Renogy 40 Amp DC-DC Charger Installation and Demo

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A few weeks ago, I played around with repurposing a spare Bogart sc2030 solar charge controller as a DC-DC charger to increase charging from my truck alternator to my trailer batteries. The experiment worked, but my results were lukewarm. So, I decided to buy, install, and review a charger designed for the purpose, of the Renogy 40 amp DC-DC charger.

Having the ability to get a high current charge into my new Lion Energy lithium battery bank while towing will be most helpful on those overcast days when solar power is limited. I have a generator, but it can be a pain to set up on stormy days and, of course, have to listen to it. With the extra power, I also have future plans to run my RV fridge in electric mode while traveling powered off by an inverter.

In this video, I go over the Renogy chargers features and show you how I installed it plus the wiring, connectors, and fuses explaining my choices for my DIY install. Then I give you a quick demo of the charger in action showing amperage drawn from the truck battery/alternator and charging current into my batteries. In the future, I will return with a review video detailing how the Renogy charger performed, but early indications are encouraging.

Disclaimer: Working with electricity can be dangerous. The following is for entertainment purposes only and should not be taken as instructional. If you decide to do the same, then research and beware of the risks involved. I don’t advise it without advanced knowledge of electricity. I accept no liability. You have been warned! – Ray

Renogy 40A DC-DC Charger Install and Demo

Max Off-Grid Charging Amps Test (Solar + Generator + Alternator)

I test how much amperage I can pour into my 315AH Lion Energy lithium battery bank if I combine my 30 amp solar controller with a 60 amp Intelipower charge converter and my new 40 amp Renogy DC-DC charger. The battery bank was at a 50% state of charge during the test and all chargers were set to 14.4V.

In this informal test, it came out to right around 100 amps with all charging at the same time and around 85 amps with the generator and DC-DC charger from the truck alternator combined. All and all not bad.

Parts/Tool List:

Related Links:

Update May 2021 – Adding a Wireless Remote Switch

In this video, I install an inexpensive 12VDC wireless switch to turn my Renogy 40 amp DC-DC charger on and off remotely. This will be a nice option to have when towing the trailer.  In hot weather, stop-and-go traffic, or while pulling a long steep hill, I’d rather have the DC-DC charger off to keep the alternator from overheating. I won’t have to stop and manually switch it off.

I used the incoming alternator voltage from the truck to power the eMylo 12V switch. It then remote switches the 12VDC trigger power line to the DC-DC charger I had previously wired from my trailer marker light circuit.

7 Pin Tow Cable Charging Tests using Lithium Batteries

Install and Demo of the Renogy 40 Amp DC to DC Charger

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