[DONE/SOLVED] Possibility to record small power consumption ?
Posted: Wednesday 31 August 2022 10:30
Hi,
I'm measuring power with my CurrentCost clamps (one Watt measure every 6 seconds).
I'm using the Dummy hardware with "Electric (instant + counter)", and counter is computed.
With small power (even some tens of Watts), the result in counter is either false (0) or inacurate.
In SQLHelper.cpp, I see this calculation :
float energyDuringInterval = static_cast<float>(powerDuringInterval * intervalSeconds / 3600);
float energyAfterInterval = static_cast<float>(energyUpToInterval + energyDuringInterval);
(for testing purpose, we start at 0, energyUpToInterval = 0)
So, for 20W and 6s : 20*6/3600 = 0.033Wh and for 30W : 30*6/3600 = 0.050Wh
Later, we can see :
sprintf(sValueUpdate, "%s;%.1f", powerUpdate, energyAfterInterval);
Ha ! So, if energyAfterInterval < 0.050, the %.1f brings us back to 0.
The value stored in the dB should be more precise, at least %.3f to avoid such problems.
In the database, sValue is a string (100 char if I recall correctly), so it shouldn't be a problem.
I've compiled Domoticz with this only change, and it perfectly works.
Thanks !
I'm measuring power with my CurrentCost clamps (one Watt measure every 6 seconds).
I'm using the Dummy hardware with "Electric (instant + counter)", and counter is computed.
With small power (even some tens of Watts), the result in counter is either false (0) or inacurate.
In SQLHelper.cpp, I see this calculation :
float energyDuringInterval = static_cast<float>(powerDuringInterval * intervalSeconds / 3600);
float energyAfterInterval = static_cast<float>(energyUpToInterval + energyDuringInterval);
(for testing purpose, we start at 0, energyUpToInterval = 0)
So, for 20W and 6s : 20*6/3600 = 0.033Wh and for 30W : 30*6/3600 = 0.050Wh
Later, we can see :
sprintf(sValueUpdate, "%s;%.1f", powerUpdate, energyAfterInterval);
Ha ! So, if energyAfterInterval < 0.050, the %.1f brings us back to 0.
The value stored in the dB should be more precise, at least %.3f to avoid such problems.
In the database, sValue is a string (100 char if I recall correctly), so it shouldn't be a problem.
I've compiled Domoticz with this only change, and it perfectly works.
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