Well, I replaced the batteries in my Robotron with the Lithium Battery upgrade from Bob Roberts and it worked great. Had a little issue (wouldn't boot) at first, but that was probably my fault. The problem went away by itself, so it could have been garbage in NVRAM or a bad connection on the connectors.
I highly recommend this upgrade to your Williams boards. The Lithium battery will last a lot longer then the AA batteries and you don't have to worry about your board being destroyed from Battery Acid Damage. The kit is only $5 from Bob Roberts and only takes a few minutes to install.
Next up is Defender, Stargate, and probably Sinistar.