Battery to Battery Chargers

Here we have a couple of Promariner battery chargers that are designed expressly for the purpose, one is to charge from 12 volts to 24 and the other is from 24 volts to 12. These have voltage sensing switches so they only operate when the source battery is on charge.

I have also included a sample Victron MPPT solar charge controller in this category. This is not expressly designed with the intent of charging one battery from another but it can be used that way and is programmable to suit the chemistry of the destination battery. Any of the Victron MPPT solar charge controllers can be used in this way but it is recommended to choose the Bluetooth enabled ones to facilitate programming. I recommend setting the voltage of the destination battery in the program and disabling the autodetect. The destination battery can be 12 or 24 volts, the source battery must be at least 5 volts higher. This will run all the time unless you figure out some way to stop it when you dont want it on.

We also have a Victron DC DC Converter that functions as a single stage battery charger. The output voltage if adjustable but because it is single stage it should be set to the battery float voltage. There is a remote switching option that could be operated by an engine ignition wire so it would only operate when the engine if running.