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Author Topic: Charging and turning on questions  (Read 3121 times)

Offline Halloween Jack

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Charging and turning on questions
« on: May 13, 2014, 01:05:04 PM »
Hi guys,

My son has a Nexus 7 and we're having a couple of issues.

Firstly, if the charge is really low and we plug it in we still can't use it for an hour or so. Perhaps it drains faster than it charges? Is this normal?

It makes it really hard to use as the charge doesn't last that long anyway. Other devices I've used still charge up while you're using them, just at a slower rate.

And also, to turn it on you have to hold the power button for 10secs or so. This coupled with the fact it doesn't come on if the charge is low, or tell you it's low make it frustrating to turn on.

Is this a fault or a bug or something?

Cheers



Offline StewMc

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Re: Charging and turning on questions
« Reply #1 on: May 13, 2014, 03:21:41 PM »
Which N7?

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Offline matt

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Re: Charging and turning on questions
« Reply #2 on: May 13, 2014, 04:40:20 PM »
You're draining it until it shuts down, instead of sleeping.
I use https://play.google.com/store/apps/details?id=ccc71.bmw  to show when it is charging, should be green ma in status. Sometimes I have to reconnect the USB cord several times before getting an actual charge going. Once you have it charging, shut off the screen. Use a good power supply and cord, the computer and other 500 ma sources are very slow.

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Offline matt

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Re: Charging and turning on questions
« Reply #3 on: May 13, 2014, 04:44:33 PM »
With the screen on, that app may only show 200-800 ma of charge with the 2amp stock charger as the device will use some power while on. WiFi, bluetooth, NFC, GPS can be turned off to use less of the available power, and I run the screen brightness at far less than maximum.

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Offline S.Prime

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Re: Charging and turning on questions
« Reply #4 on: May 14, 2014, 03:09:31 AM »
With any of my Nexus Devices, if the battery becomes completely depleted, I have a lag time between connecting the charger and a a sufficient charge for the Nexus to become usable. The fastest recharge rate is achieved with the screen off and using the original charger and USB cable, so expect slower charge rates with any variations. For maximum battery life, purchase a cover with the screen off feature or make it a habit to hit the power button when not in use to turn off the screen and charge as soon as possible when the battery status drops below 20%.

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Offline Halloween Jack

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Re: Charging and turning on questions
« Reply #5 on: May 14, 2014, 01:24:57 PM »
Hi there,

StewMC, it's 1st gen is there more than that? I'm not sure how to check.

matt, Sorry how do you mean draining until it shuts down instead of sleeping? I tried that app but it tells me there's -ve ma, like -2 ma in red. This happens no what charger I use. The app also says 'Discharging' which is alarming. I tried reconnecting many times (why should you need to anyway?) But it always says the same.

What's going there?

S.Prime, we have a cover that turns the screen off. But we were hoping to use it while charging sometimes.

But shouldn't plugging it in power it for use? even if the charging is low, surely you should be able to run a device off the mains indefinitely?

Thanks for your help guys :)

Offline Halloween Jack

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Re: Charging and turning on questions
« Reply #6 on: May 14, 2014, 02:04:32 PM »
Really confused now:

After resetting the tablet the ma had gone up to +723. So I checked the help file to understand what the ma flow was exactly.

Then it went down to -823ma. I thought this might be chrome open so I closed it but the ma stayed the same.

Is there just a big lag on the readings?

Is it +ve will charge and -ve will drain?

After typing this its up to 590ma.

Sorry if I'm being dense but can someone explain what it's telling me?

Cheers

Offline matt

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Re: Charging and turning on questions
« Reply #7 on: May 14, 2014, 05:12:49 PM »
I tried a number of USB cords to find one that charges reliably. There might be an intermittent connection so that a wire works sporadically, or some dirt or lint in the USB jack itself. My 1st gen has a quirk where the battery graph shows no rise in the graph while charging and I have to reconnect. It may be a ROM issue, waiting on the next ota update. Try another cord, short and thick seem to deliver more amps, dedicated charging cords that short the data pins may charge quicker.

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Offline matt

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Re: Charging and turning on questions
« Reply #8 on: May 14, 2014, 05:16:35 PM »
And using a dock to charge makes no difference with mine. Try to keep it in the green.

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Offline matt

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Re: Charging and turning on questions
« Reply #9 on: May 14, 2014, 05:21:51 PM »


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Offline matt

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Re: Charging and turning on questions
« Reply #10 on: May 14, 2014, 05:48:17 PM »


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Offline matt

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Re: Charging and turning on questions
« Reply #11 on: May 14, 2014, 05:51:50 PM »
683+211=894ma from charger. (Full battery) another cause of non-steady state current might be background processes syncing. Facebook, SMS, email, location, etc.

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Offline Halloween Jack

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Re: Charging and turning on questions
« Reply #12 on: May 15, 2014, 01:44:04 AM »
thanks Matt, I've bought a better quality lead (hopefully  :) )

So, just one more thing...

Any idea why I have to hold the power switch down for 8 secs or so when powering on? This happens even when battery is charged.

Cheers

Offline S.Prime

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Re: Charging and turning on questions
« Reply #13 on: May 15, 2014, 07:40:28 PM »
My 2012 model has the same lag when turning on from complete power off state. If you continue to have battery issues, you may want to consider that it is battery age.

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Offline matt

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Re: Charging and turning on questions
« Reply #14 on: May 15, 2014, 08:04:54 PM »
Yeah, there may be some processes running that discharge the battery in sleep mode to the point of shutting down the tablet. Mine takes that long as well from off state. But from hibernation it is instant on.

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