EmonTH + Optical Sensor in meter box

I’d like to use the optical sensor on my meter which is located in a meter box outside. Rather than run a 8+ Metre cable I was thinking of getting an emonTH and locating it in the meter box. This gives me the advantage of having an outside temperature sensor ( albeit slightly isolated inside the meter box ), outside humidity sensor and a very short cable to the optical sensor.

So my questions -

  1. Is there any issue with placing the emonTH outside the house ( albeit inside a weather protected meter box )?

  2. I’ve seen battery consumption data relating to the emonTH but I’ve not seen anything relating to the emonTH with an optical sensor. At high usage, the meter LED could be flashing quite regularly ( meter states 1000 impulses per KW ). Does the emonTH buffer flashes for periodic updates or is it real time? Anyone know what the effect on the emonTH battery life is?

  3. Does the emonTH monitor the battery and alert a low battery state to the App?


Welcome Peter.

There shouldn’t be, although it doesn’t have any specific environmental protection on the pcb. But I would apply a smear of silicone grease to the battery contacts and the pins of the sensor in the hope that it will slow down any possible corrosion. That was reported as a problem a little while ago, No longer receiving inputs from RFM12B - #15 by Francis_Donnelly.

If I’m reading the code correctly, it counts and updates the count as per its normal update rate (approximately every minute), or after 100 pulses, whichever comes first.

I don’t, but although the pulse sensor allegedly has a very low quiescent power drain, its use will reduce the battery life somewhat.

The battery voltage is sent along with the rest of the data.

Thank you, that’s very helpful.

I do have some conformal coating spray so a quick application of that before installation would probably be beneficial as well as the grease.

I should have looked at the code myself. It just didn’t occur to me!

The boost device in the emonTH will allow me to use rechargeable batteries. So two sets of low self discharge NiMh should make battery consumption a non issue.

Thanks again.