Float Light Only Multi (Toolkit says no such LED)

Q&A and troubleshooting
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1

Hi Guys

this is a Clients Caravan im trying to remotely Diagnose,

After A low battery event. i have a Mp that just has the FLOAT light on, No mains LED or any Inverter LEDs

Victron Toolkit suggests this combo does not exist,

its plugged into the Grid, system will also not Pass any power, tried shutting on an off from the DMC nothing seems to change,

any thoughts?

the Low voltage event was caused by i think maxing out the internal BMS of the LIFEPo4 battery ( we did not install) i think the battery’s maybe now flat also, so theres a chance no power is getting to the inverter on the DC side but it should boot up when put into the Grid,

2

No, the inverter needs DC to operate, applying AC only might even brick it.

3

Hmm don’t think that’s correct from previous bench testing,

4

FYI

Yes, a Victron Multiplus (or Multiplus II) can operate in pass-through mode without a battery, allowing it to feed AC power from an external source (like shore power or a generator) directly to connected outlets.

Here’s a more detailed explanation:

  • Pass-through Functionality:

When an AC source is available, the Multiplus will automatically feed that AC power through to its output, bypassing the inverter and battery charging functions.

  • No Battery Required:

The Multiplus can function in pass-through mode even if no battery is connected.

  • Automatic Transfer:

The Multiplus has a built-in transfer switch that automatically switches to pass-through mode when an AC source is detected.

  • “On” or “Charger Only” Mode:

To enable pass-through, the Multiplus needs to be in the “On” or “Charger Only” position.

5

Hi @morganb,

Ludo is closer to the mark here.

The MultiPlus and MultiPlus-II needs to be connected to a battery for reliable operation.

The Multi is intended to be able to “black start”, so even when no battery voltage is detected at the DC terminals, it will use the AC input power to power the AC to DC circuits to provide DC voltage. This is intended to begin charging a battery, or ‘wake up’ a lithium battery BMS that has disconnected its battery due to low voltage.

On a test bench where there are no or very stable loads, it is possible to run a MultiPlus like this however I would say that it is impossible to do it reliably in a ‘real world’ situation where there is fluctuations in load connected to the AC output.

You will get warnings and alarms like low DC voltage, high DC ripple, etc. It is also possible that there would be a very high DC voltage generated, which without the absorptive buffer of the battery could do damage to the MultiPlus, or anything else on the DC circuit.

I am not sure where you got your quotes above from? Looks like it might be an AI hallucination as there is no text like that in any of our documentation as far as I am aware.

Pass-thru mode can give the impression that this is a reliable thing to do, but it is not. Even when in pass-thru the system still expects there to be a battery for DC voltage stability.

6

Thanks Guy appreciate ur more detailed response as usual.

Yes it was a quick google AI check to confirm I wasn’t going nuts and had seen it on a bench.

More my concern though anyone seen the float only light?

1 Like
7

I’ll ask and see what I can find out about the steady on float light with nothing else.