Redarc 40 amp DC to DC Charger issue

dead short?

Horsedoc wrote:
dead short?

I don't see how. It would trip immediately.

Might be normal, If your Redarc is anything like my Victron 18amp which has no current regulation. Me I'm very disappointed in the Victron DC to DC chargers they offer no way to adjust the output current. Check out their web site forum and the many many complaints regarding this issue. Even worse my Isolated 18A max DC to DC charger, charges my 200amp/hr Li battery at 26amps! WTF! Had to return the 40amp version it went to as much as 70amps with no way to adjust the current.

What voltages? Where are you measuring current; on the input or output? If you are charging to 14.7 volts at 40 amps but only receiving alternator power then it would take 14.7 x 40 / 13.8 = 42.6 amps input not accounting for the converter efficiency.

Teleman wrote:
After about 15 seconds or so when I start the engine my shunt reads up to almost 49 amps and then the 60 amp input breaker pops. Whats going on here? Isn't the charger supposed to limit the output current to 40A?

what side are you reading on? its 40a on output, breaker shouldn't be tripping at 50 amps either.

LittleBill wrote:

Teleman wrote:
After about 15 seconds or so when I start the engine my shunt reads up to almost 49 amps and then the 60 amp input breaker pops. Whats going on here? Isn't the charger supposed to limit the output current to 40A?

what side are you reading on? its 40a on output, breaker shouldn't be tripping at 50 amps either.

Looking at the house battery shunt. Seems to have stabilized at about 43 amps. Breaker trips at about two minutes making me think it's a **** breaker. I'll check with a clamp on ammeter tonight.

Any time there is a current question check/clean all connections !

KD4UPL wrote:
What voltages? Where are you measuring current; on the input or output? If you are charging to 14.7 volts at 40 amps but only receiving alternator power then it would take 14.7 x 40 / 13.8 = 42.6 amps input not accounting for the converter efficiency.

Check voltage at the vehicle battery and at the house battery (before the trip).

Something sounds off, I have the 50amp Redarc and it draws exactly 50amps from the alternator/truck battery and output is about 47amps to the batteries.

Not sure if all Redarc dc to dc chargers operate the same. It appears some Redarcs may set an output/charge current ceiling (and vary input current), whereas other models may set an input current ceiling (and vary output/charge current).

Our 40a Renogy dc to dc charger can vary the output/charge current from 0 to 40a. After 9 months of heavy use, under all conditions, I've never seen the output/charge current increase beyond 40a---it's a hard ceiling. Although the *input* current on our Renogy always stays below 45a, some installations (with longer cable runs & smaller gauge cables) can force the input current to rise as high as 60a to compensate for various voltage drops between the alternator and Renogy input.