Electric Reverse Trikes. Ideas, Rants, Collaboration?

[jmygann]

so we are looking at an electric reverse trike ... no pedals ... 1200-1500 lbs ??

http://www.evalbum.com/2558

http://www.evalbum.com/2959

http://www.evalbum.com/2559

http://www.evalbum.com/2311

http://www.evalbum.com/559

http://www.evalbum.com/416

http://reversetrike.com/all-electric.html

 

[chaster]

so we are looking at an electric reverse trike ... no pedals ... 1200-1500 lbs ??

http://www.evalbum.com/2558

Hey, that's Sparky!

i didn't realize that Kale had put that page up. I guess he didn't want to keep things under wrap... oh well. I guess I should give some more info, since it's part my baby too.

Some notes about this vehicle prototype. The information on the page is a bit out of date... Kale and I have been working on an all aluminum frame for a tilting reverse trike. We started about a year ago, and this was the first fruits of that collaboration. Kale is a master fabricator of aluminum and the frame is something he designed from scratch. I have been "spec'ing" the design at the high level, which Kale has been implementing. In other words, I told him what I wanted in basic layout, tilt mechanism, suspension design, etc. and he sits down with Rhino3D, designs it, and then builds it. The image you see above is "Sparky" (aka Prototype #1). Sparky is currently non-tilting (we experimented with tilting on Sparky, but in the end, Kale decided to go with non-tilting for simplicity sake). Sparky uses Lead Acid batteries (72V) and is geared for a top speed of 60 mph if I am remembering correctly. Sparky uses wheels/tires from a Kawasaki 600 Ninja.

Currently, prototype #2 (aka "Chamobile" - my frame) is under construction and nearly complete. Proto#2 is slightly longer than Sparky (about a foot), accommodates two passengers, and will include a unique tilting system which I call PHACS FTC (Passive Hydraulic Assisted Counter Steer Free To Caster). PHACS is something that I came up with, but FTC is already a known phenomena (see "tiltingvehicle.net" if you are curious). Anybody who has designed a high speed vehicle with tilt capability will tell you that it is a VERY difficult proposition which almost NOBODY has gotten "right". The beauty of this system is that it provides complete dynamic stability at all speeds with simple steering input (i.e. no manual counter steer) without the use of computers, powered hydraulics, or other complex electronics/dynamic stability control systems.

I've been working with Travis Gintz (of evfr.net fame) on designing and sourcing the electrical system components for the past 9 months or so. The current design calls for Prototype #2 to be powered by an AC-31 72V AC motor with a 100AH 72V LiFePO4 pack (although it has room for a significantly larger pack). I'll be using an Elithion BMS to monitor & protect the pack. The charger is a DeltaQ Quiq 72V charger. I was going to go with a 96V system, but finances prevent that at this point. Unlike Sparky, we decided to go with Ninja 250 size wheels/tires for Proto#2 in order to decrease weight/rotational inertia, maximize parts availability (lots of 250 Ninjas running around), and decrease cost.

While the frame of the vehicle is aluminum (and pretty darn light too - I have a picture of Kale lifting it with one hand), I plan to fabricate a complete fairing/shell for it which will be comprised of composites (Carbon Fiber, Aramid, & Fiberglass) and polycarbonate for windshield and windows. I am looking forward to the challenges of designing & fabricating the body as I am an aerospace engineer by training, and body design is an extremely "fun" challenge. I am hoping to maintain a Cd of less than 0.2, but that may be difficult considering the concessions needed for a practical "real world" vehicle meant for daily use (as opposed to a "no rules" concept car). We've already made several concessions to real-world concerns which compromise the aerodynamics, but that's just the way it goes I guess.

Total vehicle weight *target* (minus passengers) is ~700 lbs. This will be very challenging to achieve as this vehicle is designed to travel at high speeds (top speed of ~75 mph give or take...) and possess nimble handling at all speeds. Still, given that I will be using LiFePO4 instead of SLA and the shell will not be structural, I think it's within the realm of possibility.

Originally, Kale wanted to sell these frames to other people who wanted to build an EV (tilting or not). However, I think that after building Sparky, then Chamobile, and then another frame for yet another EV enthusiast on top of his regular work that he does for customers of his Metal Fabrication business, I think he is a bit tired. But if anyone is interested in commissioning another frame, feel free to give me or Kale an e-mail.

Whew. Well, now that I no longer have to keep my lips zipped, I feel a bit better. Maybe I should start another thread for my vehicle...

Eric "Chaster" Cha

 

[jmygann]

Is the 2 passenger tandem or sociable(side by side) ?

Any pics or links ?

