Review on ⚡️ Renogy 20A On-Board Battery Charger for Flooded, Gel, AGM, and Lithium Batteries: Multi-stage Charging by Donald Waller

This Renogy 40A DC Charger is a very good product with a reasonable price. Most similar products cost over $300, but this one costs less than $200. I just hooked up this charger to charge a 12 volt 100 amp lithium iron phosphate battery (second battery) in my van from the van alternator. Setting the DIP switches was a little confusing, but I figured out the setting for a 12V lithium iron phosphate battery. My settings are s1=off, s2=on for a constant voltage of 14.1V (you can set 14.4V but I'm afraid of reducing battery life); s3 = on, s4 = on for DC 40.0A to voltage 14.6V; s5 = disabled for lithium iron phosphate battery. The signal cable D+ must be connected to the signal voltage of the ignition switch (usually +12 V), otherwise there will be no charging voltage at the output. You will see a green light on the output side of the panel when your signal voltage is on. I checked this by hooking up a multimeter to measure the charge current, it was 39.5A. I usually camp overnight and need a battery to run my mini fridge, have lights and my phone with me charge a second battery. When driving my van during the day, I want to quickly charge the secondary battery; So I went with a 40A charger instead of 20A. So far so good, only time will tell if this product is reliable.