Did I Just Blow My 3rd (and updated part) HVBJB???

[Hammered]

Don't underestimate a nice high pressure fan blowing air through the HVBJB -- there's already enough spacing between components and the case to allow for a retrofit. You really don't want liquid around the HV. Huge liability point and not required. The air would be blown around the battery box and would make its way into the cooling plates.

If you've ever seen a heat gun or hairdryer motor fail, they quickly burn themselves out. A little active air cooling can go a long way.

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[dtbaker61]

Don't underestimate a nice high pressure fan blowing air through the HVBJB -- there's already enough spacing between components and the case to allow for a retrofit. You really don't want liquid around the HV. Huge liability point and not required. The air would be blown around the battery box and would make its way into the cooling plates.

If you've ever seen a heat gun or hairdryer motor fail, they quickly burn themselves out. A little active air cooling can go a long way.

HVBJB are sealed
only option is direct Thermal siphoning with chill plate

 

[Hammered]

HVBJB are sealed
only option is direct Thermal siphoning with chill plate

LOL, I don't think you know what sealed means. They're not sealed.

 

[Fixbear]

Don't underestimate a nice high pressure fan blowing air through the HVBJB -- there's already enough spacing between components and the case to allow for a retrofit. You really don't want liquid around the HV. Huge liability point and not required. The air would be blown around the battery box and would make its way into the cooling plates.

If you've ever seen a heat gun or hairdryer motor fail, they quickly burn themselves out. A little active air cooling can go a long way.

That is a nice idea, but would not work. The HVBJB is sealed and pressurized to prevent intrusion. Any fan would bring in foreign matter even with filtration. I lost a large panel due to the same thing in 69. When you have medium voltage, humidity, and dust, It will create a electron path.

 

[Mach-Lee]

Guys, the battery case is sealed, not the HVBJB. The HVBJB has covers over for handling safety but is not airtight. The contactors are hermitically sealed with an inert gas inside. Putting fans or cold plates inside HVBJB is not a wise idea considering the high voltage risks involved. They could make it less covered to increase convection, but that would significantly increase personal and handling risks due to exposed busbars.

You may want to review my photos: https://www.macheforum.com/site/thr...age-battery-junction-box-nk4z-10c666-c.20425/

 

[dtbaker61]

LOL, I don't think you know what sealed means. They're not sealed.

Months ago when we were having discussions on what we could possibly do or recommend to fix the problem I had suggested venting in and out of the cabin and circulating cabin air. It was quickly shot down.

Chill plates in contact with busbars would be far more effective than circulating air in any case

 

[dtbaker61]

Guys, the battery case is sealed, not the HVBJB. The HVBJB has covers over for handling safety but is not airtight. The contactors are hermitically sealed with an inert gas inside. Putting fans or cold plates inside HVBJB is not a wise idea considering the high voltage risks involved. They could make it less covered to increase convection, but that would significantly increase personal and handling risks due to exposed busbars.

You may want to review my photos: https://www.macheforum.com/site/thr...age-battery-junction-box-nk4z-10c666-c.20425/

Oooohhhhhh, I thought the HVBJB section was sealed. So now I am back to wondering why there is not an inlet and Outlet duct from Cabin to HVBJB.... muffin fans could be in the ductwork, even with filters to prevent particulate intrusion. Circulating cabin temperature air would help and not require extra chill plates or a change in plumbing

 

[Mach-Lee]

Oooohhhhhh, I thought the HVBJB section was sealed. So now I am back to wondering why there is not an inlet and Outlet duct from Cabin to HVBJB.... muffin fans could be in the ductwork, even with filters to prevent particulate intrusion. Circulating cabin temperature air would help and not require extra chill plates or a change in plumbing

Because ducts from the battery to the cabin is a major fire propagation risk, and it would create horrible condensation issues in winter that could corrode or short out the pack. The pack must remain sealed and isolated from the outside environment so water vapor cannot enter the pack.

 

[AKgrampy]

Guys, the battery case is sealed, not the HVBJB. The HVBJB has covers over for handling safety but is not airtight. The contactors are hermitically sealed with an inert gas inside. Putting fans or cold plates inside HVBJB is not a wise idea considering the high voltage risks involved. They could make it less covered to increase convection, but that would significantly increase personal and handling risks due to exposed busbars.

You may want to review my photos: https://www.macheforum.com/site/thr...age-battery-junction-box-nk4z-10c666-c.20425/

Are other BEV’s having this same issue and if not then how are they preventing “meltdown?” I would think Ford engineers, or subcontractors, would learn from others mistakes. I am not really worried and have had no issues but it is a bit concerning to see what may be failures (at least one for certain) of the newer HVBJB.

