Senior Engineering Project - E-Trike - suggestions welcome!

[SimpleCJ]

Solar Electric Tricycle

Schwinn Meridian Adult Tricycle

For my senior design project I have chosen to design an electric adult tricycle. For this project I will adapt the pictured tricycle to electric power using a brushless motor coupled with a A123 LiFe battery pack.

My primary focus will be first to choose the proper motor, controller, charger and accessories from available retail sources. I will have to choose a compatible battery configuration and assemble the pack using loose cells. I will also have to determine if there is a commercially available charging system that is compatible with my battery pack. If there is not, then I will also have to design the charger myself. These A123 cells are capable of very high charge rates and it is possible to get a 10 to 30 minute charge with a high powered charger.

I will also be designing a frame extension to lengthen the chassis and move the seat down and back to lower the CG and improve stability. This will also require some creative linkage system for steering. My proposed motor mounting location is at the rear of the trike driving a separate sprocket next to the peddle driven sprocket. Exact gearing will be calculated from motor output RPM and desired cruising speed.

My secondary focus will be determining the feasibility of a compatible solar panel system. Many factors such as cost, complexity and efficiency must be considered. Mainly, will the added weight and drag of the solar array be counter-productive in energy efficiency.

My proposed configuration
Motor: 200W to 500W brushless motor (with planetary gears if possible), under 20mph
Controller: 24V to 48V, 20A to 40A, immediate start capability (versus peddle first)
Energy Monitor: Something to allow me to monitor energy usage, distance, speed, etc, for analysis.
Battery Pack: A123 LiFe batteries – either (36.2V - 13.8Ahr - preffered) or (26.4V - 18.4Ahr)
Charger/BMS: Undetermined. Preferably something that can charge at between 10A to 40A. Balance charging preferred...
Solar Array: Minimum of 50W mounted on a detachable trailer
Solar Power Controller: Undetermined. Must be able to supply power to motor during use and control charge to batteries when not in use
TOTAL SYSTEM WEIGHT: ~300+ lbs

TOP QUESTIONS/NEEDED SUGGESTIONS

What brushless motors with planetary freewheel gearing would you suggest for my project? I have looked at many motors... right now I'm considering the 500W Cyclone motor with planetary gearing and internal controller. It's priced reasonably and the internal controller and gearing greatly improves design complexity. On the downside, it is apparently a 24V motor with a 30V max. What's the major advantages/disadvantages of a 24V motor vs a 36V motor?

Are there any good balance chargers/BMS units available for A123 batteries?

Suggestions for steering linkage?

Cycle Analyst?

 

[etard]

I guess you want to keep the speed legal? The advantage of using a trike in the first place is that solid rear axle, you could mount a sprocket on there with an efficient Mars or similarly efficient motor. The Cyclone I would think an excellent choice. You could even use a Kohlmorgan (spelling?) which is 24 volt and has the motor and controller in one unit. I'm not sure why you would extend the frame on the trike since you are planning on attaching a trailer anyway. I would just feed the solar energy to the battery since its assistance to the motor will be minimal. Plan on using the batteries in 36 volt fashion since speed isn't part of your focus. Contact Gary (ggoodrum) about the bms, he has developed a very nice one. Good luck, a build thread might be in order.

 

[MidniteTweeker]

Curious. Why did you choose a delta trike configuration instead of a tadpole?

MT

 

[SimpleCJ]

Well, being a trike, I don't think speeds over 20mph are safe. I am actually extending the frame because I am going to mount a different seat (maybe a riding lawnmower seat) on a platform built on top of the rear assembly. This will greatly lower the CG and increase stability. With the normal riding position, speeds over 10mph would be unsafe. I could easily get it on one wheel turning at less than 5mph.

Extension brackets will move the rear assembly about a foot back, making room for a seat and small trunk on the back and putting enough distance between the crank and seat for comfortable pedaling. The biggest challenge right now is rigging up steering linkage from the front headset down to the existing seat post. I have some rough ideas on how this will be done, but I have to keep machined parts to a minimum, so I'm still deciding on the best approach to this.

You said that the 24v motor/controller would be good, but then you said to configure the batteries for 36v? I could do that, but I would need a voltage converter. Might as well configure the batteries for the desired voltage right? A 24v system with the number of cells I have gives me a nice 8x8 brick (18.4ahr 26.4v).

Thanks for the tip on BSM systems, I'll PM him. I am hoping I can get a hold of individual parallel circuits like what's in the picture here... or a consolidated system with wires to each parallel would work too..

As for the trailer... that will be for the solar power system and won't really be addressed until I get the trike modified, wired-up and running... if I even decide to try it and/or can afford it. The rest of the build is going to cost enough as it is. Without getting the solar panels donated, I doubt that I'll be able to afford it.

