The current electrical system of the van consists of a few lights, powered by the van’s car battery. While I do not intend to live permanently in the van, my goal is to be completely self-sufficient on trips that might last up to a couple of months.
Upgrading to go off-grid involves power storage, generation and monitoring.
Power storage decisions
- battery voltage: 6V or 12V.
6V batteries will generally perform better than 12V batteries. My choice: 6V.
- battery type: deep cycle flooded cell, sealed flooded, gel, AGM or Li-Ion.
Wet-cell is the cheaper alternative, but has the disadvantage of requiring maintenance and venting.
AGM batteries have advantages, but carry a high price.
Li-Ion are expensive and the DIY technology is still in its infancy. My choice: flooded cell.
- battery capacity: enough capacity for your energy needs.
Calculate battery bank size in AmpHours.
The Trojan T-105 battery is the standard, Sams Club golf cart batteries are similar and cost less. Four of them give 200Ah if drawn down 50%.
Power generation decisions
Will charge your batteries when you are moving. I plan to move little when at my destination. My choice: No.
- power grid:
Emergency power through battery charger at a campground. My choice: Yes.
- generator to battery charger:
Complete independence does not outweigh the noise and storage issues. My choice: No.
Panels are largely maintenance free and prices are still coming down. A balanced system requires enough panels for the amount of amps in the batteries. Rule of thumb: 1 amp of storage for each watt of solar panel. Four Trojan T-105 batteries at 400Ah need 400W of solar panels. My choice: Yes.
A large one to run the microwave, etc. or a smaller one that only runs occasional small appliances. My choice: Yes (a smaller one).
- monitor the status of the system.
- battery monitor with cumulative amp hours. This will tell you how much battery capacity is left, and will let you know when the bank is properly recharged.
Daily monitoring your off-grid system is crucial for the longevity of its parts. Maintaining a sufficient battery charge will extend its battery life.