Coolant leak
After seeing that the battery coolant level was low, we were concerned that it might be a leak. It’s also possible that there was an air bubble trapped in the lines that finally worked its way out, as well, but we needed to be sure.
After consulting with ZeroLabs, we used a scope to view the bottom of the battery pack from the access window. We ended up finding traces of coolant, not much, but enough to warrant further examination.
We removed the bottom of the battery box and found, thankfully, that there was no more coolant than what we saw. So, with the bottom off, we filled the coolant and ran the pumps for 24 hours and found no active leaks. We feel confident that the leak might have only been present during assembly of the pack and that the low coolant was due to an air bubble.
We did, however, find some condensation/moisture in one of the battery modules. This may have been present during assembly or repair of the pack in the past or it’s possible it was due to the coolant evaporation. We ended up removing the cover of the module, and drying it out with a fan for 24 hours and installed a dessicant pack to absorb whatever might be left in the air. Then we sealed it all back up.
