18650 external camera battery

When directly powering cameras a 7.4V battery-pack is required. Sony NP-FW50 (and all related batteries) are two-cell Lithium-Ion battery packs (two-cell = two cells á 3.2V in series). If more capacity is required, either a 2S LiPo battery works well (up to 5000mAh is easy to get).

Another option is to use Lithium-Ion battery cells in standard sizes (for example the common 18650). Since I don’t want to spot weld and permanently connect the cells a battery holder on a PCB seems to be the better choice. To charge the cells they can either be removed and individually charged in a battery charger or the whole pack via a balancing charger for LiPo packs.

Idea taken from Jehu Garcias 7S powerwall packs: youtube link



PCB Fusion360 cad

Deep discharge and overcharge protection for Li-Ion cells is done with an Hycontek HY2120 IC. This chip requires a charger to be connected before the pack can be used when the batteries have been changed. To circumvent this, battery ground can be shorted to a IC sense pin for a moment, that’s the reason why there is a button on the PCB.

Bill of Materials:

Amount Part Details
12 18650 cell  
  Filament for 3D printing PETG
4 M3 screw 40mm DIN912
4 Heat insert M3  
6 Keystone 1048 holder  
1 DC 5.5/2.1mm barrel jack  
1 PCB  
1 HY2120 2S-battery protection IC  
2 AOD514 N-channel mosfet  
2 1206 330 Ohm resistor  
1 1206 2k Ohm resistor  
2 1206 0.1uF capacitor  
1 Omron pushbutton  


Eagle schematics
Fusion360 enclosure file