GM set up a prototype Hummer EV and a Hummer EV chassis (vehicle without the body), and let the creator of the Engineering Explained videos (Jason Fenske) take a tour. His comments don't add much, except in the battery configuration description, the gearing, and one protective feature, but it's the most detailed look at the Hummer EV that I have seen yet.
Hummer EV First Look! All The Details Of GMC's All-Electric Supertruck
Some interesting bits, specific to the EV aspects:
Motors
Charging configuration:
Hummer EV First Look! All The Details Of GMC's All-Electric Supertruck
Some interesting bits, specific to the EV aspects:
Motors
- separate left and right rear motors, driving through fixed 10.5:1 reduction ratio
- single front motor, driving through fixed 13.3:1 reduction ratio and electronically controlled differential
- all motors 250 kW and about 335 lb-ft (peak) output each
- motor torque limited to protect CV joints when wheels are not steering straight
- virtual (and generally pointless) rear differential lock function available by dash switch
- inverters mounted directly on top of motors
- 2 layers of 12 modules each
- all modules with pouch cells in vertical plane
- 24 cells per module
- ~100 Ah per cell
- wireless communication between BMS master and slaves
- 96S or 400 volts (maximum)
- 2P [ 12S { 8S 3P } ]
{ } is the module
[ ] is a string of modules
Charging configuration:
- 96S operating configuration, or
- 2S [ 12S { 8S 3P } ], for an overall 192S or 800 volts (maximum) when connected to 800 V charger
- Yes, they have include contactors to reconfigure the two strings as parallel for operation and most charging, but in series for charging from a high-power 800 volt DC charger.
- The module configuration and arrangement in the pack are generally similar to the Bolt, but with
- fewer cells in series per module and so more module, and
- two complete full-voltage strings
- This size of module will not be useful for many high-voltage DIY conversions, because a set to produce 360 V (nominal) will be large (over 100 kWh); it may be useful for low-voltage conversion, with a 32S system requiring only four modules.
- The 500 kW dual motor rear drive unit could be interesting for a high-performance DIY car.
- Fenske attributes the single front motor (instead of dual independent motors like at the rear) to the lack of traction to use more power. That's sort of valid, but not the real reason...
- GM has three sizes of motor available, and could have used two smaller motors instead of one of the largest size;
- however, 2 smaller inverters plus 2 smaller motors plus 2 reduction gearboxes is more expensive than one larger inverter plus one larger motor plus one reduction gearbox plus a differential, and
- also, it is generally undesirable to apply unequal torque to the front wheels, so at the front it is better in most cases to just back off the power and let a simple differential keep the wheel torque equal.
