It depends on the type of battery, and the capacity of the battery, and the application you are using the battery for.
No, but it is good practise to fully discharge and then fully charge up your iPad on a regular basis to maximize battery life.
Yes, the battery is fully charged.
The voltage required to counteract the self discharge of the battery at a certain temperature.So it is the amount of voltage given to make the battery in fully charged condition.
When it is charging the screen reads: Battery Charging. When it is fully charged it reads: Battery Charged.
Either the battery has lived its life and need to be replaced or it is not fully charged. Just try to use it completely. Then, shut off for couple of hours. Then, use the camera again to discharge it fully. Last, charge the battery fully and see if that helps. If not, then change the battery. If you're using the EN-L1 battery, they have a history of becoming unusable after a few months of heavy use OR 12-18 months of limited use.
recycle it
No, a fully charged battery does not weigh more than an empty battery. The weight of a battery remains the same regardless of its charge level.
Laptops that's battery is fully charged does not weigh any more or less than one that's battery is not fully charged. If there is a difference, it would be so small you would not be able to tell.
A fully charged 12 volt automotive battery should have 12.68 volts.
where the battery bar is..it will be fully green
12v
A fully charged 12 volt battery will read about 12.6 volts, or 2.1 volts per cell.