Clara HD Battery life seems unusually short

[jgoguen]

This weekend has been unusually good for the battery. I accidentally left it home while I was gone over the weekend. It was fully charged and powered off when I left home, 72 hours later when I turned it back on it's at 45%.

Sounds like I'm going to be begging Kobo customer support to give me a new unit

[davidfor]

Originally Posted by 4691mls

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.

The book that is causing the problem is probably the book being read or the last book read (if you have just finished one). At most, it will be one of the previous couple of books. But, it is simple to find. Restart the device, and start reading. When the battery starts draining badly you found a problem book. To prove it, restart the device, open the book again, watch the battery level.

[John F]

Originally Posted by the.Mtn.Man

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.

The above doesn't seem to line up with many people's experience with smartphones, unless there is a further explanation for maximum capacity? Most people I know who are heavy smartphone users (charge their smartphones once a day), complain about degraded battery life after one year.

[compurandom]

Originally Posted by the.Mtn.Man

Even "over cycling" is not a problem.
Consumer rechargeable batteries will generally maintain their maximum capacity for 500 full cycles

You've just contradicted yourself. And the rest of this is wrong too.

If you overcycle the battery, you'll reach that 500 cycles much faster.

Also, draining the battery to 50% turns out to be less than half a cycle.

If you can keep the charge between about 40% and 80% you'll get a lot more than double the partial cycles out of it than if you drain it all the way to 5% and then charge to 95% every single time, which will probably end up giving you a lot less than 500 cycles before you start seeing life shortening.

And there are a lot of other bad habits that can damage the battery or severely shorten its life. The fastest way to kill a battery is to leave it in a hot car for a couple of hours. A lot slower way is to drain it to 5% and then leave it uncharged for a couple of months, which will almost certainly kill it permanently.

[the.Mtn.Man]

Originally Posted by John F

The above doesn't seem to line up with many people's experience with smartphones, unless there is a further explanation for maximum capacity? Most people I know who are heavy smartphone users (charge their smartphones once a day), complain about degraded battery life after one year.

A heavy smartphone user could easily exceed 500 full cycles in a year (by "heavy smartphone user", I assume you mean someone who recharges their phone multiple times a day), so that's not surprising.

[Calenorn]

Are you keeping the Clara in a cover? I have one cover that causes the battery to drain. I suspect a magnet used to keep the stand in place was interacting with the sleep function. Had to stop using that cover.

[John F]

Originally Posted by the.Mtn.Man

A heavy smartphone user could easily exceed 500 full cycles in a year (by "heavy smartphone user", I assume you mean someone who recharges their phone multiple times a day), so that's not surprising.

Although I'm sure there are people who charge there phones more than once a day, I'd call them very heavy users, not heavy users.

I would guess the people I was reffering to would do 75% to 100% of a charge cycle in a day. So a year and a half before reaching 500, yet complaing about battery life after 1 year. I don't think these are very heavy users, yet they complain about battery life.

I think I'm seeing degraded battery life after one year, but it is tough to say, and I'm a light user; I charge my phone every night and it is normally at 80% at the end of the day.

[jgoguen]

Originally Posted by Calenorn

Are you keeping the Clara in a cover? I have one cover that causes the battery to drain. I suspect a magnet used to keep the stand in place was interacting with the sleep function. Had to stop using that cover.

I am, but I have the sleep cover function turned off. I can at least confirm that closing the cover won't put the Clara to sleep, and opening it while the Clara is sleeping won't wake it (and if I turn on the sleep cover function, it seems to work as expected).

[the.Mtn.Man]

Originally Posted by compurandom

You've just contradicted yourself. And the rest of this is wrong too.

If you overcycle the battery, you'll reach that 500 cycles much faster.

Also, draining the battery to 50% turns out to be less than half a cycle.

If you can keep the charge between about 40% and 80% you'll get a lot more than double the partial cycles out of it than if you drain it all the way to 5% and then charge to 95% every single time, which will probably end up giving you a lot less than 500 cycles before you start seeing life shortening.