 

[chaster]

Is the 2 passenger tandem or sociable(side by side) ?

Any pics or links ?

It's tandem for aerodynamic reasons and dynamic reasons (it's a tilter - a lot easier to tilt a tandem than a sociable). I understand that some people object to this configuration for social reasons, but I am not one of them.

There aren't many links online, but here's one where Kale took Sparky over to a friend's (Kraig Schultz) to compare with his highly modified BugEV:

http://www.schultzengineering.us/bchap6.html (scroll to lower half of page).

Here's a frame rendering (which is mostly up to date, but missing many steering components for clarity) for Proto #2:



Sorry I can't put more detailed pics up at this point because Kale retains the rights over the design and he is considering selling them as the basis for kits.

In case you are wondering why Kale retains the rights to a design which I am basically specifying, the reason is simple. While I had, and continue to have, a huge role in the design, our deal is that he builds me my frame for a VERY low price (considering it is to MY specifications, and done all in aircraft grade aluminum), and he gets to keep the rights to the design. It's not often that a master metal worker is willing to cut a deal like that, so I'm not one to complain.

Chaster

 

[TomA]

Eric:

Nice design, and absolutely beautiful fabrication work!

Total vehicle weight *target* (minus passengers) is ~700 lbs.... Still, given that I will be using LiFePO4 instead of SLA and the shell will not be structural, I think it's within the realm of possibility.

I'm intrigued by this statement. With that big diameter aluminum perimeter frame, you may have the lightest possible chassis, and adding a thin shell and all its mounting hardware would probably only add maybe 25 lbs to that, but is it really lighter than a composite monocoque would have been? Did you choose the tube frame because of weight, familiarity, ease of construction, all or none of the above? I'm in the middle of this myself on my trike right now, so I'm not questioning your choices, just working the problem and asking. Clearly, with such a good frame, you can add a body envelope no stronger than aero forces require, but did you consider structural composites, and if so, how did the projected mass compare with your aluminum chassis?

Also, I point out that it isn't really all one thing or another when it comes to body/chassis strength on cars. Most "body-on-frame" cars get significant chassis strength from the body shell, and most "unitized body" cars have subframes for the driveline and suspension pickup points, so passenger car chassis are almost all "hybrid" in this sense.

This is where my project is currently. Originally, it was going to be an all-composite monocoque, using both FRP-faced honeycomb aluminum sheet and CF and Kevlar/Epoxy over EPS foam, with a stressed skin shell and aluminum hard points floxed in and reinforced as necessary. I'm now considering whether a small CrMo subframe up front to carry the batteries and suspension will be lighter than the reinforcements and bulk of the composites that will be required to take the high amplitude shock loads of the suspension pickups. Chromoly is a better material there, even over aluminum. If I then make only the cabin monocoque a stressed composite structure, and bolt it to another small CrMo subframe for the rear suspension pickups, I think the whole thing will be lighter than if I just threw flox, epoxy and layers of CF or Kevlar at all those hard points. It will also give me more confidence to have the steel subframes, as it will be easier to bolt everything together without risking damage from overtightening, and Chromoly has a much friendlier failure mode than composite when overstressed...

Obviously, its all in the details, but I can't seem to get the all-composite weight where I want it, and I'm no aerospace engineer so it is very hard for me to estimate ply and reinforcement requirements. In short, my composite structures are going to be conservative and likely heavier than they need to be. Chromoly is so good in so many ways, and easier for me to understand, so I'm now pretty convinced that small steel subframes can solve the weight, strength and fracture problems all at once. They are also much easier to fabricate and, knock wood, repair. This is pretty standard home-built aircraft practice, where the engine subframe is a 4130 steel tube structure that picks up the crankcase mounts, then is bogged and bolted over a larger surface area of the composite airframe. It may also be worthwhile to tie the front and rear subframes together with one or two steel chassis tubes, creating a hybrid chassis structure that gets most of its strength from the composite shell, but has enough steel to give it some resistance to high-amplitude shock (fractures,) and better integrity in the event of a monocoque failure (shatter.)

Your thoughts?

TomA

 

[chaster]

Eric:

Nice design, and absolutely beautiful fabrication work!

Thanks, I'll pass on the compliments to Kale. It's his handiwork. =)

Total vehicle weight *target* (minus passengers) is ~700 lbs.... Still, given that I will be using LiFePO4 instead of SLA and the shell will not be structural, I think it's within the realm of possibility.

I'm intrigued by this statement. With that big diameter aluminum perimeter frame, you may have the lightest possible chassis, and adding a thin shell and all its mounting hardware would probably only add maybe 25 lbs to that, but is it really lighter than a composite monocoque would have been?

