2WD Electric Yuba Mundo Build

[wyvernwaddell]

What an incredibly thorough and cool thread-you've just answered every question I think I could possibly had about electrifying a Mundo-THANK YOU!
I only have a rear Amped bikes motor, so I won't have quite the speed your baby does, but with all that you've written here I can do it with some confidence now instead of fumbling around for parts.
Again-Thank you! and Happy Riding!

[teklektik]

... you've just answered every question I think I could possibly had about electrifying a Mundo-THANK YOU!

You're more than welcome - post back on a build thread to show us your efforts!

[teklektik]

I Want an Analogger…

I’ve been waffling over purchasing a Cycle Analogger for some time but the new CA v3 rework prompted me to finally take the plunge. With the CA v3, the Analogger records these parameters each second:

• Ah,
• Volts,
• Amps,
• Speed,
• Distance,
• Temperature,
• RPM,
• HumanWatts, and
• Torque(Nm)

Unfortunately this bike makes data interpretation a little more troublesome because of the six motor/power level combinations that might be in play at any given time (one/two motors, lo/med/hi power). However, inspecting the Analogger manual revealed that the unit has two optional analog inputs in addition to the serial data input and that these are sampled and the results written whenever a new data line is received from the CA. These can be used to detect and record the settings of operator thumb toggles. Very cool.

Voltage Snafu

The only difficulty is that the Analogger inputs have a max voltage of 3.3v and the recently reworked motor controls were set up with a max voltage of 5v. Because of the resistor dividers on the controls, the only two workable choices were to either use resistor dividers on the two Analogger inputs, or regulate the 5v supply down to 3.3v to run the control dividers with a reduced voltage (yep – I’m looking for a simple passive component solution…)

The input divider approach proved problematic because in order to avoid disrupting the existing dividers, the input dividers had to use large value parts which yielded the usual noisy signals from the high impedance antenna effect. Not good.

Regulating the 5v supply turned out to be the solution of choice, although this had an annoying twist because of the low current restriction. Superb regulation isn’t necessary for this application so a simple zener regulator is fine except that the average off-the-shelf zener has a zener current (Iz) of 20ma to get around the knee of the curve so it can develop the specified reverse voltage. According to ebikes.ca, the CA v3 regulator is rated for 1.5W so with a fresh-off-charger battery voltage of 73v we get 1.5W/73v ~= 20ma. The CA v3 draws 10ma internally, leaving an absolute max of 10ma available for use for Iz, throttle, and Vaux circuits. With a ballpark current requirement in hand, a quick search on Mouser turned up a zener (TZX3V0C 3.1-3.3v) that would work comfortably with Iz = 5ma

The original controls circuit used a resistor to drop the throttle voltage to take advantage of the new CA v3 feature to detect broken throttle Gnd wire but that part could be eliminated by driving the throttle from the 3.3v source. The Magura is about 5K, the control divider is about 3K, so we need about 3.3v/5k + 3.3v/3k = .66ma + 1.1ma ~= 1.8ma. For Iz = 5ma we need 5+1.8 = 6.8ma total so starting with the CA 5v supply we need an Rz of (5 – 3.3)v/6.8ma = 250ohm or 220ohm using a stock part value. Checking: (5-3.3)v/220ohm = 7.72ma which is less than the 10ma max we have available. Okay.

A more power-thrifty solution would be to use an LM-385-ADJ adjustable micro-power regulator which would cut the draw by near 5ma by eliminating the need for Iz.

Controls Rework for 3.3v

Unfortunately, the selected zener wasn’t available locally and I didn’t want to pay minimum shipping and wait for Mouser, so I substituted from parts on hand – a 2.5v micro-power voltage reference (LM385-2.5) in series with a forward-biased silicon diode yielding a 3.22v reference. I super-glued an extra bit of perf board onto the end of the electronics board to hold the two extra parts. The updated controls diagram is shown below using the proper zener instead of my kluged substitution:

48-01_controls.gif (40.46 KiB) Viewed 929 times

(The original discussion of this design can be found in this post.)

