Charging problems with your tablet.
We often get posts asking for help with devices that are refusing to charge. Sometimes, the solution to the problem can be as simple as using the correct charger for your device. Not all a/c chargers are the same. Just because they have a USB connection does not mean they will charge your Tab, Note or whatever tablet you own.
So the first thing to check is that you are using the manufacturer supplied charger, or at least a charger that has the same output as the charger supplied by the manufacturer. This output can be read on the manufacturers' charger and the two important pieces of information will be the voltage and the amperage. A powered on PC USB port, for example, outputs at 5v/500ma.
The second thing to check is that you are using the charging cable that came with your device. Third party cables (especially those without a lot of owner reviews) sometimes just don't work! Also check to see that your cable and connectors are not damaged.
If you are happy that your charger and cable are fine, (or even if you are not & you want to try it anyway) then the next thing to try is the trickle charge trick.
Lithium based batteries don't like being completely flattened. Sometimes in that condition they will not accept a charge from the regular charger until they have got a little charge in them. In order for that to happen, connecting to a 5v/500ma connection - such as a powered on (& not sleeping) PC USB port, or a low power phone charger (5v/500ma) - for 8 hours or so, then enables the device to get a charge from the regular a/c charger.
So, the process would be...
- Device refuses to charge (or power on) when connected to the a/c charger.
- Using the charging cable, connect to a powered on (& not sleeping) PC USB port, or a low power phone charger (5v/500ma)
- Leave the device connected for a minimum of 8 hours. Longer won't be any problem.
- Reconnect the device to the a/c charger and try again
- If that process fails, try replacing either the charger and/or charging cable
The "long power button press & screen touch" power on trick.
On some Samsung tablets, it has been reported that the following process will get a device to power on, even if all other ideas have failed...
- Using the charging cable, connect to a powered on (& not sleeping) PC USB port, or a low power phone charger (5v/500ma).
- Hold down the power button AND touch your finger on the screen for about 30 seconds, and the battery (charging) will appear on the screen.
- Leave the device to trickle charge for a minimum of 5 hours before connecting to the regular a/c charger.
Once you are successful in charging your battery, I recommend following the "accurate battery charge reporting (calibration)" section below to put things back on a level playing field. I'd also suggest that following the advice contained in the section that immediately follows this will prevent the problem from re-occurring & also mean your battery will last longer.
Frequent, smaller charges are better for your battery.
Most will be familiar with the fact that a mechanical device wears out faster with heavy use. This analogy applies well when considering the life expectancy of a battery. Given that batteries in tablet devices are not easily replaced, it is worth considering the depth of discharge (DoD) to which tablet devices are allowed to discharge as this determines the cycle count (the number of times the battery can be recharged). The shorter the discharge, the longer the battery will last. If at all possible, avoid full discharges and charge the battery more often between uses. Partial discharge with lithium based batteries is fine; there is no memory and the battery does not need periodic full discharge cycles to prolong life.
A partial discharge reduces stress and prolongs battery life. Elevated temperature and high currents (produced when charging from a deep DoD) also affect cycle life.
In the list below you can see that charging at around 50% DoD will mean that your battery lasts around twice as long as charging at a low DoD
- 100% DoD - 300 to 500 charge cycles
- 50% DoD - 1,200 to 1,500 charge cycles
- 25% DoD - 2,000 to 2,500 charge cycles
- 10% DoD - 3,750 to 4,700 charge cycles
Accurate battery charge reporting (calibration).
That said, however, occasional full recharges, perhaps once every 8-12 weeks - from around 10% to full - are a good idea as this enables the software reporting of the level of charge in the battery to stay accurate.
Calibration occurs naturally by occasionally running the tablet down until the battery is fully depleted and “Low Battery” appears. The full discharge sets the discharge flag, and the subsequent recharge sets the charge flag. By establishing these two markers, the battery can calculate the state-of-charge by knowing the distance between the flags
If you have a tablet that is not reporting full charge levels, or inaccurate charge levels, a couple of full "low battery - recharge to full" cycles will invariably resolve that issue.
It will work best if you connect the tablet to the a/c charger and then power off the tablet. This enables the battery to charge without any need for it to maintain a powered on device. So the process would be...
- Tablet reports "low battery"
- Promptly finish whatever you were doing
- Connect to the a/c charger
- Switch on the a/c power
- Power off the tablet until the device is fully charged.
Acknowledgements to Battery University for some of the information contained in this post.