Boy, am I steamed. I put all that effort into getting good pack isolation, and the next thing I know, the car has aground fault, seemingly right in the middle of the pack. The really weird thing is that I have an odd number of batteries, and the fault really is *exactly* in the middle of the pack. Voltage from ground to the positive terminal of the most positive battery in the rear pack is +2.8V. Voltage to the negative terminal is -3.6V (this was while charging). How is that possible?
For reference, I have 19 (10 in the back, 9 up front) brand new, spotless US-125's with only a few cycles on them. Up to this point, they had perfect isolation. I've checked the obvious things, and cannot find any reason for this. There is no corrosion, no acid misting or spills, no other wires that lead to ground in contact with the batteries or the posts, and all the connections are covered. The batteries sit on aluminum sheets which are on top of heater pads (not hooked up yet), which are on top of 1/8" thick fiberglass/nomex honeycomb panels. There is silicone heatsink grease between the batteries and the aluminum, and between the aluminum and the heater pads. there is silicone adhesive between the heater pads and the honeycomb, and between the honeycomb and the racks. If the batteries were dirty, I could see a fault between the rear rack and the center cell, conducting through acid mist. But as I said, these batteries are spotless, with no acid on the outsides. Any advice? David Brandt IMPORTANT - THIS MESSAGE (INCLUDING ANY ATTACHMENTS) IS INTENDED ONLY FOR THE USE OF THE INDIVIDUAL OR ENTITY TO WHICH IT IS ADDRESSED, AND MAY CONTAIN INFORMATION THAT IS PRIVILEGED, CONFIDENTIAL AND EXEMPT FROM DISCLOSURE UNDER APPLICABLE LAW. IF YOU ARE NOT THE INTENDED RECIPIENT, YOU SHOULD DELETE THIS MESSAGE IMMEDIATELY AND YOU ARE HEREBY NOTIFIED THAT ANY READING, DISSEMINATION, DISTRIBUTION OR COPYING OF THIS MESSAGE, OR THE TAKING OF ANY ACTION BASED ON IT IS STRICTLY PROHIBITED. THANK YOU.
