diff --git a/actions-qrcode.php b/actions-qrcode.php
index 4675f256..fa29d48a 100644
--- a/actions-qrcode.php
+++ b/actions-qrcode.php
@@ -41,11 +41,11 @@ function rent($userId,$bike,$force=FALSE)
 
    $stacktopbike=FALSE;
    $bikeNum = $bike;
-   $requiredcredit=$credit["min"]+$credit["rent"]+$credit["longrental"];
+   $minRequiredCredit = $creditSystem->getMinRequiredCredit();
 
    $creditcheck=checkrequiredcredit($userId);
     if ($creditcheck === false) {
-        response(_('You are below required credit') . " " . $requiredcredit . $creditSystem->getCreditCurrency() . ". " . _('Please, recharge your credit.'), ERROR);
+        response(_('You are below required credit') . " " . $minRequiredCredit . $creditSystem->getCreditCurrency() . ". " . _('Please, recharge your credit.'), ERROR);
     }
    checktoomany(0,$userId);
 
diff --git a/actions-sms.php b/actions-sms.php
index 32e5e0a4..a19c2659 100644
--- a/actions-sms.php
+++ b/actions-sms.php
@@ -106,19 +106,19 @@ function credit($number)
 
 function rent($number,$bike,$force=FALSE)
 {
-    global $db,$forcestack,$watches,$credit, $smsSender, $user, $creditSystem;
+    global $db, $forcestack, $watches, $credit, $smsSender, $user, $creditSystem;
 
-        $stacktopbike=FALSE;
+    $stacktopbike = FALSE;
     $userId = $user->findUserIdByNumber($number);
-   $bikeNum = intval($bike);
-   $requiredcredit=$credit["min"]+$credit["rent"]+$credit["longrental"];
+    $bikeNum = intval($bike);
+    $minRequiredCredit = $creditSystem->getMinRequiredCredit();
 
    if ($force==FALSE)
            {
            $creditcheck=checkrequiredcredit($userId);
            if ($creditcheck === false) {
                $userRemainingCredit = $creditSystem->getUserCredit($userId);
-               $smsSender->send($number, _('Please, recharge your credit:') . " " . $userRemainingCredit . $creditSystem->getCreditCurrency() . ". " . _('Credit required:') . " " . $requiredcredit . $creditSystem->getCreditCurrency() . ".");
+               $smsSender->send($number, _('Please, recharge your credit:') . " " . $userRemainingCredit . $creditSystem->getCreditCurrency() . ". " . _('Credit required:') . " " . $minRequiredCredit . $creditSystem->getCreditCurrency() . ".");
                return;
            }
 
diff --git a/actions-web.php b/actions-web.php
index 752e9878..aa51a76b 100644
--- a/actions-web.php
+++ b/actions-web.php
@@ -32,12 +32,12 @@ function rent($userId, $bike, $force = false)
 
     $stacktopbike = false;
     $bikeNum = $bike;
-    $requiredcredit = $credit['min'] + $credit['rent'] + $credit['longrental'];
+    $minRequiredCredit = $creditSystem->getMinRequiredCredit();
 
     if ($force == false) {
         $creditcheck = checkrequiredcredit($userId);
         if ($creditcheck === false) {
-            response(_('You are below required credit') . ' ' . $requiredcredit . $creditSystem->getCreditCurrency() . '. ' . _('Please, recharge your credit.'), ERROR);
+            response(_('You are below required credit') . ' ' . $minRequiredCredit . $creditSystem->getCreditCurrency() . '. ' . _('Please, recharge your credit.'), ERROR);
         }
         checktoomany(0, $userId);
 
@@ -605,8 +605,8 @@ function addcredit($userid, $creditmultiplier)
 {
     global $db, $credit, $user, $creditSystem;
 
-    $requiredcredit = $credit['min'] + $credit['rent'] + $credit['longrental'];
-    $addcreditamount = $requiredcredit * $creditmultiplier;
+    $minRequiredCredit = $creditSystem->getMinRequiredCredit();
+    $addcreditamount = $minRequiredCredit * $creditmultiplier;
     $result = $db->query('UPDATE credit SET credit=credit+' . $addcreditamount . ' WHERE userId=' . $userid);
     $result = $db->query("INSERT INTO history SET userId=$userid,bikeNum=0,action='CREDITCHANGE',parameter='" . $addcreditamount . '|add+' . $addcreditamount . "'");
     $userName = $user->findUserName($userid);
@@ -636,8 +636,8 @@ function generatecoupons($multiplier)
         return;
     }
     // if credit system disabled, exit
-    $requiredcredit = $credit['min'] + $credit['rent'] + $credit['longrental'];
-    $value = $requiredcredit * $multiplier;
+    $minRequiredCredit = $creditSystem->getMinRequiredCredit();
+    $value = $minRequiredCredit * $multiplier;
     $codes = $codeGenerator->generate(10, 6);
     foreach ($codes as $code) {
         $result = $db->query("INSERT IGNORE INTO coupons SET coupon='" . $code . "',value='" . $value . "',status='0'");
diff --git a/admin.php b/admin.php
index 486c1515..d993b41e 100644
--- a/admin.php
+++ b/admin.php
@@ -53,7 +53,7 @@
 if ($creditSystem->isEnabled()) {
     echo 'var creditenabled=1;' . PHP_EOL;
     echo 'var creditcurrency="' . $creditSystem->getCreditCurrency() . '"' . PHP_EOL;
-    $requiredcredit = $credit["min"] + $credit["rent"] + $credit["longrental"];
+    $minRequiredCredit = $creditSystem->getMinRequiredCredit();
 } else {
     echo 'var creditenabled=0;', "\n";
 }
@@ -135,9 +135,9 @@
       <div class="row">
          <div class="col-lg-12">
          <button type="button" id="listcoupons" class="btn btn-default" title="<?php echo _('Display existing coupons.'); ?>"><span class="glyphicon glyphicon-list-alt"></span> <?php echo _('List coupons'); ?></button>
-         <button type="button" id="generatecoupons1" class="btn btn-success" title="<?php echo _('Generate new coupons.'); ?>"><span class="glyphicon glyphicon-plus"></span> <?php echo _('Generate'); echo ' ',$requiredcredit,$creditSystem->getCreditCurrency(),' '; echo _('coupons'); ?></button>
-         <button type="button" id="generatecoupons2" class="btn btn-success" title="<?php echo _('Generate new coupons.'); ?>"><span class="glyphicon glyphicon-plus"></span> <?php echo _('Generate'); echo ' ',$requiredcredit*5,$creditSystem->getCreditCurrency(),' '; echo _('coupons'); ?></button>
-         <button type="button" id="generatecoupons3" class="btn btn-success" title="<?php echo _('Generate new coupons.'); ?>"><span class="glyphicon glyphicon-plus"></span> <?php echo _('Generate'); echo ' ',$requiredcredit*10,$creditSystem->getCreditCurrency(),' '; echo _('coupons'); ?></button>
+         <button type="button" id="generatecoupons1" class="btn btn-success" title="<?php echo _('Generate new coupons.'); ?>"><span class="glyphicon glyphicon-plus"></span> <?php echo _('Generate'); echo ' ',$minRequiredCredit,$creditSystem->getCreditCurrency(),' '; echo _('coupons'); ?></button>
+         <button type="button" id="generatecoupons2" class="btn btn-success" title="<?php echo _('Generate new coupons.'); ?>"><span class="glyphicon glyphicon-plus"></span> <?php echo _('Generate'); echo ' ',$minRequiredCredit*5,$creditSystem->getCreditCurrency(),' '; echo _('coupons'); ?></button>
+         <button type="button" id="generatecoupons3" class="btn btn-success" title="<?php echo _('Generate new coupons.'); ?>"><span class="glyphicon glyphicon-plus"></span> <?php echo _('Generate'); echo ' ',$minRequiredCredit*10,$creditSystem->getCreditCurrency(),' '; echo _('coupons'); ?></button>
          <div id="creditconsole"></div>
          </div>
       </div>
@@ -159,9 +159,9 @@
          <div class="form-group"><label for="limit"><?php echo _('Bike limit:'); ?></label> <input type="text" name="limit" id="limit" class="form-control" /></div>
          <input type="hidden" name="userid" id="userid" value="" />
          <button type="button" id="saveuser" class="btn btn-primary"><?php echo _('Save'); ?></button>
-         or <button type="button" id="addcredit" class="btn btn-success"><?php echo _('Add'); echo ' ',$requiredcredit,$creditSystem->getCreditCurrency(); ?></button>
-         <button type="button" id="addcredit2" class="btn btn-success"><?php echo _('Add'); echo ' ',$requiredcredit*5,$creditSystem->getCreditCurrency(); ?></button>
-         <button type="button" id="addcredit3" class="btn btn-success"><?php echo _('Add'); echo ' ',$requiredcredit*10,$creditSystem->getCreditCurrency(); ?></button>
+         or <button type="button" id="addcredit" class="btn btn-success"><?php echo _('Add'); echo ' ',$minRequiredCredit,$creditSystem->getCreditCurrency(); ?></button>
+         <button type="button" id="addcredit2" class="btn btn-success"><?php echo _('Add'); echo ' ',$minRequiredCredit*5,$creditSystem->getCreditCurrency(); ?></button>
+         <button type="button" id="addcredit3" class="btn btn-success"><?php echo _('Add'); echo ' ',$minRequiredCredit*10,$creditSystem->getCreditCurrency(); ?></button>
       </form>
       <div id="userconsole"></div>
     </div>
diff --git a/common.php b/common.php
index d42751cf..1b97a4e4 100644
--- a/common.php
+++ b/common.php
@@ -320,17 +320,17 @@ function checktoomany($cron = 1, $userid = 0)
 // check if user has credit >= minimum credit+rent fee+long rental fee
 function checkrequiredcredit($userid)
 {
-    global $credit, $creditSystem;
+    global $creditSystem;
 
