[Relatively Interesting] Heat Spots in the snow

[mycrobe]

I drove my Electric Drive a few miles in light snow today. The pattern of snow melt on the hood is quite different from a ICE car: Lots of little heat spots.

 

[saabluster]

Cool observation. It does make me wonder if that is where all that wasted energy is going in these Bs what with such poor efficiency. Anyways thanks for posting.

 

[mycrobe]

I assume that all EVs do something similar.

(I'd always thought poor EV efficiency was related to vehicle weight and the fact that all ancillary components are designed for an ICE car.)

 

[saabluster]

Obviously weight does play a factor. But that effect is almost completely seen at slower speeds. Stop and go. The B weighs as much as the Tesla P90D but the Tesla has waay better efficiency. Granted the awd has a hand in that. I guess we get a double whammy in the B in that during stop and go the car weighs so dang much and at high speed it has horrible aerodynamics. Oh well. There are benefits to the weight. Namely safety.

 

[vin]

Obviously weight does play a factor. But that effect is almost completely seen at slower speeds. Stop and go. The B weighs as much as the Tesla P90D but the Tesla has waay better efficiency. Granted the awd has a hand in that. I guess we get a double whammy in the B in that during stop and go the car weighs so dang much and at high speed it has horrible aerodynamics. Oh well. There are benefits to the weight. Namely safety.

Actually the Model S is 700lb heavier than the B-Class, weighing in at 4647lb (for a Model S 60, I believe), which is a little more than a Hummer H3. Our B-Class weighs in at 3924lb. Which may seem light when compared to the Model S, but we are on the heavier side compared to other short-range BEVs on the market. We're also one of the tallest, so I think you're spot-on in guessing that it's the double whammy that kills our range.

 

[saabluster]

Actually the Model S is 700lb heavier than the B-Class, weighing in at 4647lb (for a Model S 60, I believe), which is a little more than a Hummer H3. Our B-Class weighs in at 3924lb. Which may seem light when compared to the Model S, but we are on the heavier side compared to other short-range BEVs on the market. We're also one of the tallest, so I think you're spot-on in guessing that it's the double whammy that kills our range.

1,961 kg (4,323 lb) (60)
2,085 kg (4,597 lb) (60D)
2,090 kg (4,608 lb) (70D)
2,108 kg (4,647 lb) (85)
2,188 kg (4,824 lb) (85D)
2,239 kg (4,936 lb) (P85D)

Oh my. I was only off by 1000 lbs. :shock: Not sure how I managed that as I looked it up before saying anything. That really does show there are some major issues with this drivetrain. Where is it all going? Oh wait. Heat loss shown in above pics. I wonder if this implementation of the Tesla drivetrain doesn't have the complicated heating and cooling loops and heat scavenging functionality that the Model S does. Probably Mercedes didn't want to pay for that since this was intended as just a compliance car initially.

 

[vin]

Whoa! Didn't realize the P85D is pushing two and a half tons. That's one amazing piece of engineering.

Where is it all going?

I'm still thinking that your original thinking (aero and tonnage) was spot-on, especially when comparing to other short-range BEVs. Consider that the RAV4 EV is about 4" taller and weighs 100lb more... perhaps it's not a coincidence that it gets an MPGe rating that's worse than the B-Class ED (78/74 vs 85/82 MPGe).

I think another reason why the B-Class ED and RAV4 EV are relatively inefficient is because their drivetrains may be tuned/designed/sized for performance over economy. If they had the drivetrain of the Focus Electric (3646lb, 110/99 MPGe), I'm guessing that both the B-Class and RAV4 might gain 10 MPGe or more. But that would probably kill the fun factor for both cars.