Collecting a minute or so of data while flipping the thumb controls yields the graphic below after a little Excel manipulation. Note how 2WD/Low limits the CA to same power level as RWD/Med – this is the two-motors-as-one mode added recently.

100 seconds of real time CA power limit data

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Summary of selectable power limits

48-20_switchmatrix_2a.gif (3.85 KiB) Viewed 895 times

[teklektik]

Packaging the Analogger

The Analogger is actually smaller than the large screen CA but is not sealed and has a switch, USB port, and removable micro-SD card slot. The Analogger manual suggests tucking it away to protect it from the elements and also calls out the mechanical sensitivity of the SD card slot mechanism. Not too good for trail dust, rain, etc. There are no connectors or openings for the extra two analog channels, making using this a solder and drill DIY affair. There are two connectors: one for power and one for the serial data stream – the extra analog data requires a third connector. In short, the Analogger is ruggedly constructed but is a ‘Sunny Day’ design that needs a bit of DIY tinkering to be trail-ready. The manual calls all this out so no surprises or complaints

Since the device was going to be a ‘use sometimes’ gadget and since reading the data via USB is easier than removing/handling the tiny micro-SD card, I wanted an easily removed mounting scheme that would somehow fit on or near my already cluttered handlebars. I opted to box it in a weatherproof case, hang the case from the handlebars, provide an external power switch, and direct-wire a single connector to carry the power, serial data, and analog data.

The five direct connections are brought out to a mid-stream JST connector so the Analogger can be detached from the clear plastic case. Instead of drilling the Analogger case to bring out the new leads, it’s simply notched so the PCB can be removed for easy bench work. As noted in the Analogger Manual, I removed the two pull-up resistors R8,R9 which are installed primarily to support direct connection of thermisters. Without the resistors, high impedance voltage sources can be monitored.

There are available pads for all leads except power (+). However, the female power connector uses through-hole mounting and it is easy to reflow the solder on the end pin and slip a lead into the large mounting hole.

Normally the signal and power grounds are distinct (a resistor connects them) but in this application, they both reference CA-Gnd so a single Gnd lead was shared. This isn't the best practice in general, but since there are only 5 distinct voltage levels of interest, a bit of noise was not an issue (and the mini-XLR connector on hand was only 5-pin - no extra pin for a signal Gnd ).

AnaloggerDirectConnections.gif (32.83 KiB) Viewed 924 times

Tiny cable tie is strain relief for Analogger case

48-02_AnaloggerDirectWire.jpg (92.17 KiB) Viewed 924 times

A quick trip to Sports Authority turned up a nifty box (Lifeline Weather Resistant Case model 4430) and a black twisty tie (Nite Ize 6” Gear Tie GT6-2PK-01) to hang the box from the bars. An 5-pin mini-XLR connector for Crystalyte hall sensors from the parts box did nicely for the connector. I mounted the Analogger on a small piece of .060mil styrene plastic from the hobby shop (Evergreen Scale Models plain white 6”x12” sheet item 9060) using 3M automotive emblem tape (auto stores, etc - used to mount emblems and trim on car bodies forever). A round clear vinyl bumper from Home Depot stuck on the front of the Analogger wedges it snugly into the case. The cable is tie wrapped to an extra rectangle of plastic on the bottom that acts as a removable strain relief so the case can be freed and slid down the cable by removing just the switch retaining nut.

I had a bit of an electrical loading issue with the controls when the Analogger was switched off and the inputs changed to a low impedance, upsetting the resistor dividers for bike controls. Since I had a 3PDT switch on hand, I opted to just open-circuit the two inputs when the powering down the Analogger.

