Which should be designed as a low-energy setup where the electron by default is in sleep-mode and will only momentarily wake up and send a message when it’s moved. However, after leaving the sensor unplugged from the USB overnight, I noticed the battery charge already had dropped from 86 to 83%. Is this an indication that something is going wrong here and it drains very rapidly, or is it an inaccurate measurement (Electron and all its components are just a week old)?
I’d like to have the electron be able to run for months, possibly years by consuming as little energy as possible, so this is an important thing to know for me.
In case anyone wonders, I’m pretty sure this is more like a reliability issue. Even when not using a battery at all, and just using the USB cable, the values would still go down from 92 to 83 in a matter of hours with a sleeping electron.
The SOC reading will fluctuate and it’s based on the battery voltage only.
So once the battery is fully charged the charge management chip stops charging the battery and then the battery voltage will dip back down even if you’re running off USB power and as the battery voltage dips the SOC reading will go with it.
The max SOC reading you will see when the battery is done charging will range from 90-85% usually, this was done on purpose by Particle to keep people from charging the batteries to higher voltages in hot conditions.
You can scale the SOC reading to 0-100% if the 85% SOC when full bothers you.
If you are using the asset tracker add-on and the motion sensor then the motion sensor and some other chips are probably constantly pulling power while sitting idle waiting for a movement happen to trigger a message to you or whatever your doing.
The only thing I’m using right now is the ADXL362 accelerometer which should draw very little power. Since the voltage in this case dipped so much for me, does that really mean the battery is running empty that quickly? I’m looking to have my sensor out in the field for months, perhaps more than a year and ideally I don’t really want to go out there to replace/recharge the battery every time.
Based on my experience with the ADXL362 and the Photon, I’m not sure you’ll get a year. With the Photon in stop sleep mode (pin+time) and walking 6-8 times per day, I got about 4 weeks. If you’re using SLEEP_MODE_DEEP you’ll use less idle power so you might go longer, as long as you don’t wake up too frequently, as connecting to cellular takes way more power than connecting to Wi-Fi. You should also make sure you’re actually going into deep sleep mode properly. This is trickier than you’d think.
i am using the asset tracker for an application that is mostly off but the sleep/deep sleep current is pretty high compared to what i am used to. what i have done is use a TPL5110 device for duty cycling the whole system. this allows me to totally cut off power to the asset tracker until the timer powers it up. The timer uses nano amps when the asset tracker is off. the cool part is the timer is designed so that when the microcontroller pulls down the disable line (after it has finished its mission) the timer shuts off the power to the asset tracker. You can test this easily by using a small break out board from Adafruit, here is the link