E-Trike School Project

Jammin0

100 µW
Joined
Nov 22, 2018
Messages
8
Howdy, I'm brand new to the forum and have been searching around for some info but it seems like I'm trying a fairly unique build. I was hoping someone could help.

I'm a teacher and working with a bunch of kids to build a school tricycle for assemblies. I want it to run on ryobi 18v batteries so 36v would make the most sense. I'm planning on having a total of 14Ah in the system. These batteries are ideal because they run our ryobi tools in the makerspace. I've built had powered drift trike before but nothing electric. Here's the big question, what's the best way to make this thing go slow? Realistically I only want it moving around at 5-10 mph. I'm looking at a 20" fat tire hub motor but worried that the 1000w motor will want to run too fast.

I've seen slowed down motors like this: https://www.uumotor.com/webstore/slow-speed-geared-500w-800w-hub-motor

But the easiest design to have the kids carry out would be a front wheel drive "big wheel."

Any advice? Thanks in advance.
 
Nice project for the kids!
If you want to order at that site I would suggest this motor wheel complete with tire:
https://www.uumotor.com/webstore/sc...shless-gearless16-inch-electric-scooter-motor
It has a 100mm drop out width and might fit in a steel BMX front fork. So you could weld a bracket to it for the disk brake and use the head set and frame as well.

Pair it with this controller (36V) with 3-speed switch so they can learn in steps to ride at the different speeds (1-2-3):
https://www.uumotor.com/webstore/ac...attery-brushless-hub-motor-3-speed-controller

By using the "48V" motor with the 36V controller the max speed is already lower at 25% less voltage. And with the 3 speed you can lower it further. Don't forget to order a throttle:
https://www.uumotor.com/webstore/accessories/voltage-display-meter-electric-bike-throttle
And a brake kit (with brake switch to cut off controller so is much safer):
https://www.uumotor.com/webstore/accessories/electric-bike-disc-braking-plate-and-caliper

Good luck and it would be nice if you update this thread with the build progress or a link to it.
 
Some hub motors are wound slow enough to top 10 Mph, even slower.

I am thinking wheel barrel hub motors, usually 13 inch rims that make 21 inch OD with 4 inch tires. They go walking speed at 36v, lots of torque, and pretty cheap on Aliexpress.
 
Even thought you plan on designing the trike to go 10 mph or under,
It is still best to teach your students the right way to go about making a trike in the first place ... Make a leaning trike.

With years of research the only trikes I would own , for safety reasons are

1) A tadpole trike that has both a very long wheelbase ( much longer than traditional bike reverse/tadpole trikes )
that also has full suspension. ( suspension on all axles/wheels )
or
2) A Delta trike that has full suspension ( on all wheels axles or swing arms )
and that leans.

Here is an example of what to do, apply what is done here with this pit , with regular bike parts. ( with a slow and small front hub motor )

https://www.youtube.com/watch?v=gCVFfhCErlg
 
:thumb: Thanks everyone for the replies. I'm actually seeing this kit now from the same vendor: https://www.uumotor.com/webstore/index.php?rt=product/product&product_id=81&option%5B520%5D%5B0%5D=1314 and it looks really compelling. It mentions a 2 speed switch that sounds just about right at slow speed. I could probably put a key lockout switch to make sure it isn't put into the fast mode.

My next question is about batteries. I am looking at black Friday specials right now and thinking about buying some batteries. I want to get 6 batteries, 2x18v 6ah, and 4x18v 4ah. What does that put me at in terms of voltage and wattage? The kit I mentioned above says it comes in 48v and 60v versions. That seems like I'm falling right in the middle of that if I run 3 x 3 to hit 54v. Fully charged I'm sure they will be closer to 60-62 volts but I think they shut off at about 17v when they are low. That means I would be down to 51v. Do you think the 60v controller would handle that range or is it too low?

As far as wattage, if I run 3 in series at 4ah+4ah+6ah and combine that in parallel with another of the same am I correct in thinking that I'm about 60v @ 10ah or about 600w? There is a 500w and 650w versions.

Thanks for any more help you guys can give. If I can get this stuff purchased in the next few days I would be elated. I already secured a grant for the project and have about $1300 to work with if I need it but I need to save some room for LEDs/PA system/etc. :D
I'll be sure and start a thread in the project section shortly.
 