Analogger case notched with small round file to accept wire bundle

Two large holes allow access to Analogger case screws

Rubber coated twisty tie makes solid attachment easy

Mating cable is tie-wrapped under dashboard and connects to CA and electronics board

Easy access to mini-USB port , micro-SD card slot, and mode switch

Settings of two thumb toggles on left are recorded by Analogger

The assembled unit works great. I get about 0.01v – 0.02v of noise from the monitored resistor dividers for the thumb switch controls which is in the neighborhood of 1% - fine for this application. Separate signal grounds for thermister use would likely bring the noise down near the expected 1/2bit out of 10 bits ADC resolution over 3.3v or a bit less than 0.002v.

[ohzee]

I love your yuba and am envious of your skill set to make it so functional and good looking.

Currently I am rocking a mid drive with a mac , but honestly I want to push more power thru it then It can take.

Considering adding my 5404 or 3525 to the rear so I can feed as much voltage that I want..

You were right about the handle bars they did grow on me. Thanks for sharing.

[teklektik]

Currently I am rocking a mid drive with a mac , but honestly I want to push more power thru it then It can take.
Considering adding my 5404 or 3525 to the rear so I can feed as much voltage that I want...

I certainly understand the feeling - I'm a compulsive speeder by nature. With my current 20s2p battery pack I get about 38-39mph sitting upright but the two gear motors are pretty loud when flogged at 3kW.

I'd like to go DD for a quiet road machine, but I think I see a lighter frame MAC build for stealthy bike path use as my next effort - it's hard to get away from the freewheel for unencumbered no-assist pedaling...

[GMUseless]

Hey Tek,

Having had some road time, what's your thoughts on your Torque Arm implementation?

I've got Kiwi's plates, which work great if I don't use Regen. The minute I engage regen, my hub (9C 2810) works it's way loose after 10 to 20 hard regen cycles. I'm considering some mods now, maybe using the slotted washers that Yuba sells, or perhaps the Amped arms you've got. One problem I have is that there's so much room in the drops outs, there's nothing to really guarantee proper wheel alignment. I was thinking the slotted washer might address that.

[ohzee]

Hey Tek,

Having had some road time, what's your thoughts on your Torque Arm implementation?

I've got Kiwi's plates, which work great if I don't use Regen. The minute I engage regen, my hub (9C 2810) works it's way loose after 10 to 20 hard regen cycles. I'm considering some mods now, maybe using the slotted washers that Yuba sells, or perhaps the Amped arms you've got. One problem I have is that there's so much room in the drops outs, there's nothing to really guarantee proper wheel alignment. I was thinking the slotted washer might address that.

That's too bad to hear as I have some kiwi adapters in the mail. I was considering using my 5404 on my yuba.

You using nord-lock washers also ? Wonder if that would help any.

Curious what you come up with.

[teklektik]

Having had some road time, what's your thoughts on your Torque Arm implementation?

The torque arm arrangements have worked out very well. I've got about 2500 mile on them now and they hold perfectly - no movement or loosening - no Nordlocks. I've had them both out for brake/motor tinkering and the dropouts and TA components show no deformation at all. I run the BMCs up to about 1550W each.

I clearly don't have regen, but my seized clutches did put a fair drag on the axle with the 1:5 overdrive effect when I coasted or ran with a motor shut down. Also, the bad front cluster key I had recently was giving me a hard impact on re-engagement that was a bit like an impact driver on the TA. Again, after hundreds of miles of this, no adverse TA effects.

One problem I have is that there's so much room in the drops outs, there's nothing to really guarantee proper wheel alignment.

I'm not sure I quite understand that. My axle fits pretty snugly in the slot and the wheel is aligned if I slide it to the end of the slot. Back in the original post, I described having the washers machined to allow me to do this. Is your axle 14mm or less? If you have 12mm axle, you may have problems with the Mundo washer since they are designed expressly for 14mm shafts and rely on the 14mm dropout slot to position the axle vertically.

