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david-p-1 avatar image
david-p-1 asked

temperature nonsensical values

Between 2022 12 20 05:45 and 2022 12 29 14:31 the reported temperature changed from a stable accurate value of about 10 degc with negligible spread to nonsense values ranging between -20:80 degc with huge spread(changing sample to sample) AND INCIDENCE of nan. it was a real effect with temperature faults reported. it the reverted to normal behaviour. ??? candidate is a bad firmware update with say a units mistake eg float rather than int? ideas

errortemperaturevrm firmware update
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klim8skeptic avatar image klim8skeptic ♦ commented ·
You forgot to mention what devices you have, and how they communicate with each other.
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5 Answers
david-p-1 avatar image
david-p-1 answered ·

Sorry, I'm new to this.

Canal boat system with cerbo interfaced to: -multiplus 3kw 12v multiplus via ve bus

-mppt 75/15 & 150/35 via ve direct

- bmv 700 via ve direct

-temperature sensor (ASS000001000) via temp1 analogue interface

Black water sensor via tank1 interface

-access to Internet via wifi

Note all firmware upto date except multiplus running v482

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klim8skeptic avatar image klim8skeptic ♦ commented ·

Have you used STS as per Cerbo manual. to share the temperature data between the devices?

Are you using Remote console to view the system? Or perhaps Victron Connect?

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david-p-1 avatar image david-p-1 klim8skeptic ♦ commented ·
Am using Sts which is why the mppts were raising errors on excessive temperatures.

Using remote consol to monitor.

Note disabled sts whilst bad measurements, now better re-enabled

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pwfarnell avatar image
pwfarnell answered ·

Loose connection or broken wire making intermittently higher resistance and affecting the measured voltage. Did this occur with the engine running. Another thought having a canal boat myself is condensation at this time of year if the contacts got damp causing a partial short.

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david-p-1 avatar image
david-p-1 answered ·

No engine running at all and boat on shore power.

Checked wiring and appears OK, when I disconnected manually sensor reported unconnected and not erroneously. Also with my ambient about 10degc lose connection or damp wouldn't explain both higher +80degc and lower -20 degc

I also don't understand correct consistent measurements before and after 9 day period with wild measurements inc nan values. The sensor provides an analogue voltage proportional to temp ------ I feel the long term randomness argues against lose connections and for firmware ???

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pwfarnell avatar image pwfarnell commented ·
You have same battery temperature set up as me on temp input 1, mine has been OK for more than 18 months with firmware from 2.5x to current 2.92. I know this does not help you.

Are there any other cables near the temp sensor wire that could cause interference. Clutching at straws.

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david-p-1 avatar image david-p-1 pwfarnell commented ·
Sadly no, also the boats basically in hibernation mode so no day to day changes. Grateful for straws ;)
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kevgermany avatar image
kevgermany answered ·

Not sure what you mean by nan values.

I'd suspect the sensor. Or wiring/corrosion, moisture. Unless you had a corrupt firmware update, this is a very unlikely cause and would probably have had more problems, like device not working..

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david-p-1 avatar image david-p-1 commented ·
NAN is a computing term meaning Not A Number. When you plug the temperature sensor into the cerbo it applies a voltage to it, current flows such that the voltage left and measured by the cerbo is proportional to absolute temperature 10mv/degk). The cerbo the converts it to a number in degc.

If the wire is broken it recognises this huge resistance as device unconnected an tells you. If it reports NAN it suggests it can't decode the value for f/w type reasons. (Sorry very long winded reply)


It's frustrating it's magically come good


Thx for your help




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kevgermany avatar image
kevgermany answered ·

Funny, I recently retired from a career in IT, we never used the mnemonic.

Anyway, I'd suspect wiring/corrosion/faulty component. The trouble with things like this is they come back, just when you think it's fixed.

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