Battery cycles

My new laptop battery (working fine, so far) says something about it being good for 300 cycles.

Its my understanding that it means, 300 drops from 100 percent power to almost nothing.

My question: how low can my battery go without it being one of those cycles, and starting the clock ticking? I typically keep it charged in all the time, up to 100 percent, but occasionally it does go down. How low can it go, before it counts as a cycle?

 

Thanks for the link. The page was down, but archive.org gave me the info I needed.

My battery box said it was guaranteed for 300 cycles, which the page you linked to, defined as a charge below 50%, and then a recharge to 100%. A "full cycle" was evidently defined as fully draining the battery before recharging.

Unfortunately, the similarity of terms makes me wonder which cycle my package was talking about. I'll email the maker (uBatteries) and see if they have anything to say.

 

Wow! I just called ubatteries on their 877 number on the box, left a voicemail, and I actually got a call back about 15 mins later.

The lady I talked to said that the "300 cycles" was a full power down to 1 or 0 percent. Of course, she recommended that I let my battery power down like this, instead of keeping it at 100%, but I'm thinking that approach is good for their business.

I kept my stock Toshiba battery always recharging, usually at 100%, and it stayed that way for about 2 years, with something like a 6 hour life span. A month or so ago, it started reporting a lot lower life span, and hten a couple of weeks ago, it stopped taking a charge. I'm not sure if it was due to my constantly recharging my battery or not, but I gotta say that if I always let it drop to 0-5% before plugging it back in, my battery probably wouldn't have lasted a year, if it would have konked out at 300 cycles. So I'll maintain this strategy for my new battery as well.

 

Hi Paul, This is a good read - How to look after Lithium Batteries - http://h10025.www1.hp.com/ewfrf/wc/document?cc=us&lc=en&docname=c00596784

It should apply to any Brand. Neil.

 

Well if you keep it plugged in all the time, take the battery out and then when you need it for real, plug it back in and use it.

 

You can let it go down to 12% before you charge it. The only time you let the battery get down to 0% is if you are going to calibrate it. In order to calibrate the battery you have to create a new power plan.

 

Here's some more food for thought: http://www.wired.com/gadgetlab/2013/09/laptop-battery/

The general consensus appears to be running the battery between 40-80% and that the battery will not last forever. Neil.

 

Interestingly enough, at the Wired article, commenters are suggesting the same thing I've been--simply leaving it plugged in, charged to 100%, to avoid the 300 or 1200 cycles. Even the HP article didn't address this point.

Of course, I have a battery that won't hold a charge after 2 years of doing this. However, its not at all clear to me that keeping it charged up all the time is what wore down the battery. Up until a couple of months ago, it had close to a 6-hour charge life.

 

The problem with all these articles is they tend to be very generalized, or to the other extreme very specific to one particular notebook and battery. But notebook batteries come in all sorts of types, shapes and sizes. While Li Ion is the most common not all use Li Ion and not all Li Ion batteries require the same "cycling" routines. There are still nickel-cadmium (NiCad) and nickel-metal hydride (NiMH) batteries out there. And fuel cells are becoming more popular too.

IMO, the ONLY guide you should use is the one printed in your notebook's owner's manual.

My 4+ year old Toshiba with a Li Ion battery rarely ever gets unplugged. But it rarely ever gets "shutdown" either - it just goes to sleep. When new it got almost 2 1/2 hours of run time (17" widescreen and with wifi enabled). It still gets about 2 hours 15 minutes of run time - pretty good, IMO, for a 4 year old battery.

In my Toshiba manual it lists a bunch of Tips on "how to take care of your battery and prolong its life" and not one says anything about keeping it between any percentage or to disconnect the charger when not in use (see exception below).

As for deep cycling (fully discharge then charge) it only says to do this "periodically" to "allow better accuracy of the battery meter ". That might happen every 2 or 3 months with this Toshiba.

For disconnecting the charger when not using the computer for extended use, that is shown as a "safety" measure - and not to extend battery life. I read that as "legalese" - words their legal department made them put in. Also under "safety" it says to remove the battery if the computer will not be used for 30 days.

Note I just bought a new TV and under safety, it says if unused for long periods to unplug the TV and remove the batteries from the remote.

 

With my experience in the Motor Industry, the Service Periods were suggested as the "Safe" time. Naturally these get extended and there are millions of vehicles that continue to run OK well overdue for servicing. There is a margin for error.
It comes down to personal choice - whether you follow the manufacturers Service Schedule or do it your way.
I cannot see the reason to leave a Laptop charger plugged in with the battery fully charged all the time. Rechargeable batteries require a load to drain the charge and then charge to cycle the battery material - usually in a controlled environment. (Temp/humidity etc.)
When you leave batteries in devices (torches/radios/remotes) unused for a long period of time - corrosion is usually the first problem to occur.
Then you may recover the device by cleaning and renewing the batteries, but quite often the device is so badly affected by the corrosion that you are faced with complete renewal.
As I said - user choice. Neil.

 

I don't see the connection between the first sentence and second. To me, the second sentence would be an argument/excuse not to worry about leaving it in.

Reason to keep it plugged in? Is a reason really needed? One reason is those connectors are not very robust - in fact, they are rather fragile. Broken connectors are a common reason notebooks go into shops. Constantly plugging it in and out increases wear and tear (weakens essential tension on the contacts).

Another reason to keep it plugged is most notebooks are used as desktops most days and scrambling for the power connector during the middle of an important computing session is a real PITA - especially if the charger is not already plugged into the wall and ready to go.

You are absolutely correct that leaving batteries in unused torches (flashlights on this side of the Big Pond) can, and often does result in corrosion. But I don't know of any "alkaline" notebook battery. But more importantly, I don't believe this topic is about "unused" notebooks. FOR SURE, if you will not be using your notebook for weeks on end, you should remove the battery.

As for the second part, not sure your point but the chemical process in rechargeable batteries continues even when not in a circuit - though admittedly, at a much lower rate - especially with rechargeable Li Ion batteries (not all Li Ion batteries are rechargeable - CMOS batteries are not, for example).

That said, when the notebook battery is installed, there is still a load on it - albeit a tiny load. The notebook battery is used to keep the RTC (real-time clock) running when in circuit. And if the notebook is in sleep mode (instead of full shutdown) for example, it will use a little more power.

This is why a notebook battery will run down faster in a shutdown notebook than if removed.

And when using the notebook with the battery installed the battery is in the power circuit even with the power connector connected. There is no "cutover" when you pull the plug. This is why notebooks don't need to be on a UPS.

So I return to my point earlier, follow the specific instructions for your specific notebook and battery as spelled out in the manual for that notebook and battery.