Renogy 12V 20A DC to DC Battery Charger with Multi-Stage Charging and Bluetooth Compatibility for Flooded, Gel, AGM, and Lithium Batteries in RVs, Commercial Vehicles, Boats, and Yachts

Updated review - I made a mistake. I have a parasitic load on my system but it's not this DC DC charger. I pulled the charger out of the system and still had the same discharging of my batteries I was attributing to this charger. Adding the charger back into the system and no detectable difference to this discharge rate. This charger works great and it's easy to set up and modify the charging parameters through the app; which I really appreciate. Easy to set it up so it keeps my LiFePO4 house batteries at ~80% while my boat sits during the week. ---- old review ---- Charger works as advertised but there is a much larger than anticipated parasitic load when not charging. I estimate it to be about 1 amp. Drained a 100Ah AGM dual purpose battery from 12.7 to 12.0V in ~48 hours. Anyone else experiencing this? Is there a fix (softwear or otherwise)? This charger isn't useful for marine applications where there are often days to weeks between motor use with this magnitude parasitic load.

Fonctionne très bien. Une article obligatoire pour une batterie au lithium sinon prend le 100% de l’alternateur et le fait bruler.

For someone who wants to keep their batteries in their RV full and working well, there's nothing, in my opinion, that will carry out that task like a Renogy DC to DC charger. I used to have 4 AGM batteries in my converted RV van, with a 3000W Inverter. Those batteries just didn't hold enough power to go but a couple or few days without putting a charger on the batteries. The DC to DC charger has done wonders to keep the batteries charged. But little did I know that Lithium batteries would really take care of the DC to DC charger. I wouldn't run my van RV on a trip without the DC to DC charger along with my 2 lithium batteries.

Works as should

I purchased this Renogy REGO 12V 20A DC-DC charger (RBC20D1U) in May 2025, and it has been a nightmare. This is actually my SECOND unit, as the first one failed completely and Renogy made me jump through endless troubleshooting hoops to get a replacement. Now, the replacement has failed in a way that is incredibly dangerous. The internal isolation components inside this charger completely failed and allowed massive BACK-FEEDING from my house battery bank straight back into my vehicle's starter battery and alternator system. It began severely overcharging my vehicle's electrical system while the engine was running, spiking the voltage and nearly causing catastrophic damage to my vehicle's computers and wiring harness. This is a severe fire and safety hazard. When you try to get a warranty resolution, customer service forces you right back into a script of repetitive tech-support loops instead of honoring their warranty. If you value your vehicle's electronics and safety, avoid this charger. I am demanding a full refund.