question

Pierre-Andre avatar image
Pierre-Andre asked

Can Venus GX sense voltage and temperature by itself?

Can the Venus GX be setup to sense voltage and temperature by itself, without a BMV or a MultiPlus? I would like to send temperature and voltage to two BlueSolar 100/30 without leaving the MultiPlus on when I don't need it. The MultiPlus will still consume 8W in search mode and the system is on a boat where energy is precious!

I wasn't able to find a definite answer anywhere! Thanks for your help.

MPPT ControllersVenus GX - VGXvoltageTemperature SensorDVCC
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6 Answers
JohnC avatar image
JohnC answered ·

Hi. The Bluesolars have an internal temp sensor and of course V is what they do. Shut the rest down, and they'll still work fine. Providing you're happy with the temp correlation with the batts. Usually not an issue for most people.

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Pierre-Andre avatar image
Pierre-Andre answered ·

The batteries are in a boat and a compartment that it is not as well ventilated as it should. I want proper temperature compensation and voltage sense.

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regardless of temperature/voltage, lead acid batteries give off explosive/corrosive gases so probably need to put in good ventilation anyway

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Mark avatar image
Mark answered ·

Hi Andre,

As far as I'm aware, currently the Multiplus can NOT share temperature data to other connected devices (such as MPPT controllers) via DVCC anyway (apart from running in full ESS mode where the MPPT is a slave).

Currently the only source for DVCC 'shared temperature sense' is limited to a BMV 702/712 & this feature was added in Venus v2.20.

Accordingly I beleive that the answer is 'NO', currently you can't use a temperature sensor connected directly to your Venus GX (to share temperature data with the MPPT's)

However, the ability to select 'other' available sources for 'shared temperature sense' is currently in progress & seems to be almost complete - Github ticket link below;

https://github.com/victronenergy/venus/issues/374


So as an alternative, you may want to consider adding a 'smart battery sense' device to your setup & link it to both your MPPT's via Bluetooth (this will work with a Venus device as long as you don't enable DVCC).

https://www.victronenergy.com/live/smart_battery_sense_manual

If your MPPT's are not the 'SmartSolar' versions (with inbuilt Bluetooth) then you will also need a Bluetooth dongle for each. But if you also want to connect them to your Venus GX (via VE Direct) then you can't do both simultaneously, so this proposal may not be an option (unless you upgrade to 'SmartSolar' MPPT's)...

Lastly, the 'internal' sensor in the MPPT only measures the temperature in the morning before startup & does NOT constantly monitor temperature & adjust/correct the voltage set point during the day as the ambient temperature rises & things warm up (which is NOT ideal).

I assume that this is because the MPPT would warm up when operating, so the internal temperature reading would no longer be a good representation of the ambient air temperature, let alone battery temperature.

Refer to extract attached below;



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3 comments
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My understanding is that Shared Temperature Sense from other sources including the Multi will be in Venus OS 2.30. Can someone confirm?

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Yes I can confirm that.

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Stefanie avatar image Stefanie ♦♦ mvader (Victron Energy) ♦♦ ·

When connecting my Multi (12V 1600) to the Pi with 2.30~43 and firmware 2606459, I had temperature coming from the Multi visible in Venus GUI. Had to downgrade firmware to 2606159 due to possible problem with the Multi Compact and now I can't get Venus to display temperature again. It's showing two dashes.

System has a BMV set as battery monitor without temperature sensor. What I'm missing or how to get it showing temperature again?

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Paul B avatar image
Paul B answered ·

buy a bluetooth dongle for the Blue Solar MPPT reg P/N ASS030536011

and a Smart Battery Sense P/N SB050100200


You also then can monitor the Solar input on your phone using victron connect and cofigure both units


this will then allow full battery and tempature sensing for the MPPT regulator,

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If I add a Bluetooth dongle, I won’t be able to connect the BlueSolar to the Venus GX.

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Pierre-Andre avatar image
Pierre-Andre answered ·

What about voltage sensing? Is there a way for the Venus GX to sense voltage by itself, without using a BMV or Multi, and then share it via DVCC?

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Based on the related info, I believe so;

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1552553310544.png (22.1 KiB)

Thanks Mark. But the way that I interpret this, is if there is a source of voltage measurement on the VE.Bus, then it will select the best and share it. What it does say, at least explicitely, is that if there are no sources of voltage on the VE.Bus, the Venus GX will use it's own voltage measurement.

