N7 JB 4.2 strange charging issue

dexterslab · Nov 15, 2012

My stock unrooted 16gb n7 received the 4.2 update this morning, all has been fine until this evening when it needed charge.

It often gets plugged into a htc phone charger, which has worked fine since i bought the tab a few months ago until today, its a 1amp charger so it takes ages to charge, but thats fine as it is plugged in until the morning normally.

So i plugin as normal, and come back after setting up google play music on my desktop pc, and i see the unit rebooting showing the glowing X. The screen goes blank and is unresponsive, eventually the google logo appears and it boots normally (its still plugged in btw), after unlocking the screen goes mental after maybe 5 seconds with random noise on it, then goes black.

So i unplug and use the genuine asus charger and cable, it does the same twice over, reboot, freeze, long wait then reboot.

I have now left it on charge using the asus charger and it seems to be ok now

Have google changed some charging requirements? Anyone else seen this?

Sent from my Nexus 7 using xda premium

RusherDude · Nov 15, 2012

Not sure, but my nexus 7 on Android 4.2 charges like 35% slower than did with 4.1.2..... what the hell did they do??

dexterslab · Nov 15, 2012

Funny you mention that, i might agree with you there

The N7 seems fine today, i did make a couple of videos of it misbehaving last night, watching back my circle battery widget app jumps from 16% to 0% battery just before it goes blank, indicating it might have simply run flat but thought it still had 16% battery?

Wonder if they have changed the battery meter scaling?

I think i will run it flat and check it shuts down properly like it used to

Sent from my Nexus 7 using xda premium

jbird92113 · Nov 15, 2012

dexterslab said:
Funny you mention that, i might agree with you there

The N7 seems fine today, i did make a couple of videos of it misbehaving last night, watching back my circle battery widget app jumps from 16% to 0% battery just before it goes blank, indicating it might have simply run flat but thought it still had 16% battery?

Wonder if they have changed the battery meter scaling?

I think i will run it flat and check it shuts down properly like it used to

Sent from my Nexus 7 using xda premium

Hi dexterslab,

On a side note when you update to 4.2 were you already rooted and did you have superSU version0.98 installed? I have been reading other posts in this forum that folks have been rooted, superSU installed and the update has completely crashed their N7. ANy info would be greatly appreciated.

Thanks,
JBIRD

dexterslab · Nov 15, 2012

Its still as stock, locked and unrooted

Sent from my Nexus 7 using xda premium

scubastevegk · Nov 15, 2012

I've noticed slower charging since the 4.2 update too - did a quick Google search and landed here. Using the same genuine Asus charger and generic cable that I did before the update, and I would agree with the roughly 35% slower estimate.

jbird92113 · Nov 15, 2012

dexterslab said:
Its still as stock, locked and unrooted

Sent from my Nexus 7 using xda premium

Thanks, did you do a factory reset prior to updating?

dexterslab · Nov 15, 2012

No, update received ota so just installed it

Sent from my Nexus 7 using xda premium

dexterslab · Nov 17, 2012

Been working and charging fine since, guess it was just a random glitch!?

Sent from my Nexus 7 using xda premium

Guhrasoh · Nov 17, 2012

scubastevegk said:
I've noticed slower charging since the 4.2 update too - did a quick Google search and landed here. Using the same genuine Asus charger and generic cable that I did before the update, and I would agree with the roughly 35% slower estimate.

Are you using the new Daydream feature (you can find it in the display settings). If yes this may be the cause of slower charging, because it doesn't turn of the display.

dexterslab · Nov 17, 2012

Daydream is off.

Tbh, now it seems to have settled down i think maybe charging time is pretty much the same as it was. The whole debacle seems to be a complete non-event in hindsight!

Sent from my Nexus 7 using xda premium

scubastevegk · Nov 19, 2012

Guhrasoh said:
Are you using the new Daydream feature (you can find it in the display settings). If yes this may be the cause of slower charging, because it doesn't turn of the display.

No Daydream for me.

breal4sho · Nov 23, 2012

Mine is stock and unrooted. After the update I'm having the same charging issues. Incredibly slower charging. It's been plugged in for 6 hours now and it's at 80%. I did play a bit of pandora for about 30minutes but it was still plugged in. Other than that I haven't touched it other than to check the level. I turned daydream. Let's see if that help though I doubt it.

chismay · Nov 23, 2012

i think when you install the 4.2 update it does a battery stat wipe. this could produce the battery jumping from 16%-0% i reset the battery stats on my gt-i9003 the other day charged, its went from 100% - 40% instantly after about 2 charge cycles it should go back to normal.

it would also explain the battery seeming to take longer to charge, its just the voltage counter resetting itself. it might even in some cases charge faster....then run out quicker....

charge- discharge about 3 times and it should go back to norm.:good:

example :

dexterslab said:
Tbh, now it seems to have settled down i think maybe charging time is pretty much the same as it was. The whole debacle seems to be a complete non-event in hindsight!

still bro i wouldnt use any charger expect the asus one, phones maybe i mean i always use other peoples chargers,or pickup the wrong end from my snake-pit of charger cables hanging under my tv unit. but for tabs....nah lol

Wilks3y · Nov 23, 2012

chismay said:
i think when you install the 4.2 update it does a battery stat wipe. this could produce the battery jumping from 16%-0% i reset the battery stats on my gt-i9003 the other day charged, its went from 100% - 40% instantly after about 2 charge cycles it should go back to normal.

it would also explain the battery seeming to take longer to charge, its just the voltage counter resetting itself. it might even in some cases charge faster....then run out quicker....

charge- discharge about 3 times and it should go back to norm.:good:

example :

still bro i wouldnt use any charger expect the asus one, phones maybe i mean i always use other peoples chargers,or pickup the wrong end from my snake-pit of charger cables hanging under my tv unit. but for tabs....nah lol

Agreed, phones seem to be more universally compatible when it comes to charges.

