High performance & durability Cannondale Semi Recumbent

qwerkus said:
Hmmm. I'd need 98 cells minimum, better 112. How did you make that niiiiiiice triangle box ?
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Thanks! I have some info on the link in my signature. I bought some 1/8th inch aluminum and hardware from Amazon, and basically used a jigsaw, vise, hammer, and drill. I need to update my parts list on the first post, and copy to the "custom enclosure" thread.
 
neptronix said:
I have decided to have a two part battery that hangs off the sides of the frame. Where it will hang off is still up for debate. But i want a minimum of 1.5kwhrs so i can do a >100 mile ride at ~20mph. It will probably require custom 3d printed mounts for the large diameter tubes.
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Did you know that cannondale made some custom racks for their recumbents ?

A42Hqu


If one manages to actually find this thing, it could help you out with your dual battery setup.

Here I'm not so convince anymore. After the first excitement, it turns out with a recumbent I'd really miss the one thing I love the most when cycling: standing on the pedals and being able to actually see over all the cars...
 
Oh wow, even though that's a maxarya bike ( and probably a rack to fit ), that looks to be a fairly solid idea for mounting.
My seat rails are not so easy peasy but i might be able to come up with something, so thanks for the idea.

Yes, you can't see over cars on a semi recumbent. I never get up on the pedals to see other cars, so i can't say i exactly miss that feature.
 
neptronix said:
Oh wow, even though that's a maxarya bike ( and probably a rack to fit ), that looks to be a fairly solid idea for mounting.
My seat rails are not so easy peasy but i might be able to come up with something, so thanks for the idea.
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On flickr, the picture's legend reads:

"Cannondale designed this underseat pannier rack for their Bent I & II (formerly "Easy Rider") recumbents. Maxarya doesn't currently (as of March 2006) sell an underseat rack for their bikes. It's a miracle the Cannondale rack fits with no modification. I used underseat racks on my BikeEs, and recommend them as the best way to carry gear on a recumbent."

If this is correct,it means easyrider, bent I and bent II seats are interchangeable with maxarya's, just like the rack. This guys has the racks mounted on a bent I: https://www.youtube.com/watch?v=b9S6CXS5fPk

One other thing I wanted to ask you: why not move the DD motor forward ? Since it's a 16" wheel, you could reach an even better climbing efficiency. Also, the motor weight would more than offset the rather light handling feeling of the semi. My only concern would be if the "heashock" suspension can take it, but at least on MTBs it looks rather overbuilt.
 
Interesting! i thought you'd maybe made a mistake.. i'm going to have to seek one of those out. Thanks again.

Putting a DD in the 16" wheel would be great from a power density perspective but i do not feel confident enough in the front fork ( with the extreme angle it is bent at, and the fact that it is a suspension fork ) to run the ~4000W i plan to run through it.

I agree that it might be better for steering feel, as the front end is indeed very light and twitchy. Changing out to wider BMX handlebars, however, has seemed to help with that effect quite a bit.

I am not super confident in the rear swingarm's power handling either, but perhaps it is stronger than your typical mountain bike's swingarm simply because of the shorter length.
 
I found some other pictures of the rack, but could not find one for sale anywhere. Though this is not exactly a shocker.

Found a for sale ad that had a pretty good picture of the rack. The bike is of course already sold. but it clearly shows where the rack's weight sits. Which is a good hint.

Untitled-1.gif

I may be able to custom cut some aluminum plates, or hack up some used bicycle racks to mount a shark pack on each side. Thanks again for the killer idea. In the last 2 days, i've increased my ability to walk with a cane a lot, so i'm gonna hop down to the garage and experiment with some 'cardboard aided design'.
 
Okay, looking over how that rack is made, it's clear to me that it would not be too great for carrying 2x 9lbs batteries.

IMG_20190602_174023534.jpg

I cannot just make an easy flat plate because the rear of the bike protrudes into that space :/
It is also not the best idea to hang 100% of that weight off those tiny quick release bolts, even though some tension holds the plate to the frame..

