did you put an dc amp meter on the wire comming from the battery to the 60 amp breaker to see if the amperage was close to the 60 amp breaker value

I think what could be happening is the cable gauge may be too small for the run length. If the voltage drops a lot from the battery to the Renogy box it then has to increase the current draw to maintain the same power transfer.
For example, if its output is 14.6V at 40 amps power equals 584 watts
If the input is 12.3V then the amperage needs to be 47.5 amps
If the input is 11.6 then the amperage draw needs to be 50.34 amps

Figures are just for illustration but you can see how the voltage drop affects the input amperage draw. There will also be some losses from the unit itself via heat so the amperage would be higher. I find in my setup the draw is around 50 amps or so.

Another thing that can affect the amperage is the battery and alternator. Maybe the batteries are on the older side and have degraded a bit in performance, ie. weak cells so can't hold the voltage as well or the alternator is varying in voltage. My alternator is what they call a smart alternator, with built-in regulation, so it will vary the voltage based on demand. Generally though when it sees the draw of the DC-DC charger it should raise its output to around 14.4.

Cheers, Ray

Thanks Ray, I am using 4 gauge wire like the manual says, and brand new batteries (3 weeks old). I wonder if my alternator does not have generate enough amps? Do you think that could cause the issue, if it does not generate enough amperage? It looks like I could either have a 200 amp or a 125 amp. Not sure which one I have, so I will investigate that.

Thank you Luc, that is a good idea. However, my multimeter does not measure amps. I have been wanting to get one, I guess this is a good excuse to do so.

I'd guess it must be able to generate the amps if it is able to blow the breaker. I used 4 gauge as well. I'd want to check the voltage at the DC-DC chargers input terminals and the trucks battery terminals and see if there is an excessive voltage drop. I guess it could be a poor connection along the way but since you just installed, it not as likely. Might want to check at each connection on the path and see if any are much hotter than any of the others.
I'd also want to use a check the actual amperage just to rule out a faulty breaker tripping for no reason.

OK, thanks. I just ordered the Digital Clamp Multimeter you have on your amazon page. My multimeter is old and very basic does not show amps, only volts and ohms.

*** Update ***

Well, I am now officially a full time (or mostly full time) rv'er. I wanted to give an update with my findings with the DC-to-DC charger, now that we have been on the road for about a month now. I hope it might help others if they have problems.

I have identified a few things that happen to the DC-DC charger.

1. Circuit blows next to the battery in the engine compartment: I think this happens when I have a lot of rpm, for example when going up steep hills. After going up steep hill's I will check the breaker when I get a chance.

2. DC-DC charger fails to charge, and there is a red light on the charger: This was a very interesting issue and took a little time to solve. What I found that is when plug into shore power, this will happen. So, what I do is turn off the circuit breaker by the DC-DC charger, so power does not get to it when plugged in.

So, now every time we take off, I check for the popped circuit breaker and the red light and then verify that the DC-DC charger is working. I will also check how its working every time we stop.

All in all I love having the DC-DC charger. I can now run the inverter when driving so I can run the fridge on AC instead of propane, and at the same time charge my batteries. I also figure that is a big safety feature, not having the propane on.

PS. We are currently at Palm Canyon, in Kofa Wildlife refuge area. Thanks to a video from Ray about 5 or 6 years ago. What a wonderful spot.

Thanks for the update!