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
"The whole idea of the dc to DC is to boost the voltage going into the battery bank. Therefore voltage drop to the charger doesn't matter--so long as the ampacity of the wire size is not exceeded."
Yes it does matter.
The unit is "buck/boost" and the output voltage will be higher than the input's in many situations so it has to boost. The voltage drop to the charger is vital to keeping the input watts high enough to keep the watts up. It also affects the amps draw on the alternator, which you want to keep as low as possible.
I had a problem where my output amps fell off from 20 and it turned out the input voltage was too low. The unit has a boost spec from about 8 volts but not quite so in real life. Anyway, you improve your input voltage "somehow" until the unit can sustain its full output amps at the chosen output voltage. You cannot control the input amps directly.
I am using the thin and long positive wire in the 7-pin as input so to get the whole circuit better, I had to swap over to using the frame instead of the neg 7-pin long thin wire. If that had not worked, I would have had to run a fatter positive wire too.
Yes it does matter.
The unit is "buck/boost" and the output voltage will be higher than the input's in many situations so it has to boost. The voltage drop to the charger is vital to keeping the input watts high enough to keep the watts up. It also affects the amps draw on the alternator, which you want to keep as low as possible.
I had a problem where my output amps fell off from 20 and it turned out the input voltage was too low. The unit has a boost spec from about 8 volts but not quite so in real life. Anyway, you improve your input voltage "somehow" until the unit can sustain its full output amps at the chosen output voltage. You cannot control the input amps directly.
I am using the thin and long positive wire in the 7-pin as input so to get the whole circuit better, I had to swap over to using the frame instead of the neg 7-pin long thin wire. If that had not worked, I would have had to run a fatter positive wire too.
