VE Hex interruption when not connected via app

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hour asked Mar 5, '21

VE Hex interruption when not connected via app

BMV: v4.05
Smart bluetooth interface: v2.23

SmartSolar 75/15: v1.54
SmartSolar Bluetooth Interface: v2.25

(Firmware versions on equipment, which are indicated as the latest)

I'm using the hex protocol to ask the SmartSolar for some typical values: battery voltage, charge current, and panel voltage. This seems to work fine.

I decided to add in temperature using "7ECED0075" yesterday which from the docs states it will provide the BMV temperature - which is acquired over VE Smart networking. My MPPT is indeed connected to the BMV smart network and receiving voltage and temperature information.

This temperature request works and reliably returns something like "297150" = 297.15 kelvin = 75*F which matches what I see on the BMV and SmartSolar through the app.

However, when I disconnect from the MPPT via the Victron app on my phone, the temperature request begins to return bogus values such as "655300" and it never resolves itself. If I open the app back up and connect to the MPPT, the temperature response returns to a valid number like "297150"

Any clue why this is? Hex protocol can be used on devices that are apart of a VE.Smart network without conflict, right?

communication protocol

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Answer 1 · 2021-03-07T05:17:09Z

hour answered · Mar 07, 2021 at 05:17 AM

Upon further testing it appears that the value returned is valid if I am either

a) connected to the MPPT (not BMV) via the Victron app

or b) the MPPT is charging.

I suppose that makes sense as the concern for temperature on the MPPT side relates to charging, and if no charging is going on it's irrelevant. It's a slight bummer for my project but I still have temperature readings from my BMS. Ah well.

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Answer 2 · 2021-03-10T08:55:31Z

Thiemo van Engelen (Victron Energy staff) answered · Mar 10, 2021 at 08:55 AM

Hi,

I can indeed confirm that the reception of VE.Smart networking is data is disabled when the MPPT is not charging. The reason is that the reception of the temperature does take a non-negligible amount of power, unnecessarily draining the battery.

The reception of data is however always enabled when a BLE connection is established, to be able to provide the list of devices that are actually seen by the SmartSolar/BLE dongle. This explains why the temperature is available when VictronConnect is connected with the MPPT.

As a side note: The value returned by the MPPT when the temperature is not available is 0xFFFF (=65535). In general, this value is used for 2 byte unsigned values when the value is not available/known. And for 2 byte signed values, the invalid/unknown value is 0x7FFF.

Kind regards,

Thiemo van Engelen

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