Luke's race bicycle of Doom 2.0

In those pictures he isn't using an esp120. He is using multiples of one power supply.

BULK CHARGING LIPO WITHOUT BMS?!?! CRAZY

Can you recommend a cheap lab supply solely for current limiting up to say 30-40A?
 
You're right--I hadn't noticed the four supplies before. (just more lab equipment to me when I first looked at the pics :))

I am not sure, but I think if he could he'd take the BMS out of the batteries in his phone, computer, etc. :p (yeah, I'm exaggerating...but I'm pretty sure he sees no need for a full BMS, rather just monitors for cell-level LVC/HVC if he's worried about the packs themselves. And I am actually in agreement with that, with manual balancing when needed, though if I were doing it I wouldn't put mine up as high in voltage as he probably does, or run them as low. For those willing to take the time to do the manual balancing, and periodic cell checks, it's worth the peace of mind of knowing you don't have electronics (bleed-balancing BMS) installed that if they fail could just drain a cell/group down to nothing, resistively. For those that need just a plug-in-wall, disconnect-and-ride solution, a BMS is probably as good an idea as any).
 
Most people running RC LiPo don't run any BMS, and quite a few bulk charge often.

My bike is sitting in the garage right