diff -r e6b5510ca1d9 -r e06b04ef1579 src/ChartiSpindel.cpp
--- a/src/ChartiSpindel.cpp	Mon Nov 14 16:05:02 2022 +0100
+++ b/src/ChartiSpindel.cpp	Tue Nov 15 09:42:25 2022 +0100
@@ -44,9 +44,9 @@
     buttonBox->setStandardButtons(QDialogButtonBox::Ok);
     buttonBox->addButton(saveButton,QDialogButtonBox::ActionRole);
 
-    temperature = new QSplineSeries();
-    density = new QSplineSeries();
-    battery = new QSplineSeries();
+    temperature = new QLineSeries();
+    density = new QLineSeries();
+    battery = new QLineSeries();
 
     query.prepare("SELECT * FROM log_ispindel WHERE code=:code ORDER BY datetime");
     query.bindValue(":code", code);
@@ -55,7 +55,7 @@
         timestamp = query.value("datetime").toDateTime().toSecsSinceEpoch() * 1000;
         temperature->append(timestamp, query.value("temperature").toDouble());
         density->append(timestamp, query.value("sg").toDouble());
-        battery ->append(timestamp, query.value("battery").toDouble());
+        battery ->append(timestamp, round(query.value("battery").toDouble() * 500) / 500);
     }
 
     temperature->setName(tr("Temperature"));
@@ -107,9 +107,9 @@
     chart->addAxis(axisYB, Qt::AlignRight);
     battery->attachAxis(axisYB);
 
-    connect(temperature, &QSplineSeries::hovered, this, &ChartiSpindel::tooltip);
-    connect(density, &QSplineSeries::hovered, this, &ChartiSpindel::tooltip);
-    connect(battery, &QSplineSeries::hovered, this, &ChartiSpindel::tooltip);
+    connect(temperature, &QLineSeries::hovered, this, &ChartiSpindel::tooltip);
+    connect(density, &QLineSeries::hovered, this, &ChartiSpindel::tooltip);
+    connect(battery, &QLineSeries::hovered, this, &ChartiSpindel::tooltip);
 
     chartView = new QChartView(chart);
     chartView->setRenderHint(QPainter::Antialiasing);