question

sebcbien avatar image
sebcbien asked

Why is the CanBus Battery T° is not available in the parameters to control temperature relays on the GX device?

I'm using a Multiplus II/Cerbo GX to charge my LiFePo4 Pylontech battery with solar panels.

The relays on the GX device can now be controlled by temperature, for example to switch a fan, or heating pad.

That's really great and saves me from installing the Venus Large image with NodeRed !


BUT (yes, sorry ;-) )


The CanBus reported Battery t° is not available in the parameters to control the relay.


Here is the scenarios where it can be VERY usefull (for me at least):

- An external t° sensor does not give the same t° as an inside battery t° sensor (due to the great inertia of a battery) I measured as much as 7° between the external case of my battery and the Internal t°. The outside shell heat up way quicker than the internal cells of the battery.

- The CanBus batteries are connected with the CanBus to the controller (My CerboGX/Multiplus II)

- If I want to and another external "dumb" charge source like an alternator charge who has no access to the CanBus, I would like to be able to disable the charge trough the relay controlled by the CanBus INTERNAL temperature of the battery to prevent high current charging when the battery is in the freezing range.

Is it possible, did I miss something ?

If not, can it be added in a future release ?

Thanks a lot for the good work ! :-)

Seb


Edit: below you can see that the internal battery t° sensor cools down and heat up way slower than an external battery t° sensor.

1646997773269.png

Battery Temperature Sensor [512] : Internal CanBus sensor

Temperature - T* Batterie [26] : Victron external sensor glued to the battery case (with offset -1°)

Temperature - T* Inside [25] : T° of the room where the batteries are stored (Van)

Temperature - T* Outside [24] : T° outside... ;-)

Multiplus-IIcerbo gxLithium BatteryPylontechTemperature Sensor
1646997773269.png (117.5 KiB)
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2 Answers
Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

If it is not shown then the Cerbo is not receiving that information.

What battery do you have exactly? An older version of the US2000/US3000 maybe doesn't transfer the temperature information.

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sebcbien avatar image
sebcbien answered ·

Hi Matthias,

Thank you very much for trying to help me (again ;-) )

I have an 2 year old US3000 3.5kW.

The Cerbo GX is receiving the temperature information, please look at the screenshot of the original post, the top left graph is the CanBus internal battery T° trace.

Here are two more screenshots, in the T° conditions for the relays, only the T° of the CerboGX probes appears:

1647337798794.png

The internal T° displayed in the battery settings page:

1647337817936.png

Are you sure that the Relay conditions accepts the internal T° of the Pylontech ?

I use firmware 2.84



1647337798794.png (68.8 KiB)
1647337817936.png (66.4 KiB)
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