Urban Commuter M-Drive Yuba Mundo build

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inkeeper77   100 mW

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Urban Commuter M-Drive Yuba Mundo build

Post by inkeeper77 » Mar 15 2012 1:02am

Well I am just starting this build, but I figured a build log is in order! Sorry, no complete . but I do believe I shall have some photos of the bike in running condition soon!

Contents:
1. Design goals and choices: This post
2. Battery packs and chargers
3. Battery cycling
3. The bike and basic motor and electronics installation
4. Future projects! Lighting systems, true battery enclosures, etc.

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Photo: Current state:
(Coming soon)

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This build is my first attempt at building an electric bike, and it was after a long while of ES lurking. I determined I wanted a longbike due to wanting one (a longbike) for years, and I chose the yuba mundo due to lower cost and greater cargo capacity. Design goals are to create a cargo bike with electric assist, and the capability to eventually be a semi high speed electric bike. I also want to include good lighting for night riding, including turn signals. But that is for the future. Currently I am in the simple "adding a motor and batteries" stage.

The motor choice was between mid drive and a rear hub motor. I don't like the idea of a front hub, as I am so used to rear drive, and also the paranoia of the motor seizing would bother me. I love the idea of a mid drive, and being able to use the transmission already in use on the bike in order to switch between torque and speed. I first found the stoke monkey, but then found the urban commuter m-drive. It is cheaper (somewhat), and it freewheels unlike the stoke monkey. It does not use the front chainring, but it takes advantage of the rear gears. So I chose to use it as it is far better than whatever I could rig up myself with the limited manufacturing capability I currently have.
http://urbancommuterstore.com/M-Drive-C ... IVEKIT.htm

The maker of the m-drives, Sonny, has been EXTREMELY helpful and willing to correspond with me! I highly recommend him so far.
Last edited by inkeeper77 on Mar 15 2012 10:02pm, edited 7 times in total.

inkeeper77   100 mW

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Joined: Jan 17 2012 4:15pm

Re: Urban Commuter M-Drive Yuba Mundo build

Post by inkeeper77 » Mar 15 2012 1:15am

Batteries:

The current packs are going to be 39.6v nominal, and 9.2 ah- with the idea bing that I will expand voltage and or capacity later.

I chose A123 batteries for a few reasons. Modularity, safety, abuse tolerance, and decent cost. I bought them from these forums HERE - Seller/Member migueralliart (the seller) has also been helpful, and a pleasure to deal with!

For the charger I chose a Hyperion EOS1420inet3 , and I am using a modified meanwell from EP buddy to power it. (24v 25A)

On to the build:

I opened up the 3s a123 packs I received, and assembled them into two bricks, using the same idea as member leamcorp had on his big dummy build.

That idea was using wood to hold in copper bus bars with battery clips. The only changes I made were that I have connecting copper on both sides of the bus bars, with smaller copper sheet underneath for extra protection against disconnection. (I had scrap) (The wood and screws I also had on hand. They might not be ideal but should suffice)

0. Batteries were all charged individually to the same level prior to parallel connection
1. Wood was cut out into the right size for this size pack
2. I connected the wood using some all purpose screws, and then used trim nails to reinforce the connection against twisting.
3. Copper strip was cut into the right lengths (eyeballed), cleaned with steel wool for best electrical contact, and then clamped down to the battery box frame. A pilot hole was drilled, then in the copper itself I drilled a larger hole for the screws threads to pass through. All copper strips were screwed down, battery clips snapped on and soldered in place, balance connectors were soldered onto one of the clips on each parallel connection, and then the batteries added and screwed into place. (No soldering while cells are in the pack! This WILL be bad for them.)

Parts:
Copper strip: Mcmaster Carr Part # 8964K721 (I used most of 3 strips)
Clips: Mouser Electronics Part # 534-209

Photos:

1. The charging setup
Image

2. Opening the battery packs as shipped. (Not very clean, some need insulating tape as the CA used to hold them together was a bit too strong and tore the casing apart, but aesthetics are not what I care about! The cells are good)
Image


3. Assembling the battery packs
Image

4. Completed battery pack
Image

5. First charge: Not great balance, but I will see how it settles in. EDIT: they have been settling in nicely!
Image
Last edited by inkeeper77 on Mar 18 2012 8:20pm, edited 11 times in total.

inkeeper77   100 mW

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Re: Urban Commuter M-Drive Yuba Mundo build

Post by inkeeper77 » Mar 15 2012 1:46am

Motor kit and installation:

Currently I am eagerly awaiting a package, but here is a photo of what will be in it!

Image

(reserved)

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migueralliart   10 kW

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Re: Urban Commuter M-Drive Yuba Mundo build

Post by migueralliart » Mar 15 2012 11:43am

Hi Erik,

Did you got to do some more cycle charging with the cells? And balancing?

