In order to find the problem you need a multi-meter to measure current so you can do a parasitic draw test. Unhook the negative battery cable and hook up the multi-meter between the battery cable and the battery.
You should now get a current reading, I don't remember what the Chargers should read, because it's been a couple years since I've had to do one, but it should be a few hundred milliamps to several. This reading depends on how much equipment is installed but it should not be over 1amp, if it is then you defiantly have a problem. Start pulling fuses one at a time, re-installing them before you move on to the next one. When you get to one that drops the current significantly, not just a couple milliamps, then you have found your problem. Start with the camera system first since it was the last thing to be installed.
Important notes: After the multi-meter is hooked up the cars computer systems will start up for a short period. It's best to watch the meter for a small drop in current to ensure the computers have went into sleep mode and won't give you a false positive making you think you found a problem. Sometimes you can hear them turn on and off.
It's the same reason to shut off the interior lights or wait for them to time out, if you can turn them off do so or find and pull the fuse for them. On the charger I usually unplug the light in the trunk during the test.
It's also a good idea to open all the doors because if you open a door during the test you will cause the vehicles computers to come out of sleep mode.
Finally, if you start the car up or trigger the ignition you will have to wait for all the equipment to fully shut down. So you will have to wait 2 hrs before doing the test to let the camera system turn off or reprogram it to turn off sooner for the tests.