Not necessarily, but it was a multifactorial decision. Weight was just one of the factors that had to be balanced in the design.

Did you choose the tube frame because of weight, familiarity, ease of construction, all or none of the above?

All of that, plus many other issues. Cost was a huge issue since the budget for this vehicle is relatively small (and I've already gone over budget). Failure mode of the structure was another issue (bending versus shattering). I had originally planned on going with CF as the primary structural material, but there are significant fabrication issues when attempting to use handlaid CF for precision structures. There are a lot of other technical issues to consider (conductivity, thermal transmission, etc.) but in the end the biggest reasons for going with aluminum were cost/risk/benefit. Creating a vehicle that is primarily CF would be an expensive gamble when high quality CF runs $50/yard....

I'm in the middle of this myself on my trike right now, so I'm not questioning your choices, just working the problem and asking. Clearly, with such a good frame, you can add a body envelope no stronger than aero forces require, but did you consider structural composites, and if so, how did the projected mass compare with your aluminum chassis?

See above statements. It is hard to project mass of handcrafted composite structures (CF cloth is pretty easy to measure, but epoxy must have a very controlled application to make an accurate projection), and even then, it would have required significant computational dynamic modeling to determine the number of layups in the structure. This kind of projection is outside of my budget, resources, and time. Especially since handlaid CF requires a certain amount of overengineering (higher safety factor) to compensate for inevitable imperfections in the layup. CF has a very unidirectional nature and so works particularly well in compression/stretching loads. So, a unibody (monocoque) design makes more sense than a space frame. However, this also means a lot more material = a lot higher cost. Just to be clear though, the CF version would have been significantly stronger, and significantly lighter. However, it would have blown my budget out of the water and the failure mode would be catastrophic. In a vehicle that I plan to use as a daily commuter, this was just not a good choice. The conclusion may be different for you.

Also, I point out that it isn't really all one thing or another when it comes to body/chassis strength on cars. Most "body-on-frame" cars get significant chassis strength from the body shell, and most "unitized body" cars have subframes for the driveline and suspension pickup points, so passenger car chassis are almost all "hybrid" in this sense.

Agreed. I think my initial statement about the shell being "non-structural" was misleading. The composite body will actually have components that reinforce the structure significantly (A-pillars for example). However, the vehicle is solid without the shell (unlike most unitframe cars). We made a conscious decision to design the frame to serve as a "skateboard" on which to place different body styles as desired. The front and rear roll hoops are there in aluminum, but they didn't need to be. It's just cheaper to make those out of aluminum than CF (and again, failure mode is better for aluminum).

This is where my project is currently. Originally, it was going to be an all-composite monocoque, using both FRP-faced honeycomb aluminum sheet and CF and Kevlar/Epoxy over EPS foam, with a stressed skin shell and aluminum hard points floxed in and reinforced as necessary.

Sounds pretty similar to what I had originally planned. Be aware, FRP honeycomb/aluminum isn't very light. It's pretty strong for it's cost though. But if you are making significant structure from it, it gets heavy pretty quickly. Also, you are probably already aware, but just in case - know that CF will form a dielectric (not sure if that is the correct term..?) with aluminum (or steel) if placed in direct contact and will cause the metal to rapidly corrode(not good).

I'm now considering whether a small CrMo subframe up front to carry the batteries and suspension will be lighter than the reinforcements and bulk of the composites that will be required to take the high amplitude shock loads of the suspension pickups. Chromoly is a better material there, even over aluminum.

Agree. While the majority of my frame is high strength aluminum, certain parts of the suspension are steel for the same reason.

If I then make only the cabin monocoque a stressed composite structure, and bolt it to another small CrMo subframe for the rear suspension pickups, I think the whole thing will be lighter than if I just threw flox, epoxy and layers of CF or Kevlar at all those hard points. It will also give me more confidence to have the steel subframes, as it will be easier to bolt everything together without risking damage from overtightening, and Chromoly has a much friendlier failure mode than composite when overstressed...

I think that's a pretty good plan. I do not know what your primary considerations are (weight? Cost? Strength? etc.) nor what your resources are (skills? funds? tools? materials?) but there's a reason that F1 teams go with a similar tack. I have limited funds, and actually, limited time (both time to work on the vehicle, and a time limit to when I must have the vehicle functioning on the road). Compromises were and are inevitable in that kind of situation.

Obviously, its all in the details, but I can't seem to get the all-composite weight where I want it, and I'm no aerospace engineer so it is very hard for me to estimate ply and reinforcement requirements.

