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Old 05-18-2020, 07:05 PM   #1
bastringue777
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Lightbulb Kobo Libra H2O battery drain?

Hi,

I decided to try to charge my battery when it's at around 20% and charge it until it's around 80%. I've read that it's best for a li-ion battery to do it this way, so it could theoretically last up to 1,500 cycles.

I've noticed something strange when doing this (I only did it twice so far). I charge it to about 80%, then get it off the USB plug, and let there on sleep. A couple of hours later, when going back to read, last time I saw battery back to 64% (16% lost with no reason) and today it was back to 54% (26% lost!).

I wonder what could explain such a situation and if I am doing anything bad.

Thanks!
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Old 05-19-2020, 01:00 PM   #2
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Anyone?
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Old 05-21-2020, 02:31 AM   #3
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if u're using sleep cover, chances are the cover is not closed properly
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Old 05-21-2020, 11:20 AM   #4
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Originally Posted by babygau View Post
if u're using sleep cover, chances are the cover is not closed properly
It seems to be. When opening it, I see the light coming back.

Did the thing again (but was reading, so different a bit). This time I waited until 92%, then read for about 2 hours and was back to 60% or so. Strange.

Am I the only one charging from 20% to 80% or so instead of waiting until 100%?
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Old 05-21-2020, 11:41 AM   #5
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Battery percentage is guesstimate at best. Li-ion battaery voltage does not drop linear to the charge left. You will have to periodically let it get a good full charge so the battery meter has a baseline to work with.
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Old 05-21-2020, 08:09 PM   #6
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Quote:
Originally Posted by bastringue777 View Post
I decided to try to charge my battery when it's at around 20% and charge it until it's around 80%. I've read that it's best for a li-ion battery to do it this way, so it could theoretically last up to 1,500 cycles.
Honestly, it isn't worth the hassle. Yes, doing that will extend the overall life of the battery. But, will the hassle of it actually be worth it? Will the fact you a will only be able to you 60% of the battery runtime be worth it? And then needing to charge the battery twice as often and remembering to watch it to not charge it to much.

And here's the thing, what exactly are you saving the battery life for? From reports here, and my experience, the battery is lasting long enough to get to the point replacing the device is attractive.
Quote:
I've noticed something strange when doing this (I only did it twice so far). I charge it to about 80%, then get it off the USB plug, and let there on sleep. A couple of hours later, when going back to read, last time I saw battery back to 64% (16% lost with no reason) and today it was back to 54% (26% lost!).
One issue with not using the full charge/discharge is that the fuel gauge won't be calibrated properly. The top level won't necessarily match 100% and the bottom 0%. The usual recommendation to do that is a couple of full charge/discharge cycles. And the discharge rate isn't necessarily linear.

I'm also not sure about the report. It dropped from about 80% to 64% with the cover closed over a couple of hours. Then it dropped to 54% over the next how long? The "today" doesn't tell me how long between looking at the battery level other than implying at least a day. Plus, there appears to have been some reading. That will have used power, depending on how long, what and how fast a reader you are. So, I can't judge if that is bad or not.

The battery usage depends on a lot of things. And has been discussed a lot. There have been a few recent threads that you can refer to. But, it depends on things like was WiFi on, the light level, any syncs done, what sort of things you read, how fast you turn the page, what else the device was doing. There are issues triggered by badly constructed books that can cause high battery usage even after closing the book. To be able to diagnose, we need more details. Have a look at the other threads for some ideas.
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Old 05-22-2020, 06:46 AM   #7
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Quote:
Originally Posted by rashkae View Post
Battery percentage is guesstimate at best. Li-ion battaery voltage does not drop linear to the charge left. You will have to periodically let it get a good full charge so the battery meter has a baseline to work with.
OK, will do, once in a while. Thanks
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Old 05-22-2020, 06:57 AM   #8
bastringue777
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Originally Posted by davidfor View Post
Honestly, it isn't worth the hassle. Yes, doing that will extend the overall life of the battery. But, will the hassle of it actually be worth it? Will the fact you a will only be able to you 60% of the battery runtime be worth it? And then needing to charge the battery twice as often and remembering to watch it to not charge it to much.

And here's the thing, what exactly are you saving the battery life for? From reports here, and my experience, the battery is lasting long enough to get to the point replacing the device is attractive.
I don't remember where I've read this, but charging 20 to 80% could triple the number of cycles from a "normal" 0 to 100% charge.

I read with backlight on from 70 to 95% all the time, because it hurts my eyes if it is too dark. That way, I rarely get more than 10-15 hours of reading, and since I read A LOT, it's not much more than 3 days without a charge.

So if I could triple the number of cycles, that would be nice, because as it is, in a year or so I could have to charge it every two days, etc. and then it would go South fast...


Quote:
Originally Posted by davidfor View Post
One issue with not using the full charge/discharge is that the fuel gauge won't be calibrated properly. The top level won't necessarily match 100% and the bottom 0%. The usual recommendation to do that is a couple of full charge/discharge cycles. And the discharge rate isn't necessarily linear.

I'm also not sure about the report. It dropped from about 80% to 64% with the cover closed over a couple of hours. Then it dropped to 54% over the next how long? The "today" doesn't tell me how long between looking at the battery level other than implying at least a day. Plus, there appears to have been some reading. That will have used power, depending on how long, what and how fast a reader you are. So, I can't judge if that is bad or not.

The battery usage depends on a lot of things. And has been discussed a lot. There have been a few recent threads that you can refer to. But, it depends on things like was WiFi on, the light level, any syncs done, what sort of things you read, how fast you turn the page, what else the device was doing. There are issues triggered by badly constructed books that can cause high battery usage even after closing the book. To be able to diagnose, we need more details. Have a look at the other threads for some ideas.
OK, I have wi-fi off, sync off, and am reading pretty simple epub books (no images). Turning pages pretty fast because font is bigger than normal (maybe 14), and light is between 70 and 95% all the time, but mostly around 75%.
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