Helper: Battery: Add NUM_CELLS_IN_SERIES support to bring down the voltage to a single cell version

Signed-off-by: Luis Garcia <git@luigi311.com>

Author: luigi311

src/helpers/Battery.cpp

@@ -15,6 +15,11 @@ int batteryPercentFromMilliVolts(uint16_t batteryMilliVolts) {
   const uint8_t stepPct = 10;         // distance between table entries (100 → 90 → ... → 0)
   const size_t n = kOcvTableSize;     // should be 11
 
+  if (NUM_CELLS_IN_SERIES > 1) {
+    // Adjust the input voltage to per-cell basis
+    batteryMilliVolts /= NUM_CELLS_IN_SERIES;
+  }
+
   if (n != 11 || batteryMilliVolts <= 0) {
     // Error: invalid OCV_ARRAY table size or voltage
     return -1;

src/helpers/Battery.h

@@ -31,6 +31,14 @@
   #endif
 #endif
 
+/**
+ * Number of cells in series (for multi-cell battery packs)
+ * Default to 1 if not defined.
+ */
+#ifndef NUM_CELLS_IN_SERIES
+  #define NUM_CELLS_IN_SERIES 1
+#endif
+
 
 /**
  * Convert a battery voltage (in millivolts) to approximate state-of-charge (%),