One of the best bits of help I can recommend is to look around at all the other relevant Trike threads, as many of them have to be slow due to their high-COG / short-wheelbase designs, and some of them are also school projects. They may have solutions to problems you havent' thought of yet, too.

This just finds all trike-subject threads, but you can either search within the list or look thru the titlesl to see what looks relevant.
https://endless-sphere.com/forums/search.php?keywords=trike&terms=all&author=&sc=1&sf=titleonly&sr=topics&sk=t&sd=d&st=0&ch=300&t=0&submit=Search

This one excludes a bunch that I'm pretty sure are not relevant, but still has a lot to look at
https://endless-sphere.com/forums/search.php?st=0&sk=t&sd=d&sr=topics&keywords=trike+-kmx+-typhoon+-leaning+-drift+-elf&sf=titleonly

Jammin0 said:
It mentions a 2 speed switch that sounds just about right at slow speed. I could probably put a key lockout switch to make sure it isn't put into the fast mode.
Or just don't install the switch, and hardwire it in the low speed mode.


Fully charged I'm sure they will be closer to 60-62 volts but I think they shut off at about 17v when they are low. That means I would be down to 51v. Do you think the 60v controller would handle that range or is it too low?
A "48v" pack or controller is 13s. (of LiPo or LiCo or LiIon; common ebike or tool batteries, vs LiFePO4 which would be more like 16s).

A "52"v is 14s.

A "60v" would be 16s, which would be unusual. You would want to find out it's LVC and HVC (which the seller probably doesn't know if it isn't printed on it clearly--typically sellers have no clue at all about what they sell, even if they are big volume sellers doing it for a long time).


As far as wattage, if I run 3 in series at 4ah+4ah+6ah and combine that in parallel with another of the same am I correct in thinking that I'm about 60v @ 10ah or about 600w?
Keep in mind that Ah only adds in parallel, and voltage only adds in series.

You want a pack that can handle much more wattage (or rather, churrent) than the controller will ever ask for under any conditions, so you don't stress it. It has little to do with the A, and everything to do with the A rating of the cells and BMS (if any). (A and Ah are completely different things).

Controllers' maximum current rating is what is important, as the wattage ratings are often whatever they feel like putting on there, but the current rating is what the controller would be able to draw at maximum load.




I'll be sure and start a thread in the project section shortly.
I would strongly recommend just keeping it all in this thread, so all the info is in one place (both for you and for others looking for similar solutions); if you want the thread somewhere else just ask a mod to move it. ;)
 
Thanks for all the search help and tips Amberwolf. How can I get a Mod to move this thread to the project build section?

I just bought this bike for a donor from Malwart for $63. Thought that wasn't bad at all and I have a spare front tire and tube that way. Biggest complaint from reviews is that it is really heavy. :) exactly what I'm looking for in a stable front end.
139da634-215b-4b50-bbe0-682c7acf6af8_3.f591ba72e35b7b7fbd04b6d9af8ab1d3.jpeg


I'm starting to think that using Ryobi drill batteries might not be the best idea? It would sure be handy to just be able to pop them out and use our 6 port charger to charge them. That's where I'm coming up with the weird voltages that I mentioned in the previous post. We have already designed a 3d printable receptacle for another project that these types of batteries click into so we could build a fairly elegant solution where they just pop in and out for charging. They also have the advantage of being fairly rugged with nice protection circuits built in. Any thoughts?
 
4 Ah + 4 Ah + 6 Ah in a series, is making 4 Ah effective capacity. The 2 extra Ah in your third pack is useless. Double 2 such series, and you have 8 Ah effective capacity. Probably enough for a school project, that won’t ride far away.

Your Ryobi battery packs are 18v ?
That would be 5 cells lico chemistry. Your 3 pack series (15 cells) would charge 63v max. That is a lot of voltage for a trike that you want very slow. I would recommend only 2 packs in a series, so you can benefit the extra Amps assembling them 3p.
 
MadRhino said:
4 Ah + 4 Ah + 6 Ah in a series, is making 4 Ah effective capacity. The 2 extra Ah in your third pack is useless. Double 2 such series, and you have 8 Ah effective capacity. Probably enough for a school project, that won’t ride far away.

