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      08-29-2020, 05:19 PM   #1
MolarBear
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2 Speed Electric gearbox in eDrive

So I've been having a play and reading the technical manual on how the drive train works. Am I right in thinking that the electric gearbox cannot change gear whilst in use - either it's stuck permanently in first gear in edrive mode up to 75mph, or stuck in second gear in all other modes with no maximum speed?

I press the edrive button for the end of my commute as it's largely motorway based, often I have a ton of battery to use up and the car will not use up the remaining charge before I reach home.

Would I be right in thinking then, theoretically we should get much better electric range (at the cost of acceleration performance) if we kept the car in comfort mode and NOT edrive, as the gearing would be suited for higher speeds?

I also wonder then for the electric 'range indicator' if that is only accurate for comfort/eco pro modes, as opposed to e-drive modes (or vice versa)?
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      08-30-2020, 02:38 PM   #2
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Your understanding is correct. From my testing to and from work over a year or so, regular comfort mode (second gear) nets me 10-15% more electric range than eDrive (first gear) does. That being said, the acceleration at low speeds in eDrive is so much better that I typically drive in that mode. That easily outweighs the efficiency for me in most scenarios.
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      09-01-2020, 05:43 AM   #3
patsgarageonline
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Quote:
Originally Posted by MolarBear View Post
Am I right in thinking that the electric gearbox cannot change gear whilst in use - either it's stuck permanently in first gear in edrive mode up to 75mph, or stuck in second gear in all other modes with no maximum speed?
The electric gear box shifts between 1st and 2nd when in eDrive when there is no load on the gear box.

From the i8 Technical Training guide:

"The shifting of the two gears is assumed by the gear selector actuator. This consists of a 12 V direct current motor and a spindle gear. The spindle gear converts the circular movement of the engine into a linear movement and moves the gearshift fork.

The gears are always shifted without a load. Before the gear shift the load of the electrical machine is withdrawn. After the gear is disengaged by the gear selector actuator, the speed of the electrical machine is adjusted to the gear being shifted. The speed adjustment and the activation of the electrical machine is effected by the EME. Then the gear selector actuator engages the new gear. Only after the PLCD sensor confirms the engaging of the gear and the speed of the electrical machine has been adapted by the EME, is the load of the electrical machine increased again. The driver can generally not notice the entire gear shift. In the event of a failure of the gear selector actuator or the EME, the gearshift fork remains in the current position."
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      09-01-2020, 05:54 AM   #4
patsgarageonline
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Quote:
Originally Posted by MolarBear View Post
Would I be right in thinking then, theoretically we should get much better electric range (at the cost of acceleration performance) if we kept the car in comfort mode and NOT edrive, as the gearing would be suited for higher speeds?

I also wonder then for the electric 'range indicator' if that is only accurate for comfort/eco pro modes, as opposed to e-drive modes (or vice versa)?
Keeping the car in Comfort/Eco and engaging Hold State of Charge will keep your electric range preserved and it will increase range when decelerating. I have a 2015 i8 and was on a long trip through the mountains of northern NY state and each downhill stretch resulted in regeneration. I left my hotel with 10mi of range and by the time I got through PA, I had 20 mi of range by using Hold State of Charge the entire time.

The Range Indicator is predictive based on your driving habits and environment. It's never accurate and makes a lot of assumptions. My commute home from work includes a 10 mile section where I'm in eDrive the entire time. There's a 4 mile section of road in that commute that is a mild downslope. My range does not decrease over this stretch because I'm barely in the throttle at 35mph.
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