Is it possible to limit battery charge to say 80%?

[Hzj_jie]

Originally Posted by atonement

That's good to know. What's the battery cycle count?

if you are asking me

[root@kindle max77696-battery]# for i in * ; do echo $i ; cat $i ; done
capacity
87
charge_full
1293
charge_full_design
790000
charge_now
1179
current_avg
-36
current_now
-48
cycle_count
507

[atonement]

That is a pretty good result. Mine's currently at 14 after 1.5 years. Thanks.

[Barty]

BTW, does anyone know if there's a way to determine current battery capacity (jail broken). Recently picked up a used Voyage and I'm curious how much better it has left

[j.p.s]

Originally Posted by Barty

BTW, does anyone know if there's a way to determine current battery capacity (jail broken). Recently picked up a used Voyage and I'm curious how much better it has left

Try

cat /sys/class/power_supply/max77696-battery/charge_full

My 2014 Voyage says 1293, which I assume is mah.

If you don't trust that, charge it as far as it will go and

cat /sys/class/power_supply/max77696-battery/charge_now

[Barty]

Originally Posted by j.p.s

Try

cat /sys/class/power_supply/max77696-battery/charge_full

My 2014 Voyage says 1293, which I assume is mah.



If you don't trust that, charge it as far as it will go and

cat /sys/class/power_supply/max77696-battery/charge_now

Thank you, j.p.s.!

[Hzj_jie]

Originally Posted by atonement

That is a pretty good result. Mine's currently at 14 after 1.5 years. Thanks.

The capacity is the battery level for now. You may want to take a look at charge_full / designed capacity. The charge_full_design may not accurate, at least on my voyage. Also the charge_now * 100 / capacity != charge_full, so ... anyway, use it as a reference only.

For my voyage, charge_full / designed capacity (1320mAh), it's pretty much at 97.95% full capacity. But usually the battery designed capacity is slightly smaller than actual capacity; it's safe to assume the battery decayed less than 5% during the last 500 cycles. I have pretty much zero knowledge about the li-ion battery, but it matches https://www.mdpi.com/2071-1050/11/23/6697/pdf very well - usually I charge my kindle at 10%-15% to 99% or 100%.

But again, I am not quite sure how accurate the values are, as a reference only.

[Barty]

I have 2 voyages bought used and one has cycle count > 500 and one in the low 100, but both have charge_full at 1293. Not sure what to make of that.

[atonement]

Is it possible to limit the max. charging voltage? If somehow limited to say 4.1V charging should stop at 85-90% from what I have read.

[j.p.s]

Originally Posted by atonement

Is it possible to limit the max. charging voltage? If somehow limited to say 4.1V charging should stop at 85-90% from what I have read.

I am not aware of any way to stop charging without also having the kindle switch to running only from the battery.

[atonement]

OK. Looks like this is a dead end. Just yesterday I was able to trigger bypass charging in my primary Android mobile by limiting max. charging voltage. Previously it only used to kick when fully charged. So thought to ask if it was also possible in the case of Kindle. Thanks.

[j.p.s]

Originally Posted by atonement

OK. Looks like this is a dead end. Just yesterday I was able to trigger bypass charging in my primary Android mobile by limiting max. charging voltage. Previously it only used to kick when fully charged. So thought to ask if it was also possible in the case of Kindle. Thanks.

It may well be possible, but I suspect it will take someone who knows their way around the PMIC and its driver to look into it to find out.

[atonement]

Upon checking charge_full was 1408 and charge_now 1463. Is this overcharging? I had left my PW3 to charge long after 100%was shown in the system. With a USB Power Tester I could see that 74mA was being drawn constantly. Meanwhile the battery level had gone down to 99%.

[j.p.s]

I doubt you had overcharging. But percent charged is somewhat arbitrary even if calibration weren't an issue. Some might consider 95% overcharged.

I suspect the various battery state variables need to be recalibrated. amazon will truncate percentages over 100% to 100%. I have seen /sys/class/power_supply/max77796-battery/capacity on my Oasis 2 as high as 105%.

[mergen3107]

Originally Posted by Barty

I have 2 voyages bought used and one has cycle count > 500 and one in the low 100, but both have charge_full at 1293. Not sure what to make of that.

Sorry, an old thread, but decided to chime in.
Kindle Voyage battery capacity is 1300 mAh. So, these two Voyages were pretty good.