This depends on the type of battery and the charger. Smart chargers are the easiest, as they tell you when it is done. If you don't have one, look at the instructions to see how long, or look at an online chart using your mAh and battery cells.
normally 8 hours
You shouldn't. Different voltages aren't compatible.
21 inches.
See related links below.
charge 4-6 hours, no more.
20 to 30 min
12 hours
This completely depends on the model of the electric car.
1000000.1000000 days
It uses a 7.2V NI-CD 400 mAh battery. If anyone knows how long to charge it, please say so. I have this airsoft gun too.
Depending on the battery size most take 2-4 hours
As long as it is on your property or at a designated field then you should be fine.