 

[Mach-Lee]

Are other BEV’s having this same issue and if not then how are they preventing “meltdown?” I would think Ford engineers, or subcontractors, would learn from others mistakes. I am not really worried and have had no issues but it is a bit concerning to see what may be failures (at least one for certain) of the newer HVBJB.

Tesla had problems with melted contactors in the P85 Model S back around 2015. They upgraded the contactors to Inconel contacts which solved the problem and added ludicrous mode. Very similar to how Ford upgraded the contactors in the new part.

Here is a Model Y contactor assembly (similar to our HVBJB): https://www.ebay.com/itm/165575147430
And these are the contactors they use: https://www.sensata.com/sites/defau...ac-gv35-sereies-800v-contactors-datasheet.pdf

They can handle 1000 amps (max output for a GTPE) for 90 seconds. Ours are rated for 60 seconds.

The Tesla assembly uses much thicker bus bars than our HVBJB so it probably has better heat dissipation and greater thermal capacity. Ford could do the same with our HVBJB, I think some thicker bus bars would do the trick (I suggest going from 3mm to 5mm thick busbar).

 

[Hammered]

Tesla had problems with melted contactors in the P85 Model S back around 2015. They upgraded the contactors to Inconel contacts which solved the problem and added ludicrous mode. Very similar to how Ford upgraded the contactors in the new part.

Here is a Model Y contactor assembly (similar to our HVBJB): https://www.ebay.com/itm/165575147430
And these are the contactors they use: https://www.sensata.com/sites/defau...ac-gv35-sereies-800v-contactors-datasheet.pdf

They can handle 1000 amps (max output for a GTPE) for 90 seconds. Ours are rated for 60 seconds.

The Tesla assembly uses much thicker bus bars than our HVBJB so it probably has better heat dissipation and greater thermal capacity. Ford could do the same with our HVBJB, I think some thicker bus bars would do the trick (I suggest going from 3mm to 5mm thick busbar).

Go back and take a look at the specs, the contactor's ratings are much worse. Things get real ugly when it's hot. It can't even handle its rated load long at 60c. A 9k RPM capable fan ducted into the side of the HVBJB with a temp probe would do the thing wonders. One, the heat wouldn't be forced to slowly dissipate through the various openings, and 2 by keeping lower temps it could keep the resistance lower preventing additional heat. It'd also help the contactors as by their nature they're generating ~100w (IIRC, it's late) under load. Thicker busbars would also be a very easy addition to reduce resistance heating.

Did you run thermal calculations for the busbar sizes at load? How much heat are they adding to the equation? They're probably C110.

 

[heisnuts]

Newberg Ford finished the car yesterday and I picked it up last night. The repair took 9 days, but some of those days were due to the field engineer coming out to look at the car and another big project their EV tech was involved with on a transit van they had in the shop at the same time.

This was my first time at Newberg Ford, but it will now be the dealer I go to for any future service/repairs.. Their EV tech‘s attention to detail is very impressive and after talking to him a little bit I feel very comfortable having him work on the car. The staff was also awesome. The service manager was there at pick up and asked about how I learned so much about the car. When I showed them the forum I could tell they were pretty impressed on how much info we have here and I wouldn’t be surprised if it becomes another reference for them in the future when it comes the the MME.

 

[dtbaker61]

Because ducts from the battery to the cabin is a major fire propagation risk, and it would create horrible condensation issues in winter that could corrode or short out the pack. The pack must remain sealed and isolated from the outside environment so water vapor cannot enter the pack.

Ok, so we are back to a possible improvement in some future version might be a chill plate on the bottom under the hvbjb with thermal bridge to siphon heat from bus bars
.... but unlikely to see additional work unless the current unit starts failing

 

[phil]

Very similar to how Ford upgraded the contactors in the new part.

Do you know of any available documentation of how Ford upgraded the part? Or is this more word-of-mouth anecdotes?

 

[alangant]

Guys, the battery case is sealed, not the HVBJB. The HVBJB has covers over for handling safety but is not airtight. The contactors are hermitically sealed with an inert gas inside. Putting fans or cold plates inside HVBJB is not a wise idea considering the high voltage risks involved. They could make it less covered to increase convection, but that would significantly increase personal and handling risks due to exposed busbars.

You may want to review my photos: https://www.macheforum.com/site/thr...age-battery-junction-box-nk4z-10c666-c.20425/

It is my perception that the HVBJB is within the sealed battery case, and therefore not accessible for external cooling. Can someone confirm or deny my perception?

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