CroBorg Super Commuter

General Discussion about electric bicycles.
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Alan B
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Re: CroBorg 2kWh Super Commuter

Post by Alan B » Jun 21, 2015 11:17 pm

Battery pack monitored carefully during charging and balance was maintained. Not sure what the noise was, but apparently it wasn't the bike. There were a lot of cars in the golf club parking lot, much more than usual, perhaps they were the source. Ready to roll tomorrow.

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Last Ebike Work Commute

Post by Alan B » Jun 24, 2015 7:03 am

I suspect yesterday was my last ebike work commute.

Two work days left, (today and Monday) but will not take the ebike. Have a few things to bring home, requiring a vehicle.

End of an era.

When I started work at this workplace I had a Motobecane Mobylette Moped (and it was fairly new). It went up the steep front drive at 9 mph, angering the cars. Later I got a Honda CB125S which did better, and then a CX500D which could do more speed up the hill than was safe. Years later I stopped commuting by motorcycle, mostly due to the difficulty of wrestling a 500 pound machine around the yard at home and no decent place to park it. Then I found ES in 2010 and began the lithium powered ebike journey. Several bikes and 8k miles later I've made a lot of e-commutes and had a lot of fun. My CroBorg will make it up the back hill (which is steeper than the front) at about three times the speed the Moped made up the front hill. It is reliable, the only thing that has stopped it are nails in the tires from construction projects. Almost forgot, several melting FETs in the controller stopped it a few times as well. Once I had a charging failure and ran out of juice, had to push it up a couple of hills near work since the pedal gearing isn't low enough for climbing. This machine is four times lighter than the motorcycle was, and really easy to move around, I pick it up regularly to help with that. Now the improved Lipo battery can make a round trip with 1/3 remaining. The wide thick moped tires eat the glass, gravel, chipseal road surface complete with ripples and potholes with no complaints, sticking with no excitement in the sharp turns through the park roads.

Thanks for all the help, ES. Without the information from this site I probably would not have embarked on this journey.

Onward into whatever's next.

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Re: CroBorg 2kWh Super Commuter

Post by docnjoj » Jun 24, 2015 7:16 am

Wow! What happened to change your mind?
otherDoc
E-bike stable at our house

Steintrike Mad Max full suspension trike rear Cute 100H going on: Whoops, Cute wheel broke but I fixed it.
Sun USX delta trike EbikeKit small geared front wheel sort of front suspension for wife

Agniusm/A123 AMP 20 36 volts on the Steini has been taken off.
2x16000 Multisport from HK now gone as they died after 2 years
New Luna 10S bottle battery 13.6AH now on mine
Relatively New 10S4Px2 for wife's bike giving 20ah @ 40 volts home made Panasonic from Tumich. BMS's rule.

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Re: CroBorg 2kWh Super Commuter

Post by docnjoj » Jun 24, 2015 7:16 am

Wow! What happened to change your mind?
otherDoc
E-bike stable at our house

Steintrike Mad Max full suspension trike rear Cute 100H going on: Whoops, Cute wheel broke but I fixed it.
Sun USX delta trike EbikeKit small geared front wheel sort of front suspension for wife

Agniusm/A123 AMP 20 36 volts on the Steini has been taken off.
2x16000 Multisport from HK now gone as they died after 2 years
New Luna 10S bottle battery 13.6AH now on mine
Relatively New 10S4Px2 for wife's bike giving 20ah @ 40 volts home made Panasonic from Tumich. BMS's rule.

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Re: CroBorg 2kWh Super Commuter

Post by striker54 » Jun 24, 2015 8:02 am

docnjoj wrote:Wow! What happened to change your mind?
otherDoc
He is retiring from work. :wink:

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Alan B
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Re: CroBorg 2kWh Super Commuter

Post by Alan B » Jun 24, 2015 10:05 am

I'm retiring from this job after 37 years. I suspect I'll be busy with many other things however, including more ebike projects. The nature of the projects may change, as the focus was always mainly on commuting. Now I'll have to find other applications for my ebikes. I need to morph this Super Commuter into something else. It needs a sturdier rack, maybe a trailer so I can do grocery runs. Not sure exactly which direction it will take.

I'll be using my other ebikes more, this one's for when you are wanting to get there, but it isn't the best for getting exercise or enjoying the scenery. So my recumbent BikeE will probably get a lot more attention.