Your Ryobi battery packs are 18v ?
That would be 5 cells lico chemistry. Your 3 pack series (15 cells) would charge 63v max. That is a lot of voltage for a trike that you want very slow. I would recommend only 2 packs in a series, so you can benefit the extra Amps assembling them 3p.

Thanks MadRhino. I'm looking at buying this kit which says that it comes with 48v or 60v controller.
https://www.uumotor.com/webstore/index.php?rt=product/product&product_id=81&option%5B520%5D%5B0%5D=1314

Correct me if I'm wrong but that puts me around 36v and not enough for the 48v controller. The kit is geared down for high torque and slow moving.
 
Sorry. I was with the impression that you wanted to build with a hub motor.

The gear bridge kit does weight 30 to 50 kg depending on the bridge length. That will make a heavy trike. You plan to carry heavy loads ?

48v is 14s and 3 packs series does make 15s. It will do for a 48v controller. Ideally you would assemble a series of 3 packs of the same capacity. You could series three 4 Ah packs, then series three 6 Ah packs, then parallel them and it will make 10 Ah capacity.
 
I dug up a YouTube video that tears apart a Ryobi battery and confirms it uses a 5s configuration. So it is a "true" 18 volt battery. Some power tool battery systems designate voltages different from the standards used for most ebikes and related systems. That standard is to rate a lithium cell at 3.6 to 3.7 volts, a value that is about halfway between the full charge voltage of 4.2v and the full discharge voltage of around 3.0v

As Amberwolf explained, a 48v system is 13s. So you can't really combine 5s system packs so that they add up to 13s. You can add them to get 10s or 15s, 36v and 54v respectively. I ran into this situation when wanting to use some very inexpensive 36v hoverboard packs on a 48v system. I chose to use a DC-DC boost converter to get the battery output to match my 48v system.

This is not a popular choice because it adds an extra component to the system and loses some efficiency. But I've put 5500 miles on my bike and have had essentially one problem where the DC-DC boost converter failed and needed to be replaced - and that failure was probably precipitated by an improperly seated connector. I commute 30+ miles back and forth to work five times each week using one of these $30-40 converters that boost my 36 volt system to 48v. (More info can be found in the link in my signature).

The actual boost voltage is 54v which is the voltage of a fully charged 48 volt battery. My controller's low voltage cutoff is 41v, So I could set the output voltage to anything between probably 43v (a tad above the cutoff) and 54v.

All this said, I'm not a big fan of using power tool packs for batteries. They are usually a pretty expensive choice for a given capacity. In fact, I sometimes wonder if these companies make power tools at a near loss so that they can profit from battery sales.

But if you aren't using the trike frequently and you can get dual use from the packs, using them may make sense. So In short, if you choose to use the Ryobi packs you might want to consider pairing them up with a DC-DC boost converter. Your other good alternatives are to find a 36v system, or to change out the controller in the system you are looking at to a 36v controller.

Ultimately what you do depends a long on what this project is supposed to accomplish. I see you making decisions online and being concerned about Black Friday specials. I see you buying a donor bike from Walmart in advance of having a clear design. Why not have the kids scrounge Craigslist, Goodwill or yard sales? How involved in the project are your students going to be? Do you want to invite them into a process where they end up trying different things and learning about the pros and cons of each? Maybe you want them to help decide on the pros and cons of which battery system to use and how to control it. Maybe you can provide a budget and let them help decide the best approach? Or are you looking to get an end project done fairly quickly that has provides specific utility and are just including the students in the design and build process in a minor way?
 
Well, I did feed 48v controllers with 15s lipo fully charged, and they survived pretty high power too. When I build a 48v system for someone, I feed it 14s to be on the safe side.

I agree that power tools battery packs are not the best choice to power a bike, but it will work. Most of ES members who are using power tools batteries are dealing with recycling. They are disassembling the packs, test the cells, then assemble a battery with the good ones.

Depending on their age:
Recycling batteries is also an interesting project for students.
ScooterMan did mention leaning trike design, suspension. If they are old enough to deal with complications, have them build an ambitious project.
 
