The difference a roof rack load makes to EV efficiency? the Kayak test!
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- เผยแพร่เมื่อ 15 ส.ค. 2023
- A small but intriguing test to see how the efficiency is affected when carry a load on a roof rack. Electric cars are sensitive to efficiency, you want to get the best so you can get the most miles from your EV battery , so adding anything will affect aerodynamics and therefor efficiency. But by how much?
Is it half the range? Is it better? We wanted to find out and took used our 2019 Tesla Model 3 Dual Motor Long Range Performance (with 93,000 miles!) in the normal course of daily duties but this time loaded a kayak onto the roof bars.
A Kayak is not heavy and its quite an aerodynamic shape compared to some things, but it seemed a worthy test to do to satisfy our curiousity.
If YOU have carried loads on your roof bars, what was it and how did that affect efficiency on your EV? Let us know in the comments below.
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Speed is the key. If you double the speed you quadruple the drag!
HI. Good to see this video. I did a trip to Ireland with roof box, 2 bikes on the room, boot full and family of 4 in a Kona and probably lost about 20% range. A bit better the slower we went.
I did 180 miles with a set of aluminium ladders on the rack of a model 3. Lost 35% range and the howling was uncomfortable above 35mph. Taped up all the holes in the rungs for the return journey and it was much much quieter and less than 10% loss in range.
Probably worth saying, albeit obvious, that ICE cars would also have an efficiency penalty to a similar amount!
Yep - I remember taking 4 MTB bikes to Wales on the roof on my Ford Focus, in 2009, and the range was destroyed, less than half. I had to fill up again before I got to the destination.
This point seems to be forgotten by everyone when they compare an EV to ICE for towinf or roofrack, well anything more than the basic car. They always compare to a standard car.
I just came back from a 7700km roadtrip with my Model Y and a roof top tent through Norway. The efficiency was surprisingly good. In Norway I only had a slightly higher consumption than normal, thanks to the speed limit of 80 km/h. In Germany at 120 km/h the efficiency was way worse. The speed is really the key here.
Richard - You're fired 😂
Great to see Joe doing a nother video. Interesting to see this information and more tests comparing same route with/without trailer/ items on roof.
Brilliant thank you. I’m considering roof bars for my model 3 and this video answers exactly the question I had! Nice one ! 🤩
Stopped off at Exeter services last week, Great to see all the new chargers being installed👍
another wonderful film and a great follow up to 'how to fit roof bars'. My kayak goes in boot (inflatable type).
I was in that services a week ago and it’s EV charging is all now up and running.
Also heavily dependant on the weather. We rent a holiday house in France that we’ve driven to on the same route with the same load, roof box and roof bikes each year. Normally ~35% hit to efficiency with those bits on. When we went this year it was very very windy along the way and efficiency was reduced by ~50%
Great vid, informative , nice watch 😉
I think what you put on the roof also make a difference. I’ve done a couple of long trips with a roofbox and rear cycle carrier with a bike on, in our M3 LR. Leeds to London on M1 and Leeds to Cambridge for Uni drop offs. I’ve averaged 250wh/m over 36k miles. With the roofbox & cycle carrier, that drops by about 30%. At 70mph I don’t think that’s too bad and it’s still more efficient at that speed with the extra loads than our Zoe is at 70mph ;)
Great vlog indeed and would definitely like to see on e on a higher mileage three and S and how they handle that mileage. Looked amazing. And lovely to see Exeter services getting loads of chargers. Pity Gridserve has cancelled such plans at Rownhams tho. Would’ve been handy. Best wishes.
Excellent efficiency from the M3P. It's also great to see Gridserve expanding in Exeter, Devon. The heart of Cornwall desperately needs many rapid 100-150+ kWh chargers though. Cornwall is a long county - you can be holidaying in Bude, go to Penzance and back on a whim and you're looking at 150 miles. In a ICEV you just do it - it'll cost you big, of course. In a BEV, much cheaper, but you have to plan it.
"You don't see many M3 with roof racks!" I saw a nice white one in Christchurch last week!
Great to see the extra chargers at Exeter, interesting to see the extra drag from the canoe!
