New motor/range increase and towing

[ohmman]

I've been hovering over the order button on a new “long range” X since the range improvement announcement. The only reason I’d order is for adding range while towing our camper. I realize we are at a point where there have been no deliveries and limited information, but I’m curious about how this efficiency will translate at higher sustained power rates. Is it possible that the efficiency was tweaked at the standard consumption and that it won’t be as notable at my normal towing rates (currently around 575-600Wh/mi)?

If indeed it does scale proportionally, it makes a pretty big difference over my degraded 90D (240 miles at 100%) and the faster supercharging would be icing on the cake.

Any thoughts on this?

 

[TexasTeslaRacing]

I’m also considering the new Model X LR. We tow a 4,500lbs travel trailer and only see 150 miles of range. An additional 30ish miles would help.

 

[j-rho]

I have a 100 and use more like 700wh/mi towing - so the usable increase is maybe 10-12 miles?
Figure this won’t be my last X (or, EV daily driver and tow rig), will be holding off on the second depreciation hit until there’s a bigger/better battery, at least a 120 but ideally a 150. Combined with efficiency improvements, could get usable range for me well up over 150. May have the pickup by then too, who knows.

 

[Solarman004]

I've been hovering over the order button on a new “long range” X since the range improvement announcement. The only reason I’d order is for adding range while towing our camper. I realize we are at a point where there have been no deliveries and limited information, but I’m curious about how this efficiency will translate at higher sustained power rates. Is it possible that the efficiency was tweaked at the standard consumption and that it won’t be as notable at my normal towing rates (currently around 575-600Wh/mi)?

If indeed it does scale proportionally, it makes a pretty big difference over my degraded 90D (240 miles at 100%) and the faster supercharging would be icing on the cake.

Any thoughts on this?

Ohmman, the improved efficiency of the motors will help whether or not you are towing. However, given the large consumption when towing is due to increased drag and weight, which are independent of motor efficiency, the percentage gain in range when towing, I believe, will be very small compared to non-towing.
If you do go this route, I'd be interested in hearing what Tesla offers you for trade in on your 2016 MX.

 

[SSedan]

Isn't the upgraded efficiency mostly the front motor? I thought that was swapped to permanent magnet but not the rear I might be wrong.
If that is the case though I would expect the rear motor to be primary towing so you might see very little gain.

 

[mattack4000]

I would wait one more year for the new battery unless you have a 75

 

[ohmman]

Tesla reached out to me yesterday on a sales call about the update. I told him I was waiting on more information from engineering about my towing concerns. He promised he'd follow up with engineering, then called back to say he couldn't reiterate my question, so asked for an email. I emailed him and he promised to send it on to engineering for an answer. I'll be impressed if I get a response.

For reference, here is how I phrased my concerns:

Currently we tow a ~4100lb Airstream with our X90D. Highway consumption at 55mph averages approximately 600Wh/mi, and obviously goes higher at higher speeds. Remaining estimated 100% range on our 90D is approximately 240mi. Rated consumption is based on 320Wh/mi, so that tells me I have about 76.8kWh of pack capacity available. At 600Wh/mi towing, our range is then 76.8kWh/.6kWh/mi = 128 miles. Hopefully you’re following that math so far. A new 100D appears to have about 98.8kWh of usable capacity. At 600Wh/mi, that gives me 98.8kWh/.6kWh/mi = 165 miles of range. Not a bad improvement, but it wasn’t enough for me to swallow a $50k transactional loss.

Now there’s a new motor, but the same pack. This makes it is very difficult for me to estimate my range with the new X, because the implication is that the additional range comes from motor efficiencies. My question, then, is how do these efficiency improvements look across the power output curve? Is there a way to measure how much more efficient this motor is at the previous power draw of 600Wh/mi? I know that the advertised extra range is specifically intended to be at normal power draw, so I worry that these efficiencies will be lost at the higher power output level.
A new X means capturing $50k of depreciation, losing unlimited lifetime Supercharging (remembering that we’re chewing up 600Wh/mi), and gaining some additional range as well as upgraded AP, which we cannot use when towing. This is why I haven’t been jumping at the opportunity.

 

[ecarfan]

I think your letter to Tesla engineering is very clear. Based on your analysis, I suspect that if you traded up to a new X100D your effective towing range increase compared to your aging X90D would be modest; perhaps less than 15 miles of additional range at your 600Wh/mi towing usage level.

Let’s hope Tesla engineering gets back to you.

 

[Saghost]

I expect the motor efficiency increase will apply to your towing environment as well - even at 600 Wh/mile you're still talking a steady state load that's only 36 kW at 60 mph - something like 15% of the max rated load for the new front motor alone (and in steady state on the freeway I'd expect the new cars to run almost entirely on the front motor.)

