Laptop Batteries: Is 80 / 20 Rule Correct?

A local computer repair shop told me about the 80 / 20 laptop battery rule to make battery last longer & make laptop last longer. Are the following rules correct? If so, what is the reasoning behind the rules?
Rules:
(1) Keep battery below 80%
(2) Keep battery above 20%
(3) Do not fully charge battery
(4) Do not fully discharge battery
(5) Once battery charge reaches about 80%, remove battery from laptop
(6) Do not remove battery or install battery when the laptop is on. This could damage battery and/or laptop.

 

No (except #6). The rules you follow are the ones stated in your notebook's user manual. This is because the notebook makers have designed the battery charging and battery monitoring circuits and software to properly maintain the battery - safely. And not all notebooks do it the same way, just as not all batteries are the same.

I will comment on those rules, however.

Rule # 1 makes no sense. While Li Ion batteries don't suffer from "memory effect" like older batteries technologies, studies have shown they do indeed suffer from it to some extent. And for sure, older NiCad notebook batteries definitely suffer from memory effect. So if you only charge to 80%, eventually, the battery will never let you charge beyond 80% because it will think it is fully charged. Beyond that, a notebook's battery charging and monitoring circuits will not let you overcharge the battery.

Rule # 2 makes no sense either for the same reasons as I stated for #1. If you never let it fully discharge, eventually due to memory effect, the battery will think 20% is the lowest it will go - and the notebook will shutdown at 20%. And for the record, every owner's manual I've seen tells you to fully discharge the battery on a regular basis. Mine says once a month. This is to "exercise" the battery, but also to calibrate the battery to the notebook's battery monitoring feature. And like above, the notebook's battery charging and monitoring circuits will not let the battery discharge to 0% - but it does get really close and that's okay.

Rule #3 and #4 - see #1 and #2.

Rule #5 makes no sense. The only time you should remove the battery is when the notebook will not be used for a long period of time - which is what every battery operated device says. Even a simple flashlight. So if you are going to be away for several weeks, then remove the battery and put it in a cool, dry place.

Rule #6 is the only one that makes real sense. Though damage is unlikely, it could happen if a "clean break" is not made. I think the greater risk is to the data on your drives. Any time you suddenly remove power from any computer (PCs too) without properly shutting down Windows and the computer, you risk file corruption.

For the record, I have a Toshiba A505 I bought in February 2012. I keep the charger plugged in 24/7. Every couple weeks, I unplug the charger and let it run until the notebook's battery monitoring circuits automatically put the notebook into hibernation mode. Then I plug it back in and let it fully charge again. I have never removed the Li Ion battery and still after 6 1/2 years, the battery works just fine. Note that all batteries lose strength as they age. My notebook used to run for 2 1/2 hours before the battery discharged. Today, it lasts just over 2 hours. I can't complain about that. In fact, just the fact my battery is still good after 6 1/2 years is pretty darn good.

 

Thank yo so much. I thought the info fro the computer repair shop seemed bogus. Makes me question the shop's competence.

 

There are a lot of old myths and wives tales floating around computer tech circles that may at one time been centered on fact. We see them still be repeated and recirculated on forums all the time. At one time, it was possible to overcharge and destroy a battery (and start fires!). And at one time, it was possible to discharge a battery so thoroughly, you could actually reverse the polarity (turn the + to - and - to +) and destroy the battery. But notebooks and notebook batteries themselves are intelligent devices and unless physically damaged through some sort of abuse, they just don't get damaged like that anymore.

And we have all seen an old flashlight or other device where the batteries leaked and corrosion was formed - so the advice to remove batteries from unused devices has been a longstanding recommendation and does still apply for notebooks if not going to be used for awhile (BTW, you should fully charge the battery before removing it for long term storage).

And there is a history of faulty notebook and other Li Ion batteries (hover boards, cell phones, etc.) melting or catching fire too.

So my point is, all those rules lean towards safety. So I would not dismiss your local tech just yet if this is the only thing you have to base your suspicions on. Erring on the side of caution is better than making suggestions that might create a hazardous situation.