Here's a post about mixing Mundo washers and Kiwi plates.
Here's a post about addressing smaller axles.

One possibility is to drill the Kiwi plate and dropout, and run in a bolt to hold the plate in place against the chain stay. And, of course, there is always Doc's DP-420 epoxy...

I'm thinking a PM to Kiwi may be in order to get some authoritative advice...

[GMUseless]

I've got 14mm axles. When I mentioned the alignment, it was in terms of the axle shifting from the top of the dropout...again caused be some looseness introduced by the regen. Definately not a safe situation.

Thanks for the links, it makes sense that Kiwi's plate require the axle to be all the way into the drop out, and the Yuba washers would prevent that.

I like your idea of bolting the plate into the drop out. Perhaps a bolt at the tip of the front and rear triangle. I'll have to look at the frame to see how that might affect things. I'll PM Kiwi, mention this thread, and ask him if he's got any ideas or comments. I know Philistine has had a similar problem with the plate and strong regen...which he mentioned in his fork failure thread.

[teklektik]

I've got 14mm axles. When I mentioned the alignment, it was in terms of the axle shifting from the top of the dropout...again caused be some looseness introduced by the regen. Definately not a safe situation.

Gotcha - makes sense.

I kind of thought you already had the links, but the info is spread around a bit, so they were more for new readers playing catch-up on the Mundo

[teklektik]

And, of course, there is always Doc's DP-420 epoxy...

Well, gee whiz - that was a solid 11 on the 'cosmically stupid' scale...
(Kiwi plates have holes, not slots! )

[teklektik]

Spreading the Frame

My Mundo rear dropouts are exactly 135mm - precisely the width of my BMC axle. Unfortunately, I need a couple of 1.5-2mm washers to prevent the shaft shoulders from sinking into the dropouts. The massive seat and chain stays make it hugely difficult to spring the frame to force in the wheel plus 3-4mm of washers. This was a miserable job before the disk brakes, but now it's close to impossible without dismounting the caliper - too hard to get the motor in square with the rotor aligned in the caliper and then work the wheel straight down the long dropout while keeping the stays sprung apart.

I twanged the disk rotor a few days ago remounting the wheel and decided it was time to spread the frame. I had looked at this during the initial build but had been deterred by the stoutness of the tubing along with the array of extra welded luggage rack stays. The Sheldon Brown 'lumber pry-bar' approach and other recommendations like car jacks or a threaded rod in the dropout seemed unlikely to succeed and very likely to twist the dropouts due to the unequal number, sizes, and angles of the many stays.

rigid 400lb capacity cargo bike = one tough SOB to spread...

52_02_annotated.gif (55.75 KiB) Viewed 693 times

I opted to whip up a quickie spreader tool from a couple of pieces of oak with two threaded rods so I could apply different force to chain and seat stays as needed to keep the dropouts square vertically. The wood is 1.75" x 1.75" x 10" with 5/8" holes 8" apart. The rods are 1/2-13 x 6.75". The inside edges of the wood are rounded slightly and sections of old inner tube are taped down to protect the paint. The holes are oversize to allow the wood to be set at an angle (like an 'A'). This gave just barely enough play and it might have been good to elongate the hole openings somewhat by racking the drill bit the long way after the holes were drilled. A stick of 2x2 used for deck railing vertical kid-proofing bars would probably work pretty well as an alternative.

52-04_spreader.JPG (123.02 KiB) Viewed 747 times

The spreader was positioned as shown in the image below so the force was applied to the tubing and the dropout welds took little stress. The nuts were then run out as needed to get the desired spread while keeping the dropouts from twisting. As suspected, there was quite a bit of difference in the force required to deflect the chain and seat stays. The operation went quickly and easily and it spread just right on the first try, picking up 3-4mm. As shown in the first image, I probably could have positioned the spreader a bit better, but it worked out fine anyhow...

Hard to see in photo, but threaded rod is above and not touching the stay...

