Should I drain my battery or is it okay if I charge it when it is lowbat?

change battery

Possible that the battery has gone weak or that the main board has an hardware issue and so drains more current than the usual.
So connect the adapter and check the voltage on the phone battery terminals. If this seems good then the charging must be correct , clean the battery terminals and set it in so that there is good contact at the pins. If this wont solve then check with another battery to confirm or the board is a suspect. Choose a lower volume ringer, display light and allow the keypad lock to come in at the shortest time.

How long did you let it charge, when the device is completely drained of power it may not turn on at first when you connect it. Let it charge for a little while and come back to see if it fixes it. Failing that, your probably going to have to contact apple for warranty help.

Try to buy a new battery. If the problem still persist, there a hardware failure to your camera. Bring it to camera repair shop as soon as possible.

Replace the battery if, even after you charge it, it shows Low Battery. If it is a new battery, your battery contacts in the camera may be faulty, or something in the camera may be faulty. I am sure it is just a bad battery though.

I’m happy to help further over the phone at https://www.6ya.com/expert/jeremy_69f3cc28d95bf514

There is a battery in your themostat replace it.

do they come back when battery is charged? items on memory stick or non essential storage devices will vanish as the unit cant provide the power to initialise the drives, but they should be there when the power is restored

Replace battery.

First thing you need to do is make sure battery is fully charged & have it load tested. If that and the rest of your charging system checks out, then you'll have to test for a battery draw, when vehicles off.

change the battery...