Arduino LTO Charger
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This Instructables show how to use an Arduino Nano to charge some small LTO battery in constant current constant voltage basic.
Why LTO Battery?
Lipo battery is around 4.2 V when fully charged, it is a little bit too high to power a 3.3 V board (like ESP8266) without regulator. You may found a little bit too hot on the metal case surface.
LTO battery has lower voltage relatively. It is around 2.9 V when fully charged.
LTO battery also claim it can charge in larger current (charge faster) and more safety.
Preparation
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Bread board
I use 2 small bread boards connect vertically, it can make the circuit more neatly
Arduino board
I use an Arduino Nano, other Arduino model should also work
Display
I use a SSD1331 breakout board, any Ucglib supported display should be ok
Current monitor
INA219 breakout board
PNP transistor
I use A1013, any PNP transistor that can support the charge current (my LTO battery is 60 mA if charging in 1 C) should be ok
Battery connector
I use 2 Alligator Clips with Pigtail
LTO battery
I bought a 60 mAh LTO battery
Bread Board Circuit
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Here are the connection summary:
INA219 breakout board
Vcc -> Arduino 3.3 V pin Gnd -> Arduino Gnd pin, Battery -ve Scl -> Arduino A5 pin Sda -> Arduino A4 pin Vin- -> Battery +ve Vin+ -> PNP transistor Emitter pin
PNP Transistor
Emitter -> INA219 Vin+ pin Collector -> Arduino 5 V pin Base -> Arduino D10 pin
SSD 1331 OLED display
CS -> Arduino D2 pin GND -> Arduino Gnd pin RST -> Arduino D3 pin VDD -> Arduino 3.3 V pin CLK -> Arduino D13 pin DIO -> Arduino D11 pin DC -> Arduino D7 pin
Program
Here is the Arduino program summary:
- check charge current and voltage from INA219
- control the output PWM to meet constant current constant voltage charging method
- calculate the charged power
- display figure and plot the graph
Downloads
Happy DIY!
You may now make your next projects much smaller by saving the voltage regulator space.