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VE.Bus Smart dongle Temperature?


Ingo
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I decided to add a VE.Bus Smart dongle to my Multi and suddenly my charge voltage just dropped. If I disconnect it it restores to normal. Any idea why this would happen?

*I do have an existing wired sensor connected to the battery.

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Ok, so for anyone finding this post and have similar concerns. I did some tests and the VE.Bus Smart Dongle overrides both Quattro connected as well as GX connected temperature sensors. While the GX sensor was connected I held the Smart dongle in my hand to increase the temperature and the charge voltage started to drop even though it's confirmed by VictronConnect to be in 'Secondary Mode'.

The documentation states that it should be the other way around, all other sensors should override the Smart dongle data. I've now removed this device from my system.

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On 2020/09/13 at 9:42 AM, Ingo said:

Ok, so for anyone finding this post and have similar concerns. I did some tests and the VE.Bus Smart Dongle overrides both Quattro connected as well as GX connected temperature sensors. While the GX sensor was connected I held the Smart dongle in my hand to increase the temperature and the charge voltage started to drop

out of interest and possible completeness for anyone with a more useful contribution that stumbles on this, @Ingo is your system:

ESS consisting of Quattro + Venus GX + Battery + 1 wired temp sensor connected to Quattro + 1 wired temp sensor connected to Venus GX and then also try to add VE.Bus dongle ?

Is this on a (Bluenova?) LiFePO4 battery with comms? If so, why the two external temp sensors even before the VE.Bus dongle is added - does the BMS not provide voltage and temp info to the Venus GX? I am curious about the potential role and conflicts of an ESS system with BMS provided voltage+temp info and TWO extra external wired temp sensors (Quattro and Venus)  and now a potential third voltage+temp source (VE.Bus dongle). Something in the victron manuals leave me with a hunch that a single source of both voltage and temperature (like the dongle) could be bumped up the pecking order over a source that only provides one or the other. Even then, should this override BMS info?

Any other assistants running? @plonkster IF the BMS provides voltage+temp info, I would assume no external temp sensor should influence charge voltage?

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Nope, here is the setup:

No ESS, Quattro + Venus GX + Lead-Acid Battery + 1 wired temp sensor connected to Quattro + 1 wired temp sensor connected to Venus GX and then also try to add VE.Bus dongle. Dongle added with either Quattro Temps sensor alone or Venus Temps sensor alone, the VE.Bus dongle overrides either/both.

Document states any other Temp source has priority and then lists "EG. CANbus" only but my gripe is with the first part stating 'any other source' has priority. I think the person that developed the Smart Dongle code only considered CANbus to be a priority instead of all other sources as well. Possibly small oversight but impact is that I can't use the device at all.

No assistants running as my long-standing ACOut2 Relay Assistant that doesn't work on 'micro grid breaks' no one wants to acknowledge and or even look at - my peeve with a certain company's Support process (sorry).

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1 hour ago, introverter said:

F the BMS provides voltage+temp info, I would assume no external temp sensor should influence charge voltage?

When the BMS provides a charge voltage, the Multi assumes the BMS has already done any temperature compensation and will not add anything extra to it. In other words, for most people with managed batteries (ie with CAN-bus connection), no need to bother with temperature. The battery already handles that.

Mmmh found the post...

https://community.victronenergy.com/questions/61583/vebus-smart-bluetooth-temperature-overrides-venus.html

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Your temperature sensor selection is set to "default". A decision was made not to be too "smart" about auto-selecting one, because people do really weird things. They put a sensor in their freezer on their boat, forget to configure it properly, and next thing we're overcharging the batteries because it's -15°C. So the only sensor (that is not connected to the Multi) that will be used automatically is a temperature sensor connected to the battery, in other words, a BMV-702/712. All others must be explicitly selected.

So just select the temperature sensor under System Setup.

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2 minutes ago, Ingo said:

DVCC is Off.

Aaaah... that has to be on, or it won't work. With a lead acid bank that's not going to cause anything unwanted.

Also, turn off SVS, SCS, but turn on STS (shared temperature sense). And then select the sensor. Which I have done already for you.

The extremely long text for the temperature sensor... that is fixed in Venus 2.60.

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1 minute ago, plonkster said:

Aaaah... that has to be on, or it won't work. With a lead acid bank that's not going to cause anything unwanted.

Also, turn off SVS, SCS, but turn on STS (shared temperature sense). And then select the sensor. Which I have done already for you.

The extremely long text for the temperature sensor... that is fixed in Venus 2.60.

Thanks. I try to be n-1 with firmware, or until enough time has passed for me to see the open issues won't affect me. And Yes, that is the correct temperature, I will now go and plug the dongle back in and warm it up a bit to test but I am sure it will work.

A note perhaps: Maybe the documentation could be a bit clearer when it comes to this dongle and other sources not being from a BMS.

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And here we go... dropping dropping and more dropping after the VE.Bus dongle is plugged back in. Temperature on the dongle is 28 degrees with the actual temperature being 20 degrees. See the drop reported by VRM portal.

image.thumb.png.027a441c41bf582d79d44d4fa2a4b8e2.png

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Excellent! The temperature reported on VRM, and on the VenusGX remote console for the Multi, is now the correct value and the voltage has gone up to +- the value before you enabled DVCC.

Is the configured temperature correction value in the Multi, for the charger, still used or is it a different internal value from the GX device?

 

Edited by Ingo
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2 hours ago, Ingo said:

Is the configured temperature correction value in the Multi, for the charger, still used or is it a different internal value from the GX device?

The temperature sent from the GX device merely overrides the temperature reading from the Multi. The voltage compensation adjustment is still done by the Multi.

In an ESS system (not sure if you run that, probably not), the compensated charge voltage from the Multi will then be sent to the MPPTs as well (in other words, the Multi is in complete control). In a non-ESS system (aka off-grid), the temperature is sent to the solar chargers and the Multi, and each one does its own compensation depending on the coefficient it has configured (so you probably want to make them the same). But I don't see an MPPT at your site either.

Edited by plonkster
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