SnBGC
Well-Known Member
- First Name
- Greg
- Joined
- Apr 20, 2020
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- Phoenix
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- 2021 Mach-E FE, 2021 Wrangler 4xe High Altitude
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The front motor is different in the GT vs the other AWD models. (I am sure you are aware of this already but just repeating it here for others that might come along later...)It's not the "78 kWh" part that limits it. It's the "288 cells" part.
The Standard Range pack is a "3P96S" configuration, with 3 parallel banks of 96 cells in series, for a total of 288 cells.
The Extended Range pack is a "4P94S" with 4 parallel banks of 94 cells in series, for a total of 376 cells.
We can assume the same cells are used in both packs, so the cells have a common maximum discharge current.
The SR pack has {CELL DISCHARGE POWER} * 288 cells = 190 kW pack discharge limit
The ER pack has {CELL DISCHARGE POWER} * 376 cells = ? kW discharge limit
Assuming 190 kW is the limit, and assuming the system is at 400V that would yield:
190,000W/400V = 475A
475A / 288 cells = 1.65A /cell
If we assume that's right, we can then get the theoretical discharge limit for the ER pack:
1.65A * 376 cells = 620 A
620A * 400V = 248,000W
Looking at the Mach-E ER AWD, the total system power is: 248 kW.
We know the PDU is capable of 210 kW (ER RWD). We know there are two SDUs, a GT and a non-GT. Neither SDU's power has been directly confirmed, but adding the non-GT SDU to the ER pack only bumps system power by 38 kW, so either that's the world's smallest SDU, or Ford is throttling the ER AWD.
Why would that be the case if the GT's ER battery can support 342 kW peak discharge? That's an interesting question. My theories are that:
1.) Ford is upgrading the cell inside the GT pack
2.) that the actual current limit is not the cell, but the internal wiring inside the pack, which would be upgraded for the GT
and/or
3.) that Ford is software limiting the non-GT pack, or possibly any combination of the three.
This is just rough "non-scientific" math to get a sense of why things are this way, but they're things we can easily assume from the public specs sheet, and a healthy bit of inference and speculation.
The front motors are usually limited for a variety of reasons. Even though they may be capable of a certain output, they are controlled to minimize torque steer, traction limits, traction vectoring etc. The very best AWD system that I have driven is the one in the Jaguar I-Pace. The Mach E is also pretty good.
I have no idea how Ford is going to solve that problem in the GT. They must have a pretty good method planned because the preliminary figures are quite impressive.
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