Hub Motors for Cargo Bikes

[amberwolf]

The cells in the middle of the pack will get a lot hotter than the ones exposed to the thermal management system, unless you individually heatsink each one with fluid cooling in the heatsinks. :/

It's much easier (and cheaper in the long run) to get better cells in the first place.

But if you have to use cells that don't really fit the application as well as you'd like, then you can parallel two or more sets of them.


As for power used on a cargo bike, it depends on the loads and terrain, and the controllers and motors.

On SB Cruiser, my heavy cargo / dog carrier trike, in it's present configuration it pulls over 80A at startup, using two hubmotors in 20" wheels, one on a "40A" controller, and one on a "30A" controller (both 12FETs). Obviously if it's pulling 80A then one or both controllers are actually using more current than their ratings, by some amount. I dont' know it's exact weight but I'd say over 300lbs easy.

It also only gets about 60Wh/mile on a 20+ mile trip with long stretches between stops/starts (maybe one every mile on average if I make a few lights), and is much worse (80-90Wh/mile or more) on a 4-6 mile trip with at least 30 stops/starts, with little difference in total load. This is cruising at just under 20MPH, and accelerating *to* that speed as quickly as possible (several seconds at best right now). No pedalling (it's only geared to pedal at a few MPH or less, in case the motors fail).

 

[dogman dan]

Re the batteries. I get it that 30 ah is a convenient size,, and plenty of course, if your controller max amps is 30. They should do ok if max is 1.5c, 45 amps for 30 ah. Cruise at 30 amps should be ok.

I just meant that if the weight gets high enough, you pull some serious amps. With my current setup, I weigh 190, the bike 90 with batteries. Trailer is about 35, and I can carry up to 200 pounds on it.

So I am at about 500 pounds total? The motor is slow, and max amps 22. Volts 48. Loaded like this I cruise at about 12 mph, and pull about 18 amps. A 30 ah lifepo4 would easily handle this. Faster speed though, would easily reach 30 amps, if I put a bigger controller on it. On any hill weighing that much, I pull close to max amps continuous, and slow till the motor would overheat.

You'll pull less amps of course, if you, the bike, and cargo only weigh 350. Or rather, go faster on 20 amps cruising.

If your controllers max amps is about 1.5c for your battery, that should work ok for lesser cost lifepo4. So a 40 amps controller max for your 30 ah battery will work ok I think. I just meant don't whack it with 50 or 60 amps, or more like AW's dual motor trike can.

 

[mechanix]

I'm just trying to wrap my mind around why the cheap batteries don't last at all. If it's thermal management - that is no problem, I can cool those batteries easily. If it's improperly built packs - I can build a pack that protects and compresses them to the correct levels. If it's over-discharging, using too much current, not balancing etc., I can deal with that as well. If they are just cheap pieces of junk that will never last - well, I can't do anything about that.

It's just not clear to me why all the cheap batteries fail within a few years. It almost seems like they have short calendar lives and are really just disposable cheap junk...I've looked at this thread:

https://endless-sphere.com/forums/viewtopic.php?f=14&t=7681

It had some good info, but I'm wondering what makes the cheap packs fail so quickly. I see instances where A123 fails quickly, and times when it lasts 8 years at 95% capacity. Maybe the generic cell packs are not being built to the same standard that the A123 cells are. I know that I would spend more time and money to protect something that costs so much, and would be more likely to just wrap up cheap cells in duct tape and call it a day. I'm not saying that we will get A123 performance out of $0.15/wh cells, but I'm guessing that their lifespan could be greatly improved if they were given the chance. What is the upper limit of these cells? For the right application, they could be a great value if their lifespan could be extended longer than a couple years.

 

[Voltron]

There could be many reasons.. impurities in the materials used would probably be number one.

 

[mechanix]

So the only way you'll really know what you are getting is to go A123, or roll the dice buying from China. Got it.

Anyone have a positive experience with an overseas vendor recently? I might try my luck over there if I can hear of any positive experiences recently.

Thanks all

 

[mechanix]

I gave up on trying to source Lifepo4 - now I'm excited about Leaf modules, but I'm trying to find a way to fit it on my frame in a discreet manner. It's a Yuba Mundo Frame, and I was hoping to put it in the rear triangle. the module would be slightly larger than a ream of paper:



Most likely, I'd weld up a mild steel piece, then braze it into the existing seat stays. Wouldn't be too hard, I'd just have to make sure the OD of the new member is equal to the ID of the existing stays.

If there is any frame that I could buy so I didn't have to go to all this work, I would rather go that route. I found the Xtracycle Edgerunner, but it has a pretty small payload capacity and I don't think the battery would fit in that frame either. Also, I'm not sure if it is available for sale just the frame:



Any other suggestions on batteries? I'm all ears - I couldn't find a way to source Volt cells...