I'm thinking of just building a box in the back.. or some kind of rear pannier thing. It seems like the most sane option for mounting batteries.
 
Made some decisions...
Gonna use a 30mm wide DD hub, if leafmotor will supply me with a special 3T winding..
Should do about 40mph on 52v, which is perfect.

Batteries? one em3ev 14S7P brick ( 50v 24ah ) for starters. Will design a rear rack around it's dimensions once i get the battery in my greedy little paws.

If i need more range, i'll shift my focus to aerodynamics, as it doesn't get much better than a 90% peak efficiency hub, and this bike is going to be an 80lbs tank.

If leaf won't make me a 3T, then it's back to the drawing board, as i have not managed to convince any other companies to sell me a winding that can do 40mph on 50v.
 
neptronix said:
Batteries? one em3ev 14S7P brick ( 50v 24ah ) for starters. Will design a rear rack around it's dimensions once i get the battery in my greedy little paws.
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For 14s7p,I find this aluminium box from ali better than the em3ev: https://www.aliexpress.com/item/32950985280.html?spm=a2g0s.9042311.0.0.3bc64c4dQJtWeC

It's a bit expensive for just an aluminium tube,but seems worth it. Ditch the crappy plastic covers, and cut 2x simple aluminium plates to size instead.
The inside dimensions allow you to squeeze at least 98 18650 cells sidewards + nickel/copper strip + insulator firmly against the aluminium walls, which make for an excellent cooler. I built one pack for a bbs02, and on peak 1500W it doesn't even feel warm.

Check it out on my corratec thread: https://endless-sphere.com/forums/viewtopic.php?f=6&t=99376&p=1455453&hilit=climber+commuter#p1455099

98cells is the max if you are usind a ladder style layout. My next build will use the same box,but honeycomb layout. I hope to squeeze 14s8p inside this time.
 
Thanks for the idea.
I've seriously considered building my own battery pack, as 72v is a bit too much voltage, but 50v in common 14S packs is not enough.

14S8P would be pretty badass.

I'd prefer to use 26650's or 21700's though to minimize the number of connections needed and also the number of cells i need to concern myself with.

Currently on the hunt for a good 26650. I suspect that with mainstream Japanese/Korean chemistries, you could jam 8AH into one of those and make a 20S2P 72v 16AH pack ( 1152whrs ) with just 40 cells.

The 21700's seem to max out at 5AH, so we are talking about 60 cells for a 72v 15AH pack, or 1080whrs, which isn't too bad.

Of course i'd rather have some giant high density 15-20AH prismatic cells so that one can just bolt together and/or service a pack easily.. but those don't exist..

Word on the street is that Agnuism is working on a 21700 cell holder, so maybe i will be his test hamster.
 
neptronix said:
I'd prefer to use 26650's or 21700's though to minimize the number of connections needed and also the number of cells i need to concern myself with.
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Never heard of a 26650 that beats a 18650 in volumetric and/or gravimetric energy density. NCR21700A and Samsung INR21700-50E slightly beat their 18650 counterpart in terms of weight to energy density, but not volume. For high power batteries, I'd suggest staying with 18650 simply because the power will be spread over more cells, which means less strain on each individual. There are plenty of layouts in this forum for easy maintenance or whatever you want. Also, both cells and parts (holder,boxes) are still cheaper for 18650, even if it's getting close.

Also, all the hype about 21700s forgetting that 21700s are harder to cool because of the larger volume. Tesla is using advanced cooling layouts which is not practicable for ebike use. Smaller cells are easier to deal with.

I think you are right when writing that 72V is too high. Something like 60V would probably be ideal for your build, and spare you the negotiation with hub motor manufacturers, as 4-5T winds are readily available. The only nice part of 72V is that you can plug 2x 36V in series, but that also some additional hassle.
 
