├── cover_picture.jpg ├── BMS_circuit_diagram.JPG ├── BMS 4S lithium lifepo4 charger tester.pdf ├── README.md ├── LICENSE └── Arduino_BMS_4S-v1.ino /cover_picture.jpg: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/philippedc/Li-ion-LifePo4-BMS-charger-tester-for-Arduino-Uno/HEAD/cover_picture.jpg -------------------------------------------------------------------------------- /BMS_circuit_diagram.JPG: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/philippedc/Li-ion-LifePo4-BMS-charger-tester-for-Arduino-Uno/HEAD/BMS_circuit_diagram.JPG -------------------------------------------------------------------------------- /BMS 4S lithium lifepo4 charger tester.pdf: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/philippedc/Li-ion-LifePo4-BMS-charger-tester-for-Arduino-Uno/HEAD/BMS 4S lithium lifepo4 charger tester.pdf -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # Li-ion-LifePo4-BMS-charger-tester-for-Arduino-Uno 2 | The objective of this project is to build a charging and testing device that can be universal, for a different among of cells to charge and for different technologies. The Arduino Uno based device, manage voltage readings, and according to results manages cells’ shunt or a buzzer. A SSD screen displays where we are. A buck DC-DC converter adjust the charging voltage for a constant charging current. 3 | 4 | • It can charge simultaneously from 1 to 4 cells 5 | 6 | • Cells can be either Lithium-ion technology – for instance 18650 – or LifePo4 cells (you cannot mix) 7 | 8 | • Monitoring of any cells voltage, plus overall voltage 9 | 10 | • A internal protection against short circuit also limit for a constant current of about 1 A – hardware setup – 11 | 12 | • Any power supply DC 17V to 25V @ 1.5A can fit this device. An internal buck DC-DC converter adapt the needed voltage value. A old DC 19V laptop power supply is perfect 13 | 14 | • The balancing is performed by shunts between cells 15 | 16 | • Under voltage alarm by buzzer 17 | 18 | The manual - the pdf file - describes how to build such a BMS 1S…4S charger / tester. 19 | 20 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | GNU GENERAL PUBLIC LICENSE 2 | Version 2, June 1991 3 | 4 | Copyright (C) 1989, 1991 Free Software Foundation, Inc., 5 | 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 6 | Everyone is permitted to copy and distribute verbatim copies 7 | of this license document, but changing it is not allowed. 8 | 9 | Preamble 10 | 11 | The licenses for most software are designed to take away your 12 | freedom to share and change it. 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If this is what you want to do, use the GNU Lesser General 339 | Public License instead of this License. 340 | -------------------------------------------------------------------------------- /Arduino_BMS_4S-v1.ino: -------------------------------------------------------------------------------- 1 | /* 2 | BMS Li-ion/LifoPo4 automatic charger 1S 2S 3S 4S 3 | _________________________________________________________________ 4 | | | 5 | | author : Philippe de Craene B1 input 24 | A1 ==> B2 input 25 | A2 ==> B3 input 26 | A3 ==> B4 input 27 | A4 ==> SSD1306 display SDA 28 | A5 ==> SSD1306 display SCL 29 | 2 ==> B1 shunt output - pin2 of 1A / SN754410 30 | 3 ==> B2 shunt output - pin7 of 2A / SN754410 31 | 4 ==> B3 shunt output - pin10 of 3A / SN754410 32 | 5 ==> B4 shunt