Renogy 12V 20A/40A DC to DC Battery Charger, Using Multi-Stage Charging in RVs, Commercial Vehicles, Boats, Yachts

Kept my bank1 lead acid and bank 2 lithium ion batteries at peak charge all boating season. You need to know that the terminals have shoulder tunnels that are narrower than most battery cable ends. I had to cut down the width of a couple of cable ends.

Bought to install on my RV to protect the alternator and charge my new 4 battery lithium setup. It does the gob.

Installed in my van to charge my Temgot 460ah battery off the alternator/battery. Easy to install, easy to set for your battery type. Lights stay on so a small draw but not significant. I got the 40amp version and it's great for my use. Went on an advanture with it on washboard roads for 3 hours- still performs like a champ.

One of the features that I bought this for was its automatic detection of when the alternator is running. It -does- start charging when the voltage goes up as the alternator starts producing, but when the engine is shut down the charging continues. The manual states that charging will stop when the source voltage is less than 12.7v. I monitored charging down to 12.3 volts before manually disconnecting. When I reached out to the support line I was advised that this was a known issue and I should install a switch. I did buy a switch but so much for automatic detection. If I forget to turn off the switch, will it completely drain the truck batteries to charge the RV house batteries? Hopefully I don't find out.

I never installed it. Why? Because it was an obvious used item. I paid for new and received a used, returned item. This would suggest that there is something wrong with it. Disappointed, to say the least. I will be returning it ...