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Tablet's battery not charging?? Solution found!!


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#1 eatatjoes

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Posted 29 September 2011 - 04:16 PM

You have a tablet, but the battery doesn't charge? Your warranty is voided? No replacement possible?

Here are the great news:

at DealExtreme is a "8,4V power supply" for less than $5 available. It is a perfect "CC/CV" Lithium battery charger!! :yahoo:
Unfortunately the built quality of the charger is only "chinese standard", it didn't work out-of-the-box and I had to resolder some joints. But it is no "SMD-soldering", just normal sized components! And for $5 we can not expect it to have passed any "quality control" :rofl:

Most important, the link:
http://www.dealextre...-pin-plug-66684

Out of my curiousity I ordered the charger to test it on my original 2 cell battery pack:
Up to a voltage of 8,0V it charges the battery pack with 1000mA (like the original tablet's built in circuit!). As the voltage rises, it will "slow down" and decrease the current to ~30mA. Perfect CC/CV behaviour!
The charger has an indicator-LED that shows red while charging, and green when the voltage of 8,4V is reached!

The charger will be able to charge a big (2200mAh) battery in ~2,5-3 hours when the tablet is shut down (on standby it will take a little longer).
If you use the tablet while charging (yes, it will be possible!), it will take app. 5-6 hours for a full charge from 0% to 100%.

I made a chart for anyone who doesn't believe it. My battery pack was not completely empty, therefor the chart starts at a voltage of 7,8V, the tablet was not used while charging:
Attached File  Charging 2-cell battery pack.jpg   48.04KB   149 downloads
If you'd have a working circuit in your tablet, it will do exactly the same thing, exept for the high voltage. It might be only my device to go up to more than 8,4V. It will not kill the battery, but might shorten the "lifetime" of the battery a little. If you use the indicator-LED, and disconnect the charger when the light is green, everything will be fine. Just don't leave it connected "overnight".

Edit:
If you are willing to open your tablets back, and you know how to use a solder iron (only two wires and a small plug will be needed!), you will be able to fix the charging with the DX-charger! You might also use the original power plug of the tablet, but it is not as easy to do, as I thought. It depends on your skills!
No extra wires need to hang out of the tablets housing.
End edit

The order-to-delivery-time from HK to Germany took exactly 20 days: order now, and have your battery power back in ~3 weeks...
:drinks:

Edit:
Now here is the news:
The idea to use the original tablet's plug with the DX-charger is very difficult and not recommended!
Trying to do it nearly killed my (still working) tablet's board, because I nearly cracked it! :o
I was very lucky, no electric traces seem to be damaged. :D
If your charging circuit in the tablet is completely dead (like Marcos' and Philip's) it might be possible to use the original plug, but I will not do any further tests, I will not damage my tablet for a this. :nea:

I will try to write my guide during the next weekend.
It will include three different ways to use the DX-charger:

1: the "easy way" with the original plug, that didn't work on my tablet, because my tablet's charger still works. My battery tried to charge itself, and I had a "green and red LED" at the same time! Like this the battery drained very fast, even with a switched off tablet! It might work for tablet's with a dead charger circuit, without mods on the board. You can also try it on tablets with a bad working charging circuit, it might work. It only needs the DX-charger and soldering two wires and I think, it's worth a try.

2: the very hard way, using the original plug, for tablet's with a "bad working charger circuit". It will need some modifications on the board (cutting two traces on the backside of the board!). I didn't finish it, because I don't want to "damage" my tablet.

3: the "not so easy" way with a secondary plug in the tablet's housing. You will need to drill a small hole to the housing and mount a small secondary two-pin "power"-plug for the DX-charger. I didn't do it, but it's easy to do and will work nice. I think it will be the best of the three possibilities.
End edit

Edited by eatatjoes, 06 October 2011 - 05:31 PM.

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#2 prox32

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Posted 29 September 2011 - 06:54 PM

When you do the how-to ill pin up on the board :)!

#3 vkeza057

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Posted 30 September 2011 - 05:10 AM

EDIT
Good news! I knew it would work! :clapping:
The No.1 Dropad A8/Herotab C8 problem has ALMOST been (completely) solved!

Eatatjoes will fix it! :pardon:

Edited by vkeza057, 07 October 2011 - 08:34 AM.

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#4 Enslave

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Posted 30 September 2011 - 06:35 AM

Is it possible that the lithium polymere charging circuit runs off DC that means the plug is a ac-dc and then charger circuit?

which part ( or chip ) is used for charging?

i thought about using step up& li charger circuit for the tablet to get it charging with 5V and more time @ less current, but my step up introduced to much noise and made the li charger IC nuts..

