To calculate the overall star rating and percentage breakdown by star, we do not use a simple average. Instead, our system considers things like how recent a review is and if the reviewer bought the item on Amazon. It also analyses reviews to verify trustworthiness.
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.
I bought this to charge my new DIY LiFePO4 battery in my camper. I set it up so that turning the truck driving lights on turns on the charger. The wire lugs are clumsy to work with but they seem to stay tight on the wire. The good news is it works and I've seen 20 amps of charge current through my Victron Battery Monitor. I took two stars off for the lack of support - a forum that Renogy doesn't respond to is supposed to supplement the badly translated written instruction. The dip switch configurations in the manual are incomprehensible and the forum posts states that the LiFePO4 settings in the manual are wrong anyways. Renogy said they would post the correct settings, which they never did. Luckily someone posted them here. Why am I so cranky about the dip switch settings? LiFePO4 batteries are expensive and I don't want to have to guess what the charger settings should be! Fix the instructions and they might have a hit. Victron just released a similar DC-DC charger, I wish I'd waited for theirs.
I picked this up to help my truck charge my RV battery without possibly over charging the RV battery. It does the trick, it works, and it lets me run my 12v fridge while driving around and hooked up to the truck.
Unfortunately, the ignition based switch is annoying. There's nowhere to put this in my truck engine bay, nor under my truck that wouldn't be exposed to the element. So how the hell am I supposed to get a 12v ignition switch all the way back to the camper?
So instead, I just gotta remember to unplug the camper anytime I turn the truck off, or it'll drain my truck battery... which happened once and killed the truck.
A low voltage shutoff would be SO GOD DAMN EASY to add to this! Add a pot switch that detects If the input voltage drops below 12.6v, disconnect! That will give you what is essentially an ignition controlled shut off method, since your truck battery will safely discharge to 12.6v and still start your rig with ease, and when charging will push out more than 12.6v.
An easy solution, that is annoyingly not included.
I had a hard time with this product at first because I found the instructions - especially the part about hooking up the D+ wire to the ignition - confusing. I even contacted customer support, and had a very unhelpful phone call. The technician was just searching for answers on google. As if I couldn't do that myself! I don't want to grill them too hard on that though, I'm sure customer support would be a lot better if everyone wasn't working from home right now.
Turns out "Renogy Returns" wrote an article about this on their customer portal. You can find "How To wire D+ signal" in the customer portal. Go to Renogy's website, then click Learn -> Customer Portal. You can search for the article there. I can't believe the customer service rep didn't mention this! Anyways, hope that helps! Cheers
This was my first dc-dc charger, it works but leaves some to be desired. It charges at the set voltages, my alternator runs at 14.7v to begin with, prior to using this I was using an alternator to charge a 200ah agm bank. 76a draw off the alternator on drained batteries or this I guess there’s trade offs for rapid charging and for lower amperage charging. This takes longer which is an issue because I’m not driving around 4+hrs a day. What I don’t like about the renogy is cheap construction. Now this isn’t my first electrical device that I’ve disassembled but constructionwise I've seen better. Just like some inverters I’ve seen the case isn’t really a heatsink. The components aren’t mounted to the case they’re mounted to the plate that is removed for access. Opposite of what I’ve seen before, also water resistance is very minimal probably because they depend entirely on airflow for cooling. Thought about sealing some of the seams between the parts of the case but not worth it. Plastic use isn’t the most high impact either. I got mine cheap and it operates as stated
I did not install the product. Once I looked at the product I received and could see the coils through one end, I decided to go with the waterproof Redarc. It is fully sealed against water and dust and extreme heat up to 176 degrees without any fan. I was going to install it in a bay that was protected but not sealed. The Redarc was sealed and much smaller and was so simple to install. No on switch or dip switches and was also good for lithium and solar input and had mppt. This may be great for some applications but I am glad with my choice to return it.
Spent an afternoon rewiring my RV for a lithium battery and this charger. Lithium battery works fine however this charger does not even power up. Do they even test these before shipping? Voltage in 14.4 volts and absolutely nothing on the output. Have 12.6v on the D+ that supposedly turns on the charger. Will ask Amazon for a replacement. Will update review to let you know if it is a one time deal or if Renogy has major quality issues. Update - Replacement arrived and works well once the d+ circuit is above 13v. Have a regulated 12v circuit that I tapped into for the D+ with a switch to manual control the charging. It did not work, however when I wired the switch directly to the positive input at 13.4v, it had no issue. To be honest this might have beem the issue with the first one. Edit - changed headline, rating and added review of replacement. Still a bit irked that 12.6v is insufficient to turn on the unit. No mention of it in the manual. Just states it needs a 12v input.
The first one didn’t work properly. Let’s hope the second one works and lasts. Thank goodness for Amazon’s return policy and fast replacement shipping. Renogy’s tech support was a joke and finally ghosted me. Nice care for a customer, not.
I bought this to limit the amperage delivered by my alternator in order to prevent my alternator from being damaged. The 40 amp model was perfect for me. My install location made for a difficult install. After I got it installed I tested the unit and it was putting out 16.5 Volts. Way too high. I restarted, checked the wiring, checked the DIP switches and nothing helped.
Can’t run with it, the voltage was too high and could ruin my electronics. Can’t run without it, the amperage draw straight to the batteries would kill my alternator. And I was leaving on a trip in a week.
I contacted Renogy tech support. They asked for pictures of the install and what the DIP switches were set at. I complied and sent them pictures of multiple volt meter readings verifying the 16.5 volt output. I also offered that NO DIP switch combinations could yield that high of an output voltage. After that I never heard back from them.
I returned the 40 amp DC-DC charger to Amazon and had another shipped out since the first was broken. Amazon did an amazing job of processing my claim and shipping out a née unit. They gave me 30 days to return the old one too.
The second charger bench tested correctly at 14.5 volts. After install the unit also tested correctly. I hope it lasts.
Would I buy this again? Probably not. I think I would save up for a better unit. Compatibles are quite a bit more expensive.
I also recently installed a Renogy 2000 watt inverter and a 100 watt suit case solar panel. I hope they last too.
Well the charger and quality seem fine. However the manual and tech support are terrible. There are parts of the manual that seem to contradict each other’s logic. Additionally, I’ve had some troubles with my starter battery dying. I have my own theory why, but trying to troubleshoot a solution with their tech support has been a worthless endeavor. Basically they are only there to replace defective equipment.
Fine product but if you lack experience their team will be no help with any troubleshooting you have to do.
Also, and this is my theory, I believe this charger will kill my starter battery when I take a lot of short trips. It takes to much current and doesn’t allow the starter battery to charge back up in a 10-15 min drive. Do that a few times and the starter dies. Be aware that’s a problem I’ve been having.
There is a trick to these that took a little while and a ton of research to figure out. Once we installed it the car battery died, we double checked the connections and made sure everything was hooked up right. We tested the current on the car battery side of the charger and it had a draw. Disconnected everything, it still had voltage at the connections with no wires connected. There was nothing in the manual about why, no one at tech support knew why. Finally found an article where a guy had the same problem, turns out these chargers have a memory, you can put a wire to the positive and negative on the input of the charger with everything else disconnected and it will short it. Once we did that tested voltage and everything was fine, worked perfect after that.