It will lock but the levers have to be already engaged (handle have been pushed up)
I've got one running with the module, personally, I've found the module reduces battery life quite a lot, and with the whole having the put the handle up for it to work makes it a bit irritating in my opinion.
Not having a key isn't a real issue as if it did die there is a 9v terminal on the outside you can hold a battery to and then unlock it with the fob (or whatever means) You also get plenty of warning with the batteries as the lock changes lock tone when they are running low (which is way before they die)
Personally, try another option.
