Rens metal detectors

[Brad_S.]

I plan on attending an auction at yet another sawmill dispersal in a couple weeks. I have high hopes of acquiring a Rens metal detector, model unknown, for a price within my budget. I just got done with a search here on the forum and have 2 concerns with the unit.
First is the battery issue. There was talk in threads from 5 years ago that the battery needed replacement rather often to the tune of $400 a pop using prices from back then. Is this true or did one member just have a bum machine?
I'm also wondering if it is over kill. There was talk of being able to "see" right through the log and even picking up buried pipe and re-bar below the log!. I would like to be able to pinpoint the metal so it could be cut out but seeing right through the log would make it hard to zero in on the source.
I'm not looking for input on other brands, that has been covered in great depth in past threads. I would like to hear from Rens owners . Thanks.