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Re: CroBorg 2kWh Super Commuter

Post by dbaker » Jun 24, 2015 11:11 am

I am envious of your retirement :D Many thanks to all of the contributions you have made to ES. Your sharp analytical skills did not go unnoticed :mrgreen:

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Re: CroBorg 2kWh Super Commuter

Post by Alan B » Jun 24, 2015 11:59 am

Thanks for your kind comments!

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Re: CroBorg 2kWh Super Commuter

Post by docnjoj » Jun 24, 2015 1:34 pm

Retirement rules! Congrats! I still teach online but have been retired for about 8 years. Having some responsibility for work tends to keep me motivated, but still leaves plenty of time for e-bikes and other hobbies.
otherDoc
E-bike stable at our house

Steintrike Mad Max full suspension trike rear Cute 100H going on: Whoops, Cute wheel broke but I fixed it.
Sun USX delta trike EbikeKit small geared front wheel sort of front suspension for wife

Agniusm/A123 AMP 20 36 volts on the Steini has been taken off.
2x16000 Multisport from HK now gone as they died after 2 years
New Luna 10S bottle battery 13.6AH now on mine
Relatively New 10S4Px2 for wife's bike giving 20ah @ 40 volts home made Panasonic from Tumich. BMS's rule.

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Re: CroBorg 2kWh Super Commuter

Post by Alan B » Jun 24, 2015 2:30 pm

Looking forward to it!!

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Three Bears Loop Ride

Post by Alan B » Jul 26, 2015 12:27 pm

Image

I'm planning a leisurely ebike ride around the San Pablo and Briones reservoirs near Orinda in the East Bay next Sunday, a week from today. Details in the thread linked below.

https://endless-sphere.com/forums/viewto ... 25&t=71333

Enjoying a bit more free time and a more open schedule since 1 July, though it has filled up rapidly. The Borg is getting a bit less exercise, but I'm still enjoying it, just not every day. Many of my trips are too far or require carrying more than I can easily transport on the Borg. I do need to improve the rear rack and load carrying setup.
Last edited by Alan B on Aug 01, 2015 7:32 am, edited 1 time in total.

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MultiStar Balance Check

Post by Alan B » Jul 30, 2015 2:52 pm

Today I Balanced the MultiStar pack. It was less than plus or minus 100mAH out of balance, so for a 32AH pack that's 0.3 percent imbalance. It has been months since it was balance charged, and many bulk charge cycles have occurred.

I'm also setting up an auxiliary range extension pack with a set of 3 Zippy 8000's that were on hand. When connected in parallel that raises the system to 40AH and about 2.6 kWH. The downside is the trunk bag weight is up to 16 pounds and the rack is rated at 20. I plan to make a support for the rack which is tricky with the rear suspension motion.

Image

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DRT = Diagonal Rack Triangulator

Post by Alan B » Aug 01, 2015 7:26 am

Image

Image

Image

Image
Last edited by Alan B on Aug 01, 2015 9:05 pm, edited 2 times in total.

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DRT = Diagonal Rack Triangulator

Post by Alan B » Aug 01, 2015 2:10 pm

Meet the Diagonal Rack Triangulator.

Photos added in the posting above.

Don't you love it when a project takes seconds to imagine, and hours to fabricate? Well, these Topeak racks are great, but the seatpost cantilevered versions need some stiffening to increase the load capacity. Now, instead of 20 pound capacity on smooth pavement at low speed, we have 20 pounds, no matter what. I still would not put more than about 30 pounds on it, but now I will not worry about it (and the occasional auxiliary lithium battery or DSLR camera in the trunk would not be a good thing to drop into the spinning rear wheel). The aluminum cylinder grabs the seatpost tube from the inside (via the M10 capscrew and slant-cut threaded cylinder), and the U channel struts support the center of the Topeak rack. Before, putting pressure on the rack caused it to flex slightly, now doing the same thing depresses the suspension, but the rack does not seem to move. It feels very solid.

Of course now I'll have to figure out a different setup for opening the covers, the rear tiewrap is trapped.
Last edited by Alan B on Dec 29, 2015 11:46 pm, edited 4 times in total.

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Ready for Tomorrow's Three Bears Ride

Post by Alan B » Aug 01, 2015 3:11 pm

Just tested the cover removal, as it turns out there is no problem sliding the tiewrap back and releasing the cover with the new Rack Triangulator in place, it will be a little harder to keep it out from under the cover when reinstalling but this is manageable. I will probably improve the cover hold down system anyway at some point.

