Amazon.sg:Customer reviews: Renogy 12V 40A DC to DC On-Board Battery Charger for Flooded, Gel, AGM, and Lithium, Using Multi-Stage Charging in RVs, Commercial Vehicles, Boats, Yachts, 40A

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293 total ratings, 60 with reviews

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Stephen Mueller

Works great

Reviewed in Canada on 20 May 2022

Size Name: 40AVerified Purchase

I am very pleased with the charger. Once you set it up, it works perfectly completely in the background.

Alain noel

Bone qualite

Reviewed in Canada on 29 July 2021

Size Name: 40AVerified Purchase

Produit fiable

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busyteach

Lots of confusion but good support.

Reviewed in the United States on 9 November 2019

Size Name: 40AVerified Purchase

Received charger and was delayed in getting installed in my RV. The return window had closed before I had a chance to install and test the unit. I could not get the unit to charge after installation even after testing and retesting the installation. I still had no output from the charger even though the green light was on.

I fnally gave up and contacted Renogy CS and sent a video of my tests, installation, and setup. They sent me an RMA. Once they received the unit, it was tested and they notified me that it worked fine and I would need to pay for return shipping to get it back. After a lot of discussion I did agree to do that but on the conditions that if it did not work, I would want a full refund of all costs involved with the unit and shipping.

Technicians agreed to review the video I had sent before getting authorization to return and noticed the dip switches were incorrect. I did not believe that was true but rechecked and was still convinced they were correct per the manual. Since they missed that point, they did agree to return the unit without charge. I did see the ON indicator on the bottom side of the dip switches when I inspected closely in good lighting. I had the switches set exactly the opposite since I assumed up was on. With the change, the unit worked just fine.

If you purchase a unit, make sure you download the latest manual on the website. It has been changed to reflect the position of the dip switches and a few other clarifications. It is still a little vague on the wiring of the run signal and low current input but much improved from the previous manual. Mostly straight forward however. At this point I am pleased and I only subtracted a star for the confusion on the dip switches. I would give support 5 stars for helping me out however.

81 people found this helpful

J. J.

Good DC to DC Charger for Camp Vans

Reviewed in the United States on 26 October 2019

Size Name: 40AVerified Purchase

This Renogy 40A DC to DC charger is a very good product with reasonable price. Most of the similar product would cost more than $300, but this one is under $200. I just wired this charger to charge a 12v 100ah lithium iron phosphate battery (second battery) in my camper van from the van alternator. The dip switch setting was a little of confusion, but figured out the setting for 12v lithium iron phosphate battery. My settings are s1 = off, s2 = on for constant voltage of 14.1v (you can set it at 14.4v, but I am afraid of shorting the battery life); s3 = on, s4 = on for constant amp at 40.0 A up to the voltage of 14.6v; s5 = off for lithium iron phosphate battery. D+ signal wire has to be connected to your ignition switch signal voltage (usually +12v), otherwise there will be no output charging voltage. You will see a green light at the output side of the panel if your signal voltage is on. I tested it by hooking up a multi-meter to measure the charging amp, it was 39.5A. I usually camp overnight and need battery power to run a mini-fridge, lighting and cell phone charging using the second battery. When I drive my van during the day, I would like to charge my second battery quickly; thus I chosen 40A charger instead of 20A one. So far so good, only time will tell if this product will be reliable.

60 people found this helpful

Zachary W.

Get thicker cables than you think you need! This unit means business!

Reviewed in the United States on 17 August 2020

Size Name: 40AVerified Purchase

Works great but be careful when charging at full speed with the 40A model or higher!
I was using fairly thick cable that was originally used for jumper cables thinking if they could handle 700+Amps they could handle 80A.
Turned out they started melting in the middle and I had to throw them out!
Crazy!
I mean they were a heavy Gauge and still couldn't handle the load from this charger for more than an hour!
On a better note this charger let's you choose a cut off voltage and battery chemistry type so that's cool! All clearly explained in the direction booklet.
There are two small wire connections on the from of the unit.
One is basically an on/off switch that's designed to be connected to your vehicle ignition wire or something. Basically it needs positive 12v dc in order to turn on the unit.. The other connection is LC or low current mode. I believe it keeps the charge rate set to half of the units rating, so the 40A model will charge at 20A if the LC 'low current' is connected to a live 12v wire.
Handy to know.
I've used this charger a lot since getting it and found that it works well! I would definitely buy from Renogy again!

