Custom Sport Scooter Project

Since I started the project I've learned a bit more about what's available and how to improve things. The original plan for the batteries has changed some and it's likely that either Enerdel modules or else a 18650 format battery pack will be used later on when I embark on the next stage of the project. I spent the weekend reconfiguring the battery packs to be in clusters of 4. It did take a while to do this, but it's all done now!

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So played with Paintshop a little while back to get an idea of the final look.

The first image is with the current GBS cells, the second would be if using something more energy dense like the Enerdel option.

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Got an email from a guy who used to import e-moto scooters onto the island. He was looking to clear out his warehouse of old stuff not being used anymore. So was a very generous offering and will at least until I get the chance to order a high end hub motor assist in getting the bike on the road quicker.

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So finally got around to fitting the batteries into the chassis. Was some serious work, took a whole day! I had to line up and attaché all the busbars and balance boards. Not fun!

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When finally done looked good with cover in place. But then discovered a big mistake, one that would set me back a whole day. Basically the input / output connections of the balance boards are important and because of my layout without purchasing longer connection leads so I could run the cables onto apposing ends of the circuit boards the setup would not work! So Sunday evening took the batteries all back out and had to disassemble them and reconfigure with was a big undertaking! Yesterday I then refitted them back into the bike, a whole day job again.

 
Once I drew out the layout it all made sense. Shame I didn't do this at first, but I just assumed all the boards were the same. In actual fact the two end boards have 5 pins with the cable going to the BMS unit.

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One of the things I have kept on the back of my mind is what phase 2 with better batteries, controller and motor will entail. Originally I was thinking to go with 18650 cells like this: http://lunacycle.com/batteries/60v-25ah-samsung-inr-25r-monster-pack-extreme/ It would mean for the same capacity I could half the battery weight and have more power output if need be.

But I never realized how low the cycle life is as compared to LiFePO4 cells! For me 300 - 500 cycles till 20% loss seems quite low, possibly about 3 years. So the only option for now seems to improve the weight distribution of the LiFePO4 format by going with Headway cells. I originally wasn't a fan of having to build my own pack, but now having gained some comfort with my project fell that I could take it on.

The total weight would only be about 8 - 10 lbs less, but the critical bit is a section of the battery could live much lower and end up under the frame cradle. This would reduce the perceived mass of the bike so improving low speed handling. I have sketched the layout options so feel there is no reason why they would not fit.
 
The motor is a 5000W one, probably a Quanshun product so no spokes as you noticed. The controller is a KEB 72081. The plan is to upgrade later one now that it is running.

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cool built, i think 5 kw motor is enough for full electric, as you replaced the engine and all.

so that hub motor have inbuilt rim (come with rim from factory ?), so we just need to put tyre and fix it.
whats the rim size ? will it same size as front wheel rim size ?

as i am new in this, and have lot of questions.

About me :
i am now in starting stage of building my own controller, just started output stage of controller (will take minimum 1 year) will take some time to finish, as i am newbie in this field, learning electronice one by one.

my target is simple, just buy one second hand sporty look scooter, replace front wheel by bldc hub motor, put controller and battery in boot, yeah i planned to use scooter as hybrid like, with very low batteries (max 10-20 miles range is decided), my inside soul is telling within 2 or 3 years battery density will improve, so once the new type of batteries released, then remove engine and move to fully electric, as this is not the correct time (now we have enormous fossil fuel), and saving money for future batteries.
 
Yeah the motor comes ready to go. It is a 13" rim and so to match the front 14" tyre I have gone with a higher profile tyre.

That idea of making a hybrid scooter is also very cool! If you could making one with a geared hub motor so there is no drag when in gas mode would be ideal. I think finding the right motor is key. If you could step up the voltage from the gas engine to charge up the 36V pack or whatever you choose that would be cool.
 
Steel frame electric bike body :
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above image is designed by our local lathe guys, but they're not ready to share specifications and all, as they're telling, buy the design and do whatever.

Before seeing this steel frame, i thought, designing a frame is more difficult, but this steel frame image show me a light

2 wheels (one with hub motor)
front telescopic suspensions
rear suspensions
Handle bar

above parts can bought from shop, as they're universally same.
if we're able to sketch the steel frame means, we can finish it with high quality, strong, but cheaper than market available models.

any software recommendation for 3D steel frame build ?
 