Once I start getting parts together and my extension brackets machined I will start up a build thread to record the progress.

I am hoping to design a simple conversion kit out of mostly commercially available parts and a few custom machined parts like the brackets. It'll be a low rider Trike kit for one of the best/most affordable Trikes on the market along with an optional electric conversion kit. I must design with simple, yet effective and esthetically pleasing modifications. Not that it will be very affordable to do in small quantities, or that I'll ever sell it, but to keep in mind a possible market for this type of product which is important for any engineer to consider.

 

[Rassy]

Hi SimpleCJ, welcome to the forum. Looks like a fun project. Of course, I would just put a hub motor on the front and be done. . Since you intend to make it a semi-recumbent, you might consider a recumbent seat. Then the rider can lean back and be real comfortable while pedaling. On the same topic, the Overseat handlebars on some LWB recumbents are quite long. On my brother's old Burley, the handlebars tilt up for getting on and off, and then snap down for riding. Good luck.

 

[SimpleCJ]

Do you have any links for recumbent bike seats? ... I guess I can Google it.

I was at first looking at using a front hub motor because of the simplicity of it, but after realizing the stability issues and the fact that this trike has alot of potential, I decided to go with the more efficient motors and a more complex design. After all, this is supposed to be my senior capstone project and a hub would just not be as cool of a design problem. I have a CAD/CAM buddy (just graduated) who is friends with our school's machinist and is pretty sure we can get everything ready to run (design and then create the tool path in MasterCAM) and he'll do it for free (minus the cost of stock materials).

I was just out there looking at it again... I put a piece of plywood down on the rear mounting bars and when I sat on it and tried to lean back to get a feel for where the handlebars need to be, the whole thing tipped over on me... I'm fine, no big deal, but this clarifies the need to extend the bike frame so that the rear axle is behind the rider's CG. The bike itself is so light that the rider's CG is going to be close to the total CG position. I'm almost wondering if 1 foot is enough...

I am hoping that I can keep the handlebars small and not in the way of getting on or off the bike. I need to choose a seat and get the extensions attached to determine the proper placement of the handlebars. They shouldn't have to be over the seat, I was talking about the existing seat post that will be right between my legs and in good position for mounting the steering assembly into the clampable seat post. Perhaps I can make it so you unclamp the post and raise the steering column to get on or off??

I need to find a good source for small CV joints for the steering, maybe even a geared 90 degree joint, but not if I intend to raise/lower the steering cause the gears would be in a fixed position.

 

[Rassy]

All sounds good. On the steering, both my recumbent trike and recumbent bike have underseat steering, but they are designed similar to what you have described. i.e. there is a steering tube built into the frame where the handlebars are attached. Then there is a threaded rod with a small ball and sockett on each end that joins the handlebar stem to the fork. Many riding lawnmowers have a similar rod with ball and sockett joints on their steering systems. The downside of this system is that it limits the degree of turning, as compared to a typical bike. This is only a problem when moving the bike around, not when actually riding it.

 

[SimpleCJ]

Would you mind posting a few pics of your trike's steering?? I don't think under seat steering will work for me, especially without cutting out the main seat post and rewelding the frame which is something I won't do for this project, mainly because I can't really weld aluminum very well and it defeats part of my proposal for a simple as possible conversion kit that doesn't require any actual welding or changes to the existing frame.

Lawnmowers huh... I'll have to see if they sell just the joints.

 

[Rassy]

I didn't mean you should install underseat steering, but I think the principal is the same for connecting the mid-bike steering stem (handlebars) to the front fork. Here are several poor quality pictures:
The boat picture shows a marine connector available so the trolling motor steers with the main motor. These are probably available at most marinas or:
http://www.westmarine.com/1/2/engine-systems-steering-systems-auxiliary-steering-kits-for-trolling-motors-zinc-rod
They are made from 3/8" fine thread stock.

 

[Rassy]

Here is a picture of the steering knuckle from my riding mower:
Edit, it also has 3/8" fine threads.

 

[SimpleCJ]

The riding lawn mower pic didn't show up?? I know what you're talking about though... here's a pic of an old project, can you figure out what it was before I tore it up??

Now I know what you meant by the ball joints. It may be possible to rig something like this up on the top of the headset where the handlebars usually mount. All I'd need is something my handlebars can pivot in sitting on top of the seat post. Probably do dual rods, one right one left so it doesn't look lop-sided... thanks for that! It means I don't actually have to clamp a support member on the bike near the headset, brilliant!

Although, CV joints would make a nicer looking system that just twists instead of using lever arms and movement. I think I can make it look good enough...

