diff --git a/libraries/SITL/SIM_BattMonitor_SMBus_Generic.cpp b/libraries/SITL/SIM_BattMonitor_SMBus_Generic.cpp
index 459fc379ad..b343d895b5 100644
--- a/libraries/SITL/SIM_BattMonitor_SMBus_Generic.cpp
+++ b/libraries/SITL/SIM_BattMonitor_SMBus_Generic.cpp
@@ -8,6 +8,12 @@ SITL::SIM_BattMonitor_SMBus_Generic::SIM_BattMonitor_SMBus_Generic() :
 void SITL::SIM_BattMonitor_SMBus_Generic::init()
 {
     switch (cellcount()) {
+    case 14:
+        add_register("Cell14", SMBusBattGenericDevReg::CELL14, O_RDONLY);
+        FALLTHROUGH;
+    case 13:
+        add_register("Cell13", SMBusBattGenericDevReg::CELL13, O_RDONLY);
+        FALLTHROUGH;
     case 12:
         add_register("Cell12", SMBusBattGenericDevReg::CELL12, O_RDONLY);
         FALLTHROUGH;
@@ -54,8 +60,59 @@ void SITL::SIM_BattMonitor_SMBus_Generic::update(const class Aircraft &aircraft)
     SIM_BattMonitor_SMBus::update(aircraft);
 
     // pretend to have three cells connected
-    const float millivolts = AP::sitl()->state.battery_voltage * 1000.0f;
-    set_register(SMBusBattGenericDevReg::CELL1, uint16_t(millivolts/3.0f - 100.0f));
-    set_register(SMBusBattGenericDevReg::CELL2, uint16_t(millivolts/3.0f));
-    set_register(SMBusBattGenericDevReg::CELL3, uint16_t(millivolts/3.0f + 100.0f));
+    const float millivolts = aircraft.get_battery_voltage() * 1000.0f;
+    uint16_t value_even = -1;
+    uint16_t value_odd = -1;
+    const uint8_t _connected_cells = connected_cells();
+    if (millivolts > 0) {
+        const float volts_per_cell = millivolts/float(_connected_cells);
+        value_even = uint16_t(volts_per_cell - 100.0f);
+        value_odd = uint16_t(volts_per_cell + 100.0f);
+    }
+    switch (_connected_cells) {
+    case 14:
+        set_register(SMBusBattGenericDevReg::CELL14, value_even);
+        FALLTHROUGH;
+    case 13:
+        set_register(SMBusBattGenericDevReg::CELL13, value_odd);
+        FALLTHROUGH;
+    case 12:
+        set_register(SMBusBattGenericDevReg::CELL12, value_even);
+        FALLTHROUGH;
+    case 11:
+        set_register(SMBusBattGenericDevReg::CELL11, value_odd);
+        FALLTHROUGH;
+    case 10:
+        set_register(SMBusBattGenericDevReg::CELL10, value_even);
+        FALLTHROUGH;
+    case 9:
+        set_register(SMBusBattGenericDevReg::CELL9, value_odd);
+        FALLTHROUGH;
+    case 8:
+        set_register(SMBusBattGenericDevReg::CELL8, value_even);
+        FALLTHROUGH;
+    case 7:
+        set_register(SMBusBattGenericDevReg::CELL7, value_odd);
+        FALLTHROUGH;
+    case 6:
+        set_register(SMBusBattGenericDevReg::CELL6, value_even);
+        FALLTHROUGH;
+    case 5:
+        set_register(SMBusBattGenericDevReg::CELL5, value_odd);
+        FALLTHROUGH;
+    case 4:
+        set_register(SMBusBattGenericDevReg::CELL4, value_even);
+        FALLTHROUGH;
+    case 3:
+        set_register(SMBusBattGenericDevReg::CELL3, value_odd);
+        FALLTHROUGH;
+    case 2:
+        set_register(SMBusBattGenericDevReg::CELL2, value_even);
+        FALLTHROUGH;
+    case 1:
+        set_register(SMBusBattGenericDevReg::CELL1, value_odd);
+        return;
+    default:
+        AP_HAL::panic("Bad connected_cellcount %u", _connected_cells);
+    }
 }
diff --git a/libraries/SITL/SIM_BattMonitor_SMBus_Generic.h b/libraries/SITL/SIM_BattMonitor_SMBus_Generic.h
index e24ae5466d..5260568a15 100644
--- a/libraries/SITL/SIM_BattMonitor_SMBus_Generic.h
+++ b/libraries/SITL/SIM_BattMonitor_SMBus_Generic.h
@@ -18,6 +18,8 @@ public:
     static const uint8_t CELL10 = 0x36;
     static const uint8_t CELL11 = 0x35;
     static const uint8_t CELL12 = 0x34;
+    static const uint8_t CELL13 = 0x33;
+    static const uint8_t CELL14 = 0x32;
 };
 
 class SIM_BattMonitor_SMBus_Generic : public SIM_BattMonitor_SMBus
@@ -30,6 +32,7 @@ public:
 
     virtual uint8_t cellcount() const = 0;
 
+    virtual uint8_t connected_cells() const { return 3; }
 };
 
 } // namespace SITL
diff --git a/libraries/SITL/SIM_BattMonitor_SMBus_Maxell.h b/libraries/SITL/SIM_BattMonitor_SMBus_Maxell.h
index 9be6d74a8f..5652b48cbd 100644
--- a/libraries/SITL/SIM_BattMonitor_SMBus_Maxell.h
+++ b/libraries/SITL/SIM_BattMonitor_SMBus_Maxell.h
@@ -19,7 +19,8 @@ public:
 
     Maxell();
 
-    uint8_t cellcount() const override { return 3; }
+    uint8_t cellcount() const override { return 14; }
+    uint8_t connected_cells() const override { return 14; }
 
 };
 
diff --git a/libraries/SITL/SIM_I2C.cpp b/libraries/SITL/SIM_I2C.cpp
index 6a957be258..5322a4e7a0 100644
--- a/libraries/SITL/SIM_I2C.cpp
+++ b/libraries/SITL/SIM_I2C.cpp
@@ -70,6 +70,7 @@ struct i2c_device_at_address {
     { 1, 0x76, ignored }, // MS56XX
     { 1, 0x77, tsys01 },
     { 1, 0x0B, rotoye },
+    { 2, 0x0B, maxell },
     { 2, 0x28, airspeed_dlvr },
 };