Outer Limits 4x4 Board

I am having a problem with my TD42 gq. Sometimes I have to leave it for a couple days, so I take off the negative cable as it seemingly has killed two batteries in the past(I could leave the mk connected for a month and still come back and start it). However, sometimes when I reconnect and try to start it, if anything was left on, it wont start and then a buzzing sound is heard. The way that the sound is stopped is to disconnect the battery. What could be the problem?

OK possibly your alternater diodes are crook and alowing the battery to discharge , check current draw when evrything is off(good auto elec recomended) if the batteries are wired direct to each other a crook battery can cause this problem
also the noise may be a relay vibrating due to low voltage relay clicks in and out(god luck)

i recharged the battery, but still getting the buzzing. Tomorrow i am going to check the battery connectors to make sure that they are ok. i also tried to turn on the interior light, but it doesnt come on every time since this problem.