Hello
I have done Eken H8 Pro external power mod for DVR use. I've soldered li-ion charger TP4056 to battery cell and now camera can works all the time from car USB charger or power bank.
https://image.ibb.co/dFCGRF/DSC_2803.jpg
https://image.ibb.co/gozwRF/DSC_2804.jpg...