Electron circuitry to charge Lipo battery

I am wondering how the Electron prevents the battery from getting too much charge.
I will install an electron-based device inside the HVAC units at building roof so my concern is related to the fact that the battery doesn’t catch fire.
Thank you for some inside on this.

The Electron has a bq24195 PMIC which handles the charging and will prevent over-charging the battery.

However, for rooftop applications, you have to be a bit careful about temperature. The LiPo battery has a charging temperature range of 0°C to 45°C.

The Electron does not expose the charge thermistor connection, so you’d have to manually disable charging in your user firmware if you expect the temperature of the battery to exceed that range.

The operating range of the battery is -20°C to +60°C.

Thanks for your answer. The enclosure will be installed inside the air return compartment of the HVAC unit with an exterior antenna. In there the temperature is always around 73 +/- 3 or 4 F deg.
But, what consideration should I take if I would like to replace the lipo battery with Nickel Cadmio type. I am planning to supply the Vin pin 5V@1A and let the battery supplies the peak current for the modem.

You should not place a LiPo or any other type of battery in the air return, or plenum, of an HVAC system. I believe that is against building code in just about every 1st-world country. Just imagine if a battery ruptured or off-gassed… You would be breathing those toxic fumes without warning and with an effective delivery system. This is why they make special plenum-rated Ethernet cable. The outer jacket of that cable is made to not give off toxic gasses when exposed to heat or flame.


Yes, you are completely right. Thank you.

@ninjatill Do you have some background on HVAC ?

I work for an HVAC wholesale distributor in Western PA, USA. I am the Director of Operations, formerly the IT Manager. While I am not an HVAC expert, I have some very knowledgeable Mechanical Engineers in the building that I can ping with questions.


So we are in the same page. I forgot completely the danger of put the enclosure on the return side because the battery.
The point is that if de device I am planing to do lost power because the HVAC unit stop working because power issue, I want to be able to send at list some text message or email to announce that.
On the other hand I think I have two more alternatives :
A- Install the enclosure in the coil condenser compartment where the compressor is, but the temperature can be little bit higher that outside temperature when the condenser fan motor is not operating.
B- Install the whole thing outside the HVAC enclosure over one of the lateral sides.
Also, I know that Tadiran have batteries that keeping low charge current let you run at up to 85 deg Celsius., but I need to dig more deeply on spec and about Electron be able or not to charge that type of batteries.
Just sharing some thoughts with you.

A workaround that I use is to perform scheduled Publishes in addition to Event Based Publishes. For instance, if you have a minimum schedule of 10 minute check-in’s, your backend will notice when your latest update is older than 10 minutes and start the appropriate Alert routine. This also catches those times when a publish doesn’t make it to your backend/database, no matter what the reason was (cloud issues, webhook fail, etc). The first missed check-in isn’t too critical, but successive missed events become increasingly important and the Alerts/Alarms can reflect this.

This may help with your decision to not use a battery, if you go that route.

@ninjatill Yes sir, it’s a good and encouraging idea.

There is a saying that says what saves the wisdom man kills the ignorant
Thank you again.