 

[amberwolf]

You could simply build the pack under the side extensions. There is at least one build here that already does this, using a Yuba Mundo, but I dont' have enough time ATM to find the specific thread. I'm pretty sure it's in one of these
https://endless-sphere.com/forums/search.php?keywords=Yuba+Mundo&terms=all&author=&sc=1&sf=titleonly&sk=t&sd=d&sr=topics&st=0&ch=300&t=0&submit=Search
if you want to check them out, but it might be in some totally differently titled thread.

There's another that uses toolboxes to carry Headways, on top of those side extensions:
https://endless-sphere.com/forums/viewtopic.php?p=536876#p536876
I dont' know if there's enough space for the cells in question flat on their sides (they'd fit vertically) but that post has data on measurements for his frame, etc. The OP of that thread has links to various parts of his build you may find useful.

 

[Voltron]

 

[mechanix]

I'm wondering if I should start a build thread, or just continue on with this one? I finally got everything ordered, here's the list:

-MXUS V3 4T motor
-17" moto rim
-20s 41ah Leaf cells
-"gazelle" moto tires
-53t front chainring
-Fat bike cranks to clear the battery box in the rear triangle
-DJ forks
-Sabvoton SVMC 60A controller

I have a few questions:

-What is the smallest chainring that will fit in the MXUS, I think it's going to to be the 142mm hub, I got it directly from MXUS - I would love to find an 11-34t chainring so I can pedal along at full speed, and also pedal it home if something failed.

-I got 13g spoke nipples from JRH, but they won't fit in my rim, is it safe to drill the holes out? Is there a guide for that somewhere?

-I remember seeing somewhere a post about adapters for large chainrings, but can't find it for the life of me! Anyone point me in the right direction? I would be going from 104BCD four bolt to 130BCD five bolt most likely.

 

[amberwolf]

One of these?
https://endless-sphere.com/forums/search.php?keywords=chainring*+adapt*&terms=all&author=&sc=1&sf=titleonly&sk=t&sd=d&sr=topics&st=0&ch=300&t=0&submit=Search

 

[mechanix]

AW, I didn't see anything that fit the bill in with that search criteria - everything is all about bafang BBS.

I got the batteries, and am making some progress in making the battery pack, see the pics below:



View attachment 4









The plastic divider is only on the end cells that touch the metal end plates, I believe this is why the modules are more energy-dense. because the cells are touching each other back-to-back, using the space more efficiently. Isopropyl alcohol didn't seem to affect the glue used to hold these cells together. Luckily, they came apart easily without causing any bubbles to appear on the cells. I'm going to use the end plates to protect and compress the cells. The pack should be around 6.5" thick, fitting nicely between the fat bike cranks I purchased. The chainline won't be perfectly aligned, but I'll spend most of my time in the highest gear in the rear cluster anyways. 1st gear will be reserved for if something goes wrong.

 

[mechanix]

A quick update - got all the batteries out of the metal casing without incident and drilled out all the tabs. Next step, cutting all the tabs so I can put all the cells in series! Planning on using 10awg wire. Anybody have any suggestions for what kind of terminals would be best? There's not too much room between the cells. Isopropyl alcohol didn't do anything to the glue holding the cells together. WD-40 does dissolve it though. Got a few bubbles, but that's nothing to worry about, right?

 

[miro13car]

mechanix,
I can assure you Leaf cells look much better than A123 20Ah pouches I bought from Stortronics - A123 dealer in Livonia Michigan.
Of course they are different chemistries but still after separation /glue involved/ they still look better than my brand new A123 pouches with all those wrinkles, bubbles, etc. Definitely something wrong with quality control at A123.

 

[mechanix]

Yes, I was very happy with the quality of the cells. I'm about to run the cell through their paces with my iCharger 1010b+, I'll post results if I ever get the time.

 

[Philistine]

I have been off ES for a while, but I recently renovated my Yuba Mundo, I will update my thread properly when I get a chance, but I made a few big changes. I built a 50AH 12S Lipo pack out of three 50ah bricks of 4s series together, with an Adapto controller which is magic for keeping them all balanced. I understand why people didn't like Lipo before Adapto due to balancing stress, but now with the Adapto as a BMS, I will never run anything but HK Lipo. I made the batteries into flat packs so I could fix them to the running boards, then I put on the Yuba "go getter" panniers on each side. It is awesome, I will post up some photos.

The motor is a Mxus V3 3 turn (the high speed wind) built by ES member SamD into an excel motor cycle rim (19inch) which I run a Pirelli motorbike tyre on (have never had a flat, and doubt I will have to replace the tyre or a spoke for a year or two.....)

The MXUS V3 3turn in a 19inch motorbike rim is my holy grail hubmotor, and the Adapto has been 10/10 for me, it is one of the most amazingly well thought out and effective products I have ever bought. Has been a dream.

Below are some bad photos but they are what I had to hand. The second one gives a bit of a look at the size of the tyre. It is a manly sized tyre.

 

[Philistine]

I should note, the motorcyle tyre I run is so fat, that I had to cut off the rim brake posts on the Yuba with an angle grinder so the tyre could fit. Totally worth it to never get a flat again.

