And below is how Orion BMS suggests troubleshooting be done (
http://www.orionbms.com/troubleshooting/p0aa6-high-voltage-isolation-fault ). Again, this is not for the Zero, just FYI.
"Resolving the issue:
Step 1. Determine if the system is supposed to be isolated and if other isolation detection circuits are connected at the same time.
If the overall system is intentionally designed to be non-isolated, isolation fault detection should be disabled. Other isolation fault detection circuits operating on the same battery pack may interfere with each other and cause false readings.
Step 2. Check the instantaneous isolation “shortest wave†reading.
The instantaneous value for the isolation fault detection can be monitored in the Orion BMS utility by looking at the “Shortest Wave†measurement on the Live Text Data screen and selecting the “Advanced Parameters.†Every BMS unit has some variation for the maximum and minimum readings, but the readings are generally between 1.4 and 4.8, with the higher number meaning better isolation. Over 4.5 generally indicates insulation over 1M ohm and below 1.5 indicates a likely dead short, but external factors can change the exact numbers.
Step 3. If isolation is degraded only when cold, it may be due to condensation.
Water may condense on cold cables, battery terminals or other exposed connections and create a path for current to travel to the chassis or low voltage system. Additionally, conductors and cells may expand and contract and physically come into contact with other parts.
Step 4. If the isolation is degraded according to the shortest wave value, attempt to isolate various systems while monitoring the shortest wave measurement in the Orion BMS to see if removing a system improves the isolation number.
For example, if a battery charger can be disconnected or fully isolated from the battery pack, disconnect it and look to see if the isolation improves. If isolation improves after removing a part, investigate the cause of isolation breakdown or replace the defective system. Care must be taken to prevent personal injury and prevent shorting cells since a cell may be shorted to the chassis causing the chassis to be “hot.†Simply touching a cell and the chassis may cause a shock. If safe to do so, disconnect any device which may have extra capacitance to ground (chargers, inverters, DC:DC converters or any cabling which may have excessive parasitic capacitance.
Step 5. If the shortest wave measurement is still showing degraded isolation after the above steps have been performed, look for isolation faults within the battery pack.
Isolation faults may occur due to leaked electrolyte, liquids shorting to the chassis, battery terminals shorted to the chassis, chafed wiring, conductive debris or other causes. As before, care must be taken while inspecting the battery pack to prevent personal injury and prevent shorting cells since a cell may be shorted to the chassis causing the chassis to be “hot.
Step 6. Verify correct operation of the isolation fault detection circuit on the Orion BMS.
Disconnect the total pack voltage sensor connector (the 8 pin connector with 2 wires) and ensure that the “shortest wave†measurement reads over 4.5."