search

helgeerbe / OpenDTU-OnBattery

Software for ESP32 to talk to Hoymiles Inverters and Victrons MPPT battery chargers (Ve.Direct)
GNU General Public License v2.0
297 stars 63 forks source link

[Request] support for reading external temperature sensor DS18b20 #1238

Open pationair opened 3 weeks ago

pationair commented 3 weeks ago

Is your feature request related to a problem? Please describe.

Hello, is it possible to connect an external sensor for temperature monitoring?

The easiest would probably be a DS18B20.

Describe the solution you'd like

The idea would be to put this in the battery box to measure the temperature of the battery.

I would appreciate feedback.

Describe alternatives you've considered

I am currently using an Aqara Zigbee sensor

Additional context

No response

schlimmchen commented 2 weeks ago

What BMS are you using and why does it not provide temperature data?

pationair commented 2 weeks ago

Hello, I have a Power Queen 25.6V 100Ah battery, it has a BMS, but as far as I know I can't read it.

schlimmchen commented 2 weeks ago

I have to say that I don't like this idea, because at some point this will be considered a safety feature, which OpenDTU(-OnBattery) cannot provide, i.e., a request building on this temperature sensor support will be "stop discharging the battery for safety reasons if the temperature is too high". And also "stop charging the battery if the temperature is out of bounds". Then this temperature threshold shall be configurable, and then there should be a lower limit, too. And furthermore, some other dude wants to use a completely different temperature probe, and suddenly we support and maintain the code to support a dozen different temperature probes.

While I totally see that it is OpenDTU-OnBattery's job to interface with a BMS, I don't see why it is its job to interface a specific temperature probe.

For these reasons, I don't support this idea.

spcqike commented 2 weeks ago

@schlimmchen i'm with you, this request and the intention kinds of relates to #1198.

with #1198, we will be going to respect the BMS reported max (dis-)chargecurrent, which will decrease with temperature, i guess.

so, as we have an MQTT battery provider, we can just use the current topic there, if we dont have another BMS. so, to have the temperature reading inside openDTU-onBattery would be for displaying and convenience only, wouldn't it?

SW-Niko commented 19 hours ago

Hello @pationair , As an alternative solution you can maybe use the Victron "Smart Battery Shunt". The Victron MPPT can use this information to stop charging the battery at low temperature and with PR #1292 you can see the temperature in the web UI.