Batteries ran totally flat and unit wouldn't switch back on.


This one is mostly on me as I accidentally left the unit unplugged, but once the batteries were flat the unit wouldn't switch on even when plugged in until I swapped the batteries.

A few suggestions though:

  • Can the CAD beep when it's unplugged / running low on battery?
  • Could the app notify me the CAD is running low on battery?
  • Could the app notify me when the CAD has been offline for sometime?
  • Could the CAD shutdown sooner, to reserve enough battery to function when plugged in?

Thanks !


  • edited May 2020

    The MQTT JSON contains RSSI and LQI and Status so it is easy to monitor connectivity. I have been monitoring RSSI and LQI

    (Node-red - InfluxDB -Grafana) to check the signal quality as I had a few dropouts.

  • Thanks ghayne, I hadn't paid attention to those!

    I'm guessing the RSSI is a signed integer in Hex? Mine is currently B5 which converts to -75, which seems about right.

    Can the lqi be used as is?

  • Yes, signed integer, took me a while that one : ) . I believe that LQI has a maximum of 255, I have a pretty constant RSSI -71 LQI 116 and have had no dropouts for 4 days. I am logging dropouts to a file just to check.

  • Just in case anyone stumbles across this in future, the LQI is a signed integer too. Initially I saw "60" and assumed it was as-is, but after some missing data in Grafana I realised it is in fact in the same format as the RSSI

  • Good to know marrold. And my MQTT feed just went down :(

  • Actually, I think that is incorrect, as the LQI values I have been converting are the same values as shown in the CAD display, I just checked!

  • The valuables I was getting as is seemed plausible at first but I spotted gaps in my data which turned out to contain a letter so couldn't be plotted on a graph. Since converting from a signed integer there's no more gaps and the number matches that on the CAD. Strange.

  • Good morning @marrold - sorry for the delay in responding to you. I can't answer any of the technical points you guys are making but shall document the requests you have made on our suggestions / requirements list. I would point out that the batteries aren't meant to be the main power supply for the unit - the specification for displays is that they provide a battery as a back-up power source for people on prepay who need to use the unit to make a top-up if their supply is cut off. We recommend using the mains power as your primary source - otherwise you need a lot of batteries.

    A previous iteration of the App used to have that alert - we will add your request to the App roadmap.

  • Hi Jane, Thanks for the response. Unplugging the CAD wasn't intentional on this occasion, it was unplugged by mistake to plug something else in and because there was no alert it ran flat over night.

    Thanks again!

  • Hi, just a heads up this issue re-occured, the CAD was disconnected from the power, ran down the batteries and then wouldn't start until the batteries were replaced.

    Has there been any progress on adding an alert to the app, or an email, if the CAD hasn't been seen for sometime? The app is aware it's disconnected, but doesn't do anything to make you aware unless you check the app.


  • Hi @marrold - could you please mail support@ when there is an issue, it is a struggle to stay on top of all the channels. So it sounds as though even when you put the power back on that you had to have batteries in from your phrasing? Is that correct?

    No progress on the adding of alerts - sorry but we've been very busy with commercial work and these 'nice to haves' have to fit in when there is time, and get prioritised. For example, supporting export is perhaps a more important priority. But the ask is on the App!

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