geordy avatar image
geordy asked

MultiPlus 12/800/35 overload alert with no load connected

Hi There,

just bought a MultiPlus-II 12/800/35 for a small installation in my planned camper.

Today i wanted to test the device but MP-II shows an overload alert when cutting of AC power an switching to inverter mode.

It's just a testbuild with a LiTime 100Ah LiFePo4 battery and no other device connected.

Updated firmware to v502 and used VictronConnect via MK3-USB-Adapter to check configuration an alert messages.

AC throughput works.

Charger starts in bulk mode but with 0A and does not change to absorption or float.

Battery fully charged an voltage is at 13,55V. No powerloss between battery an MP-II connectors. Cables (25mm²) are short with a mega fuse and mainswitch to cut off battery connection.

Configured MP-II via VoctronConnect to LiFePo4 and checked voltage settings.

Missing informations?

Any hint is welcome!

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Alexandra avatar image Alexandra ♦ commented ·


Overload on grid outage is usually LOM detection or voltage disconnect related.

What inverter do you have exactly; I am not aware of the model of MP2 you are talking of?

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geordy avatar image geordy Alexandra ♦ commented ·

Sorry, it is just a Multiplus 800VA without "II" Realised the mistake after posting.

Battery stays on, other connected devices work as espected (e.g. 12V caravan control unit).

Will try to disable LOM detection for testing as described here:

Could a (defective) residual current circuit breaker (German: FI/LS-Schalter) be part of the problem?

Thank you!

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Alexandra avatar image Alexandra ♦ geordy commented ·

It is a possibility. No load does not necessarily mean no load in the wiring.

The only way to work out if it is, is elimination. Remove it from the circuit temporarily and see if the behaviour changes. If it does then you are on the right track.

Are you using a grid code or the ground relay?

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geordy avatar image geordy Alexandra ♦ commented ·

Thank you for helping! Exuse my late response, but today was first day this with with time for testing some things.

Multiplus is now direct connected to AC, no fuse.

I have no grid configured. I plan an island configuration with just one line.

Ground relay was enabled but actually nothing is connected to case ground.

Tested LOM enabled and disabled with grid codes for Europe, Germany and other.

Behavior did not change. After pulling AC Multiplus chnges to alert and overload state.

Added my actual configuration with AC and DC connected. Plus a small batterycharger for gardentools as AC load.

Chnaged battery voltage as described in battery manual. And added two assistants using alert relay for external AC signaling.

Jumpers are all off exept J2.



Already contacted my dealer by mail for support but no response since one week.

Any further hints and help is welcome!

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ve-charger.png (214.4 KiB)
Alexandra avatar image Alexandra ♦ geordy commented ·


If you havent already uodate firmware.

Uncheck power assist also for elimination purposes. That about all I can think of right now.

But it sounds like something is not right, and will end up being returned to the supplier for an RMA.

You can do your own PRE RMA testing before going that far though.

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1 Answer
geordy avatar image
geordy answered ·


Just wanted to give some feedback.

After giving up testing the MultiPlus, I was playing with my CaravanControl Unit. With these tests battery was discharged by around a quater.

Next day I wanted to doublecheck all checks from Pre-RMA-Checklist you mentioned. I could not belive it, after every parts were connected again, MultiPlus stayed in inverting mode, with no alert.

Connected AC to fully reload battery. Then disconnected AC again resulting in an overload alert.

That after I decided to discharge battery again to doublecheck that it's not a battery problem, even if there never had been a battery voltage alert.

Discharged a third (just guessing) and tested again. MultiPlus started inverting without alert. Fully charged again ... No alert after disconnecting AC. Tested with higher loads while inverting and charging.

Next 2 days I fully charged and partly discharged batter again, never again MultiPlus showed an alert. Changed from passthrough to inverting, loaded battery (bulk, absorption, float).

Inverting works as espected with connected load.

I really can't say where the problem was located maybe battery, maybe not.

I'm happy it works and hope it stays in this condition after nearly three weeks of testing.

Thank you for helping me!

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Alexandra avatar image Alexandra ♦ commented ·


The battery was on the suspect list.

But glad it is sorted now.

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