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Jesse avatar image
Jesse asked

Multiplus not receiving Volt and Temp data from VE.Bus smart dongle

Its a new setup still in testing phase on the benchtop. Very simple.

1x 12/1600/70 Multiplus (new style compact)

1x VE.Bus Smart dongle

1x VE.Bus MK3 USB interface

some old AGM batteries which still work, barely.

Initially everything worked perfectly - when signing into victron connect on my laptop it was clear that the multiplus received the temperature and on battery voltage as measured by the Smart Dongle. Absorption charging was getting up to 14.6V as expected for my unheated office. When the MK3-USB is disconnected using the Smart Dongle confirms a temp of 15 degrees celcius and normal operation of the multi. I can switch the multi on and off using bluetooth as expected.

Then today the Smart Dongle stopped talking to the Multiplus! There's been a couple of brief moments where it's worked, but mostly not. Smart dongle still working otherwise - smartphone bluetooth page shows normal functioning, blue light flashing as before, but none of its data is getting to the multiplus. Ethernet cables have been swapped repeatedly to no avail. To be clear I'm not using the multi's own temperature sensor at all. Thus on its own the multi has no clue what battery temps or voltages are and charging reflects this - battery absorbs at about 14.3V at high current which increases to 14.4V at low currents.

I've tried resetting settings on the multi, the only assistant I had was a simple one to disable the fan if I shorted the multi's temperature inputs, removing that made no difference.

MultiPlus Quattro Inverter ChargerVE.Bus Smart Dongle
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Jesse avatar image Jesse commented ·

Sometimes on startup the temp appears briefly but then disappears!

It absorbs so precisely at 14.4V, now, but for the previous few days it would ride up around 14.6V as expected if temp compensation was working.

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Jesse avatar image Jesse commented ·

Actually a couple of times now I've noticed the battery's absorption voltage (as measured with a multimeter) dropping from about 14.55V to precisely 14.4V within 30 seconds of me connecting the MK3-USB to my laptop.

Could it be some sort of priority thing that the Smart Dongle is getting disabled by the MK3-USB becoming active on the Ve.Bus? How would this make any sense?

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4 Answers
Jesse avatar image
Jesse answered ·

Think I can answer my own question.

After multiple tests at both absorption and float it seems the MK3-USB device, on being queried by the software on the laptop (so connecting with VEConfig, or refreshing device list in VictronConnect) causes the VE.Bus Smart Dongle to be disabled and the multiplus to ignore voltage and temperature data from it.

This is annoying - I had planned to play around with Venus on Raspberry Pi but that would be impossible if I wanted to still use the data from the smart dongle?

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Dosheimer avatar image Dosheimer commented ·

I think I have the same problem: I need the MK3 between multi and Raspi (running Venus OS) to get the data from the multi into VRM. In this setting the voltage measured from the Smart Dongle (directly at the battery) connected to the multi seems to be ignored, what is not favorable.

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Alexandra avatar image
Alexandra answered ·

The smart dongle will give way to the bigger boys for monitoring and system interaction options,as it is a very basic device in this regard.

@Jesse @Dosheimer @Darius3 @securitasepay


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darius3 answered ·

The MultiPlus switches to inverter operation when no AC source is available.VE.Bus Smart Dongle. Measures battery voltage and temperature and allows.


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Dosheimer avatar image Dosheimer commented ·

I had the situation last weekend when doing a stress test with a multiplus 12/3000/120-50.

Because of a voltage drop in the connection between the multi and a 330Ah Smart Lithium the multi made an automatic under voltage shudown at high amps consumption (>3000W) in my setting. Measured the voltage during this shutdown event directly at the lithium battery there was no voltage drop at all as expected. Because the multi was connected to a VE.Bus Smart Dongle and the Smart dongle with the battery, it shows that the multi ignored the voltage from the VE.bus smart dongle and took the voltage from the 12V input of the multi instead.

I have everything on the latest firmware versions.
As said in my comment before I have a MK3 connected to the multi in addition to the VE.Bus Smart Dongle (MK3 USB connected to a Raspi 4 B 1.2 running Venus OS 2.80-16-large21)

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Alexandra avatar image Alexandra ♦ Dosheimer commented ·
@Dosheimer

So you need to use bigger cable then.

Regardless of what your actual battery voltage is, the voltage at the terminals is what the multi uses in its conversion, there can be damage to power packs and the like with more amps drawn through to maintain the loads. Basically the inverter must try protect itself.

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securitasepay avatar image
securitasepay answered ·

When no Multi is connected VictronConnect will list the 'VE.Bus Smart Dongle' in the device list. In this case the dongle can be used as a Voltage/Temperature sensor. It takes a bit of time before a Multi is detected. When the dongle detects a Multi, VictonConnect will identify the Multi in the Device list.

securitasepay

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