In fact, you'll likely see a slightly higher efficiency there than at more typical cruising loads - most modern inverter driven electric motors are at their best near half torque and efficiency falls off near the low and high edges (though the central peak is usually pretty broad.)

That's the good news. The bad news is that motor losses are only a tiny part of the high consumption your driving regime requires, and that the Project Raven gains supposedly come from tire and wheel bearing improvements as well as motor and power electronics.

I'm gonna speculate that you'll see half to two thirds of the improvement overall - 5-7% more range per kWh, but this is very much a swag and there's a lot I don't know about the new systems that would directly affect this.

 

[SSedan]

In towing I expect the rear motor to be primary so efficiency gains from the front minimal.
Happy if I am wrong.

 

[redgt]

only the rear motor has been upgraded right?

 

[SSedan]

I thought it was only the front.

 

[redgt]

interesting. in the model 3 the rear motor is the one with permanent magnets but it has to be with a RWD option so with every S/X being AWD they could put the permanent motor in the front

 

[Saghost]

I thought it was only the front.

Not sure. Only the front motor has been replaced with a switched reluctance motor - the rear is definitely induction.

It's not clear whether the induction motors and especially their drive inverters are the same as past cars. They switched at least one power inverter module to fancy new silicon carbide power electronics for reduced losses, implied but not stated to be for the switched reluctance motor.

It wouldn't be surprising if the rear motor got at least a new inverter as well, which would reduce losses some even with the same motor.

 

[Saghost]

interesting. in the model 3 the rear motor is the one with permanent magnets but it has to be with a RWD option so with every S/X being AWD they could put the permanent motor in the front

I think they did it so they can keep the monster rear motor for Ludicrous.

 

[ohmman]

I received a response from Tesla. Unfortunately, it doesn't really give me any information I didn't already have.

Unfortunately, we cannot share details of the power output operation of our drive motors or battery range estimations.

Here is what we can share:



“With the new battery upgrade (90 to 100), the customer will see good bump in total range. His assumption is correct that the 100D will be subject to similar losses during towing operation, as with his 90D. Thanks to the new drive train, among other benefits, the customer will observe:



1 – a small increase in range (this is supplementary to the increase from 90 to 100 in the past)

2- more efficient motor control strategy, reducing overall losses during drive

3- improved power consumption during cold climates”

 

[Saghost]

In towing I expect the rear motor to be primary so efficiency gains from the front minimal.
Happy if I am wrong.

Starting the car moving Tesla usually favors the rear motor, I suspect mostly for handling feel. In steady state freeway driving with no traction or handling issues I'm sure they'll use only the switched reluctance motor whether towing or not.

You can easily put an induction motor to sleep and let it spin along with zero power for an indefinite period with minimal drag and wake it instantly, but you can't do that with any permanent magnet motor, including the switched reluctance - the magnets continue to impose their spinning fields on the copper wiring and you get drag induced by that, and you have to keep track of phase timing to restart correctly because the inverter timing has to be phase matched to the magnet rotation.

When you combine that with the switched reluctance motor being more efficient, the solution for any situation where you need a little bit of power and have plenty of torque seems obvious - put the big induction motor to sleep, and use the most efficient motor in a more efficient regime (compared to splitting the power between both motors) until you need either acceleration or regen.

 

[Gwgan]

Does the new front motor have improved cooling? If so, that could positively impact towing range. If the rear motor has more low-speed torque I would guess that motor would be favored while towing. Too bad they could not even answer with some real test results and specs.

 

[SSedan]

Starting the car moving Tesla usually favors the rear motor, I suspect mostly for handling feel. In steady state freeway driving with no traction or handling issues I'm sure they'll use only the switched reluctance motor whether towing or not.

You can easily put an induction motor to sleep and let it spin along with zero power for an indefinite period with minimal drag and wake it instantly, but you can't do that with any permanent magnet motor, including the switched reluctance - the magnets continue to impose their spinning fields on the copper wiring and you get drag induced by that, and you have to keep track of phase timing to restart correctly because the inverter timing has to be phase matched to the magnet rotation.

When you combine that with the switched reluctance motor being more efficient, the solution for any situation where you need a little bit of power and have plenty of torque seems obvious - put the big induction motor to sleep, and use the most efficient motor in a more efficient regime (compared to splitting the power between both motors) until you need either acceleration or regen.

All fine and dandy but real towing is generally a RWD thing, why stress the whole chassis by dragging it around with the front? I haven't got data to back up my opinion but still suspect significant power delivery from the large rear motor when towing if that is so then the new front motor won't be a big improvement in towing.

 

[Uncle Paul]

In addition to any gains from the motors, you will also benefit from the lower rolling resistance tires, bearings, as well as the faster charging en route.

I would imagine that if the total benefits were 30 miles when non-towing, and that you currently were getting only 50% of normal range when towing, you might end up with about 15 miles extra range....but still faster charging.