I thought about 2x 36v batteries but i cannot find anyone that sells a decent one that can handle 40A discharge at a minimum.

21700/26650 cells will have the load spread out in a different proportion, but it all works out the same as long as your bus is correctly sized and shaped for the load.

I like less cells because it means there's less cells to cycle graph and match, and less interconnects to worry about coming loose due to vibration, heat, etc.

I really like the no solder modules because they make things modular and easily serviceable like RC Lipo. There is no way i will touch RC Lipo again though. I am a reformed RC Lipo addict.. :oops:
 
neptronix said:
Of course i'd rather have some giant high density 15-20AH prismatic cells so that one can just bolt together and/or service a pack easily.. but those don't exist..
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If you can live with the weight, you could go to 45ah pouch cells:

https://www.ebay.com/i/223290104145?chn=ps
 
WOW, there are a hell of a lot of used EV batteries for sale versus a few years ago. Those chrysler batteries are really obese but i bet there's some higher whrs/kg stuff lying around. Time to investigate.. thanks for getting me thinking :bigthumb:
 
qwerkus said:
I think you are right when writing that 72V is too high. Something like 60V would probably be ideal for your build, and spare you the negotiation with hub motor manufacturers, as 4-5T winds are readily available. The only nice part of 72V is that you can plug 2x 36V in series, but that also some additional hassle.
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I feel like I asked Nep this before, but what's wrong with 72v 20s again? To me, as long as your controller supports it (which Nep has done a 72v test before), it seems like a good way to get more power without drawing more amps.

Unrelated and in my opinion, one of the best benefits of cylindrical cells like 18650s are the ability to build your own pack to closely fit the space you're working with. Doesn't sound like this build has a defined battery storage shape yet though.
 
I'm not a fan of high voltage at all and would prefer to run something lazy like 48v for the following reasons..

1) Above 48v, you really, really need a solid precharge resistor. And those cool anti spark connectors from hobbyking are said to not work well above 12S.
2) There are very few chargers designed for 72V *and* are adjustable / compact. I do have a 72v cycle satiator, but there are not many good alternatives. Drop down to 48 or 36v and the world is your oyster.
3) Since i am big into manually balanced batteries and don't like BMSes, the lower the cell count, the better. I like using RC chargers for balancing, but that limits you to 14S.
4) It is a lot easier to adjust amps than it is to adjust volts. Yes, you can do flux weakening or timing advance, but you take an efficiency hit when you do that.

I suspect the 3T motor from leafie might be optimal at 36v, which means an 18FET controller would be the bare minimum for driving it, which is a bit insane.

Well, the upside of running 60-72v is that i can use the lovely phaserunner that's been collecting dust.
 
Thanks for the response. I'm not going to try to change your mind or anything, but I do hope to use 72v 20s myself for my next bike. These are just some thoughts; no need to reply unless you want to.

1. I do use the anti-spark XT90 on my wife's bike. If the resistor actually gets hot charging the caps on a large infineon controller at 72 volts (which I have a hard time seeing), I bet there aren't as big of capacitors in the phaserunner to fill.

3. Have you had some bad problems with BMSes? The two smart ones I use have been really reliable, and I like being able to see all the cell voltages whenever I want.
 
Yes, you are probably right about the phaserunner, but there's a possibility i will want more amps than that, so i can't really bank on the idea of the easy antisparks.

Interesting to know that you can get away with 72v on the XT90 antisparks!

I have an inherent mistrust for BMSes, unless they're of high quality. The ones from em3ev seem pretty nice but if i had a pack with one, i'd solder up a set of emergency bypass leads, because this bike will occasionally travel 100 miles from home, so in the case of failure, at least i'd have power.. Otherwise, i prefer a pack without a BMS as it is just another part that can fail.

It seems that if i bought the leaf 30mm mystery motor ( 3T ), and ended up with something crazy like a 20kV motor, and tuned the throttle % down, i'd have higher efficiency than if i used flux weakening on a FOC controller, or timing advance on an infineon clone. I'd just need a lot of amps to make power and couldn't use the phase runner, but that's not the end of the world.