Great test, I haul kayaks almost every week on my 2019 M3 SR+. I normally average 240wh/mi without and with kayaks on I get. 270wh/mi with a single more aero kayak (11% loss) and up to 330wh/mi with two kayaks on one with J mounts in sideways. So 11-36%. Luckily my preferred lakes are only 40 miles or so one way so it works fine even on my standard range Model 3. It does however make some longer gaps too far which is part of why I still have an ICE backup vehicle.
Great video. Could you do video towing with a Model Y LR/Performance?1600kg?
Love those wheels, what are they and how big?
Next time try it with the kayak the other way round - it looks like it was stern first on the roof rack. I carry a couple of windsurfers on a roof rack and carrying them upside down and pointy end (and the way they normally go through the water!) first is more efficient
Bjorn Nyland did some experiments with roof boxes and found that some were slightly better reversed with the blunt end forward and the pointy end towards the boot.
A natural in front of the camera.
Hi Rich. Loving the content mate so far! I’m currently in the process of having to order a new EV for work (the company I work for install chargers and substations) I’m stuck between a Skoda Enyaq vRS estate and Mercedes EQB 350. I’ve got kids and commute everyday for work 120 mile round trip. We do have free charging at the office! Would love your opinion mate cheers 👍🏻
I'd love to see the efficiency difference between regen and coast on the motorway. Never sure which is best
Exeter services looking good.
I’ve done a couple of runs in my Q4 E-Tron with stuff on the roof to see how it goes. There wasn’t much difference in efficiency between a large (470 litre) roof box and 3 SUPs, but when I did a second run with then SUPs on a windy day there was a noticeable difference. There was more than a 10% loss due to the amount of drag. Motorway speeds make a big difference too 🤔
Haven't tried the roofbox on the MG ZS yet, but on our diesel, I'm still averaging almost 60mpg on the current tank when the roof ox has been on the whole time. The key is driving at 60 rather than 70 on the motorways. In France we were doing more like 45 mpg after long stints at 80mph on the autoroutes.
Be great to see a video on that particular model 3 with its age and millage Vs say a new standard range
Just come back from a round trip tom Devon and Cornwall with a 420l roof box and full car plus luggage for 4. I estimate approximatly 20% penalty based on similar speeds without the roofbox and full load. as you say, trip down and back is not a big problem. I drove around with the aero bars on for a week before putting the box on and didnt notice any apreciable change in efficiency from the bars alone
I drove to Barcelona with 3 windsurfers on the roof of my Y, yes did hit the range but the superchargers are so good journey was easy just a bit longer, when down there I was towing a trailer, again hit range but not as bad as I thought
Had my swivel screen & dash upgraded by RSEV the day I picked the car up from Heathrow
They’re 2 of the things passengers comment on (I’m a Tesla model Y taxi driver) other than the nestor led lights I’ve installed, oh & over the last 2 weeks I’ve added white seats (madness) to my taxi 🤷♂️
I regularly drive with a roof rack + kayaks. Generally the percentage range drop in an EV matches the percentage MPG drop in a petrol/diesel car. On a motorway at 70mph, I've seen -15% with 1 kayak, -20% with 2, -30% with 4. This is with whitewater kayaks (~2.5m long, 20kg) - sea kayaks, open canoes, sit-on-tops, etc will be different. I suspect how you tie will them to the roof bars will have an affect too (eg., upside down, via uprights, or using a cradle). Generally, I have a lot of extra weight in the car too (paddles, buoyancy aids, helmets, spray decks, throw ropes, dry suits, thermals, etc).
I've had a Kia Soul, e208, and a Leaf. The percentage drop is the same.
My biggest concern with a model 3/Y is the glass roof. At some point I'm going to drop something on it. Or I'll leave water bottle in the boat and that will fall onto the roof while loading. I always avoid anything with a glass roof, whether EV or ICE. Ideally with roof rails as they typically have a higher weight limit.
Use my roof rack and Thule box regularly - don't leave the roof bars on when not in use. I find about 7-12% impact on range, depending on speed and winds.
