Yes, I have the first DTC listed over in the other thread. And I just tested while driving home and indeed I actually do have reduced power. I was mistaken.
Interesting, thanks for the details. 5 mOhm is 10x the rated worst resistance, which will obviously fry the part. Thicker bus bars is the way to go, not only for heat transfer but also for lower resistance. Mach-lee’s excellent analysis shows a solid BVBJB design but the bars seem on the thin side indeed.The heat is extracted through the contact terminals. The bus bars in the HVBJB act like heat sinks. This was discussed recently on another topic, but it’s my opinion that the bus bar near the contactors is not thick enough to remove enough heat. It’s only 3 mm thick and I think it should be 5+ mm thick to provide enough thermal mass. Tesla puts very thick busbars on their contactors (6+mm?) for comparison:
Tesla Model Y contactors, note thick busbars:
I’ve measured a failed Mach-E contactor at 5+ mΩ, which is very high and would generate a lot of heat. If anything, the recall software was not sensitive enough, and could only detect a failing contactor under a high amp draw, such as full throttle acceleration for several seconds. It may not detect a failing contactor if you never floor the vehicle or only do so briefly.
I think another factor besides the HVBJB design was the part quality. Some of these original contactors just decide they’re going to stick even though they’ve lived an easy life and haven’t necessarily ever been overheated. No software will detect that ahead of time.
It’s my theory the new contactors switched to using Inconel or other high heat resistant contact material, and were hopefully subjected to more rigorous initial quality testing to exclude defects.
I would like to see a new HVBJB with thicker bus plates and a switch to a different contactor manufacturer such as Gigavac instead of TE.
This is further evidence that Mach-Lee is technological wizard from another planet secretly sent to help us as we bumble and fumble our way into a transportation revolution.The heat is extracted through the contact terminals. The bus bars in the HVBJB act like heat sinks. This was discussed recently on another topic, but it’s my opinion that the bus bar near the contactors is not thick enough to remove enough heat. It’s only 3 mm thick and I think it should be 5+ mm thick to provide enough thermal mass. Tesla puts very thick busbars on their contactors (6+mm?) for comparison:
Tesla Model Y contactors, note thick busbars:
I’ve measured a failed Mach-E contactor at 5+ mΩ, which is very high and would generate a lot of heat. If anything, the recall software was not sensitive enough, and could only detect a failing contactor under a high amp draw, such as full throttle acceleration for several seconds. It may not detect a failing contactor if you never floor the vehicle or only do so briefly.
I think another factor besides the HVBJB design was the part quality. Some of these original contactors just decide they’re going to stick even though they’ve lived an easy life and haven’t necessarily ever been overheated. No software will detect that ahead of time.
It’s my theory the new contactors switched to using Inconel or other high heat resistant contact material, and were hopefully subjected to more rigorous initial quality testing to exclude defects.
I would like to see a new HVBJB with thicker bus plates and a switch to a different contactor manufacturer such as Gigavac instead of TE.
While resistance is one component of what's monitored, the SOBDMC is also supposedly monitoring temperatures. Additionally, it reads as if the temperature is the first trigger while resistance is the second.
exactly.
I'll give Ford more credit than you are. I think the strategy has worked in that the 22S41 software fix is preventing complete failures. Better to limp home than completely lose power on the road.
Agreed. That is what happened to me: wrench thrown, power reduced, limped home.
Yes, it looks like part of the next remedy will include software adjustments to other modules beyond what was included in 22S41.
Mine was just over 30,000.
That's good for those of us with regular use patterns. A few cars have already rolled over 100,000 miles. For them, the recall provides a safety net.
Agreed, although thicker busbars might suffice.
The whole reason for this new recall is that 22S41 doesn’t prevent complete failures. Our car is currently in the shop waiting for a new HVBJB after experiencing a complete failure. Enough people with similar experiences filed complaints with the NHTSA that they opened an investigation, and Ford is now being forced to do what they should have done in the first place.
I think we're just splitting hairs here. I agree 22S41 was not sufficient. However, it appears 22S41 dramatically improved the odds of a soft landing rather and limp home.
Except the first part is impossible because there are no temp sensors in the HVBJB. They can try to model it, but due to part variation a thermal model could be way off. As far as I’m concerned, they only implemented the second part of that statement.
I know you've said that many times before, but I'm just quoting what they apparently told NHTSA. If Ford lied to them, well that's on them. Just kinda strange that they even list the module supposedly doing the temperature monitoring.
Even though the NHTSA text mentions “monitor contactor temperature” , there simply is no temperature sensor in the HVBJB. Not in the original, nor in the replacements that are being installed. So the text is a liberal interpretation of a software feature.
The defend Ford at all cost strategy is really tiresome.
Not supporting Ford but they did state monitoring and not measuring and obviously they must be calculating both and not actually measuring them. If they calculate a certain resistance then they can also calculate a temperature rise across that resistance over time base on amps flowing through it. Actually a good software protection to add but obviously not an acceptable fix. They probably won’t say anything but I wonder what they are changing software-wise? I often wondered if some of the HVBJB alarms may have been false positives. Or is it being fine tuned to catch the few that have slipped through to go to SSN?
At least not in the HVBJBs that are currently being installed due to failures. We still don't know Ford's remedy for this recall. They MIGHT have a new, more capable HVBJB in the works that could include heavier busbars, temperature monitors, or other improvements. I realize that may be wishful thinking.