MadRhino said:
Well, I did feed 48v controllers with 15s lipo fully charged, and they survived pretty high power too. When I build a 48v system for someone, I feed it 14s to be on the safe side.

The Ryobi (and most/all power tool batteries) batteries have a BMS. So you wouldn't have to rely on the motor controller's low voltage cutoff to protect the batteries from over discharge. So if the motor controller can tolerate 15s (54v nominal) that could be a decent solution (three packs in series) - though it would tend to run a bit (around 15%) faster than it would with a standard 48v battery.
 
Jammin0 said:
I just bought this bike for a donor from Malwart for $63. Thought that wasn't bad at all and I have a spare front tire and tube that way.
Doesn't look like a trike. :?

Are you going to custom-build the rear end? Or just use a standard "trike kit" that bolts to the rear dropouts/stays?
EDIT: nevermind, I see the link in your later post to the motor / wheel / diff kit; I guess you'd be fabricating whatever is needed to connect that to the bike's rear end.

I highly recommend you look up both my SB Cruiser thread (in my signature) and my Delta Tripper thread (linked in the first post of SBC), as they will give you some potentially useful info about some issues you may encounter, and show you some alternate ideas, and differences between a long wheelbase and a short one, etc.

I used hubmotors rather than a "middrive", simply because it was much simpler to build, and faster, and more reliable with the stuff I had to do it with, but the build principle is still the same.


Biggest complaint from reviews is that it is really heavy. :) exactly what I'm looking for in a stable front end.

Heavy doesn't necessarily make for stable. Correct geometry and COG for the speed makes for stable. That can be a challenge to get right. Also, most of the heavy bikes are heavy because they're made from cheap steel (or aluminum alloys) that has to have thick tubes to compensate for the easy-bending metal used.

My SB Cruiser trike worked out pretty well the way it started, and has stayed very close to teh same geometry throughout it's evolution; but it is also a very heavy heavy-duty hauler trike, meant to go about twice as fast as you're needing (20MPH) while hauling hundreds of pounds of dog (or whatever). At 10MPH it's very stable. (part of it's weight is the cheap recycled steel used to build most of it, part of it is the motors and batteries, part of it is the wooden bits).
 
Alright I think you all are changing my mind on the batteries. Now I'm thinking something more like this: https://www.ebay.com/itm/US-No-Tax-48V-13Ah-lithium-ion-Hairon-electrical-ebike-battery-fits-750W-motor/253905443652?hash=item3b1df19b44:g:01IAAOSwdQdbBSIt

That was exactly what I was going to spend on the Ryobis.

Kids are 11-13 years old. Mainly they are going to research, design in a simple cad software like sketchup, and then I will present it to them as a bolt together kit. Cutting and welding will have to be done in my garage as our school isn't setup for that. Kids can design accesories, paint, etc.

Trike won't be a leaner but it will have center of gravity as low as possible. Most like a drift trike with the rider 6" or so off the ground. That coupled with a max speed of 6mph or so and I'm not too worried about safety. We'll make sure to wear a helmet and most likely it will be rode by the team that made it and adults at assemblies. We can put in stops on the steering to restrict steering angles too. I'm thinking that the weight and geared down motor will probably do a decent job of braking when no throttle is applied. They sell plastic trike power wheels that go about 6mph so we should be able to come up with a safe enough design.

The working title that kids have come up with so far is LTV or Library Transport Vehicle. They want it to have a matched 4-wheel trailer/wagon type attachment to be able to pull around a load but mostly for fun. Think annual parking lot parade or to carry a class set of textbooks to a classroom.

Only other design constraint is that it be under 36" wide to fit through doorways at our school.
 
A few of footnotes:

Any speed can be reduced by putting a potentiometer inline with the return voltage wire from the throttle and dial back the voltage to the desired speed you want. You can do it with a cycle analyst as well. https://www.ebikes.ca/product-info/cycle-analyst.html

Ebike brakes will cut the power to the motor even if you have the throttle engaged. It is a standard feature on e-bike controllers.

:D :bolt:
 
e-beach said:
A few of footnotes:

Any speed can be reduced by putting a potentiometer inline with the return voltage wire from the throttle and dial back the voltage to the desired speed you want. You can do it with a cycle analyst as well. https://www.ebikes.ca/product-info/cycle-analyst.html

Ebike brakes will cut the power to the motor even if you have the throttle engaged. It is a standard feature on e-bike controllers.

