diff --git a/Battery.h b/Battery.h
index 6ecf5c3..0ea46be 100644
--- a/Battery.h
+++ b/Battery.h
@@ -127,11 +127,11 @@
  */
 void Battery::batteryUpdate()
 {
-    if (rateskip % 5 == 0 || statusColor == 0 )
+    if (rateskip % 5 == 0 || statusColor == 0)
     {
         statusColor = getBatteryColor();
     }
-    if (rateskip == 1 || i_percent == -1 )
+    if (rateskip == 1 || i_percent == -1)
     {
         i_percent = calcBatteryPercent();
         rateskip = ratecount;
@@ -139,10 +139,10 @@
     // 電池図形内部背景塗りつぶし
     _sprite->fillRect(_x, _y, _width - 1, _height - 1, TFT_BLACK);
     // 電池の外形
-    drawBatteryLines(); 
+    drawBatteryLines();
     // バッテリー残量の割合を計算して背景色塗りつぶし
     int b_width = int((_width - 2) * (i_percent / 100.0f));
-    _sprite->fillRect(_x + 2, _y + 2, b_width , _height - 3, statusColor);
+    _sprite->fillRect(_x + 2, _y + 2, b_width, _height - 3, statusColor);
 
     showBatteryPercent(); // バッテリー数値を表示
     // Serial.printf("batt %d", i_percent);
@@ -171,7 +171,7 @@
 void Battery::showBatteryPercent()
 {
     // バッテリー数値を表示
-    _sprite->setCursor(_x + _width + 7, _y + _showSize+1);
+    _sprite->setCursor(_x + _width + 7, _y + _showSize + 1);
     _sprite->setTextFont(1);
     _sprite->setTextColor(_text_color);
     _sprite->setTextSize(_showSize);
@@ -239,5 +239,7 @@
     float percent = (_vbat - MIN_BATTERY_VOLTAGE) / (MAX_BATTERY_VOLTAGE - MIN_BATTERY_VOLTAGE);
     if (percent > 1.0f)
         percent = 1.0f;
+    if (percent < 0.0f)
+        percent = 0.0f;
     return roundf(percent * 100.0f);
 }