Renogy 12V 20A DC to DC Battery Charger

The Renogy 12V 20A DC to DC Battery Charger Charges Your House Battery From the Alternator and Protects the Starter Battery

The Renogy 12V 20A DC to DC Battery Charger moves power from a vehicle's alternator to a 12V auxiliary battery at up to 20A and 292W. It works with AGM, gel, flooded, sealed lead-acid and lithium iron phosphate batteries, and it has a custom mode for other charge settings.

It's made for RVs, vans and small boats where a second battery runs your lights, fridge or electronics. Built-in alternator running detection stops charging when the engine is off, so the charger doesn't drain the starter battery.

Renogy 12V 20A DC to DC Battery Charger Features

Alternator Running Detection

Charging continues only while the alternator is running. When the alternator stops, charging stops, which protects the starter battery. Renogy says the charger also adjusts its charging mode instantly at startup.

Works With Traditional and Smart Alternators

Renogy lists an alternator input of 13.2-16.0VDC for a traditional alternator and 12-16.0VDC for a smart alternator (Euro 6). The IGN signal wire is required for smart alternators only, and it's included.

Five Battery Types and a Custom Mode

Choose AGM, flooded (FLD), gel, sealed lead-acid (SLD) or lithium iron phosphate (LI) with the Type button. A user mode lets you set your own parameters. For lithium batteries, you can turn lithium battery activation on or off.

Battery Temperature Sensor Included

The 2 m sensor reports battery temperature to the charger, which adjusts its charging parameters. Renogy lists temperature compensation of -3mV/°C per 2V for non-lithium batteries and none for lithium.

94% Charging Efficiency and Protections

Renogy rates charging efficiency at 94%. Protections include reverse polarity, overvoltage, over discharge, overcurrent and over temperature, and the charger adjusts its output in high-temperature conditions.

Compact, Corrosion-Proof Layout

The charger measures 9.31 x 5.17 x 2.36 in. Terminals are spaced apart to reduce short-circuit risk. Renogy calls it corrosion-proof and suited to small boat cabins and humid marine spaces.

Real-World Applications

RV and van house batteries. Charge a 12V lithium or AGM house battery while you drive.

Small boats. Renogy points to small boat cabins and humid marine environments as a fit for the compact, corrosion-proof case.

Vehicles with smart alternators. Wire the included IGN signal wire so the charger can tell when the engine is running.

Practical Comparison

DC to DC Charger Versus a Direct Battery Connection

A direct connection or isolator passes the alternator's voltage straight through. This charger runs its own multi-stage charge profile for the battery type you pick, and it stops charging when the alternator isn't running.

Charger Only Versus Adding Bluetooth

This option is the charger alone. Renogy says communication needs a separate BT-2 Bluetooth module on the communication port, which isn't included here. Without it, you set the battery type with the Type button and read the status lights.

Buyer Guidance

Installation and Wiring

Renogy says to mount the charger horizontally for better venting and heat dissipation, and to place it nearer the service battery. The terminals accept 10-8 AWG wire. Renogy lists a 40A input fuse rating and a 30A output fuse rating. Use the included ring terminals, and have a qualified installer help if you're unsure.

This May Be A Good Fit If

• You charge a 12V house battery from an alternator
• Your vehicle has a smart or traditional alternator
• You use AGM, gel, flooded or lithium batteries
• You want a compact charger for tight spaces

Common Questions

What Battery Types Does It Charge?

By default it supports 12V AGM, flooded lead-acid, gel, sealed lead-acid and lithium iron phosphate. A custom mode adjusts settings for other needs.

How Do I Get Communication and App Monitoring?

Renogy says you need its BT-2 Bluetooth module on the charger's communication port to connect to the DC Home app. The module isn't part of this option.

Are There Installation Precautions?

Mount the charger horizontally and close to the service battery, as Renogy advises.

What's Included

• 1 x Renogy 12V 20A DC to DC Battery Charger
• 1 x Battery Temperature Sensor (2 m)
• 1 x IGN Signal Wire (3 m)
• 4 x Terminal Rings
• 1 x User Manual

Reliable Alternator Charging for Your House Battery

The Renogy 12V 20A DC to DC Battery Charger gives your auxiliary battery a managed charge from the alternator and stops when the engine does. If you'd like help matching it to your battery and wiring, the Outbound Power team is happy to help.