Renogy 20A dc to DC report
Hi All, Regarding the Renogy 20A DC to DC Battery Charger 12V, the unit puts out 20 amps, but draws 30 amps when doing so. This is the result of bench testing.
Forum Discussion
#8 might not be enough. I had to change my input neg path to use the frame (as a really fat wire) to get my voltage drop small enough to keep input voltage in the 13s. You can tell by if it can't hold that 20 amps output, that you need more input (ie, less voltage drop)
I can't remember the unit's efficiency, but for instance:
14.7 x 20 = 294w and 85% efficiency (eg) needs 346w input.
If input voltage is 13v after v drop from engine batt, 346/13 = 26.6 amps. If you could keep input voltage at 14, then 346/14 = 25 amps
You are supposed to get input from the engine battery, not from the alternator. You need a common ground like it shows in the manual. With a Class C that would be the frame
The unit turns on and off using the little wire that connects to pos input. I have a switch on that little wire in my set-up, and just ran that wire over to the pos input terminal.
You must not also have the OEM alternator charging to house connected like in a MH, or you will add to the amps demand on the alternator, which the DC-DC is supposed to limit.
Pick the nearest charging profile on the Renogy to what your batt spec is (14.7 on mine) and then set your solar controller to match that voltage so they add their amps best while driving down the road.
I can't remember the unit's efficiency, but for instance:
14.7 x 20 = 294w and 85% efficiency (eg) needs 346w input.
If input voltage is 13v after v drop from engine batt, 346/13 = 26.6 amps. If you could keep input voltage at 14, then 346/14 = 25 amps
You are supposed to get input from the engine battery, not from the alternator. You need a common ground like it shows in the manual. With a Class C that would be the frame
The unit turns on and off using the little wire that connects to pos input. I have a switch on that little wire in my set-up, and just ran that wire over to the pos input terminal.
You must not also have the OEM alternator charging to house connected like in a MH, or you will add to the amps demand on the alternator, which the DC-DC is supposed to limit.
Pick the nearest charging profile on the Renogy to what your batt spec is (14.7 on mine) and then set your solar controller to match that voltage so they add their amps best while driving down the road.