 

[diver]

this is my 35 mph trike. same one your doing very stable also. i also extended the frame , lowered the center of gravity and updated the rear wheels and axel.I also added rear disk brakes. i added a springer front end this fall ( one of the best upgrade i made ) it runs on 60 volts and has a range of 70 miles plus


My beast is a dual mars drive hydraulic brakes and is very stable at 45 to 50 mph .It accelerates like cheetah in heat..lol

 

[SimpleCJ]

Nice Diver!! You also have realized the potential of this trike!! Looks good! So it is stable up to 35mph? Did you add that cross member from the seat post to the headset? Mine doesn't have that. Springer front end? You mean a front fork with suspension? How far did you move your back end? What did you do to upgrade the axle? Where did you mount the rear disc brake?

I keep looking at that drum and shoe brake that comes on this bike and wishing I could replace it with a disc. Something in it isn't lined up right so it rubs and makes a gnarly sound with every revolution. Thinking of removing it...

 

[etard]

CJ,

What is the budget you are working with? What machine, welding, tools do you have access to? Do you realize that trikes are not street legal in most (if not all) states? If I were judging your project for viability, I would think this one of the major parameters to make it marketable. Yes, you can easily add a rear disc, study the axle of a go-cart http://www.bmikarts.com/shop/index.php?shop=1&itemid=299&passedfrom=thumb&showFullImage=
http://www.bmikarts.com/shop/index.php?shop=1&itemid=1444&passedfrom=thumb&showFullImage=
http://www.bmikarts.com/shop/index.php?shop=1&itemid=3272&passedfrom=thumb&showFullImage=
http://www.bmikarts.com/shop/index.php?shop=1&itemid=1144&passedfrom=thumb&showFullImage=
http://www.bmikarts.com/shop/index.php?shop=1&itemid=1334&passedfrom=thumb&showFullImage=

Sorry couldn't link the pics for some reason. :? But, I hope this helps, I don't know the diameter of your axle, but your machinist buddy should be able to come up with something similar based on these components.

 

[SimpleCJ]

Anyone know where I could find a threadless headset assembly with the tub and everything, but not attatched to the frame. I have looked everywhere and I can't find one. All I can find are the heatset kits with the bearings and caps.

Can I just make one with one of the headset kits and a piece of pipe?

I need to make something that the front threadless handlebars can fit into that I can mount into the seat post. I saw something similar on the Lightfoot Bicycle site, but they didn't have any details about purchasing just the headset part. Here's a pic of it, I want to use a similar set-up but extend the linkage all the way to the seat post and perhaps using dual links.

Here's a pic of a threadless post that I can clamp the front linkage to...

I'm also looking at possibly using a motorcycle trunk that will serve as cargo, battery & electronics storage, brake & turn signals, lockable security, and also can serve as the backrest. Something like this...

 

[SimpleCJ]

CJ,

What is the budget you are working with? What machine, welding, tools do you have access to? Do you realize that trikes are not street legal in most (if not all) states? If I were judging your project for viability, I would think this one of the major parameters to make it marketable. Yes, you can easily add a rear disc, study the axle of a go-cart

Sorry couldn't link the pics for some reason. :? But, I hope this helps, I don't know the diameter of your axle, but your machinist buddy should be able to come up with something similar based on these components.

I have probably about $1000 to spend. I already have the trike and the batteries... everything else still needs to be purchased.

I have access to an arc and mig welder and a small manual mill at my dad's place. I have basic tools in my shop, vice, various saws including a small bandsaw, drills, compressor with cutoff tool, most of the other basics. Our school's machine shop has manual and CNC mills and lathes, but I will have limited access to that because they're usually busy making other stuff so they'd be doing me a favor to make the parts. That's why I have to model it, my buddy is going to help me get the toolpaths set in MasterCAM, so that all they have to do at the shop is set it up and run it. I'll probably have to at least pay for the stock materials, which is a great deal considering just my extension brackets would cost hundreds of dollars if I were paying a machinist to make them for me.

I am actually a certified machinist, never actually worked in the field, just did a 10 month program at a tech center doing mostly manual lathe and mill work. I have Inventor for 3d modeling... I'll get a pic of my extension brackets posted shortly.

The axle is a weird dimension, must be metric cause I got 0.663 inches as the diameter with my digital calipers (didn't bother checking it in metric cause I'm modeling it in inches. Haven't yet attempted to remove the axle to see how all that goes together yet, should be interesting.

Where I'm going to be powering the rear, would it really be that hard on the tires if I made both rear wheels driven?? The axle rotates out both sides, but one wheel is mounted on bearings. I understand that you basically need a differential gear to prevent tire wear and turning problems, but how serious is that on a trike? Seems like it would drive better with both wheels pushing.

 

[Rassy]

Etard wrote:

Do you realize that trikes are not street legal in most (if not all) states?

