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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,…

$129.99

(11 customer reviews)
Last updated on January 8, 2024 1:41 am Details
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  • 【Compatible Multiple Battery Types】 Compatible with a multitude of alternator types, the DC-DC battery charger offers correct charging for AGM, Flooded, Gel, and Lithium batteries.
  • 【Smart 3-stage Charging】 The DC-DC battery charger will charge your house batteries from the starter battery by 3-stage charging (Bulk, Boost, and Float), to make sure it optimally and automatically charge to 100%.
  • 【Various Protections For Ultra Safety】 Offers Over-voltage Protection, Over-temperature Protection, and Reverse Polarity Protection to ensure the operation safety. It also isolates the input and output to prevent voltage transmission errors and interfere with house battery charging.
  • 【Protect Your Starter Battery】The DC-DC battery charger is capable of identifying whether the generator is started, to prevent over-discharge of the starting battery and protect the generator.
  • 【Reliable Quality】The compact and robust design makes it suitable for all conditions. CE certification.

Specification: 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,…

Package Dimensions

11.93 x 8.7 x 4.49 inches

Item Weight

4.75 pounds

Manufacturer

Renogy

Country of Origin

China

Item model number

40A

Date First Available

April 1, 2019

Photos: 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,…

11 reviews for 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,…

3.2 out of 5
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  1. Rob

    I used it on a SLA battery for a few months without issue. When I upgraded to a LiFEPO4 battery, I found that the dip switches don’t do anything. With S5 OFF to set lithium mode (per the manual) it seems to only want to charge to a final voltage of 13.4V and no combination of switches S1 through S4 make any difference to this. So, now I have a 20A charger than only wants to put out 3A to a 100aH LiFePO4 battery that is only at a 60% SOC. My LiFePO4 battery requires a 14.6V charge. Customer service has not responded to e-mails as of yet.

    *Edit* A tentative 3 star review. Customer service did respond with the proper switch settings and it did give 19amps at 13.6V. I must cycle the battery again while connected to an alternator to see if this solves the issue entirely and it cuts off at the required 14.6V. I still can’t explain why the same switch setting only gave 3 amps when I randomly tried every possible setting.

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  2. Amazon Customer

    If you have a lifepo4 battery bank you understand that charging outside of solar can be a challenge, this unit does accomplish that. I charge a 200 AH lifepo4 battery with it on a pop up trailer that I use for off grid camping for up to two weeks at a time. I was looking for a charger that could be run off my 1800 watt generator or charge from shore but since that does not exist in my price range I found this instead. I chose the 20A version as I do not want to stress my generator too much, and maybe down the road I will tie in my tow vehicles power as well. I used a cheaper 120 volt to 12 volt 30 amp regulated power supply which thus far seems to work well. The only reason I don’t give it 5 stars is that the instructions are complete garbage, after several attempts at the DIP switch settings I contacted reneogy and they instructed me that the switches should be set to S1 off, S2 on, S3 on, S4 on, S5 off for lifepo4. I have only had a couple field trials of this charger thus far and I am not using my vehicle to charge the bank currently so longevity is unknown. The one other thing I don’t like is it pushes my bank slightly higher than my solar setup does which I have set to 14.15 volts, but it is not going to be a primary charger in my case only a shore charger that I use for backup and when solar is not available or impractical (I have to remove my panels).

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  3. J. J.

    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.

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  4. Ron Howard

    Better than what I had when the vehicle wiring only slightly charged my trailer batteries.. now I get a full charge after a short drive and don’t need to purchase a generator for boondocking.

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  5. Amazon Customer

    I bought this in order to be completely correct in charging my Renogy 50AH lithium house battery on my Volkwagen Euro Camper Van while the van is running. I have done a fair amount of 12 volt wiring on both our boat and campers but this was almost shameful. The product is way way to big and the instructions are more like a cartoon than real instructions. This is an absolutely horrible product and a quality company like Renogy (I have a Renogy solar panel, controller and lithium battery) should be ashamed of themselves for this piece of junk. I was never able to get the thing to work and would warn everyone to stay away from this oversized useless box.

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  6. busyteach

    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.

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  7. serge melancon

    Had it connected for 7 months and now it’s giving me a fault so not able to charge my lithium batteries using the engine… that was not worth it for such a short period… unless you can do something about it 😏

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  8. In the Mountains

    I spent my entire weekend re-wiring my camper to make a spot for this charger and connect everything via #4 wire and custom-made cables. I finally got everything completed and, after all of that work and money, the unit doesn’t work. Doesn’t turn on, doesn’t pass a signal. It’s going back to Amazon.

    I notice another reviewer had an issue with the “on” switch. That could be the problem with my unit, as well, but how would I know with the completely worthless, incomplete instructions that list nothing about the requirements of installing the unit?

    Save yourself the time and expense and skip this thing. Absolutely ridiculous.

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  9. Markov

    I use this in my overlanding setup. I have a 24v system in my Toyota landcruiser and I needed somthing to connect from my 24v to 12v converter to charge an auxiliary battery.

    In my situation, my alternator puts out 24v, that will fry this thing. So! I wired it to the output of my converter (12v out).

    I asked the question before buying this and everyone said ‘no it won’t work’. I bought it anyway cuz my options were limited. Well, it works. My aux battery has been staying charged while I drive and my fridge freezer has been staying cold. Mission accomplished.

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  10. wendell

    This unit has been charging my coach batteries off the engine generator for a month with no problems. It doesn’t generate much heat. Be sure to set it up so that its only enabled when the engine is running or it will drain the chassis battery.

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  11. Amazon Customer

    Installed – and worked as advertised for 3 days…until unit failed. Have verified power in, power on connection to D15+ and connection to battery – no response from Renogy for return – very disappointed.

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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,…
    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,…
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