Victron - Cyrix-ct 12/24V-120A Battery Combiner Kit Retail [CYR010120110R] MultiPlus 12V 230V

Victron - Cyrix-ct 12/24V-120A Battery Combiner Kit Retail [CYR010120110R] MultiPlus 12V 230VThis Battery Combiner Kit is for adding a 2nd or 3rd battery system in your car, boat, RV or any other vehicle. It utilizes the simplest and most advanced technology to keep all your batteries charged using the engines electrical system, but isolates the starting battery when charging ceases so you never get stranded.

The SmartShunt is a good alternative for a BMV battery monitor

The alternate source typically is an inverter

Remote on/off

The remote on/off can be operated with a low power switch or by for example the engine run/stop switch (see manual)

The MultiPlus switches to inverter operation when no AC source is available

The SmartShunt is equipped with Bluetooth

Similar to the MultiPlus

and unlike many other products that state universal input

but isolates the starting battery when charging ceases so you never get stranded

and 48V systems

like the Cerbo GX

Or the charger 1+1 model provides 3A to the starter-battery