge to the system, albeit small. Most laptop batteries will stop charging at 100%, drain to about 95-97% before it charges again. It can take seveal weeks to a month or more before it drops to that level before it's charged again. It's not like it drops to 97% in a day when not used. It holds a charge for a while and slowly drops over time.

Recommendations to remove the battery is not sound advice. They are there for a reason, and relatively inexpensive to replace. Trip on your power cord, accidentally flip the power outlet switch, power goes out, whatever, you'll wish you'd had the battery installed. It's a built-in UPS. Laptops are so much more suspetible to a power cord removal because they're usually small plugs, loosely attached, within the vicinity of your workspace. Unless the laptop is horribly horribly designed and heats up the battery significantly, it won't make much difference in the life of the battery. People pay hundreds of dollars for UPS systems for their desktops, yet I don't understand why people are so anxious to remove a $60-80 battery that serves the same purpose and more.

 

Yeah. Leave it in for convenience and buy a new one when necessary, imo.

 

You are probably right. I'm not as familiar with laptop batteries as I am regular Li-ion batteries themselves. They do have a habit of dying when left plugged in for a long time, but I'm not really all that sure why other than that.

I defer to those with more experience than I

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Yup. Plus a lot of new computers don't even have removable batteries. A lot of computers also have reduced performance once the battery is removed.

Either way, the battery is a consumable component and will start losing capacity as time goes on regardless.