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The wheel just dropped in like the frame was made for it - what a difference! The rear derailleur needed no adjustment, but the BB7 caliper got a quick re-alignment.

I'm almost looking forward to pulling the wheel again!

[Tommy L]

Sir!

This thread is incredible! I wish to have the time/resources to accomplish such a piece of art like yours.
I would have to start looking in a thesaurus to add more amazing words to describe your project.

Well done!

Tommy L sends.... \\m//

[teklektik]

Thanks, Tommy - very much appreciated!

Lots going on this summer - mostly revisions instead of new fabrication. I'm many posts behind and I'm thinking I'll just start catching up in no particular order. ...it's more fun to go riding, though...

[teklektik]

Melted Fuse Holders - Don't Use These!

Earlier this summer I had a charging issue and discovered that my MaxiFuse holders had overheated and melted. The type I used had 8ga wire and used the familiar FastOn style terminal connections. The fuses/folders simply replaced a bus link in each of the two battery packs. There had been reports of issues with these on the forum but I thought that I could skate with only 50A max and a nice dry non-corroding environment in the battery boxes. ...well, not really...

I've probably had more than my share of shorted controllers with accompanying momentary huge current draw, but the 50A breaker always tripped before either 50A fuse blew. Fuse checks after these brief incidents showed everything fine and the fuses looking out-of-box new. I have taken to running the bike harder for more extended periods and it seems that the high connection resistance doomed these fuse holders to failure under the higher continuous current draw...

As shown in the image below, the failure was identical on both packs - one of the FastOn connectors in each holder overheated and melted the surrounding plastic as well as the fuse proper - they were actually melted together and the fuse leg was brittle and snapped off trying to extract the fuse.

(click for close-up)

Since the breaker is offering faster system protection anyway, I just replaced the fuse holders with Headway bus bars - back on the road again!

I would like to restore pack protection with internal fuses but haven't found a satisfying alternative yet - there are many discussions of this here on ES, but in spite of many opinions and suggestions, for me there seems no technically superior choice with workable cost and packaging attributes. ANL fuses look pretty good but are large, moderately expensive, and are not sourced locally. There are some off-the-shelf MaxiFuse holders available that use screw-down clamps, but they are pretty big and a bit costly.

MaxiFuse holder for 8/4ga wire

60-04_KickerMaxiFuseHolder.jpg (12.1 KiB) Viewed 738 times

My current thinking is to fabricate a pair of custom MaxiFuse holders from unclad FR-4 and some small slotted copper blocks with setscrews to lock in the fuse legs (similar to above). This should give a rigid and relatively small holder that accepts the inexpensive and readily available MaxiFuse devices. More on this later this winter...

[numberonebikeslover]

I am totally speechless; I would just say that it was indeed food for the soul. Clean and neat simply awesome. You really inspired me man. Good luck and happy e-biking.

Are the single cell chargers automatic for HVC?

With great respect and kind regards
Naeem

[teklektik]

Naeem, many thanks for the kind words, but frankly your own passionate and resourceful build has been an inspiration here on ES.

Are the single cell chargers automatic for HVC?

The VoltPhreaks 2A chargers terminate charge at 3.65v with very good accuracy. They have a single bi-color LED that indicates green with no charge current or red when charge is underway - this means the indicator is green when the charger is either disconnected or the cell reaches end of charge.

Balance Charger Update

Unfortunately, I never got around to doing the temperature study since I expected to be rebuilding the battery enclosures and charger but other issues kept postponing the whole endeavor. I am still using the side-by-side power strip arrangement with fan (as shown in the pictures) on a 2p battery configuration and have about 140 cycles on the chargers. There have been no charger failures but the ambient room temp has never been above 80F - I'm not sure this configuration would be as successful at 100F.

