Battery problems, Is it bad to run the Nexus down all the way to zero?

[idaute]

QUOTE=philba;2605187]

Leaving the N7 plugged in for extended periods should not damage the battery if the circuit designers did their job (which, I am confident they did).

philba, we all know that the designers did indeed do their job, otherwise the product would have been a complete flop. The real problem is what if the circuitry in the tablet controlling the charging fails? You then have the chance of the battery overcharging if the charger is left plugged in for extended periods. There is the danger, and to be astute and avoid that danger one should simply not leave his tablet on charge for extended periods of time.

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[jpash549]

Leaving a battery at 4.2 volts for an extended period of time was shown to stress the battery and reduce it's capacity according to a Battery University study. Since LiPo chemistries vary as do manufacturing techniques this data may not apply exactly to a particular set of N7 batteries.



From my N7 or BBPB or HPTP or HP Laptop

 

[dency45]

Leaving a battery at 4.2 volts for an extended period of time was shown to stress the battery and reduce it's capacity according to a Battery University study. Since LiPo chemistries vary as do manufacturing techniques this data may not apply exactly to a particular set of N7 batteries.




From my N7 or BBPB or HPTP or HP Laptop

yes but it just stated there Li ion batteries. but the nexus 7 was fabricated with the Li ion batteries that it will discharge when it reached maximum. i observed this is true because when nexus 7 is charging a little heat occurs and when at 100% the nexus is cold.

 

[philba]

I believe that study refers to keeping 4.2V supplied to the +terminal of the LiPo. I am pretty sure that the charge manager deals with that and disconnects it when terminal voltage is reached. All batteries will self discharge and I presume the charge manager will kick in to top it off when that happens.

As to the point about "what if the circuitry in the tablet controlling the charging fails?". Well, sure, if it fails, it's broken and any manner of problems could occur. If you really think this is a likely scenario, why did you buy an N7 to begin with?

 

[jpash549]

I believe that study refers to keeping 4.2V supplied to the +terminal of the LiPo. I am pretty sure that the charge manager deals with that and disconnects it when terminal voltage is reached. All batteries will self discharge and I presume the charge manager will kick in to top it off when that happens.

As to the point about "what if the circuitry in the tablet controlling the charging fails?". Well, sure, if it fails, it's broken and any manner of problems could occur. If you really think this is a likely scenario, why did you buy an N7 to begin with?

The point of the study was that maintaining that particular test set of LiPo batteries at above 4.0 volts reduced the battery health ( amount of watt-hours stored at full charge). If you assume that this result applies to LiPo. batteries in general you may conclude that it is somewhat harmful to leave your tablet or cell phone on charge at about 4.2 volts for an extended period of time. Thus when the charging is done it is a good practise to take it off the charger. But don't worry too much about this. Batteries can be replaced although that is not easy with some devices. See iFixit site. Replacement of the N7 battery is quite easy.

As far as the overcharge problem is concerned controls built into N7 software and the battery package are designed to prevent this as stated. There is probably also a temperature shutdown device. Overcharging can lead to bad results such as fires or even explosions. The problem is the same for all tablets and phones and there is no verified incidence that I know about of problems with the N7.

Read a post somewhere of a user who liked to listen to internet radio and put the tablet under the pillow. Found out that it got quite hot because the heat had no place to go. Same problem might occur in a bag so it's a good idea to go into airplane mode and standby at these times. Experiments show that temperature above about 40 C is a strong factor in reducing battery life


From my N7 or BBPB or HPTP or HP Laptop

 

[kawana72]

So what's the answer here? Is it bad to discharge the Nexus 7 until the notification pops up telling you to recharge the tablet? I have a Razr Maxx and basically just let it run down until the notification pops up. Is this doing harm to either of my devices?

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[idaute]

So what's the answer here? Is it bad to discharge the Nexus 7 until the notification pops up telling you to recharge the tablet? I have a Razr Maxx and basically just let it run down until the notification pops up. Is this doing harm to either of my devices?

Sent from my Nexus 7 using Android Central Forums

No, you are not doing harm to either of your devices. The only caveat to what you do is that you will want to recharge very soon after you have received the notification telling you to recharge. The circuitry used in analyzing the batteries will further discharge the batteries over time. This is in combination with the batteries own tendency to discharge slowly over time could result in the batteries becoming ruined in that they will at the extreme uncharged state no longer accept recharging. Plus, the batteries are subject to overheating with dangerous consequences when discharged below the point at which you get the notification to recharge them. The bottom line is recharge the batteries when you receive that notification, and don't let them sit without recharging for any extended period of time after you have received that notification.

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[jpash549]

No, you are not doing harm to either of your devices. The only caveat to what you do is that you will want to recharge very soon after you have received the notification telling you to recharge. The circuitry used in analyzing the batteries will further discharge the batteries over time. This is in combination with the batteries own tendency to discharge slowly over time could result in the batteries becoming ruined in that they will at the extreme uncharged state no longer accept recharging. Plus, the batteries are subject to overheating with dangerous consequences when discharged below the point at which you get the notification to recharge them. The bottom line is recharge the batteries when you receive that notification, and don't let them sit without recharging for any extended period of time after you have received that notification.

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Good advice to recharge as soon as you can after reaching notification of low battery or actual shutdown. If you have to wait to get to a charger suggest at least putting in airplane mode and sleep mode or maybe shutting off altogether

Haven't heard about danger of overheating causing a dangerous situation when recharging a low battery. Overcharging above 4. 25 volts or so can cause fires and even explosive rupture of LiPo batteries. But as mentioned before software and controls are in place in tablets to prevent this. Removable LiPo or regular lithium batteries are used in remote control model planes and cars and must be carefully recharged often in a charging sock. There are of course videos on YouTube.

From my N7 or BBPB or HPTP or HP Laptop

 

[kawana72]

Good to know, thanks..

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