I belive this statement to be false. All state laws (Edit: that I have reviewed) concerning both bicycles and electric assist bicycles classify three wheel bikes (trikes) the same as two wheel bikes. IMHO I don't think readers of this forum should be mislead by a statement like that unless specific laws for specific states are included.

 

[Rassy]

The axle rotates out both sides, but one wheel is mounted on bearings. I understand that you basically need a differential gear to prevent tire wear and turning problems, but how serious is that on a trike? Seems like it would drive better with both wheels pushing.

I was going to ask you earlier if both wheels were driven. If you set both wheels up with some sort of freewheel or one way (bearing?) that would allow the outside wheel on a corner to rotate faster without any binding I think it would work okay. Of course a true differential would be best, but also might be quite heavy.

 

[docnjoj]

Etard wrote:

Do you realize that trikes are not street legal in most (if not all) states?

I belive this statement to be false. All state laws (Edit: that I have reviewed) concerning both bicycles and electric assist bicycles classify three wheel bikes (trikes) the same as two wheel bikes. IMHO I don't think readers of this forum should be mislead by a statement like that unless specific laws for specific states are included.

I agree on false! Trikes are legal in every state around the South (not sure about Florida)! 3 wheels rule!
otherdoc

 

[SimpleCJ]

Anyone know where I could find a threadless headset assembly with the tub and everything, but not attatched to the frame. I have looked everywhere and I can't find one. All I can find are the heatset kits with the bearings and caps.

Can I just make one with one of the headset kits and a piece of pipe?

I need to make something that the front threadless handlebars can fit into that I can mount into the seat post. I saw something similar on the Lightfoot Bicycle site, but they didn't have any details about purchasing just the headset part. Here's a pic of it, I want to use a similar set-up but extend the linkage all the way to the seat post and perhaps using dual links.

Here's a pic of a threadless post that I can clamp the front linkage to...

I'm also looking at possibly using a motorcycle trunk that will serve as cargo, battery & electronics storage, brake & turn signals, lockable security, and also can serve as the backrest. Something like this...

Don't mean to double post, but this got left on the bottom of the other page and I thought it was important...

 

[AussieJester]

Interesting looking project, curious though if you wanted a recumbent
why didnt you just go an buy one (or build one from scratch) rather than buying a
upright delta? Seems your making alot more work for yourself..

If you want it more stable all you really need to do is stretch it a lil, rake the front head angle
back and lower everything down...

A bad photochop but you get the idea?
My Delta Trike does over 40mph and handles corners very well for what it is, checkout the latest video of 'around the block' hill climb

The brakes suggestion by etard also arent an option....The disk is too large to fit under the trike conversion
bracing AND fitting only a single disk to the axle will only stop the drive wheel, as the other wheel simply
freewheels a disk is required on the hub of that side I fitted rear disks on my delta trike, to do this
i used a dual front disk hub, cut the disk adapters from it and fitted them to the rear hub.
checkout pics here For the drive side i attached the second front hub disk adapter to the axle drive side plate
check pics of that here Hope this might help anywayz.

As for the rear wheel driving ...you cant have both wheels powered , well...you can but you wont turn on the street too well..
In the dirt it would be awesome LoL...

Best of luck shall follow with interest..

Kim

 

[SimpleCJ]

I have solved my battery welding problem!!!

11 Farads (from 3 car audio caps) @ 15V using a 210A SCR & Yamaha foot pedal switch!
A123 Cells to .005 stainless clad nickel strips.

The results... awesome! I can build my own packs!!

 

[etard]

OK, so I guess I should stick to talking about things I know about. Is it four wheeled bikes that are illegal then?

Jesser,
I'm sure you know better than me, is that sprocket on the axle driving only 1 wheel? Hydraulic discs might be able to be split to both wheels then, if it is necessary. Is it possible to coast through a turn, but still power both wheels?

 

[AussieJester]

is that sprocket on the axle driving only 1 wheel?

Yes matey it does, the otherside simple spins free

Hydraulic discs might be able to be split to both wheels then, if it is necessary. Is it possible to coast through a turn, but still power both wheels?

You could rig up the rear to power both wheels no problems, but in doing so (if done as per the original drive side of the trike conversion kit is) it wouldn't allow the wheels to freewheel at all, both would be constant drive and same speed...If you cut the axle in half and added a freewheel sprocket on each axle half(obviously major construction here, would also need a jackshaft in there between the crank and the dual rear freewheels i wpuld imagine) you could then freewheel through corners applying the power though would instantly see both wheels locking and driving at same speed...

 

[fechter]

Driving just one wheel could be a problem at higher power levels.

They make differentials for pedicabs that would be ideal, but they are expensive.
You might be able to find a differential for a gokart or riding mower for less.

Dual freewheels would give great traction, but I think you would definitely tend to straighten out if you applied power. If you were decelerating in a corner, it wouldn't be a problem.