#5 old_fart

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Posted 30 September 2011 - 10:01 AM

Is it possible that the lithium polymere charging circuit runs off DC that means the plug is a ac-dc and then charger circuit?

which part ( or chip ) is used for charging?

i thought about using step up& li charger circuit for the tablet to get it charging with 5V and more time @ less current, but my step up introduced to much noise and made the li charger IC nuts..

Tell us more about your 'step up'. . did you put a large cap on its output ?

#6 Fyre ~

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Posted 01 October 2011 - 06:31 AM

I'm not an "electronics person" so I hope you can clarify my doubts. :) I clicked on the DX link but I found no "charger" product. Instead, I found an "AC to DC power supply". Also, the connector / socket seems a little too big to fit my tablet:

Posted Image

Am I supposed to plug this product directly into my tablet?

If not, how could a power supply serve as a charger (which would have some form of intelligence to know when to stop charging)? Thanks for answering! :good:
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#7 old_fart

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Posted 01 October 2011 - 10:28 AM

an "AC to DC power supply" is a charger. and then about the connector socket . . . does eatatjoes say it was the correct for him ? i believe he does, though he is a h/w modder kind of a guy. did you read 'both' threads ?

#8 Fyre ~

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Posted 01 October 2011 - 08:07 PM

an "AC to DC power supply" is a charger. and then about the connector socket . . . does eatatjoes say it was the correct for him ? i believe he does, though he is a h/w modder kind of a guy. did you read 'both' threads ?

I didn't know this was a follow up to some other thread(s)... In any case, do you know the rough idea of this fix? As in... is this "charger" a replacement for the original one which he had diagnosed his as faulty? Or, is this "charger" going to be somehow soldered onto the circuitry of the tablet, or, just onto the battery? If soldering is required, would the charger be permanently attached to the tablet?

Sorry for the bunch of questions. I'm very curious and excited in getting my tablet charging properly.
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#9 syan

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Posted 02 October 2011 - 01:44 AM

The problem of battery not charging finally came to me yesterday after a 6-month-use of this tablet (mine is Haipad M7).I looked into 99pad.com and find a solution.
I followed the instruction from this post: http://http://www.99...-25029-1-2.html
Now the battery is doing bussiness as usual.
This really works for my M7, and hope this may help those with the same problem.

http://www.99pad.com...EzUpEHLiM1p.jpg

The instuction in english:
1. connect charger to tablet
2. power on to see the Lock-Screen
3. short circuit the 2 leads marked: GND and VBAT >>> this will cause the tablet to power off
4. turn on the power again, go through the Lock-Screen and you can see the battery indicator shows its charging again

After an overnight charging, the indicator lamp turned green this morning. The battery icon shows 100% now while I'm writing this post.

N.B. This is the same post(#174)I put under this thread >>>"Battery not charging at all Powerless without the AC..." (http://www.slatedroi...102#entry246102)

Edited by syan, 28 October 2011 - 10:32 PM.


#10 old_fart

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Posted 02 October 2011 - 01:51 PM

i went to the website ( 99pad dot com ) and then my malwarebytes ( anti-malware active protection ) popped up and said the site was "trying" to put some stuff onto my machine without my permission. well now my machine ( being credibly smarter than me - thank goodness ) will "not" let me go back to that site again. hmmm, i'll have to remove my protection to be able to go where i want to go . . . and do what i want to do . . . ( could i use that line in a song ? )

Edited by old_fart, 02 October 2011 - 05:05 PM.


#11 Loonix

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Posted 02 October 2011 - 03:46 PM

you realy should use adblock plus and noscript ;)
but still i dont think 99pad tries to install anything malicious. it is a very active forum i think someone would have said something.

The picture shows the battery connectors on the mainboard of the Pad.
Best luck for everyone who (has to) try this!
7" Herotab C8 @Rajesh's ROM v1.1 Beta

#12 old_fart

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Posted 02 October 2011 - 05:08 PM

you realy should use adblock plus and noscript ;)
but still i dont think 99pad tries to install anything malicious. it is a very active forum i think someone would have said something.

The picture shows the battery connectors on the mainboard of the Pad.
Best luck for everyone who (has to) try this!

thanks, Loonix . . is that with the latest firefox ? . . i saw where they're pushing out a new version last week. . google chrome are the maniacs in pushing out stuff. . i read the safest way to be is in a 'sandbox' ?
. . . . .
i am sorry i am off topic.... end of useless chatter......

Edited by old_fart, 02 October 2011 - 05:14 PM.