Unless you have access to some serious computational resources AND composite manufacturing resources, it's pretty darn hard to make accurate predictions without severely over-engineering (and driving weight & cost up).

In short, my composite structures are going to be conservative and likely heavier than they need to be. Chromoly is so good in so many ways, and easier for me to understand, so I'm now pretty convinced that small steel subframes can solve the weight, strength and fracture problems all at once.

I agree to an extent... I don't think building a vehicle is a "solvable" problem so much as a multifactorial equation that has different balance points depending on your goals... But I agree that you can definitely make a very good vehicle frame with good old steel mixed with newfangled composites.

They are also much easier to fabricate and, knock wood, repair.

I suppose that is a matter of opinion. I find fabricating and repairing composites to be an order of magnitude easier to do than working with high strength metals. Composite repair involves some fabric, some epoxy, and maybe some sawing. No welding, no bending of steel...

This is pretty standard home-built aircraft practice, where the engine subframe is a 4130 steel tube structure that picks up the crankcase mounts, then is bogged and bolted over a larger surface area of the composite airframe. It may also be worthwhile to tie the front and rear subframes together with one or two steel chassis tubes, creating a hybrid chassis structure that gets most of its strength from the composite shell, but has enough steel to give it some resistance to high-amplitude shock (fractures,) and better integrity in the event of a monocoque failure (shatter.)

Your thoughts?

TomA

Pretty much agree. =)

Eric

 

[jmygann]

One of the nicest reverse trike frames with pedals ... from Josh Kerson

 

[TomA]

Wow, that sure is nice.

I really like the adjustable length tube holding the crankset. Of course, there is a lot of chain drive still to be worked out here, but the empty weight distribution seems about perfect. It all depends on where the rider goes, and how massive a rider, but this is indeed a tidy design. That long steering tie rod is interesting, but I see the Ackerman angle looks about right on that super-long spindle steering arm extension. Nice brakes, too. Lots of good, careful work on this...

 

[Papa]

One of the nicest reverse trike frames with pedals ... from Josh Kerson

Not to nitpick, but... I'd hazard a guess that his laden weight distribution is too far aft. Non-tilting tadpoles (2 front 1 rear) seem to do much better when WD is closer to 65f/35r. And why no rear suspension? Front suspension only seems a waste if it doesn't offer much rider comfort.

 

[jmygann]

josh has spent many hours perfecting the tadpole trike.

He used to make a rear sus. but dropped it I think ??

I think he holds the drag record for a elec assist trike

http://www.youtube.com/watch?v=VT8-WspUNjg

 

[144vdc]

Hello todayIcan,TomA, chaster and all,
I have been planning to build a reverse trike for highway travel for some time now. I just came across this thread and found it very interesting; I have found some useful information here. I would like a gross weight around 1200lbs. curb wt. 800lbs. I need good traction to climb a steep hill with snow and able to cruise at 55mph. Efficiency is very high on my list. I would like to look good but aerodynamics is much more important than looks. Most vehicles burn up far to much energy in the motor and drive train. I want to direct drive the two front wheels with separate motors. I have ruled out hub motors because of road crud and unsprung weight. I plan to mount them inboard and drive the wheels through cv-joints. I calculate I will need 100lb/ft (for 30 sec. to climb hill) per motor and about 6kw continuous at 800 rpm (57mph) for cruising. I can't find any motors that meet those specs that I can afford, so I am in the process of trying to design and build them. This is the start of my motor effort.http://endless-sphere.com/forums/viewtopic.php?f=28&t=14339&start=270#p225121
I favour a fiberglass-over-foam body with a minimal steel space frame embedded in it.

Thanks for all the ideas and info and I hope I can contribute.
Jerry

 

[TomA]

I would like a gross weight around 1200lbs. curb wt. 800lbs.
I need good traction to climb a steep hill with snow and able to cruise at 55mph.

I calculate I will need 100lb/ft (for 30 sec. to climb hill) per motor and about 6kw continuous at 800 rpm (57mph) for cruising.

Jerry

Hi Jerry:

Welcome aboard! Your project sounds interesting. Let's think about the two goals above, and your calculations, for a minute...

First, your vehicle will be light. If you can't find dual suitable motors, consider the front drivetrain/steering/brakes from a Citroen 2CV. Its a little bigger and heavier than your weight class, but also a nice unit with all the engineering done. If I were building something around 50% heavier, say curb weight 1100lbs, the 2CV front clip with a DC series motor would be my choice. Anyway, two hub motors will be lighter, depending on what they are. This is the trouble with your weight class- its in between motorcycles and cars, so there aren't going to be a lot of suitable donor parts to use. Few bike parts are going to be strong enough, and any car parts I can think of will be too heavy. To be efficient in your weight class, you're probably going to have to make the front drive; suspension, spindles, etc.