John in CR said:
Ever since I saw this frame hidden under the plastic of a big Zev scooter. All I can think of for a scooter build is doing a carbon tub and getting rid of all that steel along with the battery box not included yet. Of course the rear would taper to a proper aerodynamic point. ... Get rid of all that steel and weight and welding and for low weight get that massive battery space.

+1 on that. I've started disassembling electric scooters twice, cutting off unnecessary and in-the-way parts. The first time I kept cutting off heavy steel crap until I ended up with just wheels, controller and battery. The second time I stopped chopping half way but was really unhappy all the original parts that I retained (trailing arm, headset, forks).

Scottydog said:
... took the batteries all back out and had to disassemble them and reconfigure with was a big undertaking! Yesterday I then refitted them back into the bike, a whole day job again.

My current build is a scooter with one big monocoque tub enclosing the rear wheel incorporating suspension in the wheel well. It eliminates all that heavy steel which is always in the wrong place to fit components. The pack can be removed just by lifting the seat and grabbing it.

I'm using a lightweight, inexpensive and easy to work type of carbon fiber composite which doesn't require molds. Of course an adjustment of taste is required to appreciate it's aesthetics, just as is required for "real motorcycle" people to appreciate "scooters" or light weight.
 
1JohnFoster said:
My current build is a scooter with one big monocoque tub enclosing the rear wheel incorporating suspension in the wheel well. It eliminates all that heavy steel which is always in the wrong place to fit components. The pack can be removed just by lifting the seat and grabbing it.

I'm using a lightweight, inexpensive and easy to work type of carbon fiber composite which doesn't require molds. Of course an adjustment of taste is required to appreciate it's aesthetics, just as is required for "real motorcycle" people to appreciate "scooters" or light weight.

Hey john, I agree that a carbon tub should be the best option, be great to see your design. edit (just searched it)

I was thinking to do such a build but being new to the ev game, figured best not bite more than I can chew, plus not sure how the road licencing group will view such a custom build! lol I was watching the Oracle guys working on building their new racing cat the other day so learned a few new carbon build tips. Carbon honeycomb is for sure the way to go!
 
granolaboy said:
Nice build man!

Looks really slick all put together.

Cheers Granolaboy!

I have had a slight setback though. When I built the battery pack one cell was 2.5V as compared to the 3.3 of the others. I charged it up and was hoping it wouldn't be an issue. Anyway took it out for a night test ride and did about 6 miles up a few steep hills then it died. It was pretty peppy maxing out at 120amps on the Cycle analyst. Was a good 3/4 mile push up some long hills! :(

The BMS light kicked in. The pack voltage seemed fine so I figure must me a cell causing trouble. I'm going to pick up some cell monitors to fit so I can figure out the culprit or culprits.

I do want to buy some new batteries so it might just advance my plans. Thinking to go with Enerdel modules which would fit very nicely.

Here is the image of me fitting the new red plastics, it is a very sporty bike!

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I had to reassess the build as with one faulty cell my choices were either to replace the cell or remove it from the battery.

The cost of the single cell was $95, but with shipping, hazardous fees and taxes it would have landed in my country for $250! :shock:

So I gave up on that plan as with 3 - 4 year old cells mixing in a new cell just didn't seem worth it. I removed the bad cell and reassembled the battery. The next bit was to adjust the charger. I was glad I spent a bit more and bought a good quality charger, the Zivan NG-1. I opened it up and then readjusted the charger to lower the finishing voltage from 72V to 65.5V

Now with it all back in operation was time to do some proper test runs. After the second run I wanted to find out the complete range and get an idea if the batteries were working fairly well. I charged the batteries fully and the next day went to give it a test. The voltage started at 64V and I rode it in varied moderate hills with some stops and accelerations for 1 hour before it ran out. My speed when moving would be 48 kph.

The total energy used as seen by the Cycle Analyst was 2.265 kWh.

The battery on spec would be 3.365 kWh

The interesting bit for me was the charger took 2.99 kWh to bring back to full charge. But since checking on this forum this would appear to be the norm.
 
Project complete..... for now!

Over the last few months I got around to sorting out many of the minor bits needed to complete for road licencing. I just spend a whole day getting it registered on the road, I am in uncharted territory here so I had to jump through all sorts of hoops! :x

It is over now so now I can enjoy the bike and figure out what it is like to live with day to day. I was playing with the Kelly software to figure out if the regen works and yup it sure does! :lol:

The next near term step is to order a Battery Satiator and fit as an onboard charger so I don't need to keep the large 12A charger in the helmet storage. I have a cool idea on this setup which would be very tidy!