#13 Loonix

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Posted 02 October 2011 - 05:16 PM

ok, now we go offtopic ^^
yes, i use firefox 7.0.1, in that the Adblock Plus plugin 1.3.10 and NoScript 2.1.4rc2...
Sandboxing is always a good idea, also for online banking and so forth (you can setup a VirtualBox with Linux if you like) but i am not going so far.
Chrome i do not like, google has enough info about me :þ
7" Herotab C8 @Rajesh's ROM v1.1 Beta

#14 vkeza057

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Posted 04 October 2011 - 03:01 AM

I tried this unhealthy procedure last night. It doesn't work on my Dropad A8. Anyway, people should try this before the other procedures that involve soldering. Some of them will get lucky like syan.

The problem of battery not charging finally came to me yesterday after a 6-month-use of this tablet (mine is Haipad M7).I looked into 99pad.com and find a solution.
I followed the instruction from this post: http://www.99pad.com...25029-1-2.html.
Now the battery is doing bussiness as usual.
This really works for my M7, and hope this may help those with the same problem.

http://www.99pad.com...EzUpEHLiM1p.jpg
The instuction in english:
1. connect charger to tablet
2. power on to see the Lock-Screen
3. short circuit the 2 leads marked: GND and VBAT >>> this will cause the tablet to power off
4. turn on the power again, go through the Lock-Screen and you can see the battery indicator shows its charging again

After an overnight charging, the indicator lamp turned green this morning. The battery icon shows 100% now while I'm writing this post.

N.B. This is the same post(#174)I put under this thread >>>"Battery not charging at all Powerless without the AC..." (http://www.slatedroi...102#entry246102)


My Android devices:

Samsung Galaxy S I9000
Dropad A8 (Evolution v2 R4)

#15 eatatjoes

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Posted 04 October 2011 - 04:29 PM

Hi, I'm back from my trip. Didn't find the time yet, to write the "how to", but I will soon.

I tried this unhealthy procedure last night. It doesn't work on my Dropad A8. Anyway, people should try this before the other procedures that involve soldering. Some of them will get lucky like syan.


vkeza057 is right: try this first.
Don't do it for long time, less than 1 second!
If the battery is charged (10% might be enough!) and the protection doesn't work, you will burn up or "desolder" the battery connectors within seconds!!
But if it doesn't work, it might cause the battery to completely shut off (protection should kick in, because of the shorted battery!) Like that, a "bad working" battery/charging might be completely dead after that procedure. But you may reset it, like I wrote before.

@Fyre~
the "charger" will be used like the original power supply, connected to the tablet via the original or a secondary small plug. It will replace a not-working-charger-circuit in a tablet, and somehow also a not-working-original-power-supply.
It is an "external charger" with it's own regulation for charging the lithium battery. There will be two wires soldered from the original plug (inside the tablet) to the battery connection, bypassing the internal charger. The DX charger brings it's own charger circuit!

The internals of this charger are no smd-parts, they are much too big to be placed inside the tablet.
The most difficult thing will be to use the original tablet's plug. You also need to have a look at the board inside the DX-charger, mine was very badly soldered and didn't work. In the same step we will replace the plug on the DX charger with the wire/plug of the original power supply, to make it perfectly fit the original or secondary tablet's plug!
But like that, the solution (in my opinion) is better than the original: if the DX-charger later fails, you will only have to replace it! No more soldering inside the tablet, and also no more heating up the tablet while charging.


@all
for now, I will not answer any more questions, until I wrote the "how to"... :nea:
I bet, some of you will be able to do the mod, only by reading the first and this post!

Edited by eatatjoes, 06 October 2011 - 04:40 PM.

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#16 eatatjoes

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Posted 06 October 2011 - 05:29 PM

Hi all,
unfortunately I had to edit my first and #15 post! :blink:
The big font is new text.
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#17 eatatjoes

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Posted 06 October 2011 - 05:35 PM

Great news! I knew it would work! :clapping:
The No.1 Dropad A8/Herotab C8 problem has been (completely) solved! :yahoo:

Eatatjoes does it again!


Hi vkeza057!
please edit your post #3, it's not true anymore!
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#18 Zifban

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Posted 07 October 2011 - 07:20 AM

Hi eatatjoes, I'm looking forward for the details instruction! I have ordered one of this charger, and I'd see if there is solution for my dead table :S (dropad that I think is the same hardware than herotab).

Thank you!

You have a tablet, but the battery doesn't charge? Your warranty is voided? No replacement possible?