28 people found this helpful

Melodie

The 40 amp Renogy DC to DC Charger Performs Well!

Reviewed in the United States on 31 May 2021

Size Name: 40AVerified Purchase

Really pleased with the performance of our 40 amp Renogy DC to DC charger. We power it with the 220a alternator on our Ram 3500 Cummins truck. Use a battery isolator to turn the charger off when the truck's engine is not running (alternator off-line). Ran approx. 25 ft. of 2 gauge welding cable between the truck's positive battery terminal (via a 60a Zcase fuse) and the charger mounted inside our truck camper (used the truck's frame for the negative run). Connect the truck to the truck camper via two pairs of 175a Anderson-type connectors mounted in the truck bed. The 2 gauge cable nets us 40a of charge current with only a 43.5a load on the alternator. You can use smaller (physical size) gauge cable but it will increase the load on the alternator. Just used this charger extensively on a 3000 mi. cross-country trip. We use a 200ah LifePo4 battery pack in our truck camper to power our a/c unit when we stop for breaks on the road. This 40 amp Renogy dc to dc charger does an outstanding job of charging our battery pack back up to 100% SOC in plenty of time for our next break. Gotta love it!

9 people found this helpful

Amazon Customer

Total failure in less than 90 days.

Reviewed in the United States on 6 July 2021

Size Name: 40AVerified Purchase

After being an industrial electrician for 30 years i would feel my qualifications, to instal, program, and troubleshot this unit is more than adequate. Purchased new on Amazon in April 2021. Installed in a travel trailer using tow vehicle as a charging source, with the 50 % amp limiter enabled . On first use this charger worked flawlessly and did so until July 01.21 when it failed completely 2 days into trip. i have power from the tow vehicle and the enable and current limiter circuits are connected to trailer running lights, so when running lights from tow vehicle are on the charger is supposed to operate. This unit has completely failed , indicator lights show on charger and no voltage present on output terminals. A call to Renogy is forthcoming, and this review will b revised to update status .

13 people found this helpful

DaveG

Doesn't Work 2020 F150-XLT

Reviewed in the United States on 7 April 2021

Size Name: 40AVerified Purchase

I tried 2 of these 40A versions, thinking the first one may have been an infant mortality. Worked for more than 12 hours. Then next day red fault LED on and no charging. Same second unit. Tried contacting Renogy customer support: no phone response. Email reply exactly 1 week after first query. Happened on two different units. Following user manual return to vendor. My truck has a battery management system evidenced by shunt attached to - terminal on starter battery. Installed Victron Orion 30A. Hassle free no problems working great problem solved.

13 people found this helpful

Ken

20 days use and up in smoke

Reviewed in the United States on 11 April 2022

Size Name: 40AVerified Purchase

I was able to get 2 trips out of the 40A model (charging set to 20A the entire time) before it failed. It literally let out smoke and I was relieved it failed "safely" without burning down the truck. Unit was installed according to the considerations/guidelines in the manual with plenty of open space around and nothing blocking or even able to block airflow. I met a couple travelling that also had the same model fail a couple weeks before I met them- theirs lasted 3-4 months. Maybe failure is contagious with this model? Unfortunately I had bought and left the unit sitting in the box about year before installation so it is doubtful warranty will do anything. Will update if that is not the case. Shopping other brands now.

2 people found this helpful

Tim

Works great!

Reviewed in the United States on 5 November 2019

Size Name: 40AVerified Purchase

I have this mounted in my 2019 Sprinter and love it.

Pros: Does what it says it will do. I get 39-40 amps output and I don't have to worry about my LiFePO4 batties destroying my alternator because this unit should never pull more than 50-60 amps of draw.

Cons: The original manual sucks. (Supposedly it's being updated.) The dip switch settings are not correctly stated and neither is the wire size recommendations. I had to rewire my unit because of the manual costing me time and money.

Great unit, just make sure you get the proper manual before installing.

14 people found this helpful

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Renogy 12V 40A DC to DC On-Board Battery Charger for Flooded, Gel,... › Customer reviews

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Renogy 12V 40A DC to DC On-Board Battery Charger for Flooded, Gel, AGM, and Lithium, Using Multi-Stage Charging in RVs, Commercial Vehicles, Boats, Yachts, 40A

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