RV Batteries

Choosing house batteries for your rig

The big decision is chemistry, and after that it comes down to how much capacity you can fit and afford. Get the chemistry and the size right, and the rest of your electrical system has a solid foundation.

• Chemistry. Flooded lead-acid is cheapest but needs water top-ups and venting. AGM is sealed, maintenance-free, and handles vibration well. Lithium (LiFePO4) costs the most up front but is far lighter, lasts thousands of cycles, and returns nearly all its rated capacity.
• Group size. Group 24, 27, and 31 are the common RV sizes. Larger group numbers generally mean more capacity, but also more weight and a bigger footprint, so check what your tray and compartment will actually hold before you buy.
• Usable amp-hours. The number on the label is not all usable. Draining flooded or AGM below about 50% shortens its life, so a 100Ah lead-acid battery really gives you around 50Ah. Lithium can be pulled down much further, which is why one lithium often replaces two lead-acid.
• Deep cycle, not starting. House batteries should be deep-cycle, built to be drained and recharged daily. A starting battery dumps a big burst and then dies fast if you cycle it that way.
• Cold-weather charging. Lithium will not accept a charge below freezing unless it has a built-in heater, so factor that in if you camp in the cold.

Whatever you land on, hold it down in a properly sized box or tray, keep it topped with the right charger or maintainer, and if you are going off-grid, size a solar system to match the bank.