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The battery puffed up on a Windows tablet I have that installed ubuntu server on.

Easy to take the back off then because the battery lift it up.

It would not work any more so I unplug the battery and cut off the wire that goes to the board in it.

The power supply on it is 12 volts and I solder some wires from it to the plus and minus of the battery.

But it don't say up.

Just before it went down I did this command:

raymond@ray-tablet:~$ upower -i $(upower -e | grep BAT) | grep --color=never -E "state|to\ full|to\ empty|percentage" state: discharging time to empty: 9.7 minutes percentage: 15% raymond@ray-tablet:~$ uptime 06:14:21 up 13:27, 1 user, load average: 0.00, 0.00, 0.00 raymond@ray-tablet:~$

It was not 9.7 minutes but about 4 minutes and went inactive. I had to hold the power button in and it booted back up.

There is a wire wire left over from the battery. Can I solder this to ground or something then it will not think it's discharging?

Thank you.

-Raymond Day

Raymond Day
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  • How many wires are attached to the battery from the tablet? I assume its more than 2 since you're saying that there is an extra wire not connected to anything. – thisjt Oct 15 '21 at 09:27

1 Answers1

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What is the battery nominal voltage rating? Does 12V comes from nearly discharged battery?

Most likely it's 4 cells in series (4S), Li-Ion, so it's nominal voltage should be 4 * 3.7V = 14.8V. While fully charged are 4 * 4.2V = 16.8V.

If your dead battery last readings was 12V, it was connected via 2 wires only, and now you've connected 12V power supply and it's not coming back up and previous statement are 100% correct then you can try slowly rising PSU voltage (if it's regulated) to 14.8V to see if it boots up. If it works, you need to get PSU as close to 16.8V as possible and your tablet will work as with always 100% charged battery.

NStorm
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  • It had 2 side by side tape together batteries 7.5 volts each. I solder the wight wire to ground and could not get it to go on. So solder it to the power of the SD card the middle pin 3.3 volts but the acpi -b command still says Discharging. What can I put the wight wire on to make it think it's charging? It had 3 red wires and 3 back wires to the battery and one wight wire. – Raymond Day Oct 15 '21 at 11:19
  • I looked on Google for "Battery bypass circuit" there is a lot but seems like no one has a answer. The I guess BMI wire on 3.3 volts of the SD card power a acpi-b command show this: "Battery 0: Discharging, 98%, 08:18:05 remaining" it seems like it is just staying there. Time will tell. It been like this for about a hour now at 98% it thinks. – Raymond Day Oct 15 '21 at 12:01
  • After some time it shows the battery went down but it's on a power supply. It shows this: Battery 0: Discharging, 98%, 08:18:05 remaining root@ray-tablet:~# acpi -b Battery 0: Discharging, 40%, 00:38:56 remaining So maybe in a half hour it my turn off. – Raymond Day Oct 15 '21 at 12:41
  • After some time it now shows this: Battery 0: Discharging, 0%, 00:08:06 remaining root@ray-tablet:~# acpi -b Battery 0: Discharging, 8%, 01:13:30 remaining root@ray-tablet:~# So it went to 0% to 8% it says Discharging but it looks like it's charging. – Raymond Day Oct 15 '21 at 13:01
  • This is something it seems like if I keep the screen on it stays up. If I turn the screen off in 1 minute with this command: "root@ray-tablet:~# echo -e "\033[9;1]" > /dev/tty1" it will not stay up for long. Still got the wight I guess sense wire to 3.3 volt on the middle pin of the SD card slot. Why would it do this when using more power for the screen it says like this: root@ray-tablet:~# acpi -b Battery 0: Discharging, 98%, 08:18:05 remaining – Raymond Day Oct 16 '21 at 07:21
  • Turn the screen off battery went way down. I turn the screen back on but it did not help. It went in a sleep mode and I puess the power to get it out. Then it said for a while 0 remaining and then after about 1/2 a hour back to how it was 93% looks like this. root@ray-tablet:~# acpi -b Battery 0: Discharging, 0%, remaining root@ray-tablet:~# acpi -b Battery 0: Discharging, 0%, remaining root@ray-tablet:~# acpi -b Battery 0: Discharging, 93%, 08:19:05 remaining root@ray-tablet:~# uptime 10:42:54 up 1 day, 1:36, 2 users, load average: 0.00, 0.01, 0.00 root@ray-tablet:~# – Raymond Day Oct 16 '21 at 14:44
  • I am still working on this the most it stayed up is almost 2 days. I had a 100K resistor to ground on the wight wire. I just solder a 220K resistor to ground to the wight wire. So will see how long it stays up. I can do this command to see how it thinks the battery is: acpi -s Battery 0: Discharging, 96%, 00:58:26 remaining – Raymond Day Dec 02 '21 at 01:30
  • On line all I can find is hook up the plus and minus wires but they don't say how to keep it going while power is still going. Cellphone and tables will just turn off thinking the battery is 0. But there is no battery just power. – Raymond Day Dec 02 '21 at 01:34