Renogy DC to DC Battery Charger 12V 40A, Intelligent Converter for Flooded, Gel, AGM, and Lithium Batteries, for RVs, Truck, Motorhome, Commercial Vehicles, Boats and Yachts

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I so wanted to give this 5 stars, because i like the compact slim size, it does not get red hot like the victron dc/dc chargers, but this 40a charger does not charge at 40a, and it is not a constant flow of amps, it fluctuates on and off, from start up it may go up to about 35 or 36a, then within 20 seconds it goes down to zero, then after about 20 seconds it slowly goes back up to about 33a where it stays for about 30 seconds then drops back down to zero for about 20 seconds then starts going back up again, i don't know if this is how it supposed to work but its not very good in my opinion as its taking longer to get the leisure batteries charged while on the road... the victron used to charge at a constant rate, most the time at a rate higher than what the charger was rated at, as long as the engine was running it charged, it only dropped off when the batteries were nearly full at about 96 to 98% SOC, unfortunately after about 4 yrs it started to play up so this was its replacement. On the + side i have to say Renogy customer service is way better than what it used to be, where do you get help from for victron - youtube This is an update, it now charges at 40.5amps but at present it still not a constant charge, it was pretty unfair of me to slate this product so early, Renogy are back and fourth with me at present trying to find out what the problem is..if its the charger or if its something in my van that's causing the issue

Lost points on instructions. But dose a really good job of charging the liesure batteries. Can't just connect negative to anywhere. I need to run in another negative. Cable to front of van is picks up a feed from itself and keeps charging, until turned off then starts again as soon as van started. Not great at wire sizing. As information hard to find. I just used 16mm cable a bit of over kill.

charger can be dangerous so be aware, worked for a couple of weeks in the camper, noticed camper battery was getting flat so done a bit investigation found that the DC charger was not switching off when the ignition was off. Flattened the camper battery and overcharged the leisure battery, luckily i noticed it in time otherwise it would have exploded the leisure battery with overcharging. Might be a one faulty DC charger recommend you keep an eye on it if you are installing one, make sure it is switching off

Does not work with a smart alternator without a D+ signal

One day I'll buy something electronic, and it'll just work. The instructions that come with this DC to DC charger are alright, right up until it doesn't work the way it should. Then they're rubbish, and by rubbish, I mean they're just not there. No trouble shooting at all. Seems like Renogy have a lot of confidence in their products. It might be me right enough, perhaps I've done something wrong... But the instructions you do get are good, clear, concise... My DC to DC charger won't stop charging, so it flattens my vehicle battery. (No, it doesn't have a smart alternator. So it says not to connect that D+ wire...) I wonder what yours will do. ;-)

I brought this as people are wrongly saying you need this .YOU DO NOT IF YOU ARE USING LITHIUM BATTERYS .AS I FOUND OUT .AFTER I INSTALLED ONE ON MY NARROWBOAT.TOOK IF OFF ALL ITS DOES IS ADD EXTRA DRAINING FROM YOUR BATTERY. I CANNOT SAY IF YOU USE ANY OTHER BATTERY IE LEISURE BATTERY'S IM JUST SAYING MY LITHIUM BATTERY II PERSONALLY USE THE BEST BATTERY A FOGSTAR FOUND I DONT