Chargers/trickle chargers/maintainers – we get asked about ways to charge the chassis battery a lot by all Revel owners, both those with RoamRig power systems and those without.
Chargers can work well. However, the charger you choose, how you use it, and how you install it must be carefully thought out by you and your installer for your specific application and needs.
In all situations, if your chassis battery is unable to maintain adequate charge to start the engine while your van is parked/locked for 10-14 days, you have a parasitic drain and/or damaged chassis battery which should be investigated.
Before you choose a charger, make sure you understand the impact of trickle charging the chassis battery can have on your DC-DC charging of the house batteries. We’ve outlined some important considerations below:
How to stop unintended DC-DC charging in RoamRig power systems
Choosing a Charger
- There are a lot of charging options. Some chargers use 12V power from your house battery system, others use power from a 120V outlet, and some chargers use a small solar panel to charge the chassis battery. Each use case has different requirements and it is up to you and your installer to choose what will work best for your needs.
- Any 12V powered device should have a way to prevent completely draining the house batteries while maintaining the chassis battery. Configurable voltage parameters are the easiest way to accomplish this. Generally, if you only charge the chassis from the house when the house battery is above 13.2V, you will not fully drain the house battery while charging the chassis.
- Victron offers a full line of 120V and 12V powered devices that are fully configurable with settings that control both input voltage lockouts and output voltage levels. We cannot offer any specific Victron product choice or setting recommendations as the use cases and performance expectations vary widely from application to application.
If you’d like to add a charger and your system has a DC-DC charger, then you must keep the following in mind.
DC-DC Charger Considerations
- Many camper van power systems use DC-DC chargers to charge the house batteries via the chassis battery/alternator when the engine is on.
- These DC-DC chargers regularly rely on the voltage level of the chassis battery (which is higher when the engine is on) to determine when the vehicle is running. So, they charge the house batteries from the chassis battery when the vehicle is on.
- If charging occurs when the engine is off for extended periods of time due to chassis battery voltage that is higher than what the device uses to determine whether the engine is running, you may end up with a dead chassis battery.
- Full RoamRig power systems feature a Kisae DMT1250 DC-DC converter which will generally never try to charge the house batteries from the chassis battery if the chassis battery is kept below 12.7V. If your charger has a voltage above 12.7V, the DC-DC converter MAY drain the chassis battery as it believes the engine is still running long after you have turned the engine off.
How to stop unintended DC-DC charging in RoamRig power systems
- Turn off DC-DC charger via the RoamRig supplied breaker, labeled “Solar and Alternator”). On 1st Generation Revels, the breaker is on the front of the bench seat. In 2nd and 3rd Generation Revels, the breaker is in the garage above the batteries. This will also disable solar charging because the Kisae DMT1250 doubles as a solar controller.
- Add a physical disconnect device between the DC-DC charger and chassis battery that is open when the engine is off, such as a high power solenoid, contactor, or relay. When the Kisae DMT1250 breaker is on, but it is physically disconnected from the chassis battery, solar charging of the house batteries via the Kisae solar controller will still work.
- Use a trickle charger with a configurable voltage output. Generally, if trickle charge voltage is set below 12.7V, the Kisae DC-DC charger will not inadvertently begin charging the house batteries via the chassis battery when the engine is off.
Additional Guidance
RoamRig cannot provide any additional guidance outside of the generic items above. Additional guidance includes: configuration instructions, wiring instructions, diagnosis if the chosen solution does not work as expected, etc. It is up to the van owner and/or installer of the option chosen by the owner to ensure that the selected option and installation will perform as expected by the owner and is installed safely/correctly.