Ready for Tomorrow's Ride!

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Re: CroBorg 2kWh Super Commuter

Post by docnjoj » Aug 01, 2015 3:13 pm

Very cool. Kinda like dogman dan's but machined instead of cut. I like it. My rear rack is steel and supposedly can support 50 kilos. It too compresses the suspension when I push on it. Came with the trike.
otherDoc
E-bike stable at our house

Steintrike Mad Max full suspension trike rear Cute 100H going on: Whoops, Cute wheel broke but I fixed it.
Sun USX delta trike EbikeKit small geared front wheel sort of front suspension for wife

Agniusm/A123 AMP 20 36 volts on the Steini has been taken off.
2x16000 Multisport from HK now gone as they died after 2 years
New Luna 10S bottle battery 13.6AH now on mine
Relatively New 10S4Px2 for wife's bike giving 20ah @ 40 volts home made Panasonic from Tumich. BMS's rule.

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Topeak Cantilever Seatpost Rack

Post by Alan B » Aug 01, 2015 3:22 pm

Thanks docnjoj.

The Topeak cantilever seatpost rack rack is thinwall aircraft aluminum, very good quality material, with a roughly triangular cross section. It is very lightweight and clamps firmly onto the seatpost. I've read of people breaking it with batteries in the trunk, so I always try to keep it under 10 pounds (half the rated load). The regular hard-tail Topeak rack is aluminum rod that goes right down to the rear dropouts and is well supported. It is just the seatpost cantilever models that have to carry all the weight without vertical support that are in need of some help. This should do the trick, and it is not difficult to remove with the rack if not needed.
Last edited by Alan B on Aug 01, 2015 9:12 pm, edited 1 time in total.

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BorgStand

Post by Alan B » Aug 01, 2015 7:01 pm

Image

This is probably going to break in short order, but it is the first attempt at a kickstand on this machine. The mounting location is a bit complicated and mingles with the mount for the chain tensioner.

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Re: CroBorg 2kWh Super Commuter

Post by gensem » Aug 07, 2015 10:09 am

Hello Alan,

I got just my 125a dc breaker and im not sure what is the battery side, im gessing its 2 and 4. Have you checked battery/controller side on your breaker?
Pic attached.
Attachments
DC-Breaker.jpg
Justin we really appreciate what you did!

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Re: CroBorg 2kWh Super Commuter

Post by Alan B » Aug 07, 2015 11:59 am

Looks like double pole, breaking both circuits. Mine is single pole, and polarity is marked, which I followed. Looks like yours wants both positive and negative supply (battery) poles at the top, and load at the bottom.

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Re: CroBorg 2kWh Super Commuter

Post by Alan B » Sep 25, 2015 4:41 pm

Greetings folks, it has been quite busy here with non e-bike stuff, but yesterday I did take a round trip ebike ride to the old workplace for a BBQ. It was very nice getting out on the Borg again. I took it easy on the way in, partly because I wasn't in a hurry, partly to conserve battery and partly due to a dump truck poking along at 17 mph up through the park. I reached 10 amp hours (which is very low consumption for the incoming trip) consumed at the top of the hill, and regenerated a bit of that back going down the hill and into work. After a nice BBQ lunch and visit with ex co-workers and other retirees I saddled back up and climbed out to come home. I dialed it up a bit on the way home but due to the predominance of downhill still used less energy on the return trip, finishing up at about 18 amp hours (forgot to get the precise value). This out of a 32 amp hour pack. It is SO nice to be able to do a round trip without charging.

Now back to the retirement grind, which has been preparing for daughter returning home, clearing stuff and painting and fixing. Stuff that needed doing but wasn't previously such a rush.

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Re: CroBorg Commuter

Post by Alan B » Feb 24, 2016 12:40 am

windtrader wrote:...Now, you just need to make the ridge trip. If you pass Clark anyway, the trip will be shorter as you avoid the entire wildcat section.
Image

Image

Today I took the Clark road to Nimitz way to Inspiration point ride on my mountain bike. What a climb! Part of it was so steep the front wheel kept rising and I just gave up and walked that part. The BBSHD was climbing just fine though. But that's another story. Anyway, as a commute route it would not be good. But the views are beautiful from the ridge, many of them 360 degree panoramas of the bay area. No wonder they put the Nike missile site there!