I was thinking that a simple off-the-shelf cooling solution might be to simply raise every other charger in the power strip using a Euro-to-US adapter (the kind that will optionally take flat blade US plugs in the 'Euro' side). These can be had for under $0.50 and would give a fairly compact no-BMS charger with no tools required. The added air channels would certainly expand the ambient temperature operating range for fan cooled assemblies and might make operation possible with only passive cooling.

Place under every other charger in power strip for improved air flow

euroToUsaAdapter.jpg (4.07 KiB) Viewed 717 times

The price of the vPhreaks chargers has gone up a bit since I bought mine and there are more alternative charger choices than when I took this road, but these little guys have given me 3500 miles of flawless no-worries service.

[cwah]

subscribed

[teklektik]

Well, it's official - she lost her virginity last week in a bike vs asphalt episode with a pedal strike in a deep 30+ mph right turn. The bike faired pretty well - chewed up the right sideloader/battery box a bit, twanged the rear light cluster, broke a mirror, and scraped up a few other things that used to stick out. Surprisingly, none of the paintwork took a hit…

Lots of excellent support from local official folk - the EMTs patched me up and the police straightened out the bars, etc and escorted me home. Kudos to all.

Anyhow, replacement parts are already arriving in the mail so the bike should be squared away PDQ.

Gee, ...the ride was going so well up until then...

[wyvernwaddell]

Ouch, dude!! Hope you're ok and that your bike survived in good shape. We all drop one eventually, glad you had support.
Lisa

[ohzee]

Yea bud sorry to hear about that hope your body is doing ok.
Where you trying to pedal around the turn or should you have just had the reversed pedal in the up position ?

At least it's not worse. Your Yuba's about as pretty as they get so hope she's ok as well.

[teklektik]

I'm doing fine, folks - thanks for the kind thoughts.

This is a turn after a straightaway near my home in a rural/suburban area that I take at the end of every ride. The shoulders on the straight are minimal so I always take the lane and run at around 35mph with the traffic and just brake and lean it pretty deep into the side street. This time I went in a little hot with a little deeper lean than usual, and when coming out dropped the inside pedal to begin pedaling just a whit too soon. This is my 100th time in this turn and familiarity just led to sloppy technique. My bad (Big Sigh).

I did end up in the hospital for a couple of days, but mostly for observation. The bike fared better than me so I'm not sharing any of my Percocets with it.

[teklektik]

VoltPhreaks Cooling Upgrade

A couple posts back I was musing about using Euro-to-US AC power adapters (the kind that will optionally take flat blade US plugs in the 'Euro' side) as spacers to improve VoltPhreaks charger cooling (see overheating issue in original charger post).

64-02_euroToUsaAdapter.jpg (4.07 KiB) Viewed 637 times

The lot prices are so cheap, I just ordered up a bunch and plugged them in, converting this original side-by-side configuration

to this height-staggered configuration with much improved cooling. Time to upgrade: less than five minutes.

Picked up about 1/2" in height - case closes with a bit of room to spare.

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The bike and I aren't on the road just now to discharge the battery, so I only had one test charge cycle with the new setup. However, the chargers were much cooler to the touch. I will at least do some simple surface temp tests once the bike is running again, but this looks like a pretty nifty improvement for a few bucks and essentially no effort.

Here's a few edge-wise shots of the chargers in a power strip to show the added air channels. The shots with the open charger show the relative position of the heat-producing switching transistor relative to the cooling channels. As an added bonus, the chargers fit without the need to sand the sides as was necessary when squished together side-by-side.

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64-12_highunitheatsource_2.jpg (22.41 KiB) Viewed 637 times

With no temperature data this revised scheme remains an unapproved configuration, but things are looking promising - at least for forced air cooling.

[BarkMau]

Well, that's how we learn.. and it could have been worse. Got me thinking on my early motorcycle riding years and all the road rash I avoided by wearing gloves alone. Better get back on that healthy habit.. Glad you and your one-of-a-kind Mundo are ok!