Is it possible to mix lithium and AGM batteries in an RV?

Compatibility and Charging Considerations

When mixing lithium and AGM batteries in an RV, it’s essential to understand that lithium batteries require a different charging profile compared to traditional AGM batteries. Lithium batteries typically need a 14.4V to 14.6V charge to accept a full charge, whereas AGM batteries usually require a 13.6V to 13.8V charge. To ensure proper charging, you can use a multi-stage charger or a DC-DC converter that can adjust the charge voltage based on the battery type. For example, the OutBack VFX2800 inverter/charger can be programmed to charge lithium batteries with a 14.4V charge setting.

Wiring and Configuration

To maintain a compatible and efficient battery bank, it’s recommended to wire the lithium and AGM batteries in separate banks or use a battery management system (BMS) that can monitor and balance the charge between the two types of batteries. This will prevent overcharging or undercharging of the batteries, which can lead to reduced lifespan or capacity. A suitable wiring configuration can be achieved by using a combination of parallel and series connections, such as 2 x 24V lithium banks in series with 2 x 12V AGM banks in parallel.

Safety and Monitoring

Monitoring and maintaining the battery bank is crucial when mixing lithium and AGM batteries. Regular checks on battery state of charge, voltage, and temperature can help identify potential issues before they become major problems. It’s also essential to ensure that the BMS or battery management system can detect and respond to any anomalies in the charging and balancing process. This may involve using a combination of sensors, alarms, and monitoring software to keep track of the battery bank’s performance and make adjustments as necessary to maintain optimal charging and balancing.