Mysterious Nook battery drain event

[uod]

For those using NSTs ... have you ever had this happen?

I charged up the NSTs when I first got them about 3 weeks ago. I rooted, named them, connected them to the wifi, etc. Then, I put them in a box and didn't mess with them until last Thursday. I pulled them out of the box on Thursday to charge them up, and all had about 70-75% battery left. Charged them all up to 100% and put them back in the box. Spot checked a few on Friday around 5pm, and they were at about 97-98% battery.

.... pulled them out of the box about an hour before our Saturday match and 5 of the 6 were at 15% (one was at 95%). Luckily I was able to get them charged up into the 30-40% range before we started shooting.

Oddly enough, using them for 4-5 hours on Saturday only dropped the charge by 10%. But, leaving them in the box overnight somehow dropped the charge by 80%? Just for reference, I place them in a box in such a way as to make sure nothing is pressing on the screen or the back button. My only guess is that something was causing them to make sweet wifi-love all night.

Lesson learned : Check them first thing in the morning on a match day. I would have had three hours to charge them back up if I had looked at them when I first got to the range.

Edited April 8, 2014 by uod

[wgnoyes]

Wait... You made sure something was pressing on the screen and/or power button? I think you mean you made sure NOTHING was engaging either side, right?

We're they possibly still plugged into the chargers but the chargers themselves weren't plugged in or power was off? Strangely, an unpowered charger will drain a nook in exactly the way you describe.

[uod]

Yes -- sorry --- made sure NOTHING was pressing on the screen or buttons. I edited my OP to correct that typo.

The Nooks were not plugged into the chargers. They were sitting in the box as they had been for the past weeks without issue.

[jcwren]

And they were fully turned off, with the "Your NOOK has powered off completely" screen, or whatever it exactly says?

[uod]

No -- I leave them at the Practiscore screensaver. I've left one tablet that way for 6 weeks without it draining completely. Left the others like that for 3 weeks with only a 25-30% drain.

I have had bad luck with turning them off completely. Had two not come back up on me once. I had to factory restore and re-root them.

[jcwren]

Well, here's the problem. When they're asleep, they're only sort of asleep. The WiFi still wakes up periodically to poll the time servers, and PractiScore doesn't really stop running when it's moved into the background. You can prove this to yourself by going to the Sync screen on another device and you'll see a supposedly sleeping NOOK show up. The WiFi being on is a power-eater.

I have never seen a NOOK not wake up from being powered off.

My policy goes like this: The night before a match, I plug them in to charge. The next morning, as I disconnect them, I turn them off (I charge 12 at once, we typically only use 8). I turn them off primarily so they don't accidently get waken up by a button being pressed or the touch screen getting confused. At the range, about 15 minutes before registration closes, I power them all on, make sure they're on the network. Sync the match, pass them out, shoot the match. Collect them at the end, and do a final sync. After I do, I turn them off again. This is primarily an accounting function. Turned-off NOOKs are known to have been synced from. Sometimes it takes 1/2 an hour for the NOOKs to get to the shack, since some squads finish slower than others.

There are some people that believe no damage will occur to NOOKs leaving them charging all the time. I do not concur with this opinion, on several accounts. Heat is a killer of batteries. LiPo batteries have a finite number of times they can be charged. When plugged in, if the charge bleeds down below 95%, the charging circuitry will top it off again. Batteries warm up, and ultimately contributes to the battery failing sometime sooner. Sooner than what? The heat death of the universe? Maybe. But why needlessly charge them?

More importantly, they're plugged into a wall socket through a charger. A nearby lightning strike may induce enough voltage to damage the charger or the NOOK. So what was the point of leaving them plugged in? It's not like a SHTF go-bag. You don't need to grab your NOOKs and tear out the door in the event of an emergency. Matches are planned months, weeks and days in advance. Plenty of time to put them on a charger for 4 to 8 hours.

[jdphotoguy]

I follow an almost identical procedure to jcwren's, for charging and match day distribution/collection.

Only time I've had poor battery performance was a few months back when during a match on an exceptionally cold day, the Nooks being used went from a 98% charge to less then 5% in a matter of minutes. I plugged the Nooks into a portable battery and placed them inside my jacket to warm them up. After a few minutes they showed a 98% charge again and were good to go. Now on really cold days I tell the persons scoring to put the Nooks inside their jacket when not actively scoring.

