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marc-van-dijk asked

Multiplus 12/3000, Active AC input disconnected

Hello community,

I am relatively new to the Victron world and have a problem with my Multiplus 12/3000/120-16 that is puzzling me.

I am upgrading my ships electric system to lithium and moving to "Victron blue" for the most of the system. I managed to purchase a second hand but nearly new Multiplus with a certificate that it was checked to work properly by a Victron listed dealer.

After swopping out my old charger for the Multiplus still with the old lead acid bank I had a working first start in "Charger only" mode. The Multiplus charged the battery and went in to float after a while. All good I left it for a day only to return finding that the Multiplus stopped working and my battery was at a low 10.3V as the DC system on board was still on. AC was working fine.

I checked using the connected Cerbo GX finding that the AC input was not recognised/accepted and the "Active AC input" listed as "disconnected". When in "inverter" mode, the system detects AC input at around 240V, 51 Hz. There is an isolation transformer between shore and ship net (Philippi TTR 2500). The inverter also worked putting out a near perfect 230V 50 Hz. Still, shore power was on and not detected/forwarded. Starting the Multiplus in "Charger only" mode will have the "Mains on" LED flash a few times, a few clicking noises and that nothing anyone. The "state" of the Multiplus then often lists as "fault" in the Cerbo but without any error codes.

I have seen people reporting similar issues before suggesting a firmware update. I upgraded the firmware to 500 for product ID 2609. The update did not resolve the issue unfortunately.

I would appreciate tips, pointers or otherwise that may get me a working Multi again.

Best regards,

Marc

multiplus ve.bus
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Alexandra avatar image Alexandra ♦ commented ·
@Marc van Dijk

Did you disable virtual switch? After programming the inverter for your battery bank?

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marc-van-dijk avatar image marc-van-dijk Alexandra ♦ commented ·
Hi @Alexandra,

First of all, best wishes for a great 2023!
Thanks for the tip. I have not yet configured the inverter as I am still in the process of installing the BMS. The inverter is now running on the old lead acid pack still. After the upgrade of the MultiPlus firmware I expect the configuration to be reset to factory defaults which I assume to support active AC input. I am not sure though and will check again.

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marc-van-dijk avatar image
marc-van-dijk answered ·

Hi @Alexandra,

Thanks for the details. I think it is good to distinguish the present and future state of the my setup. Present is a lead acid setup where I am experiencing problems. Future state is lithium which will not be Victron batteries or Victron BMS solutions but a BatteryBalance X2. The latter will work in a similar fashion as the Victron BMS and require a few changes to the Multiplus config. However, I do believe the Multiplus should work as advertised in both the current and future state.

To illustrate the issue again, this is what happend the last two days:

  1. Multiplus powers on, "Mains on" LED fully lid blue, Multiplus cycles from bulk to absorption to float to storage charge mode and happily keeps the lead acid at 100% SOC.
  2. DC System is on and powered by the Multiplus
  3. AC System is on and connected to AC-out L1 of the Multiplus. There are two laptop chargers running actively on 230V. Because the Multiplus does not switch to inverter mode I assume that AC pass through from shore power via the Multiplus is providing power.
  4. I can monitor the system via the Cerbo CX console and the online VRM. Both provide about the same information: the Multiplus tab on the Cerbo Console lists: switch = on, state = storage, input current limit = 16A, Active AC-input = AC-in L1, both AC-in L1 and AC-out L1 = 230V, 50 Hz. This seems to look OK.

However, the situation will change if I start using more 230V devices:

  1. If I turn on the microwave I hear the Multiplus switching to inverter mode while my shore power supply should be able to manage this. Perhaps the sudden power draw triggered it.
  2. Ones switched to inverter mode, the Cerbo console lists Active AC-input = disconnected. AC pass through does not work, so no "Power Assist" functionality.
  3. From that moment on the Multiplus basically does not function anymore. It will not charge because it has no AC-input or does not accept it. Inverter mode stays on for a short while followed by "fault" as Multiplus status code. The DC system is still active and will drain the battery.
  4. Once in this state I have tried a couple of times to switch on an off the system but only manage to get it to the same working state as at the beginning of this story (1) after a couple of tries. I don't know yet what makes it work eventually.

Perhaps this issue still has something to do with virtual switch you mentioned. I looked up in the config, the active status is: "drive multifunctional (aux.) relay, VS on=open; VS off=close". Other settings in the config that are checked: accept wide input frequency range, UPS function, inverter power assist, inverter Ground relay, charger in storage mode.


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Alexandra avatar image Alexandra ♦ commented ·

@Marc van Dijk

I have deleted my comment about the ve bus bms since they are irrelevant.

If it is disconnecting under load from AC then there is another problem.

If your batteries are weak, then the system will also not behave as expected.

If the connection to the battery has high resistance the issues you describe start happening. It could be that battery cable is too small, or the connections to the battery have too much resistance, then you will also experience the issues you are describing. The same is true if the AC cabling is too small.

I am leaning toward dead battery issues, you are already looking at replacement, your system has done a 10.5v discharge and I assume they are an old set as well.

The system will go into fault when it tries a few times to reconnect unsuccessfully to the shore power again.

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marc-van-dijk avatar image marc-van-dijk Alexandra ♦ commented ·

@Alexandra

A weak battery may certainly be an issue. Since I am swopping for lithium I will commence doing that and see if it changes things for the better.

I am also changing cabling as part of that project. Most of that is new and oversized in the setup by now so I don't think cabling is an issue.

Besides the batteries it seems to be really the triggering of the inverter mode together with a disconnect of the active AC input that is the problem here. It is not even the inverter in Power Assist mode supplementing the AC, it is full disconnect of AC (Cerbo raises a Grid lost alarm). This also happens if the main AC distribution is directly powered from shore power coming in from the isolation transformer (shore supply) and thus not going via the Multiplus first (inverter supply). In the latter case the Multiplus does not need to provide any AC to loads and I read 0-2W consumed (I don't no where those 2W are coming from). When the inverter mode is triggered it also does not provide any power to any loads because there are non.

Could there be an AC grounding problem causing this behaviour perhaps? Might need to have a trained electrician take a look at it.

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Charlie avatar image Charlie marc-van-dijk commented ·
The same problem is happening to me. Did you resolved the issue?
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