Interesting, but I'm more interested in how you can holiday in a location such as Seaton for, say, a week and how you can charge regularly for days out etc. We occasionally go on hols to nearby Looe which was easy on our old diesel, but now in my ID.3 I'd be slightly hesitant if we didn't have destination charging. The local chargers don't seem to have statuses updated in Zapmap etc so I have no clue beforehand if the chargers are reliable.
Have had multiple journeys on 2019 Model 3 Performance with Roofbox + Longtravel Mountainbike on german Autobahn - its a pretty steep increase about 35% at 140km/h in my case. Roofbox only (Alumined Design) is about 25-30% at that kind of speeds.
The Exeter expansion is now live as of today! I posted on the tesla FB groups.
My 23 m3 performance has also measured 282wh/m over 10k miles 😊
Richard, clear your desk, surplus to requirements 😂
Maybe I can actually kick back a little 😂
Would be interesting to see kayak loaded other way around. Might have better aerodynamics Yes I am a nerd
Try driving with a ski box on the roof in the Finnish winter... It's a bit scary the way the battery drains. 😅 I've got a Skoda Enyaq and at a few degrees below zero (centigrade) in more or less snowy/icy conditions, with a roof box, the consumption hovers at over 30kWh/100km (2mi/kWh) in the beginning of the journey (heating up the car cabin etc), but settles down to around 25kWh/100km (2.5mi/kWh) over the whole journey. Without the roof box, winter consumptions are around 20-22kWh/100km (~3mi/kWh), so the roof box adds maybe 3-5kWh/100km. In the summer and without the roof box, consumption on longer trips with a fully loaded car is around 16-18kWh/100km (~3.6mi/kWh). I haven't actually needed the roof box in the summer yet, so I'm not sure how much it would affect consumption in the summer time, probably somewhat less than in the winter, because cold air is "thicker" and causes more air resistance in the winter.
It did alright
Seaton is in Devon surely? Or is there one in Cornwall too?
Edit: well apparently there is a Seaton in Cornwall, who knew?! It's more like three hours away from Bournemouth though, without a charge stop so I still reckon you were in Devon!😅
Excellent news about the fairly minimum charging losses though, good experiment wherever ut was you actully got to.😄👍👏
👍
Just as Tony said. The drag is a function of co-efficient and speed. Your top load aero is also very relevant. A tear drop too box is better than a tent box, kayak not bad either. The equation is basically easier if you have the symbols on your keyboard. 🙄. 1/2x density x the square of velocity. Its that square that makes all the difference. In water it’s the cube so for ships like ferries trying to catch up schedules by going flat out is a no-no.
The text on screen appears to have the wrong label at the end of the middle line. 7:36
What's interesting no one considers this in a ice car we all know about it though but it's a good education.
Oh and Joe go on a diet.
Smoooooth swivel ad 😂
From my experience, a decent roof box which is reasonably streamlined will not take off more than 10% of the range. 3 bicycles on the roof and you'll be lucky to get 60-65% of the usual range, at least driving on the motorway
Would be good, whilst you’ve got the rack on, to see what a bike on the roof does for range.
Have we done a tow comparison? Lets see exactly what towing does to range🤔👍
Hi, there are a few videos out there on this subject. Obviously depends on speed and size but from memory anything up to halving the expected non towing range. There is one guy who towed a caravan from Scotland down to a camp site in Germany so it can be done, needs more charge stop planning.
bikes are best on tow bar mounts for long journeys *except* CCS chargers are all too often designed to make it impossible to charge an EV with rear charging port and bikes on the back.
I ordered an EV today delivery is early October my wife gets her EV end of this month
Hello mate
@7:25 I think you mean 21.7kWh/100kms (not mi/kWh) - titling error
Cracking video and great presentation.
So, has Seaton moved to Cornwall from Devon...or is there another Seaton?
Yes. The Seaton by Torpoint.
@@MrPindie Thanks. Had me confused there! 😂
Who is this bloke? My guess would be Richards hipster brother ? 😂🤷♂️
Even if it was a petrol car it would also have lost efficiency and had worse fuel economy. Aerodynamics really not type of juice being used to fuel the vehicle be it electrons or dinosaurs.