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Thalinor · 03-14-2013, 09:45 PM

Joined the forums just to see if I can help; battery stuff is not my job field but I know more then most on the subject as I have done a lot of research into the subject.

I plan on getting a Kobo Glo tomorrow around 10pm EST and am worried about this issue which is why I am driving 1.5 hours to some hole in the wall bookstore. I wish Kobo would get its .... together and sell these in retail stores here in the USA, but after four months of "coming soon" on the Best Buy site, and a call to Kobo tech support where they told me not to hold my breath, I am no longer waiting.

The reason I want to see the unit in person is because (and this is important for those of you having battery issues) if the battery has sat dead for too long, it WILL cause battery issues. I have the same problem on my Libre Pro, which came new in box with a dead battery that must have sat on the shelf for a few months in that condition. Depending on how long it sits dead, the voltage of the Lithium Ion battery can drop below the built in safety kill switch which is designed to prevent battery's from exploding due to over charge.

When the battery shows "dead" it's not really "dead" it's just under the voltage which the manufacture specified as the cutoff. If the battery ever truly became completely drained it would never charge again die to safety features built into the charging circuit. In fact, it doesn't even need to be completely discharged before it will refuse to charge, it just has to reach that kill switch threshold.

Now comes the grey area. If the battery sits dead long enough to drop below the minimum voltage, but not to the point it reaches the kill switch threshold, it starts doing several bad things to the battery. First, LI batteries have a finite number of charges, again to help try and prevent explosion. Every time you plug in the device where it starts to charge, it will take all or part of one of these finite charges. For example, if the battery has 500 charges (pretty standard) charging the device may take 1 full charge, 1/2 charge, etc. It's based off of the battery specs, mAh, battery quality, and current state of charge. For example, if the battery is completely dead, you will use a full charge. If its 25%-70% you will usually use 1/2 of a charge and at 90% or above it will trickle charge the battery only talking 1/5 a charge off your max.

Lastly, LI batteries are meant to be stored at 60% charge if they will not be used in a while. Keeping them fully charged in storage will eventually degrade the battery and take off of those max charges, even if the battery has never been charged.

I am dumbing this down for readability, and there are a lot of variables, but the point is that depending on the state the battery was left in by Kobo, how long it sat in the store or warehouse, the temp of that storage unit, etc, you can get a new device with a battery that does not hold a charge.

To/dr: what state was your battery in when you got the unit? How long did it take to charge that first time if you did not look before charging it up, and how long does it take now to charge from nearly dead?

Completely depleting the battery and recharging it can help condition the battery but its also BAD to do often. I would do it no more then once a month if you want to keep your batteries in the best possible condition. There is a lot more advice I could give on how to preserve a battery but that's not really the point of this already too long post.

For those who are looking for more info on how to keep your batteries in good working shape, Google Battery University; its the first (dot) (com) link in a google search.

Hope this helps and I am looking forward to some info from those of you having issues. Again, was the units battery dead on arrival? If so, you have your answer.

03-14-2013, 09:45 PM	#201
Thalinor @Modders/Devs - Thank You Posts: 21 Karma: 60 Join Date: Mar 2013 Device: Aluratek Libre Pro / Kobo Glo	Joined the forums just to see if I can help; battery stuff is not my job field but I know more then most on the subject as I have done a lot of research into the subject. I plan on getting a Kobo Glo tomorrow around 10pm EST and am worried about this issue which is why I am driving 1.5 hours to some hole in the wall bookstore. I wish Kobo would get its .... together and sell these in retail stores here in the USA, but after four months of "coming soon" on the Best Buy site, and a call to Kobo tech support where they told me not to hold my breath, I am no longer waiting. The reason I want to see the unit in person is because (and this is important for those of you having battery issues) if the battery has sat dead for too long, it WILL cause battery issues. I have the same problem on my Libre Pro, which came new in box with a dead battery that must have sat on the shelf for a few months in that condition. Depending on how long it sits dead, the voltage of the Lithium Ion battery can drop below the built in safety kill switch which is designed to prevent battery's from exploding due to over charge. When the battery shows "dead" it's not really "dead" it's just under the voltage which the manufacture specified as the cutoff. If the battery ever truly became completely drained it would never charge again die to safety features built into the charging circuit. In fact, it doesn't even need to be completely discharged before it will refuse to charge, it just has to reach that kill switch threshold. Now comes the grey area. If the battery sits dead long enough to drop below the minimum voltage, but not to the point it reaches the kill switch threshold, it starts doing several bad things to the battery. First, LI batteries have a finite number of charges, again to help try and prevent explosion. Every time you plug in the device where it starts to charge, it will take all or part of one of these finite charges. For example, if the battery has 500 charges (pretty standard) charging the device may take 1 full charge, 1/2 charge, etc. It's based off of the battery specs, mAh, battery quality, and current state of charge. For example, if the battery is completely dead, you will use a full charge. If its 25%-70% you will usually use 1/2 of a charge and at 90% or above it will trickle charge the battery only talking 1/5 a charge off your max. Lastly, LI batteries are meant to be stored at 60% charge if they will not be used in a while. Keeping them fully charged in storage will eventually degrade the battery and take off of those max charges, even if the battery has never been charged. I am dumbing this down for readability, and there are a lot of variables, but the point is that depending on the state the battery was left in by Kobo, how long it sat in the store or warehouse, the temp of that storage unit, etc, you can get a new device with a battery that does not hold a charge. To/dr: what state was your battery in when you got the unit? How long did it take to charge that first time if you did not look before charging it up, and how long does it take now to charge from nearly dead? Completely depleting the battery and recharging it can help condition the battery but its also BAD to do often. I would do it no more then once a month if you want to keep your batteries in the best possible condition. There is a lot more advice I could give on how to preserve a battery but that's not really the point of this already too long post. For those who are looking for more info on how to keep your batteries in good working shape, Google Battery University; its the first (dot) (com) link in a google search. Hope this helps and I am looking forward to some info from those of you having issues. Again, was the units battery dead on arrival? If so, you have your answer.