 

[mechanix]

Nice! Our bikes will be twins if I ever get finished with mine. I'm going to be running 17x1.4 tires, so I don't think there will be an issue with tire clearance.

Finally got some time to work on this again, and I have a couple questions for all the gurus out there:

-What is the best variable regen throttle that is not cheesy looking and waterproof. I read some stuff about Vectrix throttles and how they are half-twist one way for throttle and twist the other way for variable regen.

-Is there a freewheel that has an 11 tooth sprocket as the highest and atleast 32 for it's lowest gear? (34 or more would be awesome, in case I actually have to pedal this beast) It would need to fit on the MXUS V3 built for 135mm dropouts, on a 135mm frame. Would one of these work?

http://www.ebikes.ca/shop/electric-bicycle-parts/freewheels/fw7spd1132.html

http://www.ebikes.ca/shop/electric-bicycle-parts/freewheels/fw8spd1132.html

Thanks everyone for the help so far, I'm planning on cutting and welding the frame this weekend, so hopefully I'll have some pics by tomorrow!

 

[mechanix]

OK, made some progress today! Got all the battery terminals clipped so I can wire it 20s1p, and cut a piece out of the frame to make $#!t real:

 

[mechanix]

Carved out some more time to work on this - got the front wheel laced up, and started on the rear wheel, but the ERD for the rear rim I got from Treatland.com was mislabeled as 410mm, when it is actually 420mm...



Also, where would I find the paper and sheathing used to insulate the leads inside the hub motor? I wanted to clean it up a bit in there, and maybe epoxy a few parts of the windings in place as well. I found a chunk of solder about the size of a bb, glad I checked inside!

 

[mechanix]

Took a break to do outdoor things this summer (Don't get me wrong, building ebikes is fun, but the winters here in Portland are long and wet, that's when I prefer to do my tinkering).

Here are some progress pics:
View attachment 4

View attachment 3

 

[mechanix]

Forgot to mention I had to extend the bottom bracket to install fat bike cranks to clear the huge battery to be mounted behind the seat tube. This project has definitely been a learning experience - learned how to oxy-acetylene braze, and tig weld!

 

[mechanix]

If anyone is actually looking at this thread, I'm back from a 5 month break and trying to remember what the heck I was even doing with this bike...I think I was about to try to mount the battery and I can see why I gave up! The chainline is going to be really difficult to re-route around the battery and I want to get the input of you guys as to how to do this. Surely someone has done something like this on this forum!

If I route the chain like normal, it would be going through the battery, so I'm going to have to either go above or below...







Cheers!

 

[markz]

Found some discarded Makita tool boxes I plan to gut, and put in a 18650's pack. Paint it black, and secure as a pannier to the back rack. There is a unique pawn shop that sells a lot of unique stuff, and in the back corner they got Makita type boxes, can't remember their prices but most likely $20-$30 depending on size.

 

[Raisedeyebrows]

If anyone is actually looking at this thread, I'm back from a 5 month break and trying to remember what the heck I was even doing with this bike...I think I was about to try to mount the battery and I can see why I gave up! The chainline is going to be really difficult to re-route around the battery and I want to get the input of you guys as to how to do this. Surely someone has done something like this on this forum!

If I route the chain like normal, it would be going through the battery, so I'm going to have to either go above or below...

Cheers!

Looks like you did a nice job brazing/welding the space for the pack, is your only option to make use of it to narrow the pack down? Looks like you're going to have a pretty hard time getting the chain around it and ending up with a useable chainline at the same time. Don't give up, they are such utilitarian, sturdy bikes, I hope you can find a solution that enables you to get the bike on the road before the good weather really breaks and you can really enjoy it. Mine is same color, V3:

 

[amberwolf]

On CrazyBike2, since I didn't need to pedal much (I couldn't really apply torque enough to move it at a speed high enough to balance it, the way my joints are), I just ran the chain inside a plastic tube over the metal ammocan's top. I'm sure I have a pic of it somewhere in that build thread, probably in the last few pages, but you can find similar tube-constrained chains on various recumbent bikes and trikes in a google image search.


Something I had planned to do, but never did, was to weld pulley-sprocket mounts to the frame in a way that would route teh chain around the pack (probably under it as that also increases chain wrap on the front chainring).

To get under the cargo/seatbox, I *am* doing this on The Raine Trike build, but haven't got that far yet so there's no pics of it in that build thread yet. Similarly, once it's worked out on the Raine Trike, I'll do the same thing on the SB Cruiser trike.

The way I'll probably be doing it is to use old steel rear hubs, cut in half, and the threaded freewheel side welded to the frame with the hub's central tube thru a hole in the frame tube, and welding the intersecting walls. Then use the freewheels as the chain guides, with the pawls taken out so they'll run freely in either direction.

Some poeple use pulleys instead, but these can be noisy as the chain's links go over it since chains are typically "bumpy" along tehir lengths.

Some poeple use old derailer jockey wheels.

The reason I want to use the hubs/freewheels is that it's possible some very high torque will be applied across these and I'd rather have something strong enough to stay in place under that.