This post will discuss the construction of a portable battery box. The box was constructed to house a 12V 7AH sealed lead acid battery.
- Plano Tactical Custom Ammo Box http://amzn.to/2ygsizL
- Schumacher SEM-1562A-CA 1.5 Amp Speed Charge Battery Maintainer http://amzn.to/2yiiqWc
- 12V 7 Amp Rechargeable Lead Acid Battery http://amzn.to/2yQhup9
- 12V Battery Low Voltage Cut off Switch PCB (see schematic for photo)
- Fuse Holder http://amzn.to/2xL0Siz
- Fast-blow Glass Fuses http://amzn.to/2x7bgiP
- 4 in 1 Socket Charger Panel http://amzn.to/2xKlQOo
- Schumacher WM-12 Cable Connector http://amzn.to/2xSR4oJ
- 100x68x50mm Project Box
- 1/2-Inch Hole Grommets http://amzn.to/2yPoF0J
- Heat Shrink Tube http://amzn.to/2xTxHf6
- Crimp Connectors http://amzn.to/2xPWCzM
The battery was wired with the SAE (WM-12) connector that came with the battery maintainer. This allows for the battery to be connected to the battery maintainer to keep the battery in good condition. The battery box uses the secondary SAE (WM-12) connector that was purchased to connect the battery to the electronics. The Battery positive is run through a 10 AMP fast blow fuse. Then the voltage goes onto the low voltage cut off switch. This will prevent the battery from over discharging and damaging itself when in use. After that the voltage passes through the panel mount switch. Next the panel meter, USB, and Lighter sockets are all wired in parallel.
The low voltage cut off switch and fuse holder are located in the 100x68x50mm Project Box. This was done to provide mechanical protection for the PCB and to also electrically isolate it since it otherwise would have been floating around in the ammo box.
The battery should not be charged with the box lid closed.
Here is a schematic: