diff --git a/includes/common.php b/includes/common.php
index 0a10d69dd..aaa4d6ea2 100644
--- a/includes/common.php
+++ b/includes/common.php
@@ -2,6 +2,15 @@
 
 ## Common Functions
 
+function sgn($int){
+  if($int < 0)
+    return -1;
+  elseif($int == 0)
+    return 0;
+  else
+    return 1;
+}
+
 function get_sensor_rrd($device, $sensor)
 {
   global $config;
diff --git a/includes/discovery/functions.inc.php b/includes/discovery/functions.inc.php
index 6b48674fc..a09b09c80 100644
--- a/includes/discovery/functions.inc.php
+++ b/includes/discovery/functions.inc.php
@@ -87,7 +87,7 @@ function sensor_low_limit($class, $current)
       $limit = $current * 0.7;
       break;
     case 'voltage':
-      $limit = $current * 0.85;
+      $limit = $current * (1 - (sgn($current) * 0.15));
       break;
     case 'humidity':
       $limit = "70";
@@ -119,7 +119,7 @@ function sensor_limit($class, $current)
       $limit = $current * 1.60;
       break;
     case 'voltage':
-      $limit = $current * 1.15;
+      $limit = $current * (1 + (sgn($current) * 0.15));
       break;
     case 'humidity':
       $limit = "70";
diff --git a/scripts/removespikes.pl b/scripts/removespikes.pl
new file mode 100644
index 000000000..b26a0774c
--- /dev/null
+++ b/scripts/removespikes.pl
@@ -0,0 +1,140 @@
+#!/usr/bin/perl -w
+#
+# matapicos v2.1 - Vins Vilaplana <vins at terra dot es)
+#
+# Translated by Humberto Rossetti Baptista <humberto at baptista dot name)
+# slight adjustments and code cleanup too :-)
+#
+
+require "getopts.pl";
+
+my (@dump,%exp,@cols,@dbak,%tot,%por);
+my ($linea,$linbak,$lino,$cdo,$tresto,$tstamp,$a,$b,$cont);
+my $DEBUG = 0;
+
+# Limit % for cutting. Any peak representing less than this % will be cut
+my $LIMIT=0.6; # obs this is really %, so 0.6 means 0.6% (and not 0.006%!)
+
+&Getopts('l:');
+
+if ($#ARGV < 0) {
+   print "REMOVESPIKES: Remove spikes from RRDtool databases.\n\n";
+   print "Usage:\n";
+   print "$0 [-l number]  name_of_database\n\n";
+   print "Where: number is the % limit of spikes to chop (default: $LIMIT)\n";
+   print "       and name_of_database ir the rrd file to be treated.\n";
+   exit;
+}
+
+if ($opt_l) { 
+   $LIMIT=$opt_l; 
+   print "Limit set to $LIMIT\n" if $DEBUG;
+}
+
+# temporary filename:
+# safer this way, so many users can run this script simultaneusly
+my $tempfile="/tmp/matapicos.dump.$$"; 
+
+###########################################################################
+# Dump the rrd database to the temporary file (as XML)
+`rrdtool dump $ARGV[0] > $tempfile`;
+
+# Scan the XML dump checking the variations and exponent deviations
+open(FICH,"<$tempfile") 
+   || die "$0: Cannot open file $tempfile:\n $! - $@";
+
+while (<FICH>) {
+  chomp;
+  $linea=$_;
+  $cdo=0;
+  if ($linea=~/^(.*)<row>/) { $tstamp=$1; }
+  if ($linea=~/(<row>.*)$/) { $tresto=$1; }
+  if (/<v>\s\d\.\d+e.(\d+)\s<\/v>/) {
+    @dump = split(/<\/v>/, $tresto);
+    for ($lino=0; $lino<=$#dump-1; $lino++) {   # scans DS's within each row 
+      if ( $dump[$lino]=~/\d\.\d+e.(\d+)\s/ ) { # make sure it is a number (and not NaN)
+        $a=substr("0$lino",-2).":".$1;
+        $exp{$a}++;                             # store exponents
+        $tot{substr("0$lino",-2)}++;            # and keep a per DS total
+      }
+    }
+  }
+}
+
+close FICH;
+
+###########################################################################
+# Scan the hash to get the percentage variation of each value
+foreach $lino (sort keys %exp) {
+  ($a)=$lino=~/^(\d+)\:/;                      
+  $por{$lino}=(100*$exp{$lino})/$tot{$a};
+}
+
+if ($DEBUG) { 
+   # Dumps percentages for debugging purposes
+   print "--percentages--\n";
+   foreach $lino (sort keys %exp) {
+     print $lino."--".$exp{$lino}."/";
+     ($a)=$lino=~/^(\d+)\:/;
+     print $tot{$a}." = ".$por{$lino}."%\n";
+   }
+   print "\n\n\n";
+}
+
+
+###########################################################################
+# Open the XML dump, and create a new one removing the spikes:
+open(FICH,"<$tempfile") || 
+   die "$0: Cannot open $tempfile for reading: $!-$@";
+open(FSAL,">$tempfile.xml")  || 
+   die "$0: Cannot open $tempfile.xml for writing: $!-$@";
+
+$linbak='';
+$cont=0;
+while (<FICH>) {
+  chomp;
+  $linea=$_;
+  $cdo=0;
+  if ($linea=~/^(.*)<row>/) { $tstamp=$1; }     # Grab timestamp
+  if ($linea=~/(<row>.*)$/) { $tresto=$1; }     # grab rest-of-line :-)
+  if (/<v>\s\d\.\d+e.(\d+)\s<\/v>/) {           # are there DS's?
+    @dump=split(/<\/v>/, $tresto);              # split them
+    if ($linbak ne '') {
+      for ($lino=0;$lino<=$#dump-1;$lino++) {   # for each DS:
+        if ($dump[$lino]=~/\d\.\d+e.(\d+)\s/) { # grab number (and not a NaN)
+          $a=$1*1;                              # and exponent
+          $b=substr("0$lino",-2).":$1";         # calculate the max percentage of this DS
+          if ($por{$b}< $LIMIT) {               # if this line represents less than $LIMIT
+            $linea=$tstamp.$linbak;             # we dump it.
+            $cdo=1;
+            $tresto=$linbak;
+          }
+        }
+      }
+    }
+    $linbak=$tresto;
+    if ($cdo==1) { 
+      print "Chopping peak at $tstamp\n";
+      $cont++; }
+  }
+  
+  print FSAL "$linea\n";
+}
+close FICH;
+close FSAL;
+
+###########################################################################
+# Cleanup and move new file to the place of original one
+# and original one gets backed up.
+if ($cont == 0) { print "No peaks found.!\n"; }
+else {
+  rename($ARGV[0],"$ARGV[0].old");
+  $lino="rrdtool restore $tempfile.xml $ARGV[0]";
+  system($lino);
+  die "$0: Unable to execute the rrdtool restore on $ARGV[0] - $! - $@\n"  if $!;
+}
+
+# cleans up the files created
+unlink("$tempfile");
+unlink("$tempfile.xml");
+