[jcwren]

Just don't put them down your pants. After that, no one wants to touch them

[jdphotoguy]

Just don't put them down your pants. After that, no one wants to touch them

LOL

[CHA-LEE]

If you simply screen saver the Nook and leave PractiScore running and WiFi turned on it will drain the battery fairly quickly (a few days), especially if it keeps connecting and disconnecting or searching for wireless networks and it being stored in a cold environment. The other factor you need to consider is that the Lithium Ion batteries are fairly cold temperature sensitive from a capacity perspective. A Nook that shows 99% battery at room temperature can easily show 30% - 40% in outdoor freezing or below freezing temps. Keeping the Nooks warm in the winter shooting months is important for maintaining solid battery capacity during a match. Have the scoring RO simply screen saver the Nook and stuff it in their jacket for a few minutes between stages will go a long way in keeping the Nook warm enough for the battery to perform properly.

After a match, plug in all of your Nooks and wait for them to become fully charged. Once they are fully charged then disconnect the Nooks from the USB charging cable. Then simply press and hold the power switch on the back until you get the power off pop up on the touch screen. Tap on the "Power Off" option then the Nook will fully power down. Store the Nooks in a room temperature environment until the day before your next match. In this fully powered off state the battery will retain 90%+ of its charge for multiple months. The day before your match plug the powered off Nooks into an active USB charging cable and they will boot up automatically. Keep them on the charger until they are fully charged or you are ready to leave for the match the next day.

[wgnoyes]

My experiences are totally different. I can leave a nook in sleep mode all month that I used in a match and it's still well above 50% when I pick it back up again. (Charge it up at the front of the month and don't use it at all and pick it up 4 weeks later and the charge is around 90%.) Difference is I specifically take down practiscore.

So you recharge the nook after the match is over, and then charge it again just before the next match? Seems like you could eliminate one of those. My understanding has always been you can recharge a battery only so many times before it won't take a charge any more. I mean, we're not going to wear these things out before we find something better to use, but still. It seems like an extra unnecessary step.

I turn mine off at the end of the match and leave them off until the day before the next match.

Edited April 8, 2014 by wgnoyes

[CHA-LEE]

All of the talk about the finite charge/discharge cycles and wearing out the batteries by keeping them on the chargers is entertaining to me. This isn't 1990's when the best rechargeable battery technology for portable electronics was nickle cadmium (NiCad) or nickle metal-hydride (NiMH) based cells along with fairly stupid/rudimentary trickle chargers used to recharge those type of batteries. In the "Old Days" you could easily end up in a situation where you could over charge a NiCad or NiMH battery, over heat it during the over charge event and ruin the battery. That is simply NOT the case today.

The charging circuits used on the Lithium Ion/Polymer/Phosphate style rechargeable batteries is far more sophisticated and is designed to eliminate ANY chance of an over charge condition. If you do end up an an over charge situation the Lithium style batteries can literally burst into flames turning into something close to a road flare type of fire output. Electronic Device manufactures go to GREAT lengths to eliminate any chance of an over charge condition on Lithium style batteries because they don't want to be responsible for or involved with a battery fire type of lawsuit situations. Is it possible that something could fail in the charging circuit and an over charge condition could happen? Sure, anything can fail at any time. But the probability of the charging circuit failing in an over charge condition is vary, vary low. Rest assured that all modern day consumer electronics that leverage Lithium style rechargeable batteries have been designed to completely eliminate the chance of an over charge condition from happening not matter how long or short the battery is attached to the charging circuit. With these facts known, please stop perpetuating the invalid stance of "It will over charge, heat up the battery and ruin it if you keep it connected to the charger". Those type of statements are simply NOT TRUE in today's electronics and battery technology.

As for the "You will prematurely wear out the battery by keeping it on the charger" comments, that is also an invalid argument. The vast majority of Lithium Ion batteries have a Full Discharge to Full Charge life of 500+ cycles. The key word there is FULL Discharge and FULL Charge. The truth of the matter here is that the Lithium style rechargeable batteries have a finite amount of times they can be fully discharged, they are really not that sensitive to partial discharges and recharges. They are VERY sensitive to being over discharged. These batteries are so sensitive to being over discharged that most modern consumer electronics will force a complete shutdown of the device (Cell Phone, Tablet, Laptop, etc) before the battery actually reaches this critical over discharge capacity level. This is done to protect the battery from becoming damaged. The Lithium style rechargeable batteries are designed to function properly for a VERY LONG TIME in partial discharge to partial recharge use conditions without requiring special discharge or recharge cycles to maintain the proper function of the battery. Lithium style batteries can be exposed to partial discharged/recharged scenarios thousands of times before the battery is actually "Worn out". The important thing here is that you need to put these discharge/recharge life span cycles into context of how the device the battery is installed in will be used. For example, even if you could produce a full discharge to full charge use case scenario once a week it would take over 9 YEARS of use to produce 500 cycles. If you intermixed full discharge/charge cycles with partial discharge/charge cycles and created a use rate of 1000 cycles for the battery that would be 18 years of use. There is NO WAY that these Nooks will be used for 9 straight years, much less 18 years, for their intended purpose, which is scoring matches. The Nook its self will be worn out, damage, or replaced by the next best thing LONG before the battery gets worn out from discharge/recharge use.