I think the minimum kV i'd get with the 30mm leaf 3T would be 18kv. Just a guess based on the idea of taking the 14.4kv of the 4T and adding 25%.

50v cellman.png

If i can optimize the aerodynamics of the semi recumbent ( shouldn't be too hard with a big zzipper bubble and maybe a tailbox! ), i could hit that 45mph target top speed on just a 14S7P em3ev pack. :shock: so, it looks like i can achieve my lofty goals here.

Here is the bike climbing up the steepest mountain in my area.. this would literally be the bare minimum motor.. the mountain road is 8 miles and i'd have to take it slow but it can be done..

7 percent grade 50v cellman.png

The situation may be better than this, as the leafie peaks 2% higher in efficiency than the MXUS.
 
neptronix said:
Yes, you are probably right about the phaserunner, but there's a possibility i will want more amps than that, so i can't really bank on the idea of the easy antisparks.

Interesting to know that you can get away with 72v on the XT90 antisparks!

I have an inherent mistrust for BMSes, unless they're of high quality. The ones from em3ev seem pretty nice but if i had a pack with one, i'd solder up a set of emergency bypass leads, because this bike will occasionally travel 100 miles from home, so in the case of failure, at least i'd have power.. Otherwise, i prefer a pack without a BMS as it is just another part that can fail.
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I plan to do 72v with the XT90 antispark connectors, only doing 52v so far. If they have big capacitors to fill, just wait on the resistor a little longer before plugging it in all the way.

Good point about the BMS bypass. I should make one just in case, or at least throw an alligator clip wire in my bag :)
 
I see. You are probably right about the resistor trick. Deserves testing :)

Pedal extenders came in today and am in the process of ordering the 3T leaf and a 14s7p batt from em3ev.

Once I have the battery, I will make a rear tailcone for the bike that can house the battery and other goodies like tools for road servicing, electrolyte water, spare tubes, rain gear, hunting gear etc :bolt:

Dunno what to do about the front aero of the bike, but election season is coming up, so there may be lots of wild urban coroplast to harvest by the time I get to deciding whether to build or buy aerodynamic aids for the front :lol:
 
lol at the election season! I agree that the tailcone should make more of a difference than the front aero. em3ev.com would definitely be my source if I weren't building my own battery. 35E cells?

Also would you mind posting a link to the 3T leaf at some point? I wish there website was more clear.
 
I think the front might make more of a difference than the tail, but the tail is a hundred times easier to design and implement. The front end of a recumbent bike makes mounting anything there difficult.

Yeah, i'm getting a pack with 23.8AH of 35E cells. I understand they'll be saggy at full speed, but at the average speed i travel at ( 25-30mph ), i'll be using less than 10 amps continuous, so 1/2 C should make for pretty good battery efficiency and amazing range. If i planned to go 45mph all the time, i'd have chosen a different cell.

Ordering with leafbike is a bit goofy. You have to specify the winding and rim size in the order comments.

2019-06-07 15_08_54-Electric bike motor _ eBike conversion kit _ Brushless hub motor - Leaf.png

They didn't even know what the speed of the 3T winding is, so i'm taking a crapshoot here. Will update the leafmotor thread i started with a kV figure on the 3T motor when it arrivves. Leafbike is the only company that was willing to sell me this crazy winding. My guess is that it'll do ~900rpm unloaded on 48v.
 
Motor and battery are now both ordered and on the way. Finally.

As for my leg, well.. i'm doing a decent amount of walking on it each day. By the time the parts arrive, i will have enough bone fused to be 100% cane free at this rate, so i'm not going to bother making a cane holder for the bike :bigthumb:

My wife is currently sewing me together a heavy duty taylor spatial frame protector so that i can ride without worrying about bugs, rocks, dust etc getting into my leg <3
 
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