Loved the battery pack idea. How much discharge are those terminals rated for?

inkeeper77   100 mW

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Re: Urban Commuter M-Drive Yuba Mundo build

Post by inkeeper77 » Mar 15 2012 11:54am

Thanks! Sadly, I have not due to being busy, but I will do a couple cycles soon. (Edit- see the rest of this post)

As to the terminals, I honestly have no idea.. but I am heaping solder on them in order to help improve conductivity, and I have doubled them up. (And I think I will double up the 8 gauge wire if I have enough just in case) - We use these on my robotics team, and haven't had a problem yet, but I will be keeping a close eye on them just in case. If they start to melt it isn't the end of the world!

Other connectors are all 6mm bullets- which should have no problems.
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Battery Cycling:

With the battery packs completed, and the bike still 12 hours or more away, I figured it would be a good idea to do as asked, and cycle the packs once. Because the hyperion charger is awesome, it can handle both packs as one large 12s pack!

I am currently in the process of doing so, with only 3000 mAh discharged, but I will post up results and the graph of the discharge-charge later tonight or tomorrow morning!

The setup: I will clearly need to make balance lead extensions..

Image

4 hours into the first discharge.

Discharge:
Image

Also, as a bonus, I hooked a kill-a-watt up to the 24v power supply! So far, discharge has only use 0.11 KWH. Lets see how much charging takes. (And as another bonus, electricity here tonight is under 3 cents a KWH!)

For the build: I dont really know what my low voltage cutoff should be. The cells did stabalize around 2.83v, so maybe I should set it on the controller to about 2.85v per cell (34.2v) and a little higher on the cycle analyst?

Recharge: Note: the first 30 minutes (and 65% of capacity) are not on the following graph. I had accidentally set the time limit to 10 minutes.... fixed, and charging again gives this:
(Coming soon)
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Hyperion 1420i Review:
Since I have it, and some photos and screenshots, here is a quick and dirty review of the Hyperion 1420i.

Cons: None so far

Limitations:
1. This charger needs a great power supply. I suspect my 24v 25A power supply will slow it down somewhat due to amperage, but it seems to make the most out of the given power supply. This is a . good thing!
2. IT CAN FRY YOUR COMPUTER IF YOU ARE NOT CAREFUL: The software tells you how to avoid this. ALWAYS follow it. (Apparently new models will not have this horrible possibility. It is safe . though if you connect everything before powering up the charger, you just need to be careful. If you are forgetful, wait for a new model!!)

Pros: It does everything I want quickly and easily.


Further details:

Presentation: Good simple box, I like it.

Features: Enough for me for a lifepo charger. I love the computer connection ability, and it seems to charge and balance well and quickly. The discharge maximum rate of 20A is a little dissapointing, but it is a feature I will rarely use and I suspect this is a good speed when compared to other RC chargers!

Ease of use: As a beginner who is comfortable with electronics and computers, I had no problems with it whatsoever. The software is self explanatory, feature filled, and useful.

Using two packs as one: It works. I have nothing more to say about it. It works, and it didn't require any setup. My 2 6s packs went together just fine.

Screenshot from the above charge cycling (halfway through discharge)

http://img607.imageshack.us/img607/8318/44734347.png (Direct link due to large size)
Last edited by inkeeper77 on Apr 08 2012 3:13pm, edited 19 times in total.

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ohzee   1 MW

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Location: Columbus Ohio USA

Re: Urban Commuter M-Drive Yuba Mundo build

Post by ohzee » Mar 15 2012 12:03pm

Look forward to following your build. How big is your battery going to be and what voltage you running ?

I just picked up the same bike last week. Still waiting on some accessories thought they have been slow to ship from yuba.

I also ordered the mid drive kit from urban and am awaiting delivery. it looks like such a well built solution cant wait to use it.

Keep up the good work.

inkeeper77   100 mW

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Re: Urban Commuter M-Drive Yuba Mundo build

Post by inkeeper77 » Mar 15 2012 1:03pm

Thanks! Most of my accessories will come later. I bought the bike used from Urban along with the m-drive.
Batteries: 9.2 Ah at 39.6v nominal. A little small, but they were cheap, and I can expand them later!

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ohzee   1 MW

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Re: Urban Commuter M-Drive Yuba Mundo build

Post by ohzee » Mar 15 2012 2:12pm

Sounds great man. I am still up in the air with what batteries I want to use. I am in on the 123 group buy , but I know
it may take some time for those to arrive.. Considering headway myself as it seems easy to put them together at least
on a temp solution.

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urbancommuterstore.com   10 mW

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Re: Urban Commuter M-Drive Yuba Mundo build

Post by urbancommuterstore.com » Mar 16 2012 2:59am

Innkeeper and Ohzee, please see attached install guide for the kit. Thanks. :D

Ohzee, I will be sending your kit soon, hopefully early next week. I got the motors and electronics today in the mail. I will just need to machine the shaft to kit spec. Thank you for your patience. In the meantime, please go through the install guide so you'll get an idea on what to expect during the build. Thank you.

Sonny
Custom Mid Drive for Yuba, Xtracycle, Surly and CETMA Cargo bikes

vacostco   1 µW

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Re: Urban Commuter M-Drive Yuba Mundo build

Post by vacostco » Oct 21 2013 11:48pm

so how does the story end? does the mundo m-drive build exist? does it work well? how about a review ?

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