A battery box will serve to protect your batteries as well as offering added flexibility in the placement of the battery bank. Flooded deep cycle batteries may be housed in a battery box so long as active ventilation is installed to adequately remove the buildup of hydrogen gas during charging.
Here are a few considerations we often share with customers looking for guidance.
- design the box with the front side hinged or removable. This will make accessing the batteries significantly easier. It will also make it easier to pull any batteries out if you need to move or swap them.
- In climates with varying seasonal temperatures, building the box with a dual wall of plywood and 2" rigid foam insulation in between will help to insulate and regulate the temperature inside the box year-round.
- Build the box with adequate spacing between each battery for proper airflow. 1-3" on each side is generally sufficient. In cold climates, cut & install rigid foam insulation sheets to place in the space between the batteries during winter months. This will help them hold the heat from charging and reduces the risk of freezing if the system sits for a while partially discharged.
- The box will also need active ventilation using a small exhaust fan. As mentioned in the attached article, a Zephyr fan should be installed to run while the batteries are off-gassing during charging. The fan should be plugged into the aux on the charge controller to trigger the fan on/off while charging.
- Ventilation exhaust should not be within 2 metres of any entry to the house. Keep this in mind when you're deciding where to place the battery box.
- If the box will be outside, avoid situating in direct sunlight to reduce heat.
The attached article from Home Power Magazine offers suggestions and further detail on proper battery box placement, construction and ventilation.