The link below has some very good information about the functional life cycle of Lithium style batteries. Please take the time to read it so you can be up to speed on the current state of Lithium battery technology verses trying to apply 1990's battery knowledge or issues to the latest battery technology.

http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

[jester121]

Bill, is your storage area located in a strong wifi coverage zone? Perhaps uod (the OP) was storing his Nooks in an area without wifi, or right on the edge of his coverage, or... inside a lead box? This is akin to watching a smartphone battery drain before your eyes in an area with spotty cell coverage.

[ZackJones]

Perhaps uod (the OP) was storing his Nooks in an area without wifi, or right on the edge of his coverage, or... inside a lead box? This is akin to watching a smartphone battery drain before your eyes in an area with spotty cell coverage.

I'm willing to bet WiFi was the problem because I had the router the NST's were trying to connect with. So there's another item to keep in mind - turn off WiFi if you have a dedicated WiFi network at the range. I have the NST's I use for steel challenge set to connect to my home WiFi so I can sync the match settings before heading to the range.

[jcwren]

I'm willing to bet WiFi was the problem because I had the router the NST's were trying to connect with. So there's another item to keep in mind - turn off WiFi if you have a dedicated WiFi network at the range. I have the NST's I use for steel challenge set to connect to my home WiFi so I can sync the match settings before heading to the range.

Turn OFF the WiFi if you have dedicated WiFi? That would seem to defeat the purpose of pulling scores during the match for backup, to verify progress, and to allow other competitors to pull in-match results...

In fact, if one of mine disappears off the WiFi network at a match, I'm visiting that device to find out why, and get it back online.

[ZackJones]

Turn OFF the WiFi if you have dedicated WiFi? That would seem to defeat the purpose of pulling scores during the match for backup, to verify progress, and to allow other competitors to pull in-match results...

In fact, if one of mine disappears off the WiFi network at a match, I'm visiting that device to find out why, and get it back online.

Sorry, let me clarify Turn off WiFi at HOME when away from the dedicated scoring WiFi at the range. That way the NST's aren't trying to connect to a WiFi network that's out of range.

During the match we pull in results every time we see a squad move from one bay to the next.

[wgnoyes]

Cha-lee, why do I need to follow any additional links after having waded through your own college-length dissertation? It's good information and thanks, but you seemed to take it a bit personally for some reason. I don't have time to follow extra links right now; I'm helping run Area 6, starting weeks ago and really ramping up starting now.

My basic statement stands; you're charging your nooks twice a month when once (the night before the match) seems like it would be sufficient.

Jester121, my storage area is in my computer room at the house, 3 feet away from my wifi router. I can leave a fully-charged nook in sleep mode all month and the drain is about 10%.

Edited April 9, 2014 by wgnoyes

[CHA-LEE]

Cha-lee, why do I need to follow any additional links after having waded through your own college-length dissertation? It's good information and thanks, but you seemed to take it a bit personally for some reason. I don't have time to follow extra links right now; I'm helping run Area 6, starting weeks ago and really ramping up starting now.

My basic statement stands; you're charging your nooks twice a month when once (the night before the match) seems like it would be sufficient.

Jester121, my storage area is in my computer room at the house, 3 feet away from my wifi router. I can leave a fully-charged nook in sleep mode all month and the drain is about 10%.

I didn't intend my post to come off as a stern slap on the wrist, but as I re-read it that is pretty much how it came across. Sorry about that. The basic points I was trying to make is as follows.....

(1) Given the technology used today, there is no way that a Lithium battery can be overcharged using the standard charging processes built into the device. So overcharging the battery and "heating it up" while doing so is not even an issue.

(2) The discharge/charge cycle capability of the Lithium batteries far exceed the use life of the device its self. So what some people would consider "Excessive" recharging is a non issue because the cycle life of the battery will far out live the actual devices use life.

(3) Over discharging a Lithium battery is the number one "Killer" of this battery technology. You over discharge a Lithium style battery even once, and it is forever damaged by the process. This usually shows its self as a significantly reduced capacity of discharge (less overall mah capacity) on future uses. I would venture to guess that over discharge of the Lithium style batteries is the most common and easiest way to ruin this style of battery. You are far better off to maintain the Lithium batteries by excessively recharging them, verses creating a use case scenario where it can become fully discharged.

(4) Overall discharge capacity is dramatically affected by the temperature of the battery. The colder the battery is, the less capacity it is going to have. This is why its important to keep the Nooks at room temperature while storing them between matches and to also keep them fairly warm in the winter months while being used in cold range conditions. Cold tempreture storage of the Nooks combined with not keeping them fully charged between matches can easily result in an over discharge condition which will ruin the battery.

[jcwren]

"Lithium-ion suffers from stress when exposed to heat, so does keeping a cell at a high charge voltage. A battery dwelling above 30°C (86°F) is considered elevated temperature and for most Li-ion, a voltage above 4.10V/cell is deemed as high voltage. Exposing the battery to high temperature and dwelling in a full state-of-charge for an extended time can be more stressful than cycling."

I can tell you with absolute certainty that NOOKs *can* get warm while charging. I have a toolbox that I put some tear-out foam in, and I charged them once while in the foam cutouts. The NOOKs were definitely warm, although I can't say what the actual temperature was. They're definitely a lot warmer than when they're sitting on the counter charging, and have good ventilation. If they weren't above 86F, they were pretty close to it.

The entire point is there's ABSOLUTELY NO POINT IS NEEDLESSLY CHARGING THEM. An overnight charge before a match is all they need, and leaving them connected subjects them to the possibility of damage from a lightning strike or other power event, and it's a waste of electricity. Furthermore, if the power goes out for whatever reason, the NOOKs will discharge through the un-powered charger. Don't believe me? Charge three, leave one connected to a powered charger, one to an un-powered charger, and the other disconnected. You'll find the second one will be discharged after a while (don't know the exact time, could be a day, could be five).

And since NOOKs are getting on the endangered species list, *I* intend to do whatever I can to avoid replacing them any sooner than necessary, regardless if 300 cycles is 9 years worth of matches or not.

[CHA-LEE]

Replacement batteries can be purchased for $7 at the below website. All you have to do is transfer the connector cable/balancing circuit from the old battery to the new one and that only takes a couple of minutes of soldering. So for about $10 worth of time and equipment you can simply replace the battery when it takes a dump. The other advantage to this is that the standard Lithium battery that comes with the Nook has a 1250mah capacity. The replacement batteries listed below have a 1800mah capacity rating in the same physical form factor. So you get a 50% bump in overall capacity when switching to this replacement battery.

http://www.batteryspace.com/polymerli-ioncell37v1800mah425085-2c67wh36arate-ullisted.aspx

I have ended up being the "Nook Technical Support" person for the Colorado USPSA section. I have had to replace about 10 failed batteries so far and ALL of them went bad due to being over discharged. The clubs that use a Nook maintenance process of keeping them fully charged and totally powered off between matches rarely have any issue. The clubs that leave the Nooks powered on with the wireless turned on and have an inconsistent recharging process are the ones that usually end up killing the batteries due to over discharge situations.

[wgnoyes]

Solder? Nope, that's a show-stopper.

[CHA-LEE]

Solder? Nope, that's a show-stopper.

For you it may be a show stopper but for many others it is a viable option.

You can find direct replacement batteries but they can only be ordered from China and usually takes months to get.

[austex]

A little pricier than Charlie's, but will come relatively quickly and has a direct plug in connector. Even get the T5 torx driver

http://www.amazon.com/gp/product/B00FGSRY5A/ref=oh_details_o02_s00_i00?ie=UTF8&psc=1

Edited April 10, 2014 by austex

[wgnoyes]

Solder? Nope, that's a show-stopper.

For you it may be a show stopper but for many others it is a viable option.

You can find direct replacement batteries but they can only be ordered from China and usually takes months to get.

I've talked before about eliminating as much of the propeller-head tech stuff out of all this as possible, so as to make the system approachable for the average match director. Usually I was talking about rooting systems, and some of the early ones were/are stupefyingly complicated. But even the worst of those pales in comparison to asking the average person to actually crack one open and start soldering on the internals. THAT is the ultimate in propeller-head geekiness and people, including me and I'm a software guy, will stay with paper scoresheets and ezws rather than do that.

A little pricier than Charlie's, but will come relatively quickly and has a direct plug in connector. Even get the T5 torx driver

http://www.amazon.com/gp/product/B00FGSRY5A/ref=oh_details_o02_s00_i00?ie=UTF8&psc=1

$5 extra to not have to wave a hot soldering iron around? That's the approachable (barely!) solution for replacing a battery.

Or just treat your nook right and avoid ever having to replace the battery at all!

[CHA-LEE]

A little pricier than Charlie's, but will come relatively quickly and has a direct plug in connector. Even get the T5 torx driver

http://www.amazon.com/gp/product/B00FGSRY5A/ref=oh_details_o02_s00_i00?ie=UTF8&psc=1

Great Find!!!