Electronic – What am I doing wrong with this dumthe battery for the camera

batterieschargingcurrentpcb

Im trying to make a camera battery grip for a Canon M50 that uses LPE12 batteries. They output 7.2V.

I'm using this PCB to try and convert 3.7V coming from a 18650 battery to the appropriate level:

this PCB

I was able to get the correct voltage but it is still not working:

voltage

my setup

battery contact

cut original cable

EDIT: I did some more tests and it turns out that the original coupler supplies the dummy battery 8V 1Amp if plugged in to a USB power bank and the same on a wallwart charger. When I remove the 18650 battery from the circuit and power the pcb through its microb usb charging port I do manage to get 8V 0.9Amp which is close enough i would suppose. When I plug it into the camera, the voltage did drop to 5V indicating that it's not able to sustain power. Which I was slightly expecting because of Dave's observation that my pcb didnt have the proper electrolytic capacitors to sustain the power. But it all seems to go batshit once I put the battery back on the circuit. I couldn't seem to measure the output Amp of the board because it seems to go over the scale. I even tried to limit the current by adding a 8ohm resistor to try and limit the circuit to 1Amp but all it does is make the resistor go hot.

Best Answer

The Canon LPE12 battery has four terminals.

enter image description here

Two are power. One of the others is probably a temperature sensor for the charger.

The fourth terminal is usually some kind of identification pin. It may be as simple as a resistor indicating the capacity of the battery, or it may be as complicated as some kind of encrypted digital query from the camera to the battery.

You have to figure out what the other two pins do, and emulate those functions in your battery grip.

The camera probably checks both of the extra pins and won't work if either gives an incorrect result.