DC to DC charger - all sources?

[N147JK]

Question for the electrical system gurus. Can a DC to DC charger be used with any and all charge sources? As is typical, my van has the following charge sources.. 1) engine alternator 2) 110 volt WFCO deckmount converter-charger 3) 200 watts rooftop solar. And all 3 could potentially be providing a charge at the same time. Can I simply wire all 3 into the DC to DC charger and let it handle charging a Lithium battery automatically? - Thanks in advance!

[boywonder]

Originally Posted by N147JK

Question for the electrical system gurus. Can a DC to DC charger be used with any and all charge sources? As is typical, my van has the following charge sources.. 1) engine alternator 2) 110 volt WFCO deckmount converter-charger 3) 200 watts rooftop solar. And all 3 could potentially be providing a charge at the same time. Can I simply wire all 3 into the DC to DC charger and let it handle charging a Lithium battery automatically? - Thanks in advance!

I have the following confg:

Alternator-DC-DC converter-lithium house battery

Old Intellipower 60A converter-charger connected between the starting battery and the DC-DC converter. When plugged into shore power it charges the starting battery and charges the lithium battery through the DC-DC converter. I've operated the Intellipower with both the charge wizard and without.

I have solar connected to the lithium house battery using a Victron MPPT controller; I thought about what would happen if the solar was connected to the DC-DC converter (without a charge controller)...well you wouldn't get any MPPT functionality for one thing.....not sure what would happen if you connected an MPPT controller to the input of the DC-DC converter since you would have both the MPPT and DC-DC converter possibly in different parts of the charge cycle.

[N147JK]

Originally Posted by boywonder

you wouldn't get any MPPT functionality for one thing

I have come across products like this one. A DC to DC charger that also provides MPPT functionality. Maybe they don't work well.. I really don't know, but seeing these has me curious.

https://richsolar.com/products/50-am...rger-with-mppt

[kbeefy]

I originally had a Renogy 50A MPPT/DC-DC combo unit but returned it and went with a dedicated DC-DC and Seperate MPPT charge controller. I'm not sure about the Rich Solar unit, but the Renogy one had some limitations on charge amperage on the solar side, if I recall correctly. My plan at the time was to allow for future upscaling to 800w of solar, and that one wouldn't support it.
I've since moved back to a van and will only have 400w on the roof, but the more robust controller I went with will still support some additional portable panels if I decide to add them in the future.

[kbeefy]

Originally Posted by N147JK

Can I simply wire all 3 into the DC to DC charger and let it handle charging a Lithium battery automatically? - Thanks in advance!

Do you have a solar charge controller?


If your 110v charger is lithium capable, I would just wire all charge sources to a common 12v buss bar. It doesn't make sense to me to run all thru the DC-DC, seems inefficient and wasteful.


What size DC-DC charger? My AC charger is 75A, I wouldn't want to run it thru my 40A DC-DC and have it throttled.

[Scalf77]

Theoretically yes, in reality it become harder.

Most DC to DC controllers would have voltage input limitations to handle the voltage of solar panels. So I guess the possibilities would be can you get a solar controller to work with all three. Then of course you run into , the higher turn on voltage that many solar controllers have may not allow you to turn on when trying DC to DC. And the hard part of finding a charger output (or power supply output), that a solar controller of DC to DC could except.

Bogart engineering at one time said that there SC30 controller could do all three, I don't see any reference to it on their site now, so maybe not quite.

REDARC, I know makes a manager-30 that does all three, includes battery monitoring. That was 5 years ago, so there are probably other options there also.

There are a bunch of dual units( Solar & DC to DC) out there. Kisae DMT1250 was doing this years ago. There are generally some compromises when working with the dual units ( limited Solar Max VOC, only one at a time, although some combine)

I like Rich Solar Solar panels, I fear them moving into controllers will be much like that of Renogy. I also like Renogy panels, but that is where it stops.

I am really not a big fan of charging one battery to get the other charged.

There are of course issue with separate controllers, as you might exceed your batteries maximum charge current, but that can be managed.

[Big_ern_101]

Depends on how much you want to spend and what your goals are.

Renogy 50A DC-DC will do the the following
-Charge house battery from solar (priority)
-Charge starting battery from solar
-Charge house batter from alternator
-In theory, charge house battery and starting battery from separate shore power 12V power supply (need to isolate starter battery to keep it from being robbed during charging or use a 24VDC power supply, hook it in to the solar connection, and disconnect or diode isolate the solar panels)
-Also in theory can power house-connected items off starting batteries by connecting a jumper and enabling "smart alternator" mode, but it would killl your starting batteries pretty fast.

The Redarc Manager 30 is an all-in-one solution and is gorgeous but is real expensive. It can charge house and starter batteries from wall and solar and house batteries from alternator. Advantage to the Redarc is it can provide more amps on shore power which would be helpful for someone with an induction cooktop, air fryer, or A/C that are connected to the house battery.

My current setup is a Renogy 50A DC-DC and a Noco 10A maintainer that is wired in to the house battery only.

This gives me a decent bit of flexibility in that I can charge the house batteries off shore power at 10A but the battery gives me the surge capability to start bigger loads, it keeps my lithium house battery happy, and if I really need to I can rig it off my inverter , swap a cable around, and charge my starting batteries. Or charge my starting batteries off shore power. Pretty simple setup and clean to install.