Buy Solo Battery Tool ($45)
I am currently out of displays, as always, all orders will be processed in ordered fashion once the displays arrive.
It’s very likely that all those who wait now will get it with firmware 1.2 , among other things , with Fahrenheit & Celsius temperature.
3DR Solo battery packs have lots of information that the average user will never see, they are also very nicely calibrated for voltage (cells and pack) & current measurement.
Some of the information, like capacity, cell voltages, cycles and manufacture date may be very useful.
Health data is very useful as well.
Below: two devices, one as delivered, the other with an XT60 connector for charging.
It’s easy to solder on XT60, charger cables, or other connectors right on the main connector.
The device is not doing any calculations on it’s own, data is read from the battery, and presented.
Values and information details:
15.31V = Pack Voltage
41% = 41% charge
2140mAh is the current remaining capacity
Internal temperature is 24.35°C
Charging current is 2.11A (Negative value indicate discharging current)
Cell voltages for cell 1…4 – should be self-explaining, any healthy pack will have very similar voltages after a flight.
Design capacity is what the pack was designed to be.
Actual capacity is supposed to show the actual capacity as the pack ages.
Relative charge level is based on actual capacity of the pack.
Absolute charge level is based on design capacity of the pack.
Manufacturing date in Y-M-D format.
Made by BMTPOW
Device name is MA03, serial number follows (not the same as barcode on the pack)
TTF: Time To Full , in this case 97 minutes till full, if not charging, will display “-1”
Cycles: how many times have this pack been used.
Status word is bitmapped at least two bits we know are used, one indicating charging/discharging , the other tell if the factory calibration data is OK.
Should factory calibration data ever be corrupted, then you can never know if a reported voltage/current (used for capacity calculation) is correct, and it’s dangerous to fly with such pack. A very clear warning will be displayed.
Health bitmap is so far unknown, its most likely to contain information about internal resistance, uneven cell capacity , or uneven internal resistance, over-temperature or other factors, we will learn from it as time goes and users report other values.
Status is expected to be 128(charging) or 192(discharging)
Health is 18 for all good packs (I do not have one that is bad) , but there are 16bit of data that can indicate quite a lot…
I’ll update this page based on user reports.
If battery pack is connected, but not charging – after 180seconds, the DONE message will show, two minutes later the battery will switch off.
This dataset is output to the same FTDI interface:
Relative charge%: 33
Remaining Capacity: 1709mAh
Cell 1: 3.771V
Cell 2: 3.779V
Cell 3: 3.780V
Cell 4: 3.781V
Design Capacity: 5200 mAh
Actual.Capacity: 5200 mAh
Relative Chg: 33 %
Absolute Chg: 33 %
Serial: 7-10-31Time to Full: -1 min
Status: 192 dec
Health: 18 dec
Design Voltage: 14800
Specification Info: 49
Charging Current: 4000
Charging Voltage: 16800
Plug into battery , switch on battery.
Plug into battery , and provide charging current. You can use any standard charger, select Li-Po 4cell program with no balancing (the smart battery does the rest)
There is an custom bootloader on the device, so if the community or I figure out more about the battery, it’s possibly to upgrade it using a standard FTDI cable and the avrdude tool (for Linux,Mac,Windows).
FTDI cable, with extra pin header.
Insert pin header into FTDI cable, the protruding, short pins will fit into the SoloBatt_OLED’s six pins on the edge of the PCB. You will need to cut away, or puncture a little bit of shrink-wrap to access the edge.
The upper & lower of the six pins on PCB, are marked BLK (black) and GRN(green) – make sure that matches the orientation of the FTDI cable. (reversing does no damage)
Observe that there are two files in the firmware package:
“VG” is for displays with pin order: “VCC, GND, SCL, SDA”
“GV” is for displays with pin order: “GND, VCC, SCK, SDA”
To write the new firmware you will need avrdude application.
On Linux, it’s installed by: “sudo apt install avrdude”
The firmware upload command is:
avrdude -patmega328p -carduino -P /dev/ttyUSB0 -b115200 -D -Uflash:w:SoloBatt_OLED.1.1.hex :i
/dev/ttyUSB0 is most likely correct, the number will be higher if you have more than one USB serial device
If you are using windows, replace /dev/ttyUSBx o COMx , also, in windows you’ll need some FTDI drivers.
Please note that the programming protocol is arduino compatible just enough to make it work with avrdude, but it’s not really arduino.
New in v1.1:
Longer auto-off delay (was 2min , now 4min) , longer time per screen 3s->6s
Serial output using FTDI cable at 115200 baud
Download version 1.1 here: SoloBatt_OLEDv1.1