As for going up a steep snowy hill in a 1/2 ton aero trike with skinny tires- wow, that's pretty bold! Its going to take some very special tires that aren't going to do very much for your dry pavement efficiency (range) or road handling, and they may not be available at all. (Do they make snow tires for motorcycles?) Don't forget to heat your batteries. I think 55mph is no problem, but it depends on your definition of "cruise" whether that's really going to be a good road speed for you. What range do you want to have at 55mph, and can you keep the motor(s) and controller cool at that speed continuously? Those are the big questions you need to answer to actually cruise at (and not just touch) 55mph.

Lastly, your power calculations: Do you need 100lb/ft from the motor, or just at each wheel? They are very different things. You can easily gear a modest motor to produce that kind of torque at the wheel, but a cheap, light 100lb/ft motor is a different story... Similarly, 6kW continuous to take a small trike 90 kph sounds pretty reasonable, but why 800rpm for the motor? That's pretty slow turning for the power curve of the motors I've seen, and will use lots of amps and get hot doing it in most cases. Is that a motor rpm or a wheel rpm you are after?

Anyway, your trike sounds cool, stay with it.

TomA

 

[144vdc]

TomA,
Thanks for all the input. I can see you have alot of knowledge on this subject; I'm glad I ran into you. A little more about my transportation goals might help to explain my requirements. I live off grid, mostly PV solar with some wind power, so the power I have to charge the batteries in limited. That is why I want to push the envelope for efficiency. I am a retired electrical engineer with a good deal on experiance with power electronics, so I intend to build all the drive electronics. I also have considerable experiance in metal working and auto mechanics. The 800 rpm is wheel speed but with direct drive it is also motor speed; same thing with the torque. Most common motors turn around 4000rpm for the rated power, that gives good power density but then you add a gearbox to get to a usable speed, adding weight, power loss and many more parts to wear and fail, you lose all the advantage to the higher power density motor. If my motor building project fails, then I will probably go with the high rpm motors and low loss speed reduction.

The curb weight goal is very flexable. I would like a payload of about 400lbs. (2 people+baggage). I want a range of 70 mi. If I can achive 100wh/mi, a 144v, 60ah LiFePo (250lbs)pack would do that. Areodynamics will be a hugh issue.

I am also considering a series hybred; 6hp ICE generator and battery pack just big enough to supply max amps; maybe 40ah.

Again thanks for the input,
Jerry

 

[TomA]

Jerry:

Nice to see your thinking. My thoughts:

1. Forget the series hybrid. The loss in efficiency is big, much worse than a heavier rig with more batteries.

2. There's a rough equivalency between a gallon of gasoline and about 8kWh of Lithium batteries. Jack Rickard had a decent technical explanation for it (ICE drivetrains are about 25% efficient, EV drivetrains closer to 80%) but whatever the math, I've been able to verify this rough number across a fairly large sample of Lithium-batteried EVs. So, if your glider got 30mpg with a gas engine, it will need about 10kWh (its really 8, but you can only do that safely over the long term by drawing no lower than 80% DOD on a 10kWh pack) of battery to do those 30 miles. Now we see the relationship between hypermiling and having a long range EV...

For your purposes, you can work backwards: 60Ah of TS or SE batteries is 3.2V x 60Ah x 45 Cells = 8640Wh. 80% of that is about 7kWh. So you have about 7/8 of a gallon of gas there.

Now, if you want to go 70 miles on that, you need a reverse trike (or any vehicle) that could go 80 miles on a gallon of gas if ICE powered. That's a tall order, indeed. I know of only one vehicle that could do it, but its way smaller and lighter than what you're thinking about:View attachment CalCom SideViewBW.JPGhttp://www.canosoarus.com/03CalifCommuter/CalCom01.htm

Craig Vetter has been trying for a couple of years to get that kind of mileage out of a fully faired Honda Helix- and after 3 years he's dialing in on it:

http://www.craigvetter.com/pages/470MPG/Freedom-Machine-intro.html

Beyond that, only 125cc and 250cc motorcycles with full fairings are in this efficiency class. My reverse trike will carry a 6kWh pack, so about 5/8 gallon gas equivalent. I think my range will be 35-40 miles, which means I'm rating the trike at about 60MPG. I'm shooting for about 125Wh/mi, and I've got a single-seater half the weight of your trike. If my design comes in at 95 Wh/mi great, I'll have a 50 mile range, but I'm not counting on it. Motorcycles and scooters that do better than that generally don't go as fast as I will be going. I think you need to at least double your pack to get the range you are looking for- but then everything gets heavier, and fast, as that extra 250lbs ripples through the design needing bigger brakes, frame, wheels, etc. etc. I'm not trying to discourage you, just pointing out that these projects are involved and expensive, and if you wound up with a range just under 40 miles after all that work, you'd be unhappy, no?

