While logged into TRMNL you can see WiFi + battery strength from your device picker or all devices view:
Calculating remaining battery power is a simple equation, but it becomes less reliable as energy is drained and playlist refresh rates change.
Low battery notification
When your TRMNL device has < 10% energy remaining, you'll be notified by the following screen on your display:
In the future you may be able to customize this screen. ;)
Charging your TRMNL
Select your device...
OG
OG
The OG model has 2 battery options, 1800mAh (default) and 2500mAh (upgraded).
Assuming 0% energy:
1800mAh - 3.5 hours to full charge
2500mAh - 5 hours to full charge
While charging, an LED on your device (above the USB-C port) will be green. When the device finishes charging, the LED will turn off.
Model X
Model X
The X model has 2 battery options, 6000mAh (default) and 12000mAh (upgraded).
Assuming 0% energy:
6000mAh - 5 hours to full charge
12000mAh - 10 hours to full charge
While charging, a "now charging" indicator will appear in the web interface.
Percent charged versus voltage
Select your device...
OG
OG
The X% charge value in your TRMNL account is approximated as follows:
def percent_charged
self.battery_voltage ||= 100
pct_charged = ((battery_voltage - 3) / 0.012).round(2)
case pct_charged
when 88..1000000 # 4.08v follows a full charge
100.0
when 85..88
95.0
when 83..85
90.0
when 10..83
pct_charged.round(2)
when -1000000..10
1.0
end
end
If you instead prefer to know your device's last reported voltage, just hover the battery icon(s) for a read out:
Model X
Model X
The Model X has a "gas gauge" chip built into the device, which reports charge levels down to 1/10th of 1%.
This value, e.g. "42.4" or "95.3," is reported to TRMNL's web app whenever your device wakes up to request new content.
Examine your precise battery charge amount by visiting your device's battery settings page: https://trmnl.com/devices/current/battery/edit
Understanding power consumption
One refresh cycle takes 32.8mA over a period of 24s. In this time the device will ping the TRMNL server, download an image, and refresh the display.
If there is no need to download and refresh the display with new image content -- for example if an image is not returned, or the returned image matches what is currently displayed -- power consumption will be around 20% of the above calculation.
For more comprehensive details on TRMNL device power consumption, see here:
Determining your battery type
TRMNL devices offer multiple battery size options. If you are not sure which one came in your device, or simply want to verify:
OG
OG
Disassemble your device (unless it is a clear case)
Compare your battery's shape and size to the photo below
For further confirmation, detach the battery (will require new tape) and look on the under side, which will show the mAh value
Top: 1800mAh
Bottom: 2500mAh
Model X
Model X
Your Model X has 1 or 2 batteries, both of the same size and shape and power (6000mAh).
If you have a clear enclosure, count them from looking through the back. Otherwise, you are welcome to disassemble your TRMNL with the included T6 screwdriver, or ask our support team to check the battery count being reported to our database by your device's firmware.