Advice on e-Xtracycle build

[Martog]

Greetings Wise Ones,

Background:
I've caught the e-bike bug and have been lurking on ES for awhile, trying to soak in as much knowledge as possible. The amount of information and experience on this site is amazing!

I've also been tinkering on cheap (and usually, broken) Craigslist purchased e-bikes to get my feet wet without breaking the bank.

One of my projects is to make an e-cargo bike. I already had an Xtracycle kit so I mounted it to one of my resurrected CL e-bikes.

My questions are:
1) Is this a safe platform to use from a structural standpoint?

1a) I have concerns about the integrity of the bottom bracket areas due to the way the controller mounting box takes the place of the normal mounting of the chainstays to the BB (see pic).

1b) Am I asking for trouble with this alloy fork? It is a Zoom with factory installed stainless steel torque plates. It looks beefy but it is still alloy and I'll be carrying some weight (I'm 190# and I'll probably carry no more than another 100# of cargo). Plus I'm interested in upping the power on this front hub motor.

2) Is the motor/controller a good starting place for a cargo bike?

Original E-bike specs:
Motor is an 350w 8FUN, code 15 (so 201 RPM)
Battery is a 36v, 12ah Phylion
Controller is 7A continuous, 15A burst (edited to correct from 20A)
3-speed Nexus IGH


Application:
Mostly local errands and beach runs carrying a paddle board, taking my daughter to/from preschool, + grocery/beer runs. Only 5-8 miles round trips but some moderate hills to overcome.

This setup is underwhelming at 36v/20A. The motor pulls decently but feels underpowered and top speed is too slow.

As a test, I pulled the 36v battery and wired (in series) two 24v Phylion batteries (actually 26+v, one 8ah and the other 10ah) and that perked the motor right up.

The combined batteries put out 55v but sagged quickly and one battery consistently drops out when stressing the setup on hills (motor and controller still feel cold to the touch). I'm assuming that is being caused by that battery's BMS detecting a low cell??

Some of the attractions of using this bike as the starting place for an e-Xtracycle build:
- Prewired/plumbed for the electrics
- Slow wind motor
- Built-in battery storage
- Already had an IGH with freewheel

However, I'm rethinking this whole project due to concerns about the frame/fork and the fact that the motor really needs 48v to wake up (which means the built-in battery is less advantageous).

If the frame and fork are not an issue, I could gut the failing 24v Phylion battery and perhaps use the shell to carry 12s/15s Lipo?
I'm planning on going to Lipo for another build shortly anyway (probably with the Yescom 1000w kit).

Sorry for the long post! I appreciate any thoughts or advice on this project!

Thanks
Martog

 

[dogman dan]

Well, your need for safety does increase with a child on board. But unless you see some issues with the frame cracking happening, I would not worry too much about it.

The forks look fine to me, with a well sorted out torque plate. But again, keep an eye on it. I have run some pretty low quality forks on my cargo bike, but have recently upgraded to a much stronger fork. I never broke the cheap forks, they just had cheap feeling performance.

Because of the above, lower speed riding might be advisable. But I would not fear 20 mph on it myself, if not more.

It will be easy to fry that motor if you climb steep hills with a lot of cargo. Dual motors would be good though. Add a rear hub? With a more powerful battery for it of course.

 

[Martog]

Thanks Dogman!
I've learned a lot from reading many,many of your posts on ES. You've helped far more folks than you probably realize.

So I just took another spin on the rig testing the motor at the higher voltage - again running on the two 24v Phylion packs (after topping off the failing one ). Again the combined resting voltage was 55v. Also I had mistakenly posted that the controller was at 20 amps - when in fact it is actually marked at 15 amps.

Running this motor at the higher voltage really wakes it up - even with the saggy, failing Phylion packs and running the controller at 15A. I think this performance would be adequate for the time being. I even successfully climbed the steepest hill I need to before the BMS kicked off the failing pack on the next (much smaller) hill (resetting the battery brings it back briefly).

So here's what I have to work with:
1 good 36v 12ah Phylion pack (but the bike is no fun with just 36v)
1 good 24v 10ah Phylion pack (borrowed from wifey's bike)
1 iffy 24v 8an Phylion pack that keeps tripping its BMS under load. This pack also only shows 2 of 3 bars on its "fuel" gauge after charging so it is shot I think

I also have a 24v 250w Bafang rear motor (and several more 36v 350w Amped front hub motors to use if I burn up the 8FUN)

It sounds like my options for adequate performance would be:
1) Run the existing front hub at 36v using the good 36v Phylion pack and add a rear motor using the good 24v battery (dual motor solution) but I lose the option of the Nexus IGH
2) Run the existing front hub at at 48-55v using new Lipo (maybe gut the bad 24v Phylion and use its case?)
3) Run the existing front hub at 48-55v using the good 36v Phylion and adding a small Lipo booster?

