Plane: added DF logging of 2nd battery voltage

ArduPlane/Log.pde

@@ -382,6 +382,7 @@ struct PACKED log_Current {
     int16_t current_amps;
     uint16_t board_voltage;
     float   current_total;
+    int16_t battery2_voltage;
 };
 
 struct PACKED log_Arm_Disarm {
@@ -393,6 +394,8 @@ struct PACKED log_Arm_Disarm {
 
 static void Log_Write_Current()
 {
+    float voltage2 = 0.0;
+    battery.voltage2(voltage2);
     struct log_Current pkt = {
         LOG_PACKET_HEADER_INIT(LOG_CURRENT_MSG),
         time_ms                 : hal.scheduler->millis(),
@@ -400,7 +403,8 @@ static void Log_Write_Current()
         battery_voltage         : (int16_t)(battery.voltage() * 100.0f),
         current_amps            : (int16_t)(battery.current_amps() * 100.0f),
         board_voltage           : (uint16_t)(hal.analogin->board_voltage()*1000),
-        current_total           : battery.current_total_mah()
+        current_total           : battery.current_total_mah(),
+        battery2_voltage        : (int16_t)(voltage2 * 100.0f)
     };
     DataFlash.WriteBlock(&pkt, sizeof(pkt));
 
@@ -544,7 +548,7 @@ static const struct LogStructure log_structure[] PROGMEM = {
     { LOG_MODE_MSG, sizeof(log_Mode),             
       "MODE", "IMB",         "TimeMS,Mode,ModeNum" },
     { LOG_CURRENT_MSG, sizeof(log_Current),             
-      "CURR", "IhhhHf",      "TimeMS,Thr,Volt,Curr,Vcc,CurrTot" },
+      "CURR", "IhhhHfh",      "TimeMS,Thr,Volt,Curr,Vcc,CurrTot,Volt2" },
     { LOG_COMPASS_MSG, sizeof(log_Compass),             
       "MAG", "Ihhhhhh",   "TimeMS,MagX,MagY,MagZ,OfsX,OfsY,OfsZ" },
     { LOG_COMPASS2_MSG, sizeof(log_Compass),