Battery life: leave plugged in or let discharge

[RobertJSawyer]

I own a lot of Kobo units of various types. My go-to is an original Kobo Aura six-inch, but I've actually got two of those, a Kobo HD, two Kobo Minis, and a Kobo Glo. Some of these go unused for weeks or even months. My question is about best practices for preserving battery longevity (not usage time per charge, but the overall life of the battery itself). Is it better to let an unused unit just slowly discharge on its own until the batter is empty/flat, or to leave that unit plugged into a USB charger (of which I have many; doing that would be no inconvenience)? Thoughts, please? Many thanks!

[frostschutz]

don't let the battery run flat

just hold the power button to turn the device off altogether (it will turn off by itself eventually, if you set a timeout in the power saving settings, and don't use mods that prevent it)

then boot it up once every 3-6 months, perhaps charge it for a bit (to 80%-ish at least), and turn it off again

batteries age even when not in use, but for most ereaders, it's possible to find replacements under $10

[rashkae]

Neither. Best practice for storage of LiOn batteries is to do so between 40-60% charge. Either leaving it fully charged at 100% or letting it run flat will be stressful to the battery.

If the Kobo is turned off, it should be able to maintain a storage charge for a *long* time. Unfortunately, there is no way to power off Kindles, so they will run down and need periodic charging. Although so far, all the readers I have let run flat, Kindles and Kobo's, have successfully powered themselves off when battery is low enough to prevent any immediate battery killing damage, (in truth, no sane LiOn powered device should ever allow you to actually run battery completely empty.)

[RobertJSawyer]

Thanks for both replies. In a perfect world, either of those answers would be applicable. But I'm lazy, and I also don't know in advance that I'm putting a unit on hiatus for weeks or months; it's only weeks or months later that I realize I haven't used the unit for a long time. So given who I am, the only realistic alternatives for me are (1) just let the battery run out over time or (2) keep the unit plugged in all the time when not in use. OF THOSE TWO CHOICES, which is better for long-term battery health (and I fully concede that neither is ideal). Thanks!

[frostschutz]

letting it turn itself off is not an option? it's in the power saving settings.

oh, I forget the max setting is 60 minutes... should be 1-2-3-7 days I guess

I would not keep it on a charger. Even if that worked, you never know. The charger might blow at some point, burn down your house, or fry the reader during a lightning storm, and it will just add to your electricity bill

[Readirect]

Originally Posted by RobertJSawyer

I own a lot of Kobo units of various types. My go-to is an original Kobo Aura six-inch, but I've actually got two of those, a Kobo HD, two Kobo Minis, and a Kobo Glo. Some of these go unused for weeks or even months. My question is about best practices for preserving battery longevity (not usage time per charge, but the overall life of the battery itself). Is it better to let an unused unit just slowly discharge on its own until the batter is empty/flat, or to leave that unit plugged into a USB charger (of which I have many; doing that would be no inconvenience)? Thoughts, please? Many thanks!

There's a lot of disinformation about Li-On batteries and continuous charging. It's an issue that usually comes up with respect to laptops but it applies to all Li-On batteries. Li-On batteries, btw, are used on all electronics devices including phones, laptops and e-readers.

Electronics batteries USED to be NIMH which had a bunch of problems with respect to charging -- both memory effects from charging before not being (almost) depleted AND overcharging. Li-On fixed both of those problems BUT you still see the same fears (and resulting disinformation) from users repeated over & over. Disregard them

You can leave your Li-On powered device charging without consequence and you can also recharge them at any point without worrying. You can also fully deplete the battery for *brief* periods. The only thing you shouldn't do is leave the battery fully depleted for many (many) months because that *will* shorten its life ... but not immediately.

The other thing is that no Li-On battery is designed to last for more than about 2-3 years although some can last for longer. That's not a function of how it's charged, it's a function of the battery itself.

