Yes, our mix and metals are different... conduits are made out of aluminum
with alodine surface treatment.  Many of the components cooled by these
conduits use copper heat exchangers to couple heat from dielectric gas to the
liquid coolant.  Some of the big conduits are steel (stainless I think)...
the resisistivity of the coolant is constantly monitored on the radar
operator's control panel... and a preset level, when passed below by the
meter, triggers a high voltage shutdown.  Cool, huh?  Perhaps if we monitored
our coolant resisitivity in real time we could set up our ECU's to shutdown
when the Megohms get too low.... just a thought

<< Your mix is different but so are your components - our phosphate free
 coolant that we mix with water is not 100% ethylene glycol. Interesting that
 for an electric system you're using distilled water... so this may apply to
 avoiding corrosion through electrolysis??? >>

Scott De Santi
86 Vanagon 2WD (The Wobbly Bus)
Anchorage, Alaska