【3-phase MPPT Charging Technology】 With Built-in Maximum Power Point Tracking (MPPT), Renogy dc to dc battery charger will charge your service batteries with maximized solar power, providing 3-phase charging (Bulk, Boost and Float) to regulate the whole charging and ensure the batteries will be accurately charged at the correct voltage levels to 100%. 【Multiple Protections】Renogy DC to DC Charger has multiple intelligent protections includes battery isolation, over-voltage protection, battery temperature protection, over-current protection, overheat protection, reverse current protection, solar panel and alternator reverse polarity protection, guaranteeing charging safety and protecting you batteries. 【Light & Small, Ready to be Set Up】 With only 24.4cm*14.5cm*7.6cm in Dimensions and 1.42kg in weight, Renogy DC-DC On-Board Battery Charger is ready to be installed and adapt to any tiny narrow installation space, resolving your concern from limited room in you vehicle. 【RJ45 Communication Port Featured】 Bluetooth Monitoring Ready! Exclusively available with the BT-2 Bluetooth Module accessory and Renogy DC Home App available on the IOS and Google Play Stores, you can monitor this dc dc charger remotely and simply through your phone and stay constantly updated. 【Multi-input for Battery Charging】 Renogy dc to dc charger is designed to charge service batteries from a starting battery linked to an alternator or by utilizing solar panels connected directly to the unit, offering multiple charging options and ensuring your battery stay fully charged. Renogy's DC to DC MPPT Charger is designed to give you options! This multi-stage, multi-input battery charger can charge a secondary battery from an alternator connected to a primary battery or by utilizing solar panels connected directly to the unit. While your vehicle's alternator prioritizes your primary battery, this unit will allow your solar system to put your secondary battery first! It's the smart way to keep yourself fully charged and off-grid longer! And with multi-stage charging and multi-chemistry functionality, Renogy's DC to DC MPPT Charger has you covered whether you're using Flooded, Gel, AGM, or Lithium batteries.