Renogy 12V 40A DC to DC Battery Charger, Using Multi-Stage Charging in RVs, Commercial Vehicles, Boats, Yachts

Very good product and it works great. Easy install.

Good

I installed the device correctly with the ignition wire that only turns on the device when the engine is running. I talked with renogy twice and we confirmed all the connections were perfect.. This device continued to drain my starter battery and it was also popping 100 amp in line fuses between the starter battery and the DC charger, as I have braided 4AWG going from the starter battery to this charger per the manual. renogy tried to tell me that my starter battery was no good. I informed them that if my starter battery was not providing enough electricity the Red fault light would be on, which is one of the design outputs of their DC charger, per thier manual. I also explained to them if there’s not enough electricity coming from the starter battery it’s not going to pop 100 amp breaker repeatedly when i'm driving. i am military and I called back to duty after i bought this charger so I couldn’t install this until three months after I bought it. amazon they said there’s no return option available. I noticed on the 40 amp charger. They did an upgrade which is an automatic alternator checker so I think this problem is well known.UPDATE: I contacted Renogy 10 days ago and they asked for photos of my installation of the charger which was done per the manual. I informed them the device failed right out of the box. I sent the photos in and they said it would be 24-48hr and i haven’t heard from them after 10 days. I then called them and was transferred many times and received the run around. they are now asking for me to conduct resistance testing on thier own device not connected to anything and to test my starter battery. they said if they’re happy with these results, they’ll send me a return authorization for me to send the device back to them. They will test it and either send it back to me or send another device back to me. This whole process will take many many weeks. so ridiculous. I have no faith in their device now. I’ve never had a company ask me to do electrical tests on their own device to ensure that it works before i can return it to them.

I installed these units to charge the 2x 600ah battery bank(s) shown above.My instalation draws power from a 250 amp engine alternator.The charging units have primary input and output hookups of solid metal with machine screws to secure the wires. They also have 2x additional wire inputs. One wire input activates the unit, it will not charge untill voltage is applied to the "D+" terminal. This allows it to fuction as a battery isolator relay, whereby it wont charge untill its told to by the activation wire. It also has a second activation wire for a 50% power mode. This knocks the charging amperage down to 30 amps, and I highly reccomend wireing this lead to a toggle switch.I installed 2x units and found that a 250 amp alternator cannot power more than one of these at idle engine speed. At highway speed and higher rpm, I can run both units at 60 amps. but at night time with all lights on in the RV, I can only run one at 60 amps and the other at 50% power without overdrawing the alternator.The installation instructions indicate that they "may draw upto" 90 amps, but upon installation i havnt seen more than 65 amps.I installed 2 of these units which is kinda crazy, i did it by isolating two battery banks with a giant diode array, in the form of a battery isolator diode set installed "upside down" on the negative terminal side. but take note that a 250 amp alternator can barely power both of them when tacked ontop of the other electrical load for the RV.Installing one unit with a common 130-150 amp alternator it would be advised to install the amperage reduction function to avoid overtaxing the alternator at low engine rpm.The units have internal cooling cans that SUCK AIR from the electrical input side, and EXPEL AIR on the electrical output side. This information is only apparent AFTER installation, so ill include it here.2 gauge cable worked fine.to install the activation leads, unscrew the tiny screw above the wiring opening, insert the wire, then tighten the screw. This information is not included in the instructions so i include it here.Since you will probibly wire the activation lead to turn the unit on whenever the engine is running, advise installing an interupt switch for that lead, or a giant battery disconnect switch for the voltage input as I did.

This charger is for my pickup bed/camper and charges a lithium battery. The power supply is isolated from the starter battery. This charger is set up to isolate itself from the starter battery. I didn’t read carefully about the two wires that appeared to be optional. They’re described in the manual and one is required.When the charger wouldn’t charge and I read instructions more carefully, I discovered the unit required connection with one of those little wires to a power source only on when the ignition was on. I made a wire, plugged it in the appropriate slot (requires a very small blade screwdriver) and connected it to the already isolated positive power wire input to the charger. Started the engine and the battery said it was charging at 20 amps. Perfect! The second little wire allows you to charge at 10 amps.I’m adding rocker switches to these wires so I can turn them on or off easily. There is a warning about using this charger around flammable fumes so I want to easily turn it off when hauling fuel.