In each scenario, I could also do a small shunt mod to give another performance boost (maybe go to 20A from the stock 15A?).

So far I'm leaning towards swapping over to Lipo since that seems the simplest way to get the same or better performance as I was getting while testing the 2x24v battery combination.

Am I capturing my options correctly?

Thanks again!

 

[dogman dan]

I missed the part about having the nexus hub. I can see wanting to keep that for sure.

But if you have other motors around, that makes risking burning one up less scary. I like the idea of running 48v. Just watch out for things likely to fry it, like long steep hills. Try to avoid hills you can't climb at 12 mph or more for sure.

Adding a small 12v, or even 8v RC lico booster to the 36v pack has great appeal. 2s packs for 8v more would be very cheap. But then you could spend a bit on a decent charger, for use later when you have a large 14s lico pack. Once you go to full lico, that would mean running a lot of motors, or bigger motors is no problem.

I think 44-48v will help you keep the rpm up on hills, and help it run with less overheating. You must really be bogging down on hills with 36v.

If you ever wanted to invest in more motor, then a bafang bb motor would work with the nexus.

 

[Martog]

Ok, I'm on the hunt for some HK Lipo.

Of course all the cheap 2S packs are out of stock in the US warehouse...

Since I'm considering building a bigger Lipo pack to use on the Yescom 1000w kit (different project), I was hoping to use the same type of packs (5S or 6S) but neither of would work on the cargo bike as a booster for the 36v without smoking the controller (I think).

Hmm... I'll need to think about how to approach this.

Thanks!

 

[Martog]

Just remembered that I have 2 new 12v9ah SLAs that I could use as a booster to the 36v12ah Lion.
Hopefully at 2P (12v/18ah) they won't sag too much and have enough headroom to not be damaged before I hit the BMS LVC on the 36v12ah Lion (as the controller LVC is useless since I'm overvolting the controller).

I'm not planning on using these for more than 5 miles per cycle, so I think I should be ok. We'll see...

Although I've only had experience with a couple of 36v bikes, from my testing on this rig, I'm convinced that 48v is where the fun really starts!

 

[dogman dan]

That will do for now. One nice thing about a good cargo bike, even hauling lead is not so bad.

Maybe use that for awhile, then make a 12s pack for the cargo bike. Buy now, the spring lico shortage in the US warehouse is on. Last spring, I ended up buying 3s hardcase packs, and was damn glad I could get anything.

This year, I made sure to buy while the snow was still deep in the north. Got the 6s packs I need to be able to run either 6s for my mower, or add some 2s for my 14s bike.

 

[neptronix]

I bought one of these and sent it back after finding out how poorly it attached to my frame. Give my review a look. Nobody seems to agree with me here, but at least give my words some consideration.

http://endless-sphere.com/forums/viewtopic.php?f=4&t=40519

 

[dogman dan]

I was just saying the frame itself didn't look too weak to handle the add on. I don't see a problem with the controller box weakening the frame, it looks pretty thick and strong to me.

I just went and read that review, and can see both sides of the argument. But I would value Neptronix review more, if the thing had been taken out and torture tested for 500 miles or more.

Bolt size is another issue. IMO, if there is a hole that's 6mm, it should have a 6mm bolt. I wonder if the supplier changed things on them, but never told them. QR squewers are very thin, but made of high quality steel. You wouldn't tolerate it if they made them too thin for the hole though. They fit the hole perfect.

 

[Martog]

Thanks for the input guys.
Neptronix, I had previously read your review and understand your thoughts about the Xtracycle kit. I've already been using one for about 6 months on my pedal-powered 700c Specialized Globe hybrid, so I'm pretty familiar with the pluses and minuses of the platform.

There is an undeniable "sway" to the setup when cranking up hills loaded - even more pronounced when I have a 10' paddleboard strapped to it (plus surf gear) and the wind whips up! But I've had no problems with the strength of X setup. Its kinda like dancing with a *ahem* "big boned" dance partner - you can either fight the rhythm or relax and go with it...

I decided that the 700c bike was not a good platform for an e-cargo build (for a variety of reasons) so moved the kit over to the non-name e-bike I brought back to life. I have to say I was surprised how much stiffer the Xtracycle/26" no-name e-bike rig is compared to the same setup on the previous 700c bike.

All that being said, this whole process is somewhat of a trial to see how a cargo bike/and/or e-bikes fit into our lifestyle. Based upon our use so far, it is very likely that we will be moving to a Big Dummy or Edgerunner before too long (and that will be a whole other e-build thread...).

Thanks again for your collective guidance!

 

[neptronix]

Yeah, i never tried it. I just won't bother with something that is loose from the factory at every single attachment part when it becomes a 'part' of the bicycle frame itself.

I wanted it to be a high power build, and had ignored all the warnings about it being flexy, so the loose mounting points/hardware was the icing on the cake for me.

I moved on to a cargo bike, but that had it's problems too.
Long story..