Overall seems the bike garners attention when I park it. I notice people come to check it out and ask all sorts of questions. A few buddies have tested it and they love it. It should be even cooler when I later exchange the GBS cells for 18650 based packs! :D


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So far the bike has been working well. I have been discovering a new challenge.

To be nice to the batteries I have been charging to 3.4V per cell approximately. I don't have every cell monitored so use the 3 I do as a reference and compare to the total voltage divided by number of cells.

When I started trying to charge fully I got a bit nervous watching the early cells creep up over 3.6V, so would stop at that point. The GBS balancers are designed to bleed at 3.55V so hence my caution. However my cell balancers are of another brand so recently I did some testing and found they bleed at 3.65V. So this means over the 500 miles I've done the cells have never balanced.

This being the case I will need to charge to 3.7V per cell, but being fairly out of balance will need to charge with a very low current to make it work. I'm hoping to get a battery satiator which I can program to have a balance charge to use on occasion. This should bring back a significant increase in range I hope.

I don't know how far the cells were out of balance when I first fitted them, they were at least 1.5 years unused (secondhand). When I first was using the bike I was achieving 32 miles, but this has slowly been coming down.

Look forward to the next stage of work on the bike.
 
You need to balance charge them at least occasionally. Worst case get yourself a single cell charger and then after a full bulk charge bring all low cells up to full charge. You don't have to worry as much going somewhat over 3.65V/cell with LiFePo4. It's the batteries with chemistry that have a 4.2V/cell max charge that do damage by going above 4.2v .

LiFePo4 doesn't stay as well balanced, and the main thing you want to avoid is continuing to draw current when one are more cells are empty. Without a BMS you need to be a human BMS and monitor cell voltages in some manner. Keep in mind that your pack's useful capacity is only the capacity of your weakest cell, and the only way to know which it is, is by fully charging all and the first to fall below 3V is the weakest.
 
Thanks for your thoughts John.

I did find a good write up on ES explaining the challenge of the balance boards I have when the cells are too far out of balance. The main issue is as they only bleed 0.5A with a charger like mine with 12A it would just overwhelm the balancer and continue to raise the voltage. hopefully with the Satiator I can set a low current such at 0.5A or perhaps even 2A will suffice and it'll do the job in balancing the cells.

One big mistake I made was never putting monitoring leads during the initial build as after 2 battery fitments, going through the exercise of stripping again was not one I wished to go through! It is basically a whole day exercise! However when I get the Satiator I want to fit as an onboard charger so along with fitting new headstock bearings and some other parts would be a good time to do it.

The bike does have crude BMS system and does seem to work as when one of the previous faulty cells dropped low it cut the bike off till it was charged up. As a general precaution I set the Kelly LVC to 51V or 2.68V per cell. Doesn't guarantee some of the weak ones go lower.

But the question is? Does the sag voltage matter as much? So if a cell drops to 2.5V for example under load but is at 2.9V at rest, is it still an okay situation? Or is the idea to remain over the 2.6V point for these GBS cells at all costs!?

I have been thinking 3 of these guys in parallel would be sweet!

http://lunacycle.com/batteries/packs/60v/60v-triangle-panasonic-pf-20ah-high-power/
 
Project update!

Around March this year one of the GBS cells started to go into a death spiral so decided to park the bike up until I could get back on it. I also had to wait because until recently we pay a 33% tax on batteries and as part of the local EV group we managed to get this reduced to 0%. Once that happened I could then pull the trigger on whichever batteries I'd go with.

I had to figure out what battery type I wanted to go with. I had looked at 18560 style packs which would be pretty light, but there were two main issues. One was the highish price per kWh and the other was the lower cycle life to 80% DOD as compared to other type cells I'd seen. So this had me looking at Enerdel, then Nissan Leaf and laterly Chevy Volt modules.

Enerdels looked great but to get the desired kWh I needed the cells at the 72V range I needed the cells at 3P which can't be done with their modules, only 2P, 4P etc. So I was looking at the Leaf modules which also looked great but based on the volume fitting 9 modules in series looked like a push. So in the end it left me looking at the Chevy modules.

The guys at Battery EV Center had a 2015 2kWh + 1kWh setup that would easily fit in the chassis to I went with that for $600 which seems like a great deal. I ride the scooter in a normal manner, ie not being gentle I typically get 75 Wh per mile. So I figured if I use 2500 Wh on the module that would get me 33 miles which is generally plenty for my use and with many charge points showing up suitable for for my 110/220V battery Satiator charger all should be good!
 
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