Victron Orion 12V to 24V - 480W 20A Non Isolated DC/DC Converter (SKU Part Number ORI122420020)

Remote on-off connector
The remote on-off eliminates the need for a high current switch in the input wiring. The remote on-off can be operated with a low power switch or by the engine run/stop switch (see manual). 

All models with adjustable output can also be used as a battery charger
For example to charge a 12 Volt starter or accessory battery in an otherwise 24V system. 

All models with adjustable output can be paralleled to increase output current
Up to five units can be connected in parallel.