There were several posts that were spot on here with what I found.
Yes the name changed to Xantrex, they told me the same thing that the sensor was there to refine the charging not really control it.
They also said that the failure of it would make the charger think the batteries were cold so the idea of plugging it in when it is hot outside is opposite of what I belive you should do, or at least to me it is.
I used to have fluid on top of my batteries (and honestly everywhere) till I unplugged it and added the Thermoil.
My temp sensor was in that sort of open part where the 4 batteries came together in the middle also when I got the MH, I move it to between two of the 4 house batteries thinking that would help, it did not.
Yea, the connection looks just like a phone jack at the inverter/converter/charger. I just unplugged it there. I ohmed the probe out and applied heat to it, the probe seemed to change resistance with heat so I think it works, maybe just not correctly?
This is a shot of my batteries 4-5 weeks after replacing the battery cables and cleaning everything to spotless! I also put the anti corrosion compound on the battery cable ends and terminals. This is sort of a thick red grease looking compound.
Just after that I cleaned everything up again, unplugged the sensor added the Thermoil and it fixed the problem.
A few months later (May of 2011) one of the batteries went bad so I replaced all 4 with new. This picture was taken 4 hours ago of the batteries installed in May of 2011 and I have done no prep or cleaning to them other than the Thermoil install back in May.
Once again, I am sold!