Here's a YouTube video from Dell about Li-On batteries. It's specific to their laptops but it applies to all batteries, regardless of manufacturer or device.
https://www.youtube.com/watch?v=mUNDZEak9E0

[rashkae]

Originally Posted by Readirect

Li-On fixed both of those problems BUT you still see the same fears (and resulting disinformation) from users repeated over & over. Disregard them

This is just not correct.. Most people making suggestion with regards to best practice/management of Li-Ion batteries do so from this *this* data:

https://batteryuniversity.com/learn/...ased_batteries

I have not, myself tried to reproduce these experiments, so I'm open to the idea of debating the data.. but the suggestions you see here to to extend the life of battereis is *opposite* of the NiCD advice. With NiCD, best practice was to always fully discharge and fully recharge batteries... with LiOn, it's the opposite, and you get better battery life by avoiding *both* those extremes.

[DNSB]

For what it is worth, I've seen the same type of information as in the link posted by Rashkae at several other sites.

Lithium Ion batteries do not have the same issues as Nickel Cadmium (horrible memories there) nor Nickel Metal Hydride but that does not mean that they don't enjoy their own issues such as temperature sensitivity being more of an issue.

@Readirect: NiMH batteries lack the memory effect that was one of the biggest problem with NiCad batteries. You can get a voltage depression from multiple partial discharge cycles but that can be cleared by a couple of full charge/discharge cycles.

[compurandom]

Draining a lithium flat does shorten its life a bit, but leaving it that way for months will *kill* it. (Draining it flat shortens the life vs. having used the same amount but topping it off several times instead.)

Topping off a lithium battery generally doesn't hurt it and may reduce the number of full charge cycles it goes through; however, I've seen studies (probably from battery university) that charging a lithium in the 95-100% range may shorten its life slightly, and some of the charge control chips don't allow that anyway under certain circumstances.

[the.Mtn.Man]

This topic seems to come up a lot, and the correct answer is to do whatever you want, because modern electronics devices have a number of safety features built in to prevent batteries from being destroyed by overcharging and over discharging.

[lumpynose]

I wouldn't worry overmuch about it; whatever you do, by the time the battery is kaput you'll probably have replaced your e-reader with something better; e.g., 600 dpi, 24 core CPU, 128 gig of flash ram, etc.

But telling worry warts to stop worrying is a waste of breath; I know because I'm one.

[Tarana]

Letting the battery run out guarantees shortening the battery life considerably. I just regularly charge older stuff every 3 weeks and newer stuff once per month. I am not giving up my Kindle Keyboards, so I just alternate them now and then for some use and to keep the battery going. Once the clicky keys are gone, they are gone forever, and I'd rather forestall that.

For the early Kindles, they were expected to last 400-500 complete charge cycles.

[the.Mtn.Man]

Originally Posted by Tarana

For the early Kindles, they were expected to last 400-500 complete charge cycles.

That's not entirely correct. It's ~500 full charge/discharge cycles before the battery will exhibit decreased capacity. It's not like the battery will suddenly stop working after the 500th charge. And even decreased battery capacity may not be that big of a deal if the battery is otherwise in good condition. I have a 160GB iPod Classic that's over ten-years old that still gives me well over 10-hours of playtime, and I've let that sucker go "flat" multiple times over the years.

[the.Mtn.Man]

Originally Posted by rashkae

With NiCD, best practice was to always fully discharge and fully recharge batteries...

Ironically, it's this practice that most often damaged NiCD batteries back in the day, because letting them run completely flat (which is what most people tended to do) could lead to an over-discharge which would damage the individual cells inside the battery which reduced the charge capacity. Most rechargeable batteries these days are a lot "smarter" and often have built in protection to prevent this from happening.

[Tarana]

Originally Posted by the.Mtn.Man

That's not entirely correct. It's ~500 full charge/discharge cycles before the battery will exhibit decreased capacity. It's not like the battery will suddenly stop working after the 500th charge. And even decreased battery capacity may not be that big of a deal if the battery is otherwise in good condition. I have a 160GB iPod Classic that's over ten-years old that still gives me well over 10-hours of playtime, and I've let that sucker go "flat" multiple times over the years.

I bow to your knowledge and appreciate your enhanced explanation. My Ipod 4th gen nano is also over 10 years old and used daily. Only recently did it need charging more often, but not annoyingly so.

Also to clarify, my personal experience with my brother's Kindle Keyboard was that it was unused for 2 YEARS with definite battery depletion. We bought our K3s at the same time. Mine continued to have excellent battery longevity and his needed to be charged every other day after that. My battery never worsened, but traded in because the power button failed.