Edited version of "ups2" munin plugin to handle some custom MIBS for MGE UPS (EATON 1500i in my case). Source of MIBS: http://soft.apc.com/emb/66244/mgeupsmib17_ac.mib

snmp__apc_ups2_

#!/usr/bin/perl -w
#
# Jean-Samuel Reynaud <js.reynaud@free.fr>
# base on snmp__if_ from Jimmy Olsen, Dagfinn Ilmari Mannsaaker
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; version 2 dated June,
# 1991.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
#
#
# Usage:
# ln -s /usr/share/munin/node/plugins-auto/snmp__ups2_ /etc/munin/node.d/snmp_ups.address.loc_mode
# with mode : batteryVoltage, batteryTemperature,inputVoltage,inputCurrent,inputFrequency,outputVoltage,outputCurrent,outputPower,outputPercentLoad,ChargeRemaining
#

#%# family=snmpauto
#%# capabilities=snmpconf



use strict;
use Net::SNMP;

my $DEBUG = 0;

my $host      = $ENV{host}      || undef;
my $port      = $ENV{port}      || 161;
my $community = $ENV{community} || "public";
my $mode     = $ENV{mode} || undef;

my $response;

if (defined $ARGV[0] and $ARGV[0] eq "snmpconf")
{
    print "require .1.3.6.1.2.1.33.1.2.7 [0-9]\n"; # Bat temp
    exit 0;
}


if ($0 =~ /^(?:|.*\/)snmp_([^_]+)_apc_ups2_(.+)$/)
{
        $host  = $1;
        $mode = $2;
        if ($host =~ /^([^:]+):(\d+)$/)
        {
                $host = $1;
                $port = $2;
        }
}
elsif (!defined($host))
{
        print "# Debug: $0 -- $1 -- $2\n" if $DEBUG;
        die "# Error: couldn't understand what I'm supposed to monitor.";
}



my $graphs = {
#### BATTERY
    'batteryVoltage' => { 'title' => 'Battery Voltage',
                          'category' => 'battery',
                          'unit' => 'V',
                          'value' => '.1.3.6.1.2.1.33.1.2.5'},
    
    'batteryCurrent' => { 'title' => 'Battery Current',
                          'category' => 'battery',
                          'unit' => 'kVA', 'value' => 
                          '.1.3.6.1.4.1.705.1.6.1.0'},
    
    'batteryTemperature' => { 'title' => 'Battery Temperature',
                              'category' => 'battery',
                              'unit' => 'DegC',
                              'value' => '.1.3.6.1.2.1.33.1.2.7'},
    
    'batteryRemainingTime' => { 'title' => 'Battery Remaining Time',
                                'category' => 'battery',
                                'unit' => 's',
                                'value' => '.1.3.6.1.4.1.705.1.5.1.0'},

   'ChargeRemaining' => { 'title' => 'Charge remaining',
                          'unit' => '%',
                          'category' => 'battery',
                          'value' => '.1.3.6.1.2.1.33.1.2.4'},

#### INPUT
    'inputVoltage' => { 'title' => 'Input Voltage',
                        'category' => 'input',
                        'unit' => 'V',
#                        'list' =>  '.1.3.6.1.4.1.705.1.6.1.0',
                        'value' => '.1.3.6.1.4.1.705.1.6.2.1.2.1.0'},
    'inputCurrent' => { 'title' => 'Input Current',
                        'category' => 'input',
                        'unit' => 'W',
                        'list' => '.1.3.6.1.2.1.33.1.3.2',
                        'value' => '.1.3.6.1.2.1.33.1.3.3.1.4'},
    'inputFrequency' => { 'title' => 'Input Frequency',
                        'category' => 'input',
                        'unit' => 'Hz',
#                        'list' =>  '.1.3.6.1.4.1.705.1.6.1.0',
                        'value' => '.1.3.6.1.4.1.705.1.6.2.1.3.1.0'},


#### OUTPUT
    'outputVoltage' => { 'title' => 'Output Voltage',
                        'category' => 'output',
                        'list' => '.1.3.6.1.4.1.705.1.7.1.0',
                        'unit' => 'Hz',
                        'value' => '.1.3.6.1.4.1.705.1.7.2.1.2'},
    'outputCurrent' => { 'title' => 'Output Current',
                        'category' => 'output',
                        'unit' => 'A',
                        'list' => '.1.3.6.1.4.1.705.1.7.1.0',
                        'value' => '.1.3.6.1.4.1.705.1.7.2.1.5'},
    'outputFrequency' => { 'title' => 'Output Frequency',
                        'category' => 'output',
                        'list' => '.1.3.6.1.4.1.705.1.7.1.0',
                        'unit' => 'Hz',
                        'value' => '.1.3.6.1.4.1.705.1.7.2.1.3'},

    'outputPercentLoad' => { 'title' => 'Output PercentLoad',
                             'category' => 'output',
                             'list' => '.1.3.6.1.2.1.33.1.4.3',
                             'unit' => '%',
                             'value' => '.1.3.6.1.2.1.33.1.4.4.1.5'},
    
    'outputOnBattery' => { 'title' => 'Output On Battery',
                           'category' => 'output',
                           'unit' => '(1 = yes, 2 = no)',
                           'value' => '.1.3.6.1.4.1.705.1.7.3.0'},
};


my ($session, $error) = Net::SNMP->session(
                -hostname  => $host,
                -community => $community,
                -port      => $port
        );

if (!defined ($session))
{
        die "Croaking: $error";
}

my $count_data = 1;
if (defined $graphs->{$mode}->{'list'}  &&
    defined ($response = $session->get_request($graphs->{$mode}->{'list'} . ".0"))) {
    $count_data = $response->{$graphs->{$mode}->{'list'} . ".0"};

}

if ($ARGV[0] and $ARGV[0] eq "config")
{
        print "host_name $host\n";
    printf "graph_title %s \n",$graphs->{$mode}->{'title'};
#       print "graph_args --base 1000\n";
        print "graph_category sensors\n";


    for(my $i=0;$i<$count_data;$i++) {
        printf "line%u.label Line %u\n",$i+1,$i+1;
        printf "line%u.type GAUGE\n",$i+1;
        printf "line%u.info %s\n",$i+1,$graphs->{$mode}->{'unit'};
    }
        exit 0;
}

for(my $i=0;$i<$count_data;$i++) {
    my $l_current = $i+1;
#    if ($count_data == 1) {
 #       $l_current = 0;
  #  }
    my $key = $graphs->{$mode}->{'value'};
    if (defined ($graphs->{$mode}->{'list'})) {
        $key = $key . sprintf(".%u",$l_current);
    }
    if (defined ($response = $session->get_request($key))) {
        printf "line%u.value %u\n",$i+1,$response->{$key};
    } else {
        printf "line%u.value U\n",$i+1;
    }

}