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mrhappy asked

Disable charger Multiplus-II, but it turns on and off by itself.

Quick one, I have disabled charging on my Multiplus-II 24/3000/70 by using the "charge current control" assistant and closing AUX2. The strange thing is that intermittently the multi goes into charging mode for half a second and then back to passthru. No relays are clicking or anything. It creates the following graph in VRM:

screenshot-2021-10-04-023445.png

A bit annoying, why is this?

Multiplus-IIbattery chargingAssistantsaux
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Removed the assistant altogether after not getting anywhere. I can change charge current limit via modbus instead, but set at 0 it still goes to charge mode. @mvader (Victron Energy), In the modbus register list, there is a note about "-1 Disables" (#2705), but that address do not accept the -1 value from node-red. The return is:

"RangeError: The value of "value" is out of range. It must be >= 0 and <= 65535. Received -1"

The register list describes the range for #2705 as "-32768 to 32767".

Is it something possible to fix in an upcoming release of VenusOS or would it require changes in firmware in the MultiplusII?

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Alexandra answered ·

@MrHappy

Is it also possible that it is also just reporting battery state?

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Every time it happens, the absorption light goes on, and the unit starts humming for just a brief half-second, so it is actually starting up the charging circuitry inside before switching over to passthru again.

Battery state is, in my system, reported by my BMV712.

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Maybe the aux relay is not receiving the signal it is programmed to respond to during those times. That would be where I would start checking against the settings you have used.

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That is my first point to check when I get the time. The aux input is used as a switch per instructions in VE.Direct. It is operated with a physical switch as well as a relay. I will test to close it with a short bit of wire to see if it's the cable length to the switch and relay that can be the problem.
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