Primer on Contactors Box (HVBJB) and how it works on the Mach-E. This is the module affected by the recall.

[BillPitman]

Very interesting lesson by John Kelly of WeberAuto


Can’t figure how to auto run video…….Duh, it did share it………

hope you all enjoy…… Bill P

 

[BigMach-E]

Thanks for the post! I have to say, if you told me 2 years ago I would care and/or be able to make any sense out of this stuff, I would say that is ridiculous.

 

[Ming]

great video. didn't know the junction box is this complicated.

 

[AZBill]

Based on this video, I believe that the software fix likely increases the pre-charge of the capacitors for a longer period to eliminate any inrush current. I suspected before this may have been an issue. Having a voltage differential between the capacitors and the battery could lead to arcing when closing the contactors.

I do not understand why he thinks all 4 contactors have to be on to DC fast charge. The inverters should not have to be on during fast charging. In fact, for safety reasons, you would not want the motors powered on while connected to the CCS charger.

 

[GrumblesTheDog]

Thanks for posting! Agree, very interesting. I am super curious, if DCFC goes through two separate dedicated contactors, why would that contribute to the positive contactor welding open/shut? Is it something generalized about the heat that's generated? Or something waaaay above my understanding regarding how current travels immediately before/after charging?

 

[Mach-Lee]

Thanks for posting! Agree, very interesting. I am super curious, if DCFC goes through two separate dedicated contactors, why would that contribute to the positive contactor welding open/shut? Is it something generalized about the heat that's generated? Or something waaaay above my understanding regarding how current travels immediately before/after charging?

Yes, current flows through the main contactors while DCFCing, so DCFC will continue to heat them if they're already hot. This is why some people have gotten stranded shortly after a high-power DCFC session. I will have more details in a future post.

 

[Ming]

I do not understand why he thinks all 4 contactors have to be on to DC fast charge. The inverters should not have to be on during fast charging. In fact, for safety reasons, you would not want the motors powered on while connected to the CCS charger.

it looks the board is designed this way, not just he thinks... the DCFC contactors connect to motor invertor side first, then through outside contactors to the battery.
there's no direct connection to battery through DCFC contactors.

 

[Matstar]

A great video that explains what a contactors box (HVBJB) is and how it works on the Mach E

This is the module affected by the recall.

 

[louibluey]

Professor Kelly is amazing, beautiful presentation!

 

[ridgebackpilot]

Very interesting video. Towards the end, Professor Kelly explains why we never see the full 150 kW rate of charge at Electrify America DC-fast charging stations. The car can accept 375 amps from the chargers (150 kW @400 volts) but the EA chargers are only capable of putting out 350 amps maximum. Which explains why I've only ever seen about 140 kW maximum rate of charge at an EA station, and then only when my car battery is pretty low.

 

[macchiaz-o]

Another post with discussion here: https://www.macheforum.com/site/threads/mach-e-contactor-assembly-discussion.20359/

(update... admin has merged the two topics)

 

[MellowJohnny]

Has anyone posted a picture of a pooched contactor? I would assume (maybe incorrectly) that there would be physical evidence of an arching / welding event?

 

[BillPitman]

Has anyone posted a picture of a pooched contactor? I would assume (maybe incorrectly) that there would be physical evidence of an arching / welding event?

It appears to be a sealed unit……. Bill P

 

[Xadion]

Figure best to ask here... Did they make any part or physical update to manufacturing or is it all even post recall prod cars just software?

 

[ElectrifyCLT]

Very interesting video. Towards the end, Professor Kelly explains why we never see the full 150 kW rate of charge at Electrify America DC-fast charging stations. The car can accept 375 amps from the chargers (150 kW @400 volts) but the EA chargers are only capable of putting out 350 amps maximum. Which explains why I've only ever seen about 140 kW maximum rate of charge at an EA station, and then only when my car battery is pretty low.

The 350 Kw units can actually put out 500A when they are at full power, and as a result many of us have seen peaks in the 160 range.

It makes a very small difference over the course of a full charge but you can get marginally better charging when hooked into a 350 Kw unit