Help Nexus 7 Charging Times/USB Cable Specs?

[iamthrealmungo]

Hello,

I'cve read a lot of conflicting info on the charging times and practises when using the supplied USB cable etc.

I think the supplied USB cable is far too short, but people have said that the supplied USB cable is capable of taking 2A which is unusual, where can I find a longer replacement USB cable of the correct specs to charge the Nexus 7 (2013)?

Also, how long should a full charge take using the mains power when the tablet is just locked with the screen off?

Is it best practise to let the battery discharge fully and charge fully a few times or would it be better to charge as often as possible and keep it as close to 100% as possible?

Thanks

 

[tukatz]

Everything I've read says do NOT fully discharge a li-ion battery. When mine gets down to 50 - 60%, I plug it in. The charger that comes with the N7 puts out 5.2v and 1.35 amps. The charger that came with my android phone puts out 5v and 1 amp. My N7 will charge off of that charger or off of a USB port in my laptop, but it does so slower. I've never timed the charging from the supplied charger, but it is fairly quick. As to a longer cable, try Radio Shack or search on-line.

 

[iamthrealmungo]

Does that mean that letting the device run down to 10% and lower could potentially damage the battery? That seems like a massive flaw if that's the case.

I've read that any replacement USB cable needs to be capable of supplying the output of the mains charger, how can you be sure a USB cable is large enough to cope with the nexus 7 mains charger?

 

[tukatz]

All I can tell you is that my reading indicates that fully discharging a li-ion battery will shorten its life. That's not a design flaw of the N7. Li-ion batteries are, as far as I know, the best technology available today for devices like tablets and smart phones.

Interestingly, the cable that came with my N7 is SMALLER in diameter than the one that came with my cell phone. I'm no electrical engineer, but I imagine it has to do with impedance. The spec for a cable should tell you what you need to know.

 

[unnamedny]

Not sure why battery would get damaged by letting it run low. I wouldn't believe that. Some USB work and some don't. If cable length is a such a big issue, and you do not want to charge it with anything besides asus charger/cable, go to any hardware store, but 6ft extention cord, duct tape it to charger. Problem solved.

 

[jhsrennie]

Does that mean that letting the device run down to 10% and lower could potentially damage the battery? That seems like a massive flaw if that's the case.

Running lithium batteries flat will cause irreversible changes that shorten the life of the battery. A quick Google will find you loads of articles on this subject.

However I believe (though I don't know for sure) that all modern devices including the N7s will not allow you to fully discharge the battery. Instead they will switch off before the battery is fully discharged (this is probably related to the notorious problems getting the 2012 N7 turned on again if you let it run flat). So while you should probably avoid letting the battery run too low, you're unlikely to do it any damage.

 

[Deleted User]

I wish this misinformation would stop. Let me be clear:

THERE IS NO DANGER IN LETTING YOUR TABELT BATTERY RUN DOWN. VIRTUALLY NO PIECE OF MODERN ELECTRONICS WILL LET YOU RUN THE BATTERY TO DAMAGING LEVELS.

All smart devices shut off before hurting your battery.

 

[tukatz]

I'm sure I'm not the only one who would like to know your source. Non of us deliberately supplies misinformation. Knowing where to find reliable information would help us all.

 

[sparksd]

I ran into an issue with my 2012 N7 - it appears that a runaway app ran down my N7 while in sleep mode and completely drained the battery within a day of full charging. After charging for a while I turned it on and got the issue with the shutdown and "flying pixels". Let it charge a good deal longer and when I booted it I got the password prompt to decrypt. Only way out of this was to start into recovery mode and then do a complete data wipe and factory reset. No physical damage to the unit but what a hassle - other users have reported a similar problem after having their battery run down --

Nexus 7, type password to decrypt storage..... - Android Forums at AndroidCentral.com

 

[Deleted User]

I'm sure I'm not the only one who would like to know your source. Non of us deliberately supplies misinformation. Knowing where to find reliable information would help us all.

I work in an electronics company, we do this all the time.

Additionally: does it even make sense? I mean, does it even pass the sniff test? Lithium ion batteries are damaged when you run them too low. How would we not be experiencing massive, widespread battery failures all over the planet if safe cut-offs were not implemented in all consumer electronics?

People run their laptops, cell phones, tablets, MP3 players, electric razors, etc. down to shut-off constantly. Sometimes you don't even know - an app goes crazy and sucks the thing dry or you accidentally leave it on, or whatever. A little logic would dictate that all of these sealed, non-user-serviceable devices would be essentially unmanageable if the majority of the population - who has no idea about battery technology - was able to run it down to a damaging state.

 

[tukatz]

I accept the fact that since you work in an electronics company you 'probably' know what you are talking about, but that doesn't provide us with an 'authoritative' source.

As to making sense or passing the sniff test, telephone scams do so for far too many people or they wouldn't be happening. I'm afraid those things don't prove the point.

By the way, I don't believe anyone said running li-ion batteries too low would cause them to fail. What a few of did say was that it was our understanding (from something we had heard or read) that doing so would degrade their ability to take a full charge and essentially shorten their useful life.