Here are the great news:

at DealExtreme is a "8,4V power supply" for less than $5 available. It is a perfect "CC/CV" Lithium battery charger!! :yahoo:
Unfortunately the built quality of the charger is only "chinese standard", it didn't work out-of-the-box and I had to resolder some joints. But it is no "SMD-soldering", just normal sized components! And for $5 we can not expect it to have passed any "quality control" :rofl:

Most important, the link:
http://www.dealextre...-pin-plug-66684

Out of my curiousity I ordered the charger to test it on my original 2 cell battery pack:
Up to a voltage of 8,0V it charges the battery pack with 1000mA (like the original tablet's built in circuit!). As the voltage rises, it will "slow down" and decrease the current to ~30mA. Perfect CC/CV behaviour!
The charger has an indicator-LED that shows red while charging, and green when the voltage of 8,4V is reached!

The charger will be able to charge a big (2200mAh) battery in ~2,5-3 hours when the tablet is shut down (on standby it will take a little longer).
If you use the tablet while charging (yes, it will be possible!), it will take app. 5-6 hours for a full charge from 0% to 100%.

I made a chart for anyone who doesn't believe it. My battery pack was not completely empty, therefor the chart starts at a voltage of 7,8V, the tablet was not used while charging:
Attached File  Charging 2-cell battery pack.jpg   48.04KB   149 downloads
If you'd have a working circuit in your tablet, it will do exactly the same thing, exept for the high voltage. It might be only my device to go up to more than 8,4V. It will not kill the battery, but might shorten the "lifetime" of the battery a little. If you use the indicator-LED, and disconnect the charger when the light is green, everything will be fine. Just don't leave it connected "overnight".

Edit:
If you are willing to open your tablets back, and you know how to use a solder iron (only two wires and a small plug will be needed!), you will be able to fix the charging with the DX-charger! You might also use the original power plug of the tablet, but it is not as easy to do, as I thought. It depends on your skills!
No extra wires need to hang out of the tablets housing.
End edit

The order-to-delivery-time from HK to Germany took exactly 20 days: order now, and have your battery power back in ~3 weeks...
:drinks:

Edit:
Now here is the news:
The idea to use the original tablet's plug with the DX-charger is very difficult and not recommended!
Trying to do it nearly killed my (still working) tablet's board, because I nearly cracked it! :o
I was very lucky, no electric traces seem to be damaged. :D
If your charging circuit in the tablet is completely dead (like Marcos' and Philip's) it might be possible to use the original plug, but I will not do any further tests, I will not damage my tablet for a this. :nea:

I will try to write my guide during the next weekend.
It will include three different ways to use the DX-charger:

1: the "easy way" with the original plug, that didn't work on my tablet, because my tablet's charger still works. My battery tried to charge itself, and I had a "green and red LED" at the same time! Like this the battery drained very fast, even with a switched off tablet! It might work for tablet's with a dead charger circuit, without mods on the board. You can also try it on tablets with a bad working charging circuit, it might work. It only needs the DX-charger and soldering two wires and I think, it's worth a try.

2: the very hard way, using the original plug, for tablet's with a "bad working charger circuit". It will need some modifications on the board (cutting two traces on the backside of the board!). I didn't finish it, because I don't want to "damage" my tablet.

3: the "not so easy" way with a secondary plug in the tablet's housing. You will need to drill a small hole to the housing and mount a small secondary two-pin "power"-plug for the DX-charger. I didn't do it, but it's easy to do and will work nice. I think it will be the best of the three possibilities.
End edit



#19 eatatjoes

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Posted 07 October 2011 - 05:09 PM

Hi zifban,
I tested it on the Dropad A8, and if the herotab has a "7,4V battery" (charger with 9V?) it will work too.

@vkeza057
thank you for the nice edit! :rolleyes:
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#20 Fyre ~

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Posted 08 October 2011 - 11:56 PM

Edit:
If you are willing to open your tablets back, and you know how to use a solder iron (only two wires and a small plug will be needed!), you will be able to fix the charging with the DX-charger
No extra wires need to hang out of the tablets housing.
End edit

Can you shed some light if I need to open up the DX charger (i.e. the big black block) to work on it? Also, where are the soldering needed? It sounds really good that the mod allows no extra wires hanging out from the housing, but I can't imagine how to do that.

Before the HOWTO is released, can you explain very briefly the steps? E.g. where are the 2 wires (what is this? from the DX charger? or some other common wires?) gonna be soldered?

I need this mod because after charging my tablet for 10 hours straight, the voltage is reportedly only 8.0 V, and the charging LED is still red. :( I suspect the charging circuit is faulty.
~ Have fun ~
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My timezone: +0800