I think I answered this already as best I could.
However, now that I thought more about it, Im not sure I can.
Where have you seen the spec for the 850? Seriously. haha Kidding...
The battery was first shown in RISE OF THE MACHINES.
That's what I shot for.
In the Next Film, the adult John Conner once again uses the batteries to blow up SKYNET.
THose batteries were the same batteries, they used different lighting.
If you want to believe they were for another Model of Terminator, 850, 875, or whatever. Cool. I'll go with it, but I dont know where it says that offically.
Seeing these were in the lab were he actually fights the T-800 (insert Arnie Cameo) for all we know these were supposed to be the T-800 power units. They just went cheap on the lighting by stuffing it with a few crappy RED Blinking LEDS, and fake boards.
At least ROTM had real boards in them, even if they were not very bright. I have two from production and its amazing they should up at all, no wonder Stan threw a &^%fit and asked for an improved version with more lights. However, I think it was probably "fixed" in post.