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mysik avatar image
mysik asked

MPPT in not following Multi (Batrium BMS) - DANGEROUS

Hi,

I've just added SmartSolar MPPT 150/35 to my ESS system and I've noticed that it is not responding to Batrium BMS signals. I have Multiplus II 48/3000 with AC-in coupled PV which is reacting to BMS as expected, but MPPT is doing whatever it wants to do ignoring BMS and Multi. Both Multi and MPPT are connected to VenusGX via VE.Direct and I can see both devices on the Device List.

I'm using ESS (without BatteryLife) and Grid Feed-in is set to OFF. DVCC is OFF as well.

When I turn off charging in the BMS, the Multi is stopping immediately, but MPPT is still keep charging. The MPPT setting page is showing that it is BMS Controlled, but obviously it is not:

1655456125304.png

What am I missing here? Is it a bug in Victron system?

Please help, because this is dangerous! My battery was overcharged by the MPPT because it completely ignoring BMS signals! Luckily my charge voltage was set low enough to be well in spec, so nothing bad happened, but still battery was charged more than the BMS wanted it to be.

Why MPPT is not stopping when BMS want it to stop? At the same time Multi is stopping as expected!

MPPT ControllersBMS
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3 Answers
nickdb avatar image
nickdb answered ·

DVCC needs to be on.

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Daniël Boekel (Victron Energy Staff) avatar image
Daniël Boekel (Victron Energy Staff) answered ·

Hi @Mysik

As @nickdb mentioned, of course you need DVCC to be 'on'

Next: this is not dangerous, as your BMS surely will disconnect when something gets out of range?

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mysik avatar image mysik commented ·

BMS sent signal to Victron system to stop charging and Multiplus II did stop but... SmartBlue MPPT DID NOT, so it is dangerous! As I mentioned before, fortunately my target voltage was set low enough to be on the safe side, so nothing bad happened, but if you have BMS in the system that the system is not listen to, that gives you false "sense of security". My system has no contactor/relay to isolate battery completely from the system, when BMS detect something wrong and this situation just showed me how important it is to have one in place so I definitely will install one as soon as possible.

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Alexandra avatar image
Alexandra answered ·

@Mysik

Have you programmed the mppt and inverter to charge to the correct voltages?

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vassilis-bourdakis avatar image vassilis-bourdakis commented ·

you don't have to configure them at all. If DVCC is on, everything is catered for centrally.

HOWEVER, and in order to avoid such misshaps, it's a good idea to go to each device and configure it so that if venus comms for some odd reason dies/cable broken/whatever system will not overcharge/overdischarge.

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mysik avatar image mysik commented ·
Of course I did. That is why nothing bad happened, but in theory there is no need to program MPPT in my system, because it should follow the Multiplus, and it did in terms of voltages, unfortunately it failed to stop charging when Multiplus stopped.
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Alexandra avatar image Alexandra ♦ mysik commented ·
@Mysik

In theory you don't but you are then relying on comms only, if for any reason that fails then you will rely totally on fail safe built into the bms.

And when they are networked with a GX the GX becomes the controller of charge not the individual components. So you need DVCC on. It is explained in the manual.

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nickdb avatar image nickdb ♦♦ mysik commented ·

@Mysik it has been said multiple times - DVCC must be on to control the mppt's charge, but make sure the correct settings are applied manually so that it behaves when the GX is not available.

https://www.victronenergy.com/media/pg/CCGX/en/dvcc---distributed-voltage-and-current-control.html

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