Can anybody shed some light?

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Don't you already have one - why don't you just give it a go?

If there is nothing else / better connected then I expect it to use its own voltage.

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> What about voltage sensing? Is there a way for the Venus GX to sense voltage by itself, without using a BMV or Multi, and then share it via DVCC?


No unfortunately. the Venus GX doesn’t measure battery voltage itself.

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Mark avatar image Mark ♦♦ mvader (Victron Energy) ♦♦ ·

When the is no BMV or other similar device connected, doesn't a ÇCGX or Venus device simply report a voltage reading based on the voltage from it's own power input?

I'm not saying that it's accurate but I thought that that was the behavior.

I think that I recall reading this somewhere, but now you have me thinking & wanting to check for myself.

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No, sorry. I’m really 100% sure that it does not do so.

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Mark avatar image Mark ♦♦ mvader (Victron Energy) ♦♦ ·

Even if it does, I suppose it is a separate question/point regarding if it will be shared via SVS.

But I also understand that a Multi is part of this particular system & the VE bus voltage can be used as the SVS source if desired.

Based on the simple test that I run the other day with my own Multi - this VE bus voltage should still be transmitted even with the multi in 'charger only' mode (with no AC in connected). And based on my 24/3000 Multi, the power draw was only 3W in this mode (vs well over 20w fully on).

An option to consider & possibly try.

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mvader (Victron Energy) avatar image
mvader (Victron Energy) answered ·

Hi @Pierre-Andre

So to summarize and confirm all thats been said here:

Option 1) to have both voltage and temp-sense, and because you have a BlueSolar Charger, either add a bluetooth dongle and smart battery sense; but then you indeed loose your VE.Direct Port.

Option 2) With a (only) a Venus GX you can (only) get temperature sensing. It doesnt measure battery voltage. Using its temperature measurement does require v2.30 which is not released yet; and you’ll need the temperature sensor accessory.

Option 3) get a BMV. Connect it to the Venus Gx; enable DVCC, Shared temperature and Shared Voltage Sense.


By the way; we’re soon coming with a firmware update for the Blue- and Smart- Solar Chargers that lets you configure the voltage drop/cable resistance.


So with that in mind you could consider to have just the real temperature sense; and let this feature take care of voltage drop for you.

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That sounds like a very nice upcoming feature & even though it's calculation based should work well!

My only small concern is the potential for users to enter in an unrepresentative resistance for the cable / fuse / connection losses & end up with more confusion.

Anyway the value should be able to be fine tuned with reference to a physically measured voltage at the battery while under load. Maybe this 'test' should be part of the setup instructions.

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Yes indeed. Thats the problem with this feature; as well as all of these advanced features.

The defaults are quite conservative; so that should be allright. VictronConnect is where we need to fix the warnings / test setup and so forth.

btw. it auto-disables it selves when it sees Voltage-sense data coming from somewhere.

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Mark avatar image Mark ♦♦ mvader (Victron Energy) ♦♦ ·

Nice!

Maybe the setup solution is to have all these more 'advanced' & potentially 'risky' configuration parameters all grouped together in a separate area/menu with a single pop-up warning that appears when you enter the area/menu - the popup should highlight the risks of misconfiguration & ask the user/installer to "accept' responsibility?

That arrangment could prevent/minimise the need for several separate warnings.

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Thanks to all. This is all very good information. I don't yet have the MultiPlus so that's why I can't test myself. But the option of leaving the MultiPlus in charger only mode is interesting though that 3W is still 5% of my solar production and is also what the Venus GX is drawing.

Maybe the best is to wait for the firmware update and configure the resistance. For battery temps use the temperature from the Venus...

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Is BMV obligatory to enable DVCC?

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Hi @mvader (Victron Energy Staff),

How can you use shared temperature measurement in v 2.30 Venus OS? I can't find such information in the release notes. Should you connect a temperature sensor to any Venus' input and configure it as a battery temperature sensor and both Smart Solar and Multi will read this temperature? Can I move the Multi's temperature sensor to the Venus?

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How can can Smart Solar MPPT can use Venus' measured battery temperature? Is it enough to configure in OS 2.30 temperature sensor as a battery one? Should I change something in Smart Solar's OS?

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