question

rod avatar image
rod asked

Quattro with only AC input/output

Im doing some DC work on my boat will disconnect the quattro from the DC circuit. Will the Quattro still switch ok between the shore pwr and genset inputs? Does it need DC power for any functions? Thanks

service
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3 Answers
ben avatar image
ben answered ·

If there is no DC input, it will only start up if ACin1 is present, but it will work okay from there. It will not start up if only ACin2 is present.

I suspect it will not be able to switch back and forth without DC, because it just flips some relays internally, and there must be a small point of time when neither AC input is switched into the circuit.

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Interesting. So AC2 is not considered a "valid" input until the unit sees DC?

Do you think that's a software or physical limit? Seems kind of odd for it to be done on purpose?

Thanks!

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My guess -- and that's all it is -- is that it's a physical limitation. The computer needs to control the relays that switch AC1 and AC2 into the circuit. It has to power up somehow. The relays might even be two-position, in which case they have a default.

In any event, the effective result is that the system can only bootstrap off DC or AC1.

I'm not totally sure it cannot switch to AC2 after it starts off AC1, but I suspect it can't. I think it will probably just shut down with no DC input and if AC1 drops, regardless of the status of AC2.

Actually, scratch that, I think I might have done this! Stayed live on AC2 while isolating my battery, that is.

I can't remember. It's a rare circumstance for me, and I don't think I have it in my notes.

I know the statement I made above is correct, though, regarding which inputs it will use to *start*.


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Thanks Ben! Good to know. You're probably right, it's likely physical and for the reasons you stated.

And I can confirm that it will indeed keep going, w/o DC (battery switch off), on AC2 -if it's already going.

I was uncertain if it would fire up on AC2 from an Off state.

Thanks again for clarification :)

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Quattro may be different from other inverters ....

Most inverters use the DC for all control and protection facilities.

Therefore if DC is turned off the inverter/charger will be destroyed, perhaps not on the first event but sooner or later....

Quattro may be different from other inverters ....


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Yes, Quattros are superior to many other inverters in this regard. With at least AC1 in (and possibly with AC2 in), it is possible to drop the battery for maintenance while keeping the loads live.

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Pat Davitt avatar image
Pat Davitt answered ·

This is a common problem. How do you keep the AC flowing when you have to do maintenance on your system. The solution is external to the Inverter/Charger system and requires rewiring the shore power input circuits. Below is a schematic of my system, note the "By-Pass" circuitry in the AC Load/Distribution panel on the left side of the schematic.

Pat


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Forgot to add a power flow diagram for my Blue Seas panel that may be clearer.

Pat

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rod avatar image
rod answered ·

Thanks guys, very helpful.

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