Renogy 20A dc to DC report

[pianotuna]

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.

[Gdetrailer]

CA Traveler wrote:
Not very efficient. 😞

Wonder if it varies by voltage or amps.

Correct.

Each time you do some sort of "conversion" there is some efficiency loss which results in some heat.

Additionally going from a lower voltage to a higher voltage means it takes more current on the input than the current you get on the output but if you check the watts they will be nearly identical minus of course the conversion loss.

For instance.. Say you are converting 12.0V to 14.0V..

12.0V at 30A is 360W.

360W at 14.0V is 25.7A not including the efficiency loss of the switching power supply..

So depending on the start voltage of the OPs test and what his target output voltage it is very possible that his input current can be 30A at the lower voltage but yet only yield 20A at his higher target voltage but yet still get the same watts..

This is no different than what the Power Company does to distribute AC on the grid.. They take the generated voltage, run through a high voltage transformer which boosts the voltage and that drops the current allowing thinner wire to be used. Then at your house run it through another transformer to drop to a more usable lower voltage at higher current for your home.

[BFL13]

I got mine to do better with a higher input voltage. What was the input voltage on yours when input amps was 30?

Of course you have to have input watts higher than output watts, so what was the output voltage when it was doing 20a?

I run my output set to 14.7v and it does the 20 amps out steady. I had to improve the wiring from engine battery to Renogy input to reduce voltage drop and so keep input up enough.

[CA_Traveler]

Not very efficient. 😞

Wonder if it varies by voltage or amps.