     if ($creditSystem->isEnabled() == false) {
         return;
     }
     // if credit system disabled, exit
 
-    $requiredCredit = $credit['min'] + $credit['rent'] + $credit['longrental'];
+    $minRequiredCredit = $creditSystem->getMinRequiredCredit();
 
     $userRemainingCredit = $creditSystem->getUserCredit($userid);
-    if ($userRemainingCredit >= $requiredCredit) {
+    if ($userRemainingCredit >= $minRequiredCredit) {
         return true;
     }
 
diff --git a/install/index.php b/install/index.php
index ab7eaf46..383d00c1 100644
--- a/install/index.php
+++ b/install/index.php
@@ -1,6 +1,8 @@
 <?php
 //@TODO ANaLYTICS!!!
 
+use BikeShare\Credit\CreditSystemFactory;
+use BikeShare\Credit\CreditSystemInterface;
 use BikeShare\Db\DbInterface;
 use BikeShare\Db\MysqliDb;
 use Monolog\ErrorHandler;
@@ -412,6 +414,11 @@ function return_bytes($val) {
  */
 $db = new MysqliDb($dbserver, $dbuser, $dbpassword, $dbname, $logger);
 $db->connect();
+/**
+ * @var CreditSystemInterface $creditSystem
+ */
+$creditSystem = (new CreditSystemFactory())->getCreditSystem($credit, $db);
+
 $configfile=file($configfilename);
 foreach ($_POST as $variable=>$value)
    {
@@ -430,13 +437,12 @@ function return_bytes($val) {
 $newconfig=implode($configfile);
 file_put_contents($configfilename,$newconfig);
 $configfile=file($configfilename);
-if ($credit["enabled"]==1)
-   {
-   $newcredit=($credit["min"]+$credit["rent"]+$credit["longrental"])*10;
-   $result=$db->query("SELECT userId FROM users WHERE privileges='7'");
-   $row=$result->fetch_assoc();
-   $result=$db->query("REPLACE INTO credit SET userId='".$row["userId"]."',credit='$newcredit'");
-   }
+if ($creditSystem->isEnabled()) {
+    $newcredit = $creditSystem->getMinRequiredCredit() * 10;
+    $result = $db->query("SELECT userId FROM users WHERE privileges='7'");
+    $row = $result->fetch_assoc();
+    $result = $db->query("REPLACE INTO credit SET userId='" . $row["userId"] . "',credit='$newcredit'");
+}
 $db->commit();
 ?>
       <h2>Installation finished</h2>
diff --git a/src/Credit/CreditSystem.php b/src/Credit/CreditSystem.php
index 41314e73..987005c6 100644
--- a/src/Credit/CreditSystem.php
+++ b/src/Credit/CreditSystem.php
@@ -11,7 +11,7 @@ class CreditSystem implements CreditSystemInterface
     // currency used for credit system
     private $creditCurrency = "€";
     // minimum credit required to allow any bike operations
-    private $minBikeCredit = 2;
+    private $minBalanceCredit = 2;
     // rental fee (after $watches["freetime"])
     private $rentalFee = 2;
     // 0 = disabled, 1 = charge flat price $credit["rent"] every $watches["flatpricecycle"] minutes,
@@ -47,6 +47,11 @@ public function getUserCredit($userid)
         return $result->fetchAssoc()['credit'];
     }
 
