Clara Battery life seems unusually short

[jgoguen]

I'm seeing some pretty bad battery life with my Clara HD and I'm wondering what it is I'm doing wrong. From searching the forum and Kobo's help I've seen a few common suggestions:

• Turn off wifi. I already do turn off wifi, only turning it on when I need it and turning it off again.
• Don't turn the device off, just let it sleep (e.g. set the power-off timeout to "Never"). If I do this the battery life gets even worse, full charge to empty within a few hours instead of about a day most days. The best battery life so far has been with sleep and power off both set to 5 minutes.
• Train the battery (drain, charge, drain, charge). Been doing this basically as long as I've had my Clara! The battery drains, I charge it up to full before using it, then I normally don't plug it in again until it's drained. Which has meant I'm normally plugging it in once or twice daily.
• Turn off sleep cover support. I turned it off during initial setup and never turned it back on. I've also confirmed a sleep cover isn't still causing a problem: I can reproduce this without any cover on at all (but maybe there's a bug where the hardware is still being powered and polled?).
• Turn down screen brightness. It's normally down around 2%, even at night.
• Remove all the books and see if there's a bad book causing a problem. I don't quite get how having a book stored would cause a problem, but I have also deleted all books and seen the battery drain.
• Update firmware. I've updated at least twice since getting the Clara.

There are occasional times (just a few times in a few months) where I've read for a few hours then left the Clara sitting for 2 days and the battery has stayed full. But then the next time I pick it up it's back to draining within a day and I've done nothing but read (no adding or removing books, no flipping wifi on or off).

[DevonHess]

You should be getting easily a few weeks of battery life with your usage, not a few days. Sounds like a defective unit.

How old is your device? Do you leave it somewhere where it could be overheating?

[LordP]

Interesting, I find the opposite.

I'm 71 and retired so my main recreation is reading, which I do for maybe six to seven hours a day. Sometimes I'll read for hours and hours at one sitting (depends on the book, naturally).

I rarely see the battery icon showing the battery depleted - maybe just a bit depleted.

When I go to sleep or maybe start some yard work, I'll plug the device in until I pick it up again.

I've often wondered at the great battery performance of my little Clara - I never had it this good with other readers.

[Quoth]

Maybe a dud battery cell.

[compurandom]

Originally Posted by jgoguen

• Train the battery (drain, charge, drain, charge). Been doing this basically as long as I've had my Clara! The battery drains, I charge it up to full before using it, then I normally don't plug it in again until it's drained. Which has meant I'm normally plugging it in once or twice daily.

Don't do this! Or at least, don't do it more often than once every 6 months or so, and don't do it twice in a row for sure!!

You only have to drain it once and then give it a full charge and that resets the charge controller chip's idea of the battery's health. Every time you do this, it reduces the battery's lifespan by some percentage. It use to be 20% but I think current lithium polymer batteries it's less than that.

The recommendation I've seen is to only do this if the battery life seems artificially short, and if it doesn't fix it, don't do it a second time.

Personally, I almost never intentionally drain my batteries to retrain, because in a 6 month period of time, it's very likely I'll have done it through normal use at least once. The kobos sip power so gently that this is less likely, but it does still happen.

[compurandom]

Originally Posted by jgoguen

I'm seeing some pretty bad battery life with my Clara HD and I'm wondering what it is I'm doing wrong.

My brand new forma drained itself yesterday, no idea why. But I've been leaving the wifi on.

I think sometimes sync gets stuck and chews the battery. Turning off wifi typically fixes that, but sometimes the sync doesn't stop even then.

Also, in the past I've done searches in large pdfs and then changed books when the search didn't find anything. I suspect that the search actually never stopped, and then drained the battery flat. I haven't been searching in pdfs lately, so I don't know if this has been fixed in recent firmwares.

I think it is possible for other things to get stuck chewing cpu too.

All of these things are (temporarily) fixed by rebooting the device. If you notice your battery draining rapidly or it is still trying to sync minutes after you turn off wifi, make sure wifi is off and then reboot the device. This always stops the battery drain for me.