Try it this way- look up all the Lithium vehicles you can find in the EV album. There really aren't that many. See what they are reporting for range and pack size. Think about their weight and aero packages, and how much more efficient yours could really be. Take a close look especially at the bikes and motorcycles. Also, be skeptical about claims of range- its pretty well established that many people are just reporting impossible figures, whether they are mistaken or dishonest doesn't really matter.

The whole point of this observation is that I think you are being optimistic about the efficiency (and range) you can get out of your design. The more I have dug into this problem, the harder it all gets. I started off with a 750lb vehicle I thought would go over 100 miles. Now I'm trying to get a 650lb vehicle to go 50, and I just don't think it will. I'd love to be surprised, but I'm making damn sure not to be disappointed.

3. I think you'll need to rethink the low motor speed approach. Chain drives are pretty efficient, and would likely offer much less drag than the corresponding loss of efficiency (and heat generation) of running the same motor without the reduction drive. I don't think you'll find any vehicles out there with the motor speed and power profiles you're suggesting, and there's probably very good reason for that...

4. Really prioritize your needs and goals. Get the hard requirements pinned down, and identify those things you care less about, put ranges of acceptable values on them, and try to weight those ranges with your preference points. Then at least you won't have 50 variables moving around with no connection to reality as you start planning and noticing that the project can morph into almost anything, so long as there are no budget or time constraints, and no specification is really a hard requirement. You're at one of the most fun stages of a project, but also the most challenging- It is very hard to solve problems until they are clearly enough defined, and harder still to pick a direction when so many of them show promise. Let me make one such (screwball) suggestion that surely could have made my life easier if it had worked out:

Can you fit into a Lotus Europa? If you can, this would be the easiest, coolest and most fun way to hit your target. You can get a clapped-out Europa for a few thousand dollars. A fair amount of fabrication and $10-$15k more and you'd have all your objectives met, as well as one really cool, recognizable car- not just an EV toy you made yourself. Unfortunately, I'm just too big for a Europa. My next EV will probably be a late 1970s Lotus Elite, for many of the same reasons. I have some really cool ideas for how do do that. Remember, the Tesla is a Lotus. Just a thought...

TomA

 

[144vdc]

TomA,
Most of my optimism is based on my Honda Insight, it averages 70mpg summer, winter, mud and snow. Its curb weight is 1800lbs with a cd of .26. Some people are getting over 100mpg average with some modifications.

My vehicle plans depends on the success of my motor building project. This motor is similarhttp://www.csiro.au/resources/pf11g.html

Jerry

 

[TomA]

TomA,
Most of my optimism is based on my Honda Insight, it averages 70mpg summer, winter, mud and snow. Its curb weight is 1800lbs with a cd of .26. Some people are getting over 100mpg average with some modifications.

Maybe you're right. If you stripped the fairly light ICE/assist motor and took it all-electric, you'd have something like Gary Graunke's Insight:

http://ev.whitecape.org/insight/

His preliminary data are between 103Wh/mi at 20-25 mph, and about 185 at 50 mph, with typical city driving using regen returning about 145Wh/mi. This is a top-shelf AC conversion with the best of everything, carefully put together. Its likely those figures have been improved over time, but still- this car is at about 150Wh/mi all day. With your pack, this Insight would have a real-world range of 45-50 miles to 80% DOD, less at highway speeds.

What that tells me is the Insight is one very efficient vehicle right out of the box. Converting it to an EV actually loses some efficiency. It is optimized to do more with less gasoline than anything else around- really overachieving on expectations. No one knows more about four cylinder engines under 1500cc than Honda. I'm not sure the Insight is a good example of what to expect from anything less meticulously engineered. Its a very high efficiency target for the home builder, make no mistake. Its also a major EV conversion challenge. Beyond the technical difficulties, people aren't converting them because you very quickly go over the GVWR doing it, even with a lithium pack. In other words, the Insight is right at the limit of efficiencies in almost every area, bone stock. Impressive vehicle. I was told by someone in a position to know that when they first came out, Honda was losing $14,000 on every car sold, but the company considered it an investment and kept going. The first Insight is just plain cool, and because the market didn't accept it, I don't think we'll see anything quite like that package produced for a long time. Its not like the design can be hugely improved and Honda missed a market opportunity with a clunker. I predict the cars themselves will be around forever, with a devoted following that solves all the downstream problems like replacement batteries and trim parts, in the collectible sector- a unique outcome for a Japanese econo-commuter, outside of the way racers hoard old CRXs. [/end autophilosophical rambling]

My vehicle plans depends on the success of my motor building project.

