eMTB - Specialized Enduro with CYC Stealth (aka The e-Duro!)

[Bengy22]

I must say that is one of the cleanest non-ebike frame builds I have seen before. When I first saw the bike I thought you didn't have a battery mounted. Really cool the are making frames with storage built into the frame now. For a cleaner battery cable can you route it down through the shock cavity? Seems like there might be enough room to not get in the way and would hide most of it. I do want to ask what made you want to go with a non-ebike frame instead of say a Dengfu e10? I'm guessing its something to do with the geo but with my light budget I've never really compared bikes geo's so I don't have the knowledge on what frame would be more modern or better etc. $2400 just for a frame makes my eyes water though :lol: I know the e10 is around $1000 new.

I do want to mention if you want a battery that can do more amps you can get Samsung 50s 5ah and 25a discharge. So the same capacity (should see a little bit more capacity due to not running the 50e's at the max discharge). Or you can wait for some new cells like the lgm58t or vapecell f58 which both offer 12.5a discharge and 5570mah and 5800mah. But both have yet to hit the hobbyist market from what I've seen. Those cells plus a water bottle extension means you could be pulling big amps and long rides. If you have a 3d printer you could always print a housing to match the lines of the bike and mount to the bottle mounts, could look clean and fix a decent amount of cells extra. And you also might be able to buy that slower reduction from cyc separately, send them a email.

And nice 500w will get you moving good when you also have gears, now think of 1500w :lol: Does the cyc not allow you to customize the wattage of each pas level?

 

[handlworks]

I must say that is one of the cleanest non-ebike frame builds I have seen before. When I first saw the bike I thought you didn't have a battery mounted. Really cool the are making frames with storage built into the frame now. For a cleaner battery cable can you route it down through the shock cavity? Seems like there might be enough room to not get in the way and would hide most of it. I do want to ask what made you want to go with a non-ebike frame instead of say a Dengfu e10? I'm guessing its something to do with the geo but with my light budget I've never really compared bikes geo's so I don't have the knowledge on what frame would be more modern or better etc. $2400 just for a frame makes my eyes water though :lol: I know the e10 is around $1000 new.

I do want to mention if you want a battery that can do more amps you can get Samsung 50s 5ah and 25a discharge. So the same capacity (should see a little bit more capacity due to not running the 50e's at the max discharge). Or you can wait for some new cells like the lgm58t or vapecell f58 which both offer 12.5a discharge and 5570mah and 5800mah. But both have yet to hit the hobbyist market from what I've seen. Those cells plus a water bottle extension means you could be pulling big amps and long rides. If you have a 3d printer you could always print a housing to match the lines of the bike and mount to the bottle mounts, could look clean and fix a decent amount of cells extra. And you also might be able to buy that slower reduction from cyc separately, send them a email.

And nice 500w will get you moving good when you also have gears, now think of 1500w :lol: Does the cyc not allow you to customize the wattage of each pas level?

Thank you kindly! Much appreciated, clean is what I'm going for haha

There's not room in the shock cavity, the shock movement uses all the room I've considered enlarging an existing hole at the bottom of the frame (a mounting hole I don't use anymore), but it's hard to justify cutting into such an expensive frame AND carbon is an unpredictable mistress. Continuing to dwell on that one.

I chose this frame because I wanted to use a frame geo that's purpose-designed for the kind of riding that I do. Specialized put a ton of R&D into coming up with this geometry, I want to use the best of the best. Def cost a pretty penny though! Close second reason is bc it might annoy some purists and I'm always a fan of that this frame is absolutely gorgeous and I don't regret it for a second - taking the big hits on this really make me realize why the Kenevo SL is such a highly regarded bike. Past a certain point, suspension is truly the differentiator.

Good call on the 50S! 50E is just what I had laying around. I'll definitely consider rebuilding this battery with 50S's since this initial build is looking pretty successful so far.

