diff --git a/app/models/reading.rb b/app/models/reading.rb
index 2651272..066909f 100644
--- a/app/models/reading.rb
+++ b/app/models/reading.rb
@@ -1,7 +1,14 @@
 require 'open-uri'
 
+UNKNOWN_READING = { :total_kwh_consumed_high => nil, :total_kwh_consumed_low => nil, :total_kwh_produced_high => nil, :total_kwh_produced_low => nil, :total_m3_gas_consumed => nil}
+EASY_ENERGY_TARIFFS = {}
+BATTERY_MAX_KWH = 10.0
+MAX_CHARGE_KWH = 5.0      
+
 class Reading < ActiveRecord::Base
-  
+
+   @@battery_kwh = 0.0
+   
   def eql_reading?(reading)
     self.total_kwh_consumed_high == reading.total_kwh_consumed_high &&
     self.total_kwh_consumed_low == reading.total_kwh_consumed_low &&
@@ -65,10 +72,7 @@ class Reading < ActiveRecord::Base
     def day(date)
       Reading.where("created_at > :begin AND created_at < :end", { :begin => date.to_date.beginning_of_day, :end => date.to_date.end_of_day})        
     end
-    
-    EASY_ENERGY_TARIFFS = {}
-    
-    
+        
     # returns a hash with keys formatted "yyyy-mm-dd-hr" and values [usage, return]
     # e.g. { 2021-12-16-06"=>[0.36058, 0.298] }
     def easy_energy_tariffs(date)
@@ -166,45 +170,37 @@ class Reading < ActiveRecord::Base
       end
     end  
       
-    
-    UNKNOWN_READING = { :total_kwh_consumed_high => nil, :total_kwh_consumed_low => nil, :total_kwh_produced_high => nil, :total_kwh_produced_low => nil, :total_m3_gas_consumed => nil}
-
     def format_cost(cost)
       cost ? "EUR %0.03f" % cost : "EUR ?"
     end
-    
-    @battery_kwh = 0.0
-    BATTERY_MAX_KWH = 10.0
-    
+        
     def charge_battery(kwh)
       return 0.0 if kwh.nil?
-      if @battery_kwh + kwh <= BATTERY_MAX_KWH
-        @battery_kwh += kwh.to_f
-        p "Battery is now at %s kwh" % @battery_kwh
+      if @@battery_kwh + kwh <= BATTERY_MAX_KWH
+        @@battery_kwh += kwh.to_f
+        p "Battery is now at %s kwh" % @@battery_kwh
         return kwh
       else
         old_kwh = @battery_kwh
-        @battery_kwh = BATTERY_MAX_KWH
-        p "Battery is now at %s kwh" % @battery_kwh
+        @@battery_kwh = BATTERY_MAX_KWH
+        p "Battery is now at %s kwh" % @@battery_kwh
         return (BATTERY_MAX_KWH-old_kwh)
       end
     end
     
     def discharge_battery(kwh)
       return 0.0 if kwh.nil?
-      if @battery_kwh > kwh.to_f
-        @battery_kwh -= kwh.to_f
-        p "Battery is now at %s kwh" % @battery_kwh
+      if @@battery_kwh > kwh.to_f
+        @@battery_kwh -= kwh.to_f
+        p "Battery is now at %s kwh" % @@battery_kwh
         return kwh
       else
-        old_kwh = @battery_kwh
-        @battery_kwh = 0.0
-        p "Battery is now at %s kwh" % @battery_kwh
+        old_kwh = @@battery_kwh
+        @@battery_kwh = 0.0
+        p "Battery is now at %s kwh" % @@battery_kwh
         return old_kwh
       end        
     end  
-
-    MAX_CHARGE_KWH = 7.0  
     
     def hours(date, year_shift=0)
       hour_start = date.beginning_of_day