One of my friends had a problem with his HP Slate 7
My HP slate 7 will not charge nor will it turn on, I have tried a different charger and different outlet plug. I tried different cables and different PC ports. Looks like the battery is not working anymore.
And true he is. The battery was discharged way bellow the operational limit. The HP Slate 7 has a Li-Polymer Battery: 3.7V, 3500mAh. Usually this type of batteries are charged up to 4.2V (Charging cut-off voltage) and work down to 2.75V (discharge cut-off voltage).
In other words, your tablet should know when to switch off, way before the voltage on the battery falls bellow 2.75V. If the battery is old and can’t hold the voltage or if you keep pressing the power button when is discharged you might force the tablet to discharge the battery bellow cut-off voltage. If you get into this kind of trouble with your HP or any other tablet/laptop/phone you can fix it quite simple. Charge the battery directly using a current limited power supply.
- Remove the backcover of your tablet
- Remove Battery connector and measure the voltage between – (black) and + (red) wires using a voltmeter.
- In my HP case, the battery voltage was around 1.8V. Next step is to connect the battery to a power supply using a current limit of 0.5A (you can go up to 1A if you want a faster charging). Charge the battery up to 4V. I stopped around 3.8V.
- Reconnect the battery to it’s tablet connector and connect the table to a PC using a charging cable. Power up the tablet.
Wait until you tablet is fully charged and enjoy! Be sure you are doing this steps with special care and read all information regarding your battery type. If you are not feeling safe doing this steps please ask for professional help.