Tangerine Dream Machine efficiency initial numbers

A

ajtest

100 mW
Joined
Mar 26, 2009
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I think a few of you have been following my Quest velomobile electrification project which has been happening with the assistance of many people including Lightningrods and his Big Block mid-drive (but at 100 Volts).

Recently I've been doing a bit of testing at 50 Volts with a very small Lyen controller using 2x6S Multistar 20Ah lipo packs.

I now have some consumption figures generated from my trip to and back from The Swansea Bay Campus which is a round trip of about 20 miles, with a total climb of 100m. I use one of Justin's fantastic Satiators which saw just over 7.2Ah bring them back to their fully charged state which would suggest that with just those two packs I could go about 110 miles.

This is excellent and means that with the 8x6s packs I will be carrying they will give me a range per charge of roughly 400 miles without pedaling.

https://youtu.be/73cHf2RVKWI

Cheers

Andrew
The Tangerine Dream Machine Man
 
How much does it weigh with the two packs, and how much does it weigh without them?

I've had a similar idea for a vehicle in mind for quite a while, but to keep it road legal as a bicycle within the jurisdiction of my location(no insurance, license, title, ect), I need to keep the vehicle weight under 100 lbs.

125 mph in a velomobile is quite ballsy. I hope that everything goes okay.
 
Following further testing I think that I have previously greatly underestimated TDM's range.

Next week I will be carrying 12x2.5kg Multistar 6s 20Ah packs which will provide around 6kWh of capacity.

Soren (Velostrada on YouTube) did 170Km on less than 500Wh so if I use my CA to restrict to the European legal limits on bike paths and roads (250W and stops over 15.6 mph/ 25kph) etc. it looks likely that I will have a range per charge of roughly 12x110 miles!

This clip sees me saying more or less that.

https://www.youtube.com/watch?v=WDDX_cfX9hs

Andrew

The Tangerine Dream Machine Man
 
7.2ah of 50v is 360 watt hours. But that was what the charge back took, so lets assume you used about 320 watt hours for that 20 mile ride.

So you are getting a very plausible 16 watt hours per mile. sounds about right to me. 6000 wh divided by 16 is 375 miles range. Not 1320 miles.

It's possible you can do better than 16 wh/mi. But not THAT much better. Well, of course you can, but why pedal so hard you get 1 wh/mi? That's just pedaling around lugging a battery. More likely to actually receive an assist, you will need to cruise at more than 100w of power. Just because the battery weighs what it does.

8 wh per mile is not an unreasonable goal for a velomobile I think. 750 mile range is not at all bad!!
 
Thanks for the update. 170 km on 500 wh is 4.73 wh/mi. That's a good level of efficiency.

Even with all of the added weight to get to 6 kWh, I think that you will get well under 8 wh/mi. The Quest is a fairly efficient velomobile design. While it is no Milan SL, 250W is easily enough power to get one of these to ~27-28 mph on flat ground. Too bad the law limits you to 15 mph.

It makes the XL1 look like an energy-guzzling pig. I've always been of the opinion that cars should be designed more like velomobiles.

How much does your TDM weigh?

Were I rich, I'd purchase a Milan SL carbon, have a titanium subframe made to slot into some holes drilled into the velomobile's body to add rigidity, then replace the rear wheel with motorcycle wheels/brakes/tires while using scooter wheels/tires for the front, put in a ~1.5 kWh LiFePO4 pack, add a titanium roll cage, and a set of dual AstroFlight RC motors and set it up for about 20 peak horsepower, where the motors only activate when the vehicle is being pedaled(other than a "limp mode" that would allow 20 mph with no pedal input at all). Imagine a 100+ mph capable road legal(in Texas) highway-capable "bicycle" that can accelerate from 0-60 mph in under 4 seconds... and still be operated on pedal-only power when desired. While such a contraption would be significantly less efficient than a stock pedal-powered Milan SL, it's efficiency would still make any car look piggish. It takes 150W to do 30 mph on a stock Milan SL, so 250W to do 30 mph on flat ground with this hypothetical setup wouldn't be unrealistic, even with the high rolling resistance of scooter/motorcycle tires... The miles per gallon equivalent would be measured in the thousands, and even at highway speeds, the human doing the pedaling would still be contributing to 10-20% of the vehicle's power. It would be legal virtually only in Texas, because of the way an "electric bicycle" is defined in Texas legal code.

It sucks that you're stuck with a 250W/15 mph limit for electric assist for it to be legal to use on your roads. Without these sorts of legal restrictions, electric velomobiles would become a much more viable form of transportation, expanding the potential market, and as a result of higher volume production, reducing the per unit manufacturing cost.
 
I guess I'm confused again. I thought it was somebody elses velomobile that got 4.73 wh/mi.

I thought yours got 16 on that test. I'm sure you can easily do better than that, depending on how slow you go. As we all know, at some point your pedal input becomes equal to or even more than your motor input, and wh/mi drops to a crazy low number.

But also at some point, you end up so low powered that you'd do less effort if you weren't hauling around an aero shell and 6 kwh of battery, to go walking speeds.

Your range at a reasonable speed, say 20 mph should be really good though. In the 200-300 miles ballpark or more.

I'm a bit surprised that your dream machine does not already have a wattmeter, like a cycle analyst. On my longer rides, I rely on the CA to tell me my wh/mi average as I ride. I can easily calculate the wh/mi I'll need to do a particular ride. Then on the road, depending on things like wind, I can vary my speed to be sure I'm hitting that number. Towards the end of the ride, I can then speed up if I'm making it with a too big margin. For me, really nice to have that watt hours per mile number always there on the fly.
 
The test done using a friends velo, which is either a Strada or Mango, was using the legal maximum for Europe namely 250W and no power at all when going over 25kph. This was the journey which resulted in 170 km on less than 500Wh.

My Quest, prior to electrification, weighed 35kg.

Now, the batteries weigh 30kg and the motor is 7kg so I have more or less doubled its weight.

I personally have lost 25kg and the current laden weight is 130kg.

I use a Cycle Analyst V3 and initially set it to the legal limit (to confirm the extraordinary efficiency that my friends test ride seemed to suggest) but for several subsequent tests have upped it to as much as 4kW (on the beach for testing) which is why many of my rides have used substantially more battery capacity than I discovered was the case when I used the European limits.
 
I think that you will succeed in setting some records.

The energy consumption per mile is exceptional, even given the limited operating conditions. On the flat or downhill, the weight isn't much of an obstacle, and up hills are going to be slow anywhere thus the governed motor-assisted speed isn't a hindrance as it still tremendously reduces rider effort required up hills at slow speeds.

I would guess that maintaining slightly more than 15.5 mph on the flat in that Quest for minutes or even hours on end doesn't take a massive amount of effort, either, even with such a heavy laden weight. Acceleration after the governed speed with nothing but your legs to propel you is going to be quite tedious and glacial, though, but maintaining a cruising speed of 20-25 mph should be relatively easy when compared to a high-end road bike.

Being able to run it with the electric drive in a safe environment with no governor is a wonderful opportunity. Try to get camera footage from various angles of the velomobile, especially a first person helmet cam view. I want to see what triple digit miles per hour in a velomobile looks like, as I don't see myself trying such a feat in the near-term:!: A whole lot can go wrong at those sorts of speeds, but it still looks like a ridiculous amount of fun to try it. I hope you enjoy it.
 
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