In general, no one will reserve a few kwh of electricity for household electric cards, but will overdraw the electricity. There is no uniform standard for how much electricity can be overdrawn. Some can overdraw 10 degrees, some 20 degrees, some even higher, but most of them are 10 degrees, 20 degrees. It can also be said in disguise that the card has reserved an overdraft of 18 degrees and 20 degrees for you, and the battery is insufficient to remind you to recharge it in time.

Some electricity will be reserved in the meter, and there are standards in different regions, such as 100 degree, 50 degree, etc. However, a limit value will be set, that is, when your overdraft reaches the limit value, the power will be cut off, but there is still electricity in the meter, and you can still get electricity when you re-insert the card until it is zero.