Prochem battery dies quickly

I have bought my 3rd battery in like a month for my Prochem legend SE ..Installed it and the next day it is dead ..Nothing is left on and the key is turned off . It drains it so much I have to crank my van to jump it at every job and if I remove the jumper cables while working my TM turns off instantly ..Any ideas what the problem may be ?
Also it's not a prochem battery !! !I meant Prochem truckmount
Thanks and I hope everybody had a wonderful Thanksgiving .
Damion