output - pin15 of 4A / SN754410 33 | 6 ==> input from Imax charging sensor 34 | 7 ==> buzzer 35 | 9 ==> PWM output for buck converter 36 | 10 ==> x1 BCD rotary contactor 37 | 11 ==> x10 BCD rotary contactor 38 | 12 ==> x100 BCD rotary contactor 39 | 13 ==> ENABLE output for SN754410 40 | 41 | Versions history 42 | ---------------- 43 | version 0.1 - 21 august 2020 - first operational version 44 | version 0.3 - 1 sept 2020 - add the limit charging current 45 | version 1.0 - 16 sept 2020 - add the buck converter 46 | 47 | Remarks 48 | ------- 49 | 50 | About Serial.print(F("bla bla") usage see https://www.baldengineer.com/arduino-f-macro.html 51 | RAM usage decrease from 81% to 34% inside this code 52 | */ 53 | 54 | #include 55 | #include "ssd1306.h" // https://github.com/lexus2k/ssd1306 56 | 57 | // Parameters 58 | //----------- 59 | 60 | const bool FIRST_USE = false; // must be set "true" the very first use to record parameters in EEPROM 61 | bool cellModel = LOW; // LOW = Li-ion / HIGH = LifePo4 62 | byte cellNumber = 4; // number of cells to charge 63 | float Vmax[2] = { 4.2, 3.7 }; // maximum voltage for Li-ion / LifePo4 cells 64 | float Vmin[2] = { 3.6, 3.2 }; // minimum volatge for Li-ion / LifePo4 cells 65 | float Vcalibration[4] = { 1.0, 1.0, 1.0, 1.0 }; // calibration to fit real voltage measures 66 | 67 | // Hardware connexion 68 | //------------------- 69 | 70 | byte VcellPin[4] = { 0, 1, 2, 3 }; // analog read of each cell : A0:B1, A1:B2, A2:B3, A3:B4 71 | byte shuntPin[4] = { 2, 3, 4, 5 }; // output to shunt for each cell 72 | const byte ImaxPin = 6; // digital input from Imax charging sensor/detector 73 | const byte buzzerPin = 7; // alarm undervoltage cell 74 | const byte pwmPin = 9; // pwm for buck converter 75 | const byte UrcPin = 10; // x1 BCD rotary contactor 76 | const byte DrcPin = 11; // x10 BCD rotary contactor 77 | const byte CrcPin = 12; // x100 BCD rotary contactor 78 | const byte enablePin = 13; // SN754410 ENABLE 79 | 80 | // Global variables 81 | //----------------- 82 | 83 | float Valim = 0; // power supply voltage 84 | float Vcell[4] = { 4.9, 4.9, 4.9, 4.9 }; // cells measured voltage 85 | float memo_Vcell[4] = { 0.0, 0.0, 0.0, 0.0 }; // past cells voltage 86 | bool runOnce = true; // run one time only flag 87 | byte pwm = 0; // buck converter pwm 88 | bool parametersMenu = false; // flag when parameters are set by the console inputs 89 | byte index = 0; // input character counter 90 | char consoleInput[7]; // console input 91 | char whatToDisplay = 'A'; // select console messages to display, 'A' for all 92 | bool Imax = false; // flag for charging max current 93 | bool memo_Urc, memo_Drc, memo_Crc; 94 | 95 | // 96 | // setup 97 | //____________________________________________________________________________________________ 98 | 99 | void setup() { 100 | 101 | // define inputs & outputs 102 | pinMode( enablePin, OUTPUT ); digitalWrite( enablePin, LOW ); 103 | for( byte i=0; i<4; i++ ) { 104 | pinMode( shuntPin[i], OUTPUT ); digitalWrite( shuntPin[i], LOW ); 105 | } 106 | pinMode( pwmPin, OUTPUT ); analogWrite( pwmPin, 0 ); 107 | pinMode( UrcPin, INPUT_PULLUP ); 108 | pinMode( DrcPin, INPUT_PULLUP ); 109 | pinMode( CrcPin, INPUT_PULLUP ); 110 | pinMode( ImaxPin, INPUT_PULLUP ); 111 | pinMode( buzzerPin, OUTPUT ); 112 | 113 | // Initialise the oled display & console 114 | Serial.begin(250000); 115 | Serial.println(F("Starting....")); 116 | 117 | ssd1306_128x32_i2c_init(); 118 | //ssd1306_128x64_i2c_init(); 119 | ssd1306_fillScreen(0x00); 120 | ssd1306_setFixedFont(ssd1306xled_font6x8); 121 | ssd1306_clearScreen(); 122 | 123 | // EEPROM check and data upload : 124 | // stored data are always positive from 0 to 255. 