Ain't that the truth. If the motor I intend to use proves unsuitable or becomes unavailable my vehicle quite literally goes back to the drawing board...

 

[jmygann]

TomA

"My reverse trike will carry a 6kWh pack,........ I think my range will be 35-40 miles, .........I'm shooting for about 125Wh/mi "

Any info on the trike ?

where will you get the pack ?

 

[TomA]

I haven't decided on a pack configuration yet, but I'm planning to use either ThunderSky or Sky Energy LiFePO4 cells- 40Ah to 80Ah size, between 96 and 154 Volts.

I've started a blog on the project here:

http://the-moonray.blogspot.com/

TomA

 

[chaster]

I haven't decided on a pack configuration yet, but I'm planning to use either ThunderSky or Sky Energy LiFePO4 cells- 40Ah to 80Ah size, between 96 and 154 Volts.

I've started a blog on the project here:

http://the-moonray.blogspot.com/

TomA

TomA, are you concerned at all with the Thundersky/Sky Energy's lower current capacity (at least, lower compared to Headway)?... I realize that you are going with a pretty high voltage (are you building your own in-wheel motor? I haven't seen any in-wheel motors that are 154V capable) but was curious ... If you're drawing even just 160A, that would be 4C on a 40AH pack and from what I remember, the SkyEnergy and Thundersky large format cells are only good for 1-2C, maybe 3C peak...?

(apologies if these are dumb questions - my field is aero and software, not electrical engin.. I depend on Frodus to figure the electrical stuff out)..

 

[TomA]

No, those are good questions, and I don't know the answers.

a 150+V 40Ah pack is an idea for speed- probably overkill and certainly would stress the batteries at 4-6C. They will do it, but it will likely hurt them. I don't even know if the motor can do that voltage. In fact, really, no one knows. The motor is also in an upgrade cycle of unknown magnitude as we speak. Fortunately, I'm not at a battery purchase point right now.

96V of 60Ah batteries is definitely a better compromise. 200A from that pack won't wreck it. Yeah, maybe shorten its life some, but draws >3C would be in VERY short bursts, and under 5C.
The Kelly controller I'm planning to use won't likely deliver that much current- even though it is rated far higher. It also probably takes less than 60A to cruise around in a 625lb gross weight vehicle with a Cd near .2, and since the weight is so low, I'm not really worried about sustained high current loads on the highway, like doing the 300' hill back to my house or accelerating into traffic. Also, these TS/SE cells are significantly improving every 6 months or so, and also being uprated at about the same frequency by their manufacturers. I am confident 3C continuous, with bursts to 5C will be OK, and I don't see the vehicle typically drawing more than that.

Yes, banks of A123 or even Headway cells would be better, but they are just still too expensive, and the budget will largely determine the selection of my first pack. I will try to shape the battery bay to accommodate as many configurations and cell types as possible. I'm actually thinking of doing the same thing at the rear for the drive system, to accommodate an inboard motor and chain or belt drive at some point should I need to, so I'm not so dependent on the EnerTrac hub motor working out. Its a lot more work and costs weight to do that, though, so we shall see.

Short answer: Yes, A123 batteries would be best.

Headways are probably also better than the large format cells, but how often? TS/SE batteries, carefully sized, are certainly good enough to start with, and probably good enough for everything but speed trials. I might be able to borrow A123 batteries to do that, and still use the 60Ah cells every day. I'm so conservative about efficiency and performance, this thing might just fly on 60Ah cells at 96 Volts, in which case I'll be careful with them and won't really have think about it for a while.

I know its a tired answer, but the best response is: It all kind of depends...

TomA

 

[144vdc]

One part of a low Cd vehicle that has no good all round solution is the windshield. If it is at a low angle for good air flow and large enough for good visibility and make the dash board black to reduce glare, you have built a very good solar oven. All these concept cars with the bubble canopies could only be driven in winter, at night or on cloudy days.

One idea would be to have outside air ducted through the surface of the dash to conduct away most of the heat. Tinting could help.

Conventional air conditioning consumes an unacceptable amount of energy. Comfort on a hot sunny day could be a real challenge.

Any ideas?

Jerry

 

[chaster]

Yeah, AC is a tough problem from an energy standpoint. One helpful solution might be a solar powered fan to circulate outside air into the cabin (I believe the Aptera was/is supposed to do this) to keep heat from building up in the first place. However, in very hot areas (where ambient heat is so high that circulating outside air in won't help) I think you are stuck with the Carnot cycle.