500W is so much already, indeed! CYC does let you customize the PAS, I'm just moving slowly with really tuning it. Goals are probably to have the battery wires tucked, with 1500W available on demand and an all-round ripper in the next few months

 

[Bengy22]

Thank you kindly! Much appreciated, clean is what I'm going for haha

There's not room in the shock cavity, the shock movement uses all the room I've considered enlarging an existing hole at the bottom of the frame (a mounting hole I don't use anymore), but it's hard to justify cutting into such an expensive frame AND carbon is an unpredictable mistress. Continuing to dwell on that one.

I chose this frame because I wanted to use a frame geo that's purpose-designed for the kind of riding that I do. Specialized put a ton of R&D into coming up with this geometry, I want to use the best of the best. Def cost a pretty penny though! Close second reason is bc it might annoy some purists and I'm always a fan of that this frame is absolutely gorgeous and I don't regret it for a second - taking the big hits on this really make me realize why the Kenevo SL is such a highly regarded bike. Past a certain point, suspension is truly the differentiator.

Good call on the 50S! 50E is just what I had laying around. I'll definitely consider rebuilding this battery with 50S's since this initial build is looking pretty successful so far.

500W is so much already, indeed! CYC does let you customize the PAS, I'm just moving slowly with really tuning it. Goals are probably to have the battery wires tucked, with 1500W available on demand and an all-round ripper in the next few months

Dang from the photos it looks like that would work. I don't think it looks as bad as your friend was making it out to be, imo put some black heat shrink over the whole thing and its going to be a lot less noticeable. Imo don't cut into the carbon unless its for good reason, I wouldn't consider this one unless you start loosing sleep over it.

Also the molicel p45b is about to hit mass market really soon. Its a 4500mah rated cell but compared to the 50s its about 8% less capacity at 5a and 10a discharge but from 15a and beyond this flips and the molicel takes the lead in capacity (independent testing found online). Now I guess it really depends on how many amps you see yourself using most of the time. 50s also get hot around the 20a mark, not sure how many amps you plan to set the max too. Based off your previous comments the 50s probably is the better fit but food for thought.

Haha watch out the saying "power is addictive" is true and you might find yourself using the 1500w mode more and more. Then you will start needing more capacity and find yourself not caring too much about how the battery looks and be more concerned with the capacity.... Ask me how I know :lol:

 

[handlworks]

Wow, it's been a while! I have small updates and then next steps:

I removed the winter camo livery from the bike and took it to Red Rocks in Las Vegas:
View attachment R0000776compressed.jpg

Those rocks are gnarly and left me with a real bad pinch flat!

WHAT'S NEXT:
I'm starting to think about a range extender. It's not really necessary for most rides, but it's interesting to dive into and I think it's just a cool addition. A benchmark that comes to mind is the Specialized Levo range extenders (can you tell I'm really gunning for Specialized with this build?).

My end goal is to have a battery inside a water bottle that I can put inside my bottle cage, plug into my powertrain, and ride longer with. Just like Specialized.

When I was loosely thinking about this at the beginning of the build, I figured I could just parallel the range extender with the main battery. I don't think I'm a fan of this anymore. The main worry is that since there's no way I could fit an equivalent pack into a water bottle, the range extender would be about half the capacity and would run out in the middle of every ride. Without programming a custom BMS for current output and low voltage cutoff, I would essentially be bouncing the cells off their voltage floor every time I want to ride far. I'm not sure how Specialized accomplishes this, but I'm guessing they have a third computer that controls the main and range extender outputs, native on the bike. Brutes...

So my other option is to connect my range extender in series. Instead of giving me more parallel cells, I'll be stepping up my voltage. Driving up power through voltage rather than current is better anyways, right? ¯\_(ツ)_/¯ This also means that every time I want to ride with the range extender, I also need to have a reflash firmware handy for the BAC855. Which isn't a huge deal for me but wouldn't be commercializable.