[davidfor]

Originally Posted by jgoguen

There are occasional times (just a few times in a few months) where I've read for a few hours then left the Clara sitting for 2 days and the battery has stayed full. But then the next time I pick it up it's back to draining within a day and I've done nothing but read (no adding or removing books, no flipping wifi on or off).

The usual thought here is that something in the book leaves a process running and that drains the battery. That's where the suggestion for removing the bad books comes from. Remove and fix them and the problem goes away. And restarting the device will solve it until you open one of these bad books again.

The problem that I don't think anyone knows what in the book causes this.

[jgoguen]

Originally Posted by compurandom

Don't do this! Or at least, don't do it more often than once every 6 months or so, and don't do it twice in a row for sure!!

Well at the moment it's not exactly being done by choice…

Originally Posted by compurandom

My brand new forma drained itself yesterday, no idea why. But I've been leaving the wifi on.

I think sometimes sync gets stuck and chews the battery. Turning off wifi typically fixes that, but sometimes the sync doesn't stop even then.

Also, in the past I've done searches in large pdfs and then changed books when the search didn't find anything. I suspect that the search actually never stopped, and then drained the battery flat. I haven't been searching in pdfs lately, so I don't know if this has been fixed in recent firmwares.

I think it is possible for other things to get stuck chewing cpu too.

All of these things are (temporarily) fixed by rebooting the device. If you notice your battery draining rapidly or it is still trying to sync minutes after you turn off wifi, make sure wifi is off and then reboot the device. This always stops the battery drain for me.

I'm seeing this even when wifi hasn't been on at all since the last reboot, and I've disabled auto-syncing. And most of the time the device is actually powered off when the battery is almost full (I've confirmed that by opening the case after a few hours with info panels enabled, it says powered off) and when I try to power it back on the next day (or two days later sometimes) it's dead.

Originally Posted by davidfor

The usual thought here is that something in the book leaves a process running and that drains the battery. That's where the suggestion for removing the bad books comes from. Remove and fix them and the problem goes away. And restarting the device will solve it until you open one of these bad books again.

The problem that I don't think anyone knows what in the book causes this.

That sounds like a fun bug to try to track down, especially since the odd time I've had it stay fully powered has been with the same book it drained quickly with! But I'm also seeing this happen when the Clara is powered off for some time. I put it to sleep by tapping the power button (and see the info panel say sleeping), occasionally I've checked later to verify it says it's powered off (which with my settings should be happening in 5 minutes, then a day (sometimes two) later it's dead.

[the.Mtn.Man]

Originally Posted by jgoguen

Train the battery (drain, charge, drain, charge). Been doing this basically as long as I've had my Clara! The battery drains, I charge it up to full before using it, then I normally don't plug it in again until it's drained. Which has meant I'm normally plugging it in once or twice daily.

There is no need to "train" a rechargeable battery. "Battery memory" is a myth that is ironically based on attempts to "train" batteries by over-discharging which can screw with the battery chemistry and reduce capacity.

This is really no longer a problem since modern electronics and even rechargeable batteries themselves have protective circuity built-in to prevent batteries from being overcharged or over-discharged, so it is almost impossible to damage a battery this way. The most likely culprit of your problem is simply a dud battery. I doubt it was caused by anything you did.

[compurandom]

Originally Posted by jgoguen

And most of the time the device is actually powered off when the battery is almost full and when I try to power it back on the next day (or two days later sometimes) it's dead.

If it is truly powered off and your battery is draining, then the battery is not holding its charge and may be at the end of its life. That is a typical failure mode.

Originally Posted by davidfor

The usual thought here is that something in the book leaves a process running and that drains the battery.

The problem that I don't think anyone knows what in the book causes this.

I've had problems with books containing javascript being slow and/or crashing the device. I figured the extra text was just causing the parser to work harder, but is it possible it is actually trying to run the javascript?

I can't imagine what else in a book would cause the cpu to chew and not actually fail to render too.

[compurandom]

Originally Posted by the.Mtn.Man

There is no need to "train" a rechargeable battery.