If the vehicle is moving, then of course, you can get cooling by air ducting...

I've looked at Thermo-electric Couples (TEC's) that use the Peltier effect but they are incredibly energy inefficient. The Carnot cycle seems like the best we can do as far as A/C goes at the present time.. Would love to hear other people's ideas..

Another option is to use a redneck a/c unit: an insulated beer cooler full of ice, ice water, or freeze packs with a fan and ducting.... Cheap and simple, but you have to "refill"... heh.

*edited for some typos*

 

[MikeB]

Tinting could help.

Tinting should simply be considered mandatory, all other approaches only become feasible if proper tinting is used.

There are some very good thin film tints out there right now, that reflect something like 90% of IR energy, as well as most of the visible light and virtually all of the UV. I can't imagine building a vehicle without this type of high-performance tint overhead and on the sides. Most states have laws to limit the allowable tint forward, but you can get films that reflect IR and UV but still transmit most of the visible light.

On the topic of AC, I think you could live without it as long as you always have really good cabin airflow. Probably, I'd suggest some high volume air ducts with very quiet fans, they'd somehow need to move perhaps 5-10x as much air as a typical automobile vent system without sounding like a jet engine.

 

[TomA]

I will have two different windscreen options from which to choose- my trike will be a "hardtop convertible" in that sense, or maybe more accurately, a "two top roadster".

First, a sealed full bubble canopy:

http://www.blueskydsn.com/re_cov_.html

Solar gain is a big problem, and needs to be minimized. I'll paint much of the canopy, so that only the parts I actually need to see out of are clear, dramatically reducing the sunlight that gets in. This is the big mistake most people make with airplane canopies- they don't realize we aren't using much of the vertical axis in ground transport, and don't need to see straight up or look at the hood and fenders! The "ceiling" of the canopy should be painted, or at least totally reflective, just like the band below the point where the drivers' eyes can see the road. This is what racers do, and it reduces both solar gain and glare. What I look through will be tinted to reduce IR/UV. I will also make a reflective mask for the inside of the canopy for when it is parked, like those "shades" things people put behind the windshield. Good ventilation is essential- not only to cool the driver, but for demisting of the canopy and cooling the motor controller, which is in the cabin with me. I'm toying with the idea of running vent fans when the car is parked to cut down the interior heat soak, but I don't expect to leave it in the sun for hours at a time, so that's a pretty low priority. The solar-powered vent fan or A/C (actually pioneered by Saab on the EV-1 show car 25 years ago) is an elegant idea, but the reason it didn't work well then still pertains- there just isn't enough available area on the vehicle's exterior for the solar cells required to keep the interior volume ventilated. A semi-trailer, maybe, but not a car. I also agree painting the interior area under the windshield black creates problems. I doesn't have to be black, that's just what people are copying from the auto industry, and the OEMs only do it because its cheap. A flocked gray or tan surface would be fine for glare reduction.

Efficient and weather tight as the canopy may be, it will also be hot, stuffy and may be claustrophobic no matter what I do. I will also make an open cockpit windscreen setup like a late-60s formula or Indy car. I think the trike will be much more fun to ride like that, and done nicely, I don't believe there will be such a huge difference in speed or range. Certainly it will be worth trading off some efficiency for the open air motoring, and I'm betting the open cockpit configuration will get more use. The trick is to make it quick and easy to swap tops, so I can go either way as conditions indicate. One of the nice things about a limited range is that you don't have to build for all-day driving far from home. The vehicle just isn't going to be run for much more than an hour, or taken very far from home.

Finally, its much easier to do all this with a single-seater. On a bigger trike, you probably need the structural value of having the windscreen fixed into the body, but a flip-top could still be done. A bubble canopy large enough for a sociable trike is going to be a big greenhouse, and expensive. Most small reverse trikes (or vehicles of any kind) are open roadsters for a reason. Passengers also tend to need better climate control than the pilot, and they put more humidity into the cabin. As you say, chaster, no easy answers here...

TomA

 

[TomA]

Probably, I'd suggest some high volume air ducts with very quiet fans, they'd somehow need to move perhaps 5-10x as much air as a typical automobile vent system without sounding like a jet engine.

That's going to be very difficult, and probably isn't necessary. OEM cabin ventilation systems, particularly American ones, move a huge amount of air and they are cheap and reliable. I would start right there, with the blower and housing from a Suburban or Excursion. You won't move more air for less money. IIRC, they use a 50Amp fuse...

TomA