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Let's make a topic on the usefullness of modding this car. It's designed like a brick so we have to add some mods.
1.:test: remove the antenna (Teslabjorn say's it's making noise) will reply soon with some results//
2: how to remove the roof railing? I will never ever use them..
3: lowering the car with 3 cm (possible)
4: I think that shutting the front is a good idea in the winter, but how...?
5: The underside should be plated, there are some available?
 

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(aerodynamic?)

underbody
  • Someone on the facebook group found an under-engine tray for the ICE ZS, probably from AliExpress. I would expect that to help a bit. Most EVs have entirely flat/smooth underbodies for a reason, and I'm sure it doesn't come free.
  • A front valence, which blocks air from going underneath might also be effective, and much easier than lowering the car.
  • I don't know how smooth the car underbody is under the boot/trunk. another flat tray might work well.

front grill and fake driving lights
  • I think you could use some heavy-duty kitchen film to make the front nose smoother, particularly the front grill/charging point. This would allow us to make some measurements to see what effect it has.
  • the fake front lower vents or fog/driving lights must surely be detrimental to drag? again, kitchen "cling film" might help prove this
roof tails
  • someone on Facebook pondered if these were structural, so I would be uncertain about removing.
  • it might be possible to reshape them by adding some sort of moulding to reduce drag.
doors windows
  • some people have fitted a sort of deflector around the front windows, I don't know what impact these have
  • it might be possible to fit a moulding to make the windows more flush with the body
  • even using masking tape to cover/smooth panel gaps can help a tiny bit
wheels and tyres
  • TelsaBjorn did a test on a Tesla, removing the wheel caps, and found that it did have a measurable but small effect. I guess we might be able to find some disks that can be fitted over the wheels to try this out?
  • some people pump the tyres up extra hard, at the expense of tread wear and probably grip, to improve things.
  • other brands of tyres probably give better drag figures without reducing grip

I was actually thinking of trying some of these things myself. I have thought about using decorator's masking tape to cover and smooth over the door shut gaps and windows, and using kitchen film to smooth the front. Then, I would do some timed circuits over a convenient bit of fast highway at a constant speed to allow the battery and motor temps to stabilise, recording the energy used. I'd then quickly rip off the coverings and repeat (thus minimising the chance of environmental changes), and see if there's much measurable effect. I'm fairly certain these would only really matter above 60 mpg.
 

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The contributions from aerodynamic drag and tyre rolling resistance can be calculated using an estimate for aerodynamic drag coefficient etc, plus the estimated tyre rolling resistance from here
which also indicates the effect of wet or dry road surface.

For comparison, the following are indications of the estimated total drag forces for 60 mph and tyre pressure 36 psi:

Dry road, total vehicle drag = 622 Newtons
Wet road, total vehicle drag = 716 Newtons

From these drag force values and vehicle speed, the vehicle miles/kWh can also be estimated, including into the calculation a likely efficiency value to account for battery /inverter / motor / transmission losses.

The point of such a calculation is that it allows assessment of the overall effect of, for example, an improvement of aerodynamic drag by say 5% etc, to see if its worth following up in the real world...
 

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I was thinking along the same lines, how to make the underside more aerodynamic; but then I thought about it a bit, why they haven't done the bottom of the engine bay on the EV when they have on the petrol version? Maybe its because the electric drive motor needs airflow around it for cooling, after all it does have an overheat warning. Taking this one step further, a proper underside moulding could in fact direct the hot/warm air coming off the motor around and either side of the battery box casing, thereby helping to bring the temp up to the nominal 21 to 25 deg needed for optimal battery charging and reducing the effects of "coldgate" quite a bit.
 

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I was thinking along the same lines, how to make the underside more aerodynamic; but then I thought about it a bit, why they haven't done the bottom of the engine bay on the EV when they have on the petrol version? Maybe its because the electric drive motor needs airflow around it for cooling, after all it does have an overheat warning. Taking this one step further, a proper underside moulding could in fact direct the hot/warm air coming off the motor around and either side of the battery box casing, thereby helping to bring the temp up to the nominal 21 to 25 deg needed for optimal battery charging and reducing the effects of "coldgate" quite a bit.
I think you'd want some sort of motorised flap to control the air flow. I would close off the underside completely and then use the front grill as an actual grill, and have suitable pipes to channel the air flow. And as you say, channel warm air over the battery according to the battery temp.
 

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..... Taking this one step further, a proper underside moulding could in fact direct the hot/warm air coming off the motor around and either side of the battery box casing, thereby helping to bring the temp up to the nominal 21 to 25 deg needed for optimal battery charging and reducing the effects of "coldgate" quite a bit.
That's an interesting possibility for possible enhancement without seriously major work.

Two questions could be :
1 How much heat energy might be available from the motor compartment - presumably it would be directly related to the motor operating power level and its efficiency ?
2 Even if 100 % of the heat energy were to be absorbed by the battery structure, what temperature rise could be achieved?
 

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I think you will find that the battery unit is sealed. Any attempt to get the small amount of heat loss from the motor (PM motors are at least 95% efficient), will not make any noticeable difference as it can only be applied to the battery casing.
 

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Any attempt to get the small amount of heat loss from the motor (PM motors are at least 95% efficient), will not make any noticeable difference as it can only be applied to the battery casing.
I was thinking that because the motor has a thermal overheat protection circuit then it must obviously get warm/hot under load.
I think you will find that the battery unit is sealed.
Yes, the battery pack is fully IP67 sealed, but any mild heating generated inside by the cells (before it gets to the point where it needs the active cooling to kick in) through normal load operation is quickly lost through the cold casing walls as the car moves forward through the cold air, especially considering the additional venturi effect generated at speed under the car which accelerates the airflow and cools it even further. So reducing the cold airflow around the battery pack and replacing it with the waste warmer air from the motor can only be a good thing for charging speeds.
 

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I think you will find that the battery unit is sealed. Any attempt to get the small amount of heat loss from the motor (PM motors are at least 95% efficient), will not make any noticeable difference as it can only be applied to the battery casing.
John, I've no experience of real world motor efficiency values, but this representative efficiency map for a generic motor/ inverter indicates values mostly in the region of of 90 % so there could be a bit of warmth there...
Getting that bit more range from donald-style driving.
 

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John, I've no experience of real world motor efficiency values, but this representative efficiency map for a generic motor/ inverter indicates values mostly in the region of of 90 % so there could be a bit of warmth there...
Getting that bit more range from donald-style driving.
Yes, if you base your chart on the 2014 motors used by Tesla that are less efficient asynchronous motors. Tesla still use one of these in their dual motor EVs. The only reason to do so is cost. The MG uses a much more efficient and costlier synchronous PM Motor. If there was any significant heat loss then it would be better used to warm the cabin.
 

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Yes, if you base your chart on the 2014 motors used by Tesla that are less efficient asynchronous motors. Tesla still use one of these in their dual motor EVs. The only reason to do so is cost. The MG uses a much more efficient and costlier synchronous PM Motor. If there was any significant heat loss then it would be better used to warm the cabin.
why is the MG e-ZS relatively inefficient then, even compared with the e-Niro?
 
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