Clark road was the opposite direction of my commute, so that added some distance. From what I can tell the "shortcut" was maybe one mile less than going around on good pavement, most with a wide bike lane, and riding up and down the ridge line is hardly efficient. There were also half a dozen gates to go through and manually re-close.

But it was definitely fun.
Last edited by Alan B on Mar 09, 2016 12:38 pm, edited 3 times in total.

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Diamondback and BBSHD for Street and Trail

Post by Alan B » Mar 08, 2016 12:17 am

Image

I started a thread on my new ebike project, a mid drive climbing machine for Street and Trail. Maybe I should call it the "Diamondback Ridge Runner".

https://endless-sphere.com/forums/viewt ... 28&t=78722
Last edited by Alan B on Mar 09, 2016 12:40 pm, edited 1 time in total.

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Re: CroBorg 2kWh Super Commuter

Post by Alan B » Mar 09, 2016 12:20 pm

Fixed the photo in the above post. Added image to the Ridge posting above.

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Re: CroBorg Super Commuter

Post by Alan B » Mar 13, 2016 12:32 am

Image

I'm working on the controls for the all wheel drive Novara MTB project, and I decided to check out some of the math that I will be using. The goal there is to make a little black box that will drive both Xie Chang type motor controllers to make the motors share the torque in a reasonable way for all wheel drive. This will be done with two rather different motors, the rear one a 9C direct drive and the front a BMC gearmotor. So I used values for the Cromotor and wrote a few lines of Python to generate some data and then tossed it on a graph to take a look. I didn't graph all the values, only the battery current vs speed (above) to generate this maximum torque. Since it is CroBorg data I though it would be appropriate to reveal it in this thread.

So this analysis is for the battery current it takes at 75 volts to drive the Cromotor with 120 amps (thus constant max torque) versus the speed. I didn't work through the Kv carefully so it is undoubtedly off, but the result looks similar to reality. Amazing how some simple equations and approximate values can reveal so much information.

First of all, based on the motor resistance and the current and 120 amps, the motor heating is over 1300 watts. Since the Cromotor cannot dissipate 1300 watts, it is going to heat up. So putting even 120 amps through it won't work on a continuous basis. But that is the max current I have set for mine (and many folks do more). The other limit I have is 80 amps battery at 66 volts nominal (75 volts fully charged). I chose 120 amps as this is enough to almost lift the front wheel off the pavement. The suspension unloads and if I pedal hard the front wheel bounces. Enough current I think, for a commuting machine. :)

So it takes 11 volts across the Cromotor to get 120 amps based on the 93 milliohm resistance. The controller is converting 75 volts to 11 volts at the zero speed point to generate this 120 amps in the motor. This down conversion in voltage results in an up conversion in current (power is conserved), so the battery current is less than the motor current. In this case it takes about 18 amps of battery current to do this (you can see this on the above graph). The power required is just over 1300 watts, after all at this point we're only heating the motor. No speed, no work being done. So it is all heat. This takes about a 15% pwm cycle, so even if you have the throttle maxed out you're only using 15% (since the controller is properly limiting at 120 amps of motor (phase) current). This is why it is so hard to control a Cromotor at low speed with an old school high current controller, zero to full torque with 15% of the throttle motion is all you've got to work in. A good torque throttle will spread this 15% out over the entire range of the throttle control.

As the speed increases, so does the back EMF, and the voltage required to drive the current into the motor goes up. This increasing voltage load also takes more power (since the current is the same 120 amps all the time) so the battery current also increases to supply this increasing power. We see at just over 20 mph that the battery current hits 80 amps. On this computed scenario the current keeps going up, but on the Borg it stops there and the motor current (which is proportional to torque) begins to drop off. PWM is up to 65% and back EMF is about 38 volts. The battery current at 80 amps is still well below the motor current of 120 amps.

A refreshingly simple look into some of the actual numbers that sheds some light on the details. The math is working.

Note that this does not take into account a lot of details (yet). The back EMF I chose for this simulation is probably low, and there's no allowance for inductance, motor heating, etc that would tend to reduce motor current. The chart above is calculated at 75V but allows the PWM to exceed 100%, so the power continues to increase as if it was a buck/boost controller.

Edit - I just worked out back EMF from motor Kv values and it is close to the estimate I used.

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