+    public function getMinRequiredCredit()
+    {
+        return $this->minBalanceCredit + $this->rentalFee + $this->longRentalFee;
+    }
+
     /**
      * @return bool
      */
@@ -62,14 +67,6 @@ public function getCreditCurrency()
         return $this->creditCurrency;
     }
 
-    /**
-     * @return int
-     */
-    public function getMinBikeCredit()
-    {
-        return $this->minBikeCredit;
-    }
-
     /**
      * @return int
      */
@@ -123,7 +120,7 @@ private function parseConfiguration(array $creditConfiguration)
             $this->creditCurrency = (string)$creditConfiguration['currency'];
         }
         if (isset($creditConfiguration['min'])) {
-            $this->minBikeCredit = (int)$creditConfiguration['min'];
+            $this->minBalanceCredit = (int)$creditConfiguration['min'];
         }
         if (isset($creditConfiguration['rent'])) {
             $this->rentalFee = (int)$creditConfiguration['rent'];
diff --git a/src/Credit/CreditSystemInterface.php b/src/Credit/CreditSystemInterface.php
index c668ad3a..8d03c923 100644
--- a/src/Credit/CreditSystemInterface.php
+++ b/src/Credit/CreditSystemInterface.php
@@ -9,6 +9,11 @@ interface CreditSystemInterface
      */
     public function getUserCredit($userid);
 
+    /**
+     * @return int
+     */
+    public function getMinRequiredCredit();
+
     /**
      * @return bool
      */
@@ -19,11 +24,6 @@ public function isEnabled();
      */
     public function getCreditCurrency();
 
-    /**
-     * @return int
-     */
-    public function getMinBikeCredit();
-
     /**
      * @return int
      */
diff --git a/src/Credit/DisabledCreditSystem.php b/src/Credit/DisabledCreditSystem.php
index 0937ecdb..25fb4546 100644
--- a/src/Credit/DisabledCreditSystem.php
+++ b/src/Credit/DisabledCreditSystem.php
@@ -9,17 +9,17 @@ public function getUserCredit($userid)
         return 0;
     }
 
-    public function isEnabled()
+    public function getMinRequiredCredit()
     {
-        return false;
+        return PHP_INT_MAX;
     }
 
-    public function getCreditCurrency()
+    public function isEnabled()
     {
-        return 0;
+        return false;
     }
 
-    public function getMinBikeCredit()
+    public function getCreditCurrency()
     {
         return 0;
     }
diff --git a/tests/Credit/CreditSystemTest.php b/tests/Credit/CreditSystemTest.php
index 37435ad3..aaee3568 100644
--- a/tests/Credit/CreditSystemTest.php
+++ b/tests/Credit/CreditSystemTest.php
@@ -16,7 +16,7 @@ public function testConstructor(
         $configuration,
         $expectedIsEnabled,
         $expectedCreditCurrency,
-        $expectedMinBikeCredit,
+        $expectedMinRequiredCredit,
         $expectedRentalFee,
         $expectedPriceCycle,
         $expectedLongRentalFee,
@@ -26,7 +26,7 @@ public function testConstructor(
         $creditSystem = new CreditSystem($configuration, $this->createMock(DbInterface::class));
         $this->assertEquals($expectedIsEnabled, $creditSystem->isEnabled());
         $this->assertEquals($expectedCreditCurrency, $creditSystem->getCreditCurrency());
-        $this->assertEquals($expectedMinBikeCredit, $creditSystem->getMinBikeCredit());
+        $this->assertEquals($expectedMinRequiredCredit, $creditSystem->getMinRequiredCredit());
         $this->assertEquals($expectedRentalFee, $creditSystem->getRentalFee());
         $this->assertEquals($expectedPriceCycle, $creditSystem->getPriceCycle());
         $this->assertEquals($expectedLongRentalFee, $creditSystem->getLongRentalFee());
@@ -40,7 +40,7 @@ public function constructorDataProvider()
             'configuration' => [],
             'expectedIsEnabled' => false,
             'expectedCreditCurrency' => '€',
-            'expectedMinBikeCredit' => 2,
+            'expectedMinRequiredCredit' => 9,
             'expectedRentalFee' => 2,
             'expectedPriceCycle' => 0,
             'expectedLongRentalFee' => 5,
@@ -60,7 +60,7 @@ public function constructorDataProvider()
             ],
             'expectedIsEnabled' => true,
             'expectedCreditCurrency' => '$',
-            'expectedMinBikeCredit' => 3,
+            'expectedMinRequiredCredit' => 12,
             'expectedRentalFee' => 3,
             'expectedPriceCycle' => 1,
             'expectedLongRentalFee' => 6,