Charge a tab with the wrong charger n you'll make up with a melted Nexus 7

chismay · Nov 23, 2012

i think its a part of certain regulations now that mobile phones needs to have an internal capacitor/transformer to make sure of this problem, as people usually run out of charge on the go and use other chargers as long as the connector fits and it begins charging, most of us including me are probably guilty of plugging a charger in, seeing its charging and thinking *yay it works fine* walking away and not really understanding what slow-fast damage can be caused to the device/battery.

for tabs 30% i would say dont have this feature:good: especially the Chinese ones. ? <no racial offence intended>

you guys know what im on about.

Optamizm · Nov 23, 2012

My Nexus 7 worked great before upgrading to 4.2. Now it can't charge while I'm using it... The battery just goes up and down as I'm surfing the web, if I load a lot of pages, it goes down, if I read a lot, it goes up... But if I try to watch a floating video while surfing the web, it just goes down... There is definitely a problem! Here is a screenshot... I'm using the original charger and cable...

najaboy · Nov 23, 2012

chismay said:
i think when you install the 4.2 update it does a battery stat wipe. this could produce the battery jumping from 16%-0% i reset the battery stats on my gt-i9003 the other day charged, its went from 100% - 40% instantly after about 2 charge cycles it should go back to normal.

it would also explain the battery seeming to take longer to charge, its just the voltage counter resetting itself. it might even in some cases charge faster....then run out quicker....

charge- discharge about 3 times and it should go back to norm.:good:

example :

still bro i wouldnt use any charger expect the asus one, phones maybe i mean i always use other peoples chargers,or pickup the wrong end from my snake-pit of charger cables hanging under my tv unit. but for tabs....nah lol

Wiping battery stats does absolutely nothing that affects reported battery charge level. That wives' tale was long ago debunked by a member of Google's Android team. The one and only thing you are wiping is a list of apps that have operated on battery since unplugging after the last complete charge. This in no way, shape, or form affects reported charge or has any effect on battery life whatsoever.

Sent from my Galaxy Nexus using Tapatalk 2

chismay · Nov 24, 2012

najaboy said:
Wiping battery stats does absolutely nothing that affects reported battery charge level. That wives' tale was long ago debunked by a member of Google's Android team. The one and only thing you are wiping is a list of apps that have operated on battery since unplugging after the last complete charge. This in no way, shape, or form affects reported charge or has any effect on battery life whatsoever.

Sent from my Galaxy Nexus using Tapatalk 2

LIKE I AM SAYING MY FRIEND,

actually the battery stats ARE WHAT THE GOOGLE DEV SAID is what gives you accurate readings it doesn't increase your battery life . i never said that it will, so please don't police me,.
heres the comment

This file [batterystats.bin] is used to maintain, across reboots, low-level data about the kinds of operations the device and your apps are doing between battery changes. That is, it is solely used to compute the blame for battery usage shown in the "Battery Use" UI in settings. That is, it has deeply significant things like "app X held a wake lock for 2 minutes" and "the screen was on at 60% brightness for 10 minutes."

when you flash a new firmware, the system must calibrate as there are no previous readings from the bstat file right?.,these are the readings that help the system produce the reported battery charge. its what it does to give you those readings, i was guiding the above member to wait and run a few cycles for readings to be more accurate i never said his battery was dead.

kinda why pretty much EVERYONE mentions after flashing a new firmware on most device they have a few days of battery "up-n-downs"= counter reset/data collection/last battstat file wiped.

cheers:good:

najaboy · Nov 24, 2012

chismay said:
LIKE I AM SAYING MY FRIEND,

actually the battery stats ARE WHAT THE GOOGLE DEV SAID is what gives you accurate readings it doesn't increase your battery life . i never said that it will, so please don't police me,.
heres the comment

This file [batterystats.bin] is used to maintain, across reboots, low-level data about the kinds of operations the device and your apps are doing between battery changes. That is, it is solely used to compute the blame for battery usage shown in the "Battery Use" UI in settings. That is, it has deeply significant things like "app X held a wake lock for 2 minutes" and "the screen was on at 60% brightness for 10 minutes."

when you flash a new firmware, the system must calibrate as there are no previous readings from the bstat file right?.,these are the readings that help the system produce the reported battery charge. its what it does to give you those readings, i was guiding the above member to wait and run a few cycles for readings to be more accurate i never said his battery was dead.

kinda why pretty much EVERYONE mentions after flashing a new firmware on most device they have a few days of battery "up-n-downs"= counter reset/data collection/last battstat file wiped.

cheers:good:

Read her entire dissertation, and you will see that it does not pertain to reported charge level. She explicitly states that batterystats.bin has no bearing on reported charge level. Interesting that you left out the portions of her post immediately prior to, and immediately following, the part of her post that you quoted... you know, the ones where she states, and then restates, that nothing in batterystats.bin affects the reported charge level? Also, the reason the battery seems more stable a few days after flashing new firmware is the kernel itself settling, not the OS.

Sent from my Nexus 7 using Tapatalk 2

N7 JB 4.2 strange charging issue

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