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Reflex439's avatar
Reflex439
Explorer
Jun 19, 2017

Charging-Solar,Alternator,Converter/Charger

Charging-Solar,Alternator,Converter/Charger - Do they play nice together?

I’m curious what happens between the solar controller, converter/charger, and the vehicle alternator, whey they are all trying to control the charging of a battery. When boondocking, the solar controller is the only device charging the battery. But when I fire up the generator, both the solar controller and the converter/charger is attempting to charge the battery. Further, when driving, the alternator is charging as well as the solar controller.

Some of these devices have different settings, and I am wondering if that can cause damage to the battery over time from overcharging, etc.

Here are the specifics;

Renogy 100w panel (currently adding a second)
Renogy Rover 20amp MPPT controller
Progressive Dynamics PD4645 converter/charger
Vehicle alternator when engine running
Single sealed lead acid 84ahr battery



Rover MPPT: Boost (2hrs)=14.4v, Float=13.8v, Boost Return=13.2v, Equalization=14.6v (2 hours every 28 days)

PD4645: Boost=14.4v, Normal=13.6v, Storage=13.2v, Desulfation=14.4v (15 minutes, every 21 hours)

Alternator: ???


1. When stored, the RV is just sitting in the sun and the solar is the main charging source.
2. When in a campground, it may be on shore power for a few days to a week, then back to solar in storage.
3. When traveling long distances, the battery would be charged by the alternator 3 to 6 hours per day, solar all day, and for multiple days to a couple weeks.
4. When boondocking, it would primarily be solar, although on very hot days the PD4645 would also charge when running the generator for A/C use (maybe 4-8 hours a day).

Will these devices sort out the charging process under those circumstances above without changing these voltage settings? Or do I need to match the Rover controller which I can change individual parameters to match the PD4656 which I can’t change. And lastly, does the alternator run at a constant charge voltage, and if so how does that fit in?
  • I just want to add that trying to recharge your battery bank from your vehicle alternator is NOT going to give very satisfying results especially if you have a true deep cycle battery bank. The vehicle charging system might be able to "prop up" the battery bank so that you can run an inverter for a household refrigerator, but that is about it.

    If you are boondocking and run short on battery reserve (due to some type of failure in your solar charging) you best option is to hook your inverter directly to the vehicle battery with the shortest properly sized wire and then run your charger off of that.
  • Once the voltage set point is reached the charging item basically shuts down.
    The source with the highest voltage will continue as normal. A low battery may receive power from all three until the voltage pops up. No worries.
  • All are voltage limited. Like screaming fans in a football game. The loudest one gets heard.