125 | // it seems that in cas of first use all are set to 255. 126 | if( FIRST_USE ) EEPROM_Update(); 127 | else EEPROM_Get(); 128 | 129 | // set Timer1 pin9 and pin10 130 | TCCR1B = TCCR1B & B11111000 | B00000001; // set Timer1 divisor to 1 for PWM frequency of 31372.55 Hz 131 | 132 | // last tasks.... 133 | RotactorConfig(); // check configuration from binary rotary contactor 134 | digitalWrite( enablePin, HIGH ); // enable SN754410 135 | 136 | } // end of setup 137 | 138 | // 139 | // loop 140 | //____________________________________________________________________________________________ 141 | 142 | void loop() { 143 | 144 | static float VcellCumul[4] = { 0.0, 0.0, 0.0, 0.0 }; // cumulative analogRead in bytes 145 | static unsigned int analogReadsCount = 0; // number of analogRead counter 146 | static bool buzzerON = false; 147 | static bool oneMinute = false; 148 | 149 | unsigned long tempo = millis(); 150 | 151 | // this is run only one time or after any config change or every 5 minutes 152 | //------------------------------------------------------------------------ 153 | if( runOnce ) { 154 | static byte counter = 0; 155 | static unsigned long memo_tempo_shuntON = 0; 156 | buzzerON = false; // stop the buzzer if any 157 | for( byte i=cellNumber; i<4; i++ ) digitalWrite( shuntPin[i], HIGH ); // shunt inactive cells 158 | if( counter > 5 ) { 159 | counter = 0; 160 | runOnce = false; 161 | } 162 | else if( tempo - memo_tempo_shuntON > 300 ) { 163 | memo_tempo_shuntON = tempo; 164 | counter++; 165 | for( byte i=0; i= (4*Vmax[cellModel])+0.5)) { // test with power voltage safety 183 | if( Imax || ( Vcell[0] < 4.9)) { // take care B1 does not exceed 5V ! 184 | if( pwm > 0 ) pwm--; 185 | } 186 | else if( pwm < 255 ) pwm++; 187 | 188 | analogWrite( pwmPin, pwm ); 189 | 190 | 191 | // the following is done after every analogReadsCount cycles of reading analog values 192 | //----------------------------------------------------------------------------------- 193 | if( ++analogReadsCount > 100 ) return; 194 | 195 | // calculate voltages 196 | for( byte i=0; i<4 ; i++ ) { 197 | Vcell[i] = (VcellCumul[i] / (float)analogReadsCount / 1023.0) * 5.0 * Vcalibration[i] * (i+1); 198 | VcellCumul[i] = 0; 199 | } 200 | analogReadsCount = 0; 201 | Valim = Vcell[3]; 202 | for( byte i=3; i>0; i-- ) { 203 | Vcell[i] -= Vcell[i-1]; // get the voltage for each cell 204 | } // end of for 205 | 206 | // this is done every second: read buttons and display data 207 | //--------------------------------------------------------- 208 | static unsigned long memo_tempo = 0; 209 | if( tempo - memo_tempo < 1000 ) return; 210 | memo_tempo = tempo; 211 | 212 | // check balancing and undervoltage 213 | for( byte i=0; i<4; i++ ) { 214 | if( Vcell[i] > Vmax[cellModel] ) digitalWrite( shuntPin[i], HIGH ); // check balancing 215 | else if( oneMinute && ( Vcell[i] < Vmin[cellModel])) buzzerON = true; // check undervoltage 216 | } // end of for 217 | if( buzzerON ) tone( buzzerPin, 440, 50 ); // one short tone every seconds 218 | 219 | // check configuration from binary rotary contactor 220 | RotactorConfig(); 221 | 222 | // console display 223 | ConsoleDisplay( whatToDisplay ); 224 | 225 | // oled display 226 | OledDisplay(); 227 | 228 | // this is done every 60 seconds: voltage tendencies 229 | //------------------------------------------------- 230 | static unsigned long memo_tempo_tendancy = 0; 231 | 232 | if( tempo - memo_tempo_tendancy < 60000 ) return; 233 | memo_tempo_tendancy = tempo; 234 | for( byte i=0; i<4; i++ ) memo_Vcell[i] = Vcell[i]; // remember past cells voltages for tendancies 235 | oneMinute = true; 236 | runOnce = true; 237 | 238 | } // end of loop 239 | 240 | //============================================================================================ 241 | // list of functions 242 | //============================================================================================ 243 | 244 | // check configuration from binary rotary contactor 245 | //____________________________________________________________________________________________ 246 | 247 | void RotactorConfig() { 248 | 249 | bool Urc = digitalRead( UrcPin ); 250 | bool Drc = digitalRead( DrcPin ); 251 | bool Crc = digitalRead( CrcPin ); 252 | if( Crc ) cellModel = HIGH; // LifePo4 model cell 253 | else cellModel = LOW; // Li-ion model cell 254 | if( Urc ) { 255 | if( Drc ) cellNumber = 4; 256 | else cellNumber = 2; 257 | } 258 | else { 259 | if( Drc ) cellNumber = 3; 260 | else cellNumber = 1; 261 | } 262 | if((Urc != memo_Urc) || (Drc != memo_Drc) || (Crc != memo_Crc)) runOnce = true; 263 | memo_Urc = Urc; 264 | memo_Drc = Drc; 265 | memo_Crc = Crc; 266 | } // end of RotactorConfig() 267 | 268 | // 269 | // TendancySet() : set the tendancy of cells voltage 270 | //____________________________________________________________________________________________ 271 | 272 | char TendancySet( byte i ) { 273 | 274 | if( Vcell[i] - memo_Vcell[i] > 0.0 ) return '+'; 275 | else if((Vcell[i] - memo_Vcell[i]) == 0 ) return '='; 276 | else return '-'; 277 | return '?'; 278 | } // end of TendancySet() 279 | 280 | // 281 | // EEPROM_Get() : read values stored in the EEPROM 282 | //____________________________________________________________________________________________ 283 | 284 | void EEPROM_Get() { 285 | 286 | for( byte i=0; i<4; i++ ) { 287 | int var = (EEPROM.read(2*i) << 8) + EEPROM.read((2*i)+1); 288 | Vcalibration[i] = var/1000.0; 289 | } 290 | Vmax[0] = (EEPROM.read(8)+300)/100.0; 291 | Vmax[1] = (EEPROM.read(9)+300)/100.0; 292 | Vmin[0] = (EEPROM.read(10)+300)/100.0; 293 | Vmin[1] = (EEPROM.read(11)+300)/100.0; 294 | } // end of EEPROM_Get() 295 | 296 | // 297 | // EEPROM_Update() : update values stored in the EEPROM 298 | //____________________________________________________________________________________________ 299 | 300 | void EEPROM_Update() { 301 | for( byte i=0; i<4; i++ ) { 302 | int var = 1000*Vcalibration[i]; 303 | EEPROM.update((2*i), highByte(var)); 304 | EEPROM.update(((2*i)+1), lowByte(var)); 305 | } 306 | EEPROM.update(8, ((Vmax[0]*100.0)-300)); 307 | EEPROM.update(9, ((Vmax[1]*100.0)-300)); 308 | EEPROM.update(10, ((Vmin[0]*100.0)-300)); 309 | EEPROM.update(11, ((Vmin[1]*100.0)-300)); 310 | 311 | } // end of EEPROM_Update() 312 | 313 | // 314 | // OledDisplay() : display to Oled 315 | //____________________________________________________________________________________________ 316 | 317 | void OledDisplay() { 318 | char flt2str[6]; 319 | 320 | //first line 321 | ssd1306_printFixed ( 0, 0, "BMS", STYLE_NORMAL); 322 | dtostrf( cellNumber, 1, 0, flt2str ); // usage : ( number_value, number_of_digits, nulber_of_decimal, char_output) 323 | ssd1306_printFixed (20, 0, flt2str, STYLE_NORMAL); 324 | ssd1306_printFixed (30, 0, "x", STYLE_NORMAL); 325 | if( cellModel ) ssd1306_printFixed (40, 0, "LifePo4", STYLE_NORMAL); 326 | else ssd1306_printFixed (40, 0, "Li-ion", STYLE_NORMAL); 327 | 328 | dtostrf( Valim, 4, 1, flt2str ); 329 | ssd1306_printFixed (96, 0, flt2str, STYLE_NORMAL); 330 | ssd1306_printFixed (120, 0, "V", STYLE_NORMAL); 331 | 332 | //cells value: B2, B1, B4, B3 333 | if( Vcell[1] < 0 ) dtostrf( Vcell[1], 5, 2, flt2str ); 334 | else dtostrf( Vcell[1], 5, 3, flt2str ); 335 | flt2str[4] = TendancySet(1); 336 | ssd1306_printFixed (0, 16, "B2 ", STYLE_NORMAL); 337 | ssd1306_printFixed (20, 16, flt2str, STYLE_NORMAL); 338 | 339 | if( Vcell[0] < 0 ) dtostrf( Vcell[0], 5, 2, flt2str ); 340 | else dtostrf( Vcell[0], 5, 3, flt2str ); 341 | flt2str[4] = TendancySet(0); 342 | ssd1306_printFixed (0, 24, "B1 ", STYLE_NORMAL); 343 | ssd1306_printFixed (20, 24, flt2str, STYLE_NORMAL); 344 | 345 | if( Vcell[3] < 0 ) dtostrf( Vcell[3], 5, 2, flt2str ); 346 | else dtostrf( Vcell[3], 5, 3, flt2str ); 347 | flt2str[4] = TendancySet(3); 348 | ssd1306_printFixed (64, 16, "B4 ", STYLE_NORMAL); 349 | ssd1306_printFixed (84, 16, flt2str, STYLE_NORMAL); 350 | 351 | if( Vcell[2] < 0 ) dtostrf( Vcell[2], 5, 2, flt2str ); 352 | else dtostrf( Vcell[2], 5, 3, flt2str ); 353 | flt2str[4] = TendancySet(2); 354 | ssd1306_printFixed (64, 24, "B3 ", STYLE_NORMAL); 355 | ssd1306_printFixed (84, 24, flt2str, STYLE_NORMAL); 356 | } // end of OledDisplay() 357 | 358 | // 359 | // ConsoleDisplay() : console displays 360 | //____________________________________________________________________________________________ 361 | 362 | void ConsoleDisplay( char what ) { 363 | 364 | Serial.println(F("\nBMS charger/tester general menu, type the command according to desired action[:value], then ENTER\n")); 365 | if( what == 'B' || what == 'A' ) { 366 | Serial.println(F("Bxaaaa with x=1..4 for cell number x with a.aaa the new voltage calibration value")); 367 | Serial.print(F(" Cal1= ")); Serial.print( Vcalibration[0],3 ); Serial.print(F(" ")); 368 | Serial.print(F(" Cal2= ")); Serial.print( Vcalibration[1],3 ); Serial.print(F(" ")); 369 | Serial.print(F(" Cal3= ")); Serial.print( Vcalibration[2],3 ); Serial.print(F(" ")); 370 | Serial.print(F(" Cal4= ")); Serial.print( Vcalibration[3],3 ); Serial.println(); 371 | Serial.print(F(" B1= ")); Serial.print( Vcell[0],2 ); Serial.print(F(" ")); 372 | Serial.print(F(" B2= ")); Serial.print( Vcell[1],2 ); Serial.print(F(" ")); 373 | Serial.print(F(" B3= ")); Serial.print( Vcell[2],2 ); Serial.print(F(" ")); 374 | Serial.print(F(" B4= ")); Serial.print( Vcell[3],2 ); Serial.println("\n"); 375 | } 376 | if( what == 'H' || what == 'A' ) { 377 | Serial.println(F("HTaaa for Li-ion to set the cell maximum voltage to a.aa")); 378 | Serial.println(F("HFaaa for LifePo4 to set the cell maximum voltage to a.aa")); 379 | Serial.print(F(" Li-ion Vmax = ")); Serial.print( Vmax[0]); 380 | Serial.print(F(" LifePo4 Vmax = ")); Serial.println( Vmax[1]); 381 | Serial.println(); 382 | } 383 | if( what == 'L' || what == 'A' ) { 384 | Serial.println(F("LTaaa for Li-ion to set the cell minimum voltage to a.aa")); 385 | Serial.println(F("LFaaa for LifePo4 to set the cell minimum voltage to a.aa")); 386 | Serial.print(F(" Li-ion Vmin = ")); Serial.print( Vmin[0]); 387 | Serial.print(F(" Lifepo4 Vmin = ")); Serial.println( Vmin[1]); 388 | Serial.println(); 389 | } 390 | Serial.print(F(" Actual : ")); 391 | if( cellModel ) Serial.print(F("LifePo4")); 392 | else Serial.print(F("Li-ion")); 393 | Serial.print(F(" pwm = ")); Serial.print(pwm); Serial.print(F(" power supply = ")); 394 | Serial.print(Valim); Serial.print(F(" / ")); Serial.print(4*Vmax[cellModel]); Serial.println(F(" maxi\n")); 395 | 396 | Serial.println(F("S to save data to EEPROM")); 397 | Serial.println(F("E to recover last saved data\n\n\n")); 398 | 399 | } // end of ConsoleDisplay() 400 | 401 | // 402 | // serialEvent() : Arduino builtin function for any console input 403 | //____________________________________________________________________________________________ 404 | 405 | void serialEvent() { 406 | 407 | if( Serial.available() ) { 408 | char incomingChar = Serial.read(); // no timeout nor delay unlike Serial.readBytesUntil() 409 | if( incomingChar != '\n' ) { 410 | consoleInput[index] = incomingChar; 411 | index++; 412 | } 413 | else { 414 | consoleInput[index] ='\0'; // null character 415 | index = 0; 416 | 417 | int val, cell; 418 | switch(consoleInput[0]) { 419 | case 'b': 420 | case 'B': whatToDisplay = 'B'; 421 | val = (consoleInput[5]-48)+(10*(consoleInput[4]-48))+(100*(consoleInput[3]-48))+(1000*(consoleInput[2]-48)); 422 | cell = consoleInput[1] -49; // -48 (because ASCII) -1 (because 1..4 becomes 0..3 423 | if( cell > cellNumber ) Serial.println(F("cell number out of range")); 424 | else if( val < 800 || val > 1200 ) Serial.println(F("Calibration value out of range")); 425 | else Vcalibration[cell] = val/1000.0; 426 | break; 427 | case 'l': 428 | case 'L': whatToDisplay = 'L'; 429 | val = (consoleInput[4]-48)+(10*(consoleInput[3]-48))+(100*(consoleInput[2]-48)); 430 | if( val < 270 || val > 460 ) { 431 | Serial.println(F("cell voltage value out of range")); 432 | break; 433 | } 434 | if((consoleInput[1] == 't') || (consoleInput[1] == 'T')) Vmin[0] = val/100.0; 435 | else if((consoleInput[1] == 'f') || (consoleInput[1] == 'F')) Vmin[1] = val/100.0; 436 | else Serial.println(F("unrecognised cells model")); 437 | break; 438 | case 'h': 439 | case 'H': whatToDisplay = 'H'; 440 | val = (consoleInput[4]-48)+(10*(consoleInput[3]-48))+(100*(consoleInput[2]-48)); 441 | if( val < 270 || val > 460 ) { 442 | Serial.println(F("cell voltage value out of range")); 443 | break; 444 | } 445 | if((consoleInput[1] == 't') || (consoleInput[1] == 'T')) Vmax[0] = val/100.0; 446 | else if((consoleInput[1] == 'f') || (consoleInput[1] == 'F')) Vmax[1] = val/100.0; 447 | else Serial.println(F("unrecognised cells model")); 448 | break; 449 | case 'e': 450 | case 'E': whatToDisplay = 'A'; 451 | Serial.println(F("cancel all changes!")); 452 | EEPROM_Get(); 453 | break; 454 | case 's': 455 | case 'S': whatToDisplay = 'A'; 456 | Serial.println(F("all data saved!")); 457 | EEPROM_Update(); 458 | break; 459 | 460 | default : whatToDisplay = 'A'; 461 | Serial.println(F("unrecognised command")); 462 | break; 463 | 464 | } // end of switch 465 | } // en of else 466 | } // end of test Serial.available() 467 | } // end of serialEvent() 468 | --------------------------------------------------------------------------------