You don't have to train the battery, but the charge control chip sometimes gets out of sync with the health of the battery. But I agree, even fixing that is rarely needed, and as I said above, doing it overly much will wear out your battery prematurely.

This is really no longer a problem since modern electronics and even rechargeable batteries themselves have protective circuity built-in

This is half true. *most* consumer grade rechargeable lithium based batteries have a charge control chip. But the chip is not built in so much as soldered on, and it is easy to get raw cells with no chip, even on batteries that require one to be safe, especially the cylindrical form factor cells.

But since no kobo has removable cells, that doesn't apply here, and is starting to get off topic. (And if you are replacing the battery pack in a kobo, care must be taken to make sure the new pack has a charge control chip or you keep the old one. But I don't repair devices like this, so what do I know.)

...so it is almost impossible to damage a battery this way.

Almost is the keyword here.
It's impossible to overcharge with a charge control chip, because the whole point of the chip is to prevent overcharging, because lithium secondary cells tend to explode when overcharged. (Lithium primary cells explode when charged multiple times, overcharged or not.)

However, while the charge control chip does try to prevent drain below 5% (which can also kill the battery), it can only reduce the chances, it can't prevent it. And it can't prevent you from cycling the battery too often either.

[4691mls]

Originally Posted by davidfor

The usual thought here is that something in the book leaves a process running and that drains the battery. That's where the suggestion for removing the bad books comes from. Remove and fix them and the problem goes away. And restarting the device will solve it until you open one of these bad books again.

The problem that I don't think anyone knows what in the book causes this.

Does anyone even know an easy way to figure out which book causes it?

When it happened to me on one of my old Sony readers it was obvious because I had only downloaded one new book within the last few days before the problem occurred, and when I finished reading that book and removed it the problem went away.

But it sounds like for the OP this problem has been going on for a while so he/she may not know which book triggered it.

[compurandom]

Originally Posted by 4691mls

But it sounds like for the OP this problem has been going on for a while so he/she may not know which book triggered it.

It's worse than that. There are multiple causes, including old end of life batteries and network issues. So even if you did narrow it down to a book and deleted the book, the problem could still continue, but perhaps not as often.

[PeterT]

Not sure if this is applicable but just saw this in a tweet from Kobo

https://help.kobo.com/hc/en-us/artic...harging-issues

[the.Mtn.Man]

Originally Posted by compurandom

You don't have to train the battery, but the charge control chip sometimes gets out of sync with the health of the battery. But I agree, even fixing that is rarely needed, and as I said above, doing it overly much will wear out your battery prematurely.


This is half true. *most* consumer grade rechargeable lithium based batteries have a charge control chip. But the chip is not built in so much as soldered on, and it is easy to get raw cells with no chip, even on batteries that require one to be safe, especially the cylindrical form factor cells.

But since no kobo has removable cells, that doesn't apply here, and is starting to get off topic. (And if you are replacing the battery pack in a kobo, care must be taken to make sure the new pack has a charge control chip or you keep the old one. But I don't repair devices like this, so what do I know.)


Almost is the keyword here.
It's impossible to overcharge with a charge control chip, because the whole point of the chip is to prevent overcharging, because lithium secondary cells tend to explode when overcharged. (Lithium primary cells explode when charged multiple times, overcharged or not.)

However, while the charge control chip does try to prevent drain below 5% (which can also kill the battery), it can only reduce the chances, it can't prevent it. And it can't prevent you from cycling the battery too often either.

Even "over cycling" is not a problem. Consumer rechargeable batteries will generally maintain their maximum capacity for 500 full cycles -- that is a full discharge followed by a full recharge. If you drain a battery to 50% and then recharge it, that's half a cycle, so frequently recharging a partially discharged battery won't shorten its life. And even if you surpass 500 full cycles, it just means a slightly reduced capacity and not that the battery will suddenly cease functioning.

Point being, there's no need to worry that one's charging habits will damage the battery in their electronic devices, and that by far the most common cause of battery failure is due to things entirely out of one's control.