diff --git a/src/Service/InvoiceGenerator/CMBInvoiceGenerator.php b/src/Service/InvoiceGenerator/CMBInvoiceGenerator.php
index c0425f31..69b4e55a 100644
--- a/src/Service/InvoiceGenerator/CMBInvoiceGenerator.php
+++ b/src/Service/InvoiceGenerator/CMBInvoiceGenerator.php
@@ -363,9 +363,10 @@ class CMBInvoiceGenerator implements InvoiceGeneratorInterface
             if (!isset($con_batts[$batt_id]))
                 $con_batts[$batt->getID()] = [
                     'batt' => $batt,
-                    'qty' => 0
+                    'qty' => $qty
                 ];
-            $con_batts[$batt_id]['qty']++;
+            else
+                $con_batts[$batt_id]['qty'] += $qty;
 
 
             // no trade-in