This means I'll need some clever wiring and two big diodes to protect the packs in the case of a pack cutout (can probably fit it all into the water bottle). The range extender will be a 5s2p to add onto my main battery of 10s2p. I'll just charge these separately to avoid any weirdness. I'm pulling info from herehttp://endless-sphere.com/forums/viewtopic.php?f=16&t=1312#p70490), thanks fechter!

Also worth noting that I'm by no means an electrical guy so I don't have the proper mental frameworks for thinking about this stuff. Anybody who knows better, chime in!

 

[scianiac]

If you put two packs in parallel the smaller pack will just discharge slower and the cells will always be at the same voltage in both packs. OK so technically this isn't 100% true but it depends on the conditions. Things like pairing batteries of much different IRs and then drawing lots of current from them starts to do weird things. In your case where you aren't pushing the batteries extremely hard and will presumably use the same or similar cells for the 2nd battery your main concern will be ensuring that both batteries are the same voltage when you plug them in. That is probably the fancy BMS that commercial versions use, and it probably amounts to just disabling the lower voltage pack until the higher voltage one has discharged down to a matching voltage.

 

[handlworks]

If you put two packs in parallel the smaller pack will just discharge slower and the cells will always be at the same voltage in both packs.
...
In your case where you aren't pushing the batteries extremely hard and will presumably use the same or similar cells for the 2nd battery your main concern will be ensuring that both batteries are the same voltage when you plug them in.

Thanks! My concern is that I do want to push these cells at their MCC, since the controller can take so much.

The solution here is probably to just make smart choices in BMS output ratings, which I should just go ahead and do. In the previous post, I'm just ruling out a parallel config without really doing any deep thinking. But I'm down to talk it through:

I have two scenarios that I'm unsure about - if I'm entertaining a parallel config, then my main battery would be 10s2p and the range extender would be 10s1p, all with Samsung 50E cells.
(1) If I'm running all these cells at MCC (10A each), then the 2p main pack will limit at 20A and the 1p range extender will output 10A. That shouldn't cause any large discrepancies in SOC between the two packs, and a diode to protect against charging between the two should fix small differences. I'll get a max of 42V*30A=1260W, which is pretty close to the controller max of 1500W.
(2) If I'm running at much lower than MCC (which is most of the time), then what is limiting the range extender output? Internal resistance? If I'm running at half MCC, then I'd be pulling 10A from the main pack and ??A from the extender. This is where I'm most unsure. Cheap BMS will only compound my worries! If I run most of the time between 0.25MCC and 0.5MCC, there's a huge band of unknown there without a way to instrument very reliably. I figured a series config gives me a max of 53V*20A=1060W, which is ... okay.

Looking forward to more thoughts!

 

[scianiac]

The internal resistance and voltage sag will limit and balance the current from both packs just is if you made 1 large pack that was 3P. If you're using all the same cells there shouldn't be any issue, it's when the cells are different and you are pushing them hard you can run into some issues. A diode shouldn't be necessary as long as you only plug them in when they are the same voltage but also shouldn't hurt, you should consider the diode choice carefully though as it there will be power lost in the voltage drop of the diode, although "ideal" diodes are an option to reduce this significantly. I believe there are BMS that will do this for you, a BMS with a separate charge port might be setup to just act as an "ideal" diode and only allow discharging through the discharge port and charging through the charge port.

 

[handlworks]

The internal resistance and voltage sag will limit and balance the current from both packs just is if you made 1 large pack that was 3P. If you're using all the same cells there shouldn't be any issue, it's when the cells are different and you are pushing them hard you can run into some issues. A diode shouldn't be necessary as long as you only plug them in when they are the same voltage but also shouldn't hurt, you should consider the diode choice carefully though as it there will be power lost in the voltage drop of the diode, although "ideal" diodes are an option to reduce this significantly. I believe there are BMS that will do this for you, a BMS with a separate charge port might be setup to just act as an "ideal" diode and only allow discharging through the discharge port and charging through the charge port.