:D :bolt:
Thanks, that's where my mind was at forever thinking about running a standard 1000w hub wheel but I was worried that I would sacrifice torque on the motor by running it at a lower voltage. Maybe I'm wrong on that but it seems like a correctly geared slower moving motor is more efficient?
 
Yes and no. A motor is most efficient once it is moving. However giving it a wide open throttle to keep it moving burns more watts then giving it a half throttle. Since you are building a very custom trike you may have to experiment a little to find your efficiency sweet spot. In general volts will give you speed, and amps will give you torque. If you are moving heavy things with that trike then think about 40a controller and a battery and motor that can handle it. My personal preference for batteries is LiFePO4 due to it's very safe low volatility. They are big and relatively heavy for lithium, but very safe.

I have no experience with the gearbridge setup you referenced so my recommendation would be to make sure it has the torque you need. The gearing might do it.
 
I thought I would post a video of the finished project. That motor and axle/gearbox setup ended up working really well. The guy that I corresponded back and forth with was super responsive and helpful despite a bit of a language barrier.

Anyway my students had a blast and are loving showing it off to people.
[youtube]L3TT5bkHd_0[/youtube]
 
Jammin0 said:
.....Anyway my students had a blast and are loving showing it off to people.
[youtube]https://youtu.be/L3TT5bkHd_0[/youtube]

Assume Job! And a really funny video... :lol:

Got to say, :bigthumb:

:D :bolt:
 
Jammin0 said:
I thought I would post a video of the finished project. That motor and axle/gearbox setup ended up working really well. The guy that I corresponded back and forth with was super responsive and helpful despite a bit of a language barrier.

Anyway my students had a blast and are loving showing it off to people.
[youtube]https://youtu.be/L3TT5bkHd_0[/youtube]

Nice project. Fun video. I'd like to see a more technical/serious video as well that give project details, stats, etc.

If you want the video to display inline, just edit your youtube tags so that only the file name is between them ... like this:

Code:
[youtube]L3TT5bkHd_0[/youtube]
[youtube]L3TT5bkHd_0[/youtube]
 
wturber said:
Nice project. Fun video. I'd like to see a more technical/serious video as well that give project details, stats, etc.

If you want the video to display inline, just edit your youtube tags so that only the file name is between them ... like this:

Thanks, I knew something was off. We'll see when I might get around to a more technical write-up of the project at least.
 
Yes, if nothing else a list of links to your purchased components would be appreciated
 
ScooterMan101 said:
Here is an example of what to do, apply what is done here with this pit , with regular bike parts. ( with a slow and small front hub motor )

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

That is actually an example of what not to do with a leaner, because at very little lean angle the rear sprockets will grind the ground. The advantage of any "leaner", whether delta or tadpole is the improvement in dynamic stability while permitting a narrow track. As far as non-leaning trikes go, a very long wheelbase tadpole can also suffer from poor stability. It's all about the location and height of a trike's CG (Center of Gravity). Here's a great reference for building stable 3 wheelers that don't lean https://rqriley.com/the-dynamic-stability-of-three-wheeled-vehicles-in-automotive-type-applications/

To the OP, why not build something useful and practical with the kids, an ebike, instead of a slow trike that's no fun to ride? My son's Artes Industriales teacher was planning this trimester to teach the kids about bicycle mechanics. The timing couldn't have been more perfect, because my son finally wants an ebike for himself, and I have a Phazor frame just begging to fill that request. The teacher jumped all over the idea of building up his ebike as the project with my assistance. He will still get to teach the kids the common bike mechanic skills needed to keep a bicycle in good operation, and I'll get the chance to create a bunch of young ebike converts all at once.

The kids and teacher have no idea what they're in for, letting me in a classroom for real hands on fun about my favorite discussion topic, why ebikes are better. Not only will they know basic ebike assembly when we're done, but also that basic math and science is easy, useful, and necessary (volts, amps, amphours, watthours, wh/km, battery types, motor types, torque, power, velocity, wind resistance, gravity and more). Hell, I'll even make sure they know Pi when I'm done with them.
 
Back
Top