--- a/graph.py	Fri Dec 22 13:05:05 2017 +0100
+++ b/graph.py	Fri Dec 22 13:10:23 2017 +0100
@@ -13,20 +13,21 @@
 import tzlocal
 
 class Column(object):
-    def __init__(self, rowname, title, table, units, limits = (None, None), conv = None):
+    def __init__(self, rowname, title, table, units, limits = (None, None), conv = None, annofn = None):
         self.rowname = rowname
         self.title = title
         self.table = table
         self.units = units
         self.limits = limits
-        self.conv = None
+        self.conv = conv
+        self.annofn = annofn
 
 columns = [
     Column('main_voltage', 'Battery Voltage', 'eprolog', 'Vdc'),
     Column('aux_voltage', 'Aux Voltage', 'eprolog', 'Vdc'),
     Column('battery_curr', 'Battery Current', 'eprolog', 'A'),
     Column('amp_hours', 'Battery Amp Hours', 'eprolog', 'Ah'),
-    Column('state_of_charge', 'State of Charge', 'eprolog', '%', (0, 100)),
+    Column('state_of_charge', 'State of Charge', 'eprolog', '%', (0, 100), annofn = lambda xdata, ydata: 'DoD: %.1f' % (100 - ydata.min())),
     Column('time_remaining', 'Time Remaining', 'eprolog', 'min'),
     Column('battery_temp', 'Battery Temperature', 'eprolog', 'C'),
 
@@ -165,7 +166,10 @@
         scale_min, scale_max = c.limits
 
         # DoD?
-        c.annotation = None
+        if c.annofn != None:
+            c.annotation = c.annofn(c.xdata, c.ydata)
+        else:
+            c.annotation = None
 
         # Work out which axis to plot on
         if c.units == yaxisunits1: