Condensation Failure Inside Battery Pack (BMS_F107 code)

[howardc64]

Reviewed 2012-20 MS, Plaid, M3, Chevy Bolt, Mach-E, Leaf breathing vent designs. Here are the probable info but can't be completely certain in some cases without detail part supplier info.

• 12-20 MS looks like has single Gore Breather. Probably PMF200484 of Gore Snap-in ePTFE breather catalog. 2.5L/min. Of course original pack also has AGM 0.2 PSI silicone valve on top of hump (removed in latest new and reman packs)
• M3 TSB has 2x NITTO ZH-Plug-S breather (on left and right of rear battery pack) Each breather = 0.26L/min
• Plaid looks like has 4x NITTO ZH-Plug Breather in rear of battery pack (service manual diagram seems to show 4x, parts catalog shows 1x) Tesla catalog PN is 1108907-00-B (identical to M3's TSB breather)
• Chevy Bolt has 4 rectangular cutouts on top of battery pack lid covered by Gore patch (GM part on Amazon) . Patches must be sealed off during pressure testing
• Mach E appears to have 1x rectangular cut out on top of battery pack lid covered by a Gore patch.
• Leaf also has a couple of breathers on top lid. Don't know the spec.

From this set of info, we can estimate the following

• 2.5L/min = ~42mL/s. For a large air volume (even after pack filled with battery) 0.19 pressure testing spec unlikely to drop instantly with this leak rate.
• 12-20 MS's single Gore breather has higher flow rate than either Plaid/M3 packs. 2.5L/min vs ~1L/min vs ~0.5L/min (after TSB, ~0.25L/min before TSB) respectively. Bolt/MachE breather flow rate likely higher than all these.
• Probably this is the reason newer 12-20 MS packs and some newer remans removed the AGM silicone valve vent on top of the frontal hump.
• Leaf/Plaid/MS/Bolt/Mach-E breathers are located on top or rear of pack. Likely dryer location compared to 12-20 MS breather / silicone valve vent location (catch front driver tire spray and windshield runoff)
• Bolt/Mach E Gore patch solutions are common for headlight assembly for breather and keeping moisture condensation out.

Would be good if someone with an updated 12-20 MS pack without the top hump AGM silicone valve inspect if just the single Gore breather under the battery pack in front driver side and any markings to locate the spec.

Ideally, 12-20 MS breather might function better on top of lid towards rear of the car (have to consider the plastic top lid cover) rather than behind front driver side tire spray pattern even with plastic cover protection. It is a high moisture high water spray location.

 

[mr_hyde]

There are certainly design improvements and things Tesla can learn from other OEMs (who likely looked at Tesla's failure modes and decided to do it better). At the end of the day, I still think the breathing is academic if we can't pull the moisture out of the packs. Does anyone have a 3D printer and some skills to help design a desiccant pack that will pop up an umbrella valve hole?