Fair enough, I could switch to a BMS with a shared charge/discharge port. What's an ideal diode? I thought that was a mental model to use for calculations, is it an actual type of diode as well? Wondering how I'd test if my separate charge/discharge ports are really behaving this way... Also just doubtful these cheap boards are really doing that haha

 

[scianiac]

If your BMS has separate discharge and charge ports you can just try and charge it through the discharge port and if it doesn't work there you go. I think most cheap separate port BMS don't do this though as they just use one bank of FETs for each port so it has no way to stop charging on the discharging port through the FETs intrinsic diode. A common port BMS will only stop one battery from charging the other if it goes above it's charge current limit which isn't a great protection but it's something, ideally you just don't plug a fully charged battery together with a dead one.

There are other names for such devices, I just used "ideal diode" because it often comes up when you search for it. It's just a device that uses a MOSFET switched by a small control circuit to simulate a diode's function but with less voltage drop since when the MOSFET is turned on there is very little resistance through it.

 

[E-HP]

Fair enough, I could switch to a BMS with a shared charge/discharge port. What's an ideal diode? I thought that was a mental model to use for calculations, is it an actual type of diode as well? Wondering how I'd test if my separate charge/discharge ports are really behaving this way... Also just doubtful these cheap boards are really doing that haha

Do you fully charge and balance your packs on each charge cycle? If your normal charging routine is to charge o 90%, for example, then the BMS isn't performing any function during charging. You can keep the batteries paralleled, and charge one via it's charging port. That will charge both packs (one via the charge port, and that pack charging the second via the discharge port until you reach the desired voltage. If the cells are matched and in good shape, you could charge like this indefinitely and not go out of balance. Actually, they only have to be matched within the pack. I have lipos paralleled with my lithium ion pack, and they've stayed in balance for over a year (per cell voltage of both packs is within a couple hundredths).

 

[handlworks]

Do you fully charge and balance your packs on each charge cycle? If your normal charging routine is to charge o 90%, for example, then the BMS isn't performing any function during charging. You can keep the batteries paralleled, and charge one via it's charging port. That will charge both packs (one via the charge port, and that pack charging the second via the discharge port until you reach the desired voltage. If the cells are matched and in good shape, you could charge like this indefinitely and not go out of balance. Actually, they only have to be matched within the pack. I have lipos paralleled with my lithium ion pack, and they've stayed in balance for over a year (per cell voltage of both packs is within a couple hundredths).

Thanks for the data point! Good to know you're doing it successfully. I do fully charge and balance for each charge cycle. I suppose it's worth trying - I have the materials needed to do it. This is great, I'd rather parallel than series for many reasons.

 

[handlworks]

Just a video overview: LINK

 

[COAR]

Haven't read this forum in a minute but this is one of the best (i.e. most discreet) FS conversions I've seen. Appreciate the price breakdown as well.

I guess these weren't available when you started this build, but there are some pretty compelling "light" factory FS e-bikes out now, like the Trek Fuel EXE and Transition Relay. I test rode an EXE and it's a sweet bike but $8k for a low-mid tier spec that will get absolutely wrecked by depreciation is not very appealing. So you saved quite a bit of coin considering yours is a relatively high end build.

 

[handlworks]

Haven't read this forum in a minute but this is one of the best (i.e. most discreet) FS conversions I've seen. Appreciate the price breakdown as well.

I guess these weren't available when you started this build, but there are some pretty compelling "light" factory FS e-bikes out now, like the Trek Fuel EXE and Transition Relay. I test rode an EXE and it's a sweet bike but $8k for a low-mid tier spec that will get absolutely wrecked by depreciation is not very appealing. So you saved quite a bit of coin considering yours is a relatively high end build.

Thanks for the kind words!

Totally agree that consumer eMTBs are pretty astronomical in price for the latest and greatest tech (although right now, depreciation is hardly a thing for eMTBs!). EX-E and Relay are both amazing contenders, and ride great. I do get much more power from my build, but those consumer bikes have a better-tuned pedal response smoothness. I think that's the only tradeoff - otherwise, this build really does everything I need it to do! (And breaks less often than my buddy's EX-E )