And there are a lot of other bad habits that can damage the battery or severely shorten its life. The fastest way to kill a battery is to leave it in a hot car for a couple of hours. A lot slower way is to drain it to 5% and then leave it uncharged for a couple of months, which will almost certainly kill it permanently.

I did not contradict myself. You only made my statements appear contradictory because you excised the surrounding context from my post.

To explain it another way, it's true that someone who uses their device heavily and thus is forced to recharge more often will reach 500 cycles more quickly than someone who is a more casual user. Think of it as two cars driving different speeds towards the same destination. They each cover the exact same distance and end up at the exact same place even if one car gets there sooner than the other.

To put it yet another way, "over cycling" will not prematurely shorten battery life even if you reach 500 cycles more quickly than another person.

[jgoguen]

Well, Kobo support finally agrees that based on my usage there's no way I should be seeing such low battery life so they're replacing it under warranty.

[the.Mtn.Man]

Originally Posted by jgoguen

Well, Kobo support finally agrees that based on my usage there's no way I should be seeing such low battery life so they're replacing it under warranty.

I love it when a plan comes together.

[davidfor]

Originally Posted by the.Mtn.Man

I did not contradict myself. You only made my statements appear contradictory because you excised the surrounding context from my post.

To explain it another way, it's true that someone who uses their device heavily and thus is forced to recharge more often will reach 500 cycles more quickly than someone who is a more casual user. Think of it as two cars driving different speeds towards the same destination. They each cover the exact same distance and end up at the exact same place even if one car gets there sooner than the other.

To put it yet another way, "over cycling" will not prematurely shorten battery life even if you reach 500 cycles more quickly than another person.

To me this it the basic thing, the more you use the battery, the quicker it dies. But, the only real way to extend the batteries overall life is to not use it. And that to me is stupid. You bought the device to use it, so use it. Charge the battery when you need to, use the battery when you need to. When the battery dies, decide whether to replace the battery or use this as an excuse to upgrade the device.

And don't forget, there are other significant factors in the lifetime of a battery. Temperature is one. The higher the temperature, the shorter the life. If the phone stays in your pants pocket all day, then it will be warmer than if you take it out and put it on the desk. Or carry it in a bag.

[the.Mtn.Man]

Originally Posted by davidfor

To me this it the basic thing, the more you use the battery, the quicker it dies. But, the only real way to extend the batteries overall life is to not use it. And that to me is stupid. You bought the device to use it, so use it. Charge the battery when you need to, use the battery when you need to. When the battery dies, decide whether to replace the battery or use this as an excuse to upgrade the device.

My thinking exactly. The only point I was trying to make is that it is extremely unlikely to damage a rechargeable battery through normal use, so stop worrying and just use your stuff.

[compurandom]

Originally Posted by davidfor

To me this it the basic thing, the more you use the battery, the quicker it dies. But, the only real way to extend the batteries overall life is to not use it.

Actually, that's not true. The best way to extend the battery is to keep it above 50% charged, which means topping it off when you can, and don't intentionally drain it flat if you can avoid it.

Agree, use the battery when you need to. But top it off when you can.
And temperature is important. I don't know if body temperature has that great an impact -- mostly it's temperatures 105F-150F that matter, but that might just have a shorter term effect.

[the.Mtn.Man]

Originally Posted by compurandom

The best way to extend the battery is to keep it above 50% charged, which means topping it off when you can, and don't intentionally drain it flat if you can avoid it.

It makes no difference whether you drain the battery to 50% and recharge it more frequently, or drain it to 5% and recharge it less frequently. In the end, it's the number of full cycles that count. There is almost nothing the user can do short of deliberate abuse that will significantly degrade battery performance. Case in point, I have a 15-year old iPod Classic that still holds a good charge despite being discharged to almost flat and even completely flat countless times over the years.