3dym avatar image
3dym asked

Orion-DC-DC Charger with existing battery parallel switch

Many, if not most motorhomes and boats have a manual house battery parallel switch to help start the engine on a low battery. Would it be a bad idea to short the Orion input and output while it is charging? How will it react? Or will the input breaker trip? Assuming this is undesired, is there a way to use the H and L connections to automatically inhibit charge with the +12V going to the parallel solenoid? (Engine ignition is used to allow Orion to be OFF with zero draw with engine off).

Does anyone know the full logic of connections L and H?

I have read the manual and asked for help from Victron and this forum but had no response.



battery chargingorion-tr smart
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wildebus avatar image wildebus commented ·

I don't actually think most motorhomes have that facility for a battery assist in fact (unless they have a Victron Cyrix-ct with start assist)

Anyhow, there is a way to do what you want and I have my Campervan setup in a similar way to as you describe.

I have a Orion-Tr Smart and a Cyrix-ct 230 both connected to the Starter Battery and the Leisure Battery Bank.

I use the "L" remote input on the Orion-Tr to control if it is allowed to come on or not (if you use the "L" input, anything other then a 0V will disable the Charger).

This is what the Victron Connect app will say in that situation

On the Venus GX, I have the relay 1 configured so it switches on when certain conditions occur (SOC below 80%, Current demand higher than 40A)

The COM of the relay is connected to 0V; the NC of the relay is connected to the "L" of the Orion; and the NO is connected to the earth lead of the Cyrix.

So when Relay is on, Cyrix will come on when engine is running; and when Relay is off, Orion will come on when Relay is closed.

This does mean that the input and output of the Orion are in a way shorted together when the Cyrix is on, but I can't see that being an issue as both sides always have a voltage anyway.

You could do the same kind of thing with a BMV-712 Relay, or even with just a mechanical On/On or On/Off/On switch.

Hope this was of some help.

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3dym avatar image 3dym commented ·

Thanks Wildebus, good to know what works for you.

For motorhomes in the USA I believe the parallel solenoid is standard, and on boats it's always been there as well.

I wonder if the Orion still attemps to charge with input/output shorted. It's rated at 60A short circuit, so the breakers might trip? At far as consumpion (or loss) it could be 13% of 60A = ~8A ? (87 % efficiency).

I know how to do it with a relay but I was hoping to keep it as simple as possible for reliability. Since the charger has two control inputs (L & H), I thought it would be reasonable to expect it to be programmable for a +12V "inhibit" function.

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wildebus avatar image wildebus 3dym commented ·

I am sure it will attempt to charge. I see no reason why not, as the input voltage will be greater than the turn-on voltage so it runs if the demand is there. It doesn't know that the source and the destination are effectively already connected together and so it is actually a waste of energy - that is down to the installer to cable up correctly to avoid that sitution.

The L and H remote functions are pretty flexible actually I found.

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1 Answer
jwfrary avatar image
jwfrary answered ·

How about changing the paralleling solenoid switch for a double pole switch and then fit a NC relay in the ignition line.

That way when you depress the switch it will be like the ignitions off.

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3dym avatar image 3dym commented ·

Thanks Jwfrary. I know how to do it with a relay but I was hoping to keep it as simple as possible for reliability. My other consideration is trying to avoid running extra wires from the front of the motorhome to the middle where the electric panels and solenoids are (under the chassis with new conduits).

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