Wiring question

[AJMike]

Originally Posted by BobC

If you plan on installing solar, Renogy makes a combo DC to DC Charger/MPPT Solar Controller combo unit:

https://www.renogy.com/dcc50s-12v-50...ger-with-mppt/

Also, here's a review:

https://diysolarforum.com/threads/re...r-w-mppt.1406/

I already have 300 watts of solar on the roof. During the Arizona summers that generally produces more than 100 AH if the RV is parked in the sun. About half of that in the shade and during the winter when the sun is lower in the sky.

[orangeminnie]

Charge current dropping before the battery voltage approaches about 13.9V (at least), can be a sign that the charger is overheating and folding back to protect itself. I've seen it often. The popular DC to DC chargers all seem to run really hot.

[AJMike]

Originally Posted by orangeminnie

Charge current dropping before the battery voltage approaches about 13.9V (at least), can be a sign that the charger is overheating and folding back to protect itself. I've seen it often. The popular DC to DC chargers all seem to run really hot.

I wonder if there are any DC-DC chargers that do not suffer from this issue. I saw a post where someone was complaining that their Victron 30 amp DC-DC charger was overheating.

In this case it is a Renogy 40 amp DC-DC charger and it had been running hot enough for it to completely shut down. You can see this in the Victron Trends display that I have attached to this post.

I tried to take care of this by mounting an external fan to constantly blow cooler air on the charger and keep it from shutting down. That worked, but the charging voltage jittered all over the place, constantly changing and slowly dropping down in charge. I have removed the charger and Renogy support says that they will send me a shipping label for them to test the unit and see if it is faulty. In the meantime I have purchased a second smaller unit and will see if it, at only 20 amps, suffers from the same issue.

This is a pain but I need something to charge the Lithium batteries while driving and I don't know what else I can do except use a DC-DC charger. I don't want to have to run the generator since it is an LP generator and I don't want to have to go searching for propane every second day.

[orangeminnie]

Whoa. The Victron DC-DC charger we use just smoothly folds back as it gets hot, but continuously charges at reduced current. I seem to recall hearing another Renogy owner with a situation similar to yours. Perhaps this is normal for Renogy

[AJMike]

Originally Posted by orangeminnie

Whoa. The Victron DC-DC charger we use just smoothly folds back as it gets hot, but continuously charges at reduced current. I seem to recall hearing another Renogy owner with a situation similar to yours. Perhaps this is normal for Renogy

The on/off operation of the Renogy charger was due to the installer having put the unit in a cabinet with no ventilation and not enough air for it to cool itself. When I moved the unit to a larger cabinet and added some ventilation holes and an external fan the on/off operation stopped and the unit then acted much as you describe the Victron unit as acting. That is, it just decreased output as it, or the wiring (I can not be sure which), heated up. That is, it continued to charge, but at a reduced rate.

What I was asking is if there were any charger units that did not reduce output due to heat. Your Victron reduces output due to heat, my 40 amp Renogy does the same now. I am waiting for a shipping label to return it to Renogy for testing and have installed a 20 amp model and will see if it also suffers from the same reduced output as it operates, just as soon as we start on our next trip.