Similar, but not quite the same to this Question; "Charging and Using a Li-Po battery simultaneously", I want to have a battery in my camera but also connect an external charger at the same time. Is there a safe way to do this please?
The application is to power my DSLR camera (Olympus OMD EM10) during an overnight timelapse shoot. The camera wakes up every minute and takes a picture. It can take 999 pictures, but the battery only lasts a few hundred..s
The battery is a Li-ion 7.2v 1210mAh unit. This lasts a few hours but isn't enough to do a full night. Because I'm using a tripod, I could have the battery compartment open and fit the battery on top of the terminals, capturing the leads of an external power supply. But I'm worried this might toast the battery or worse, destroy the camera!
(As an aside, the battery - BLS-50 - appears to have four contacts!)
If this is "dangerous" - it is certainly inconvenient away from the house! - , how could I bodge together multiple cells to safely add duration? [EDIT: SO, this isn't thought dangerous. Moving on then, how could I power this from the mains and with a battery at the same time? And could a 5v 10AH USB power bank/battery pack be used or would the voltage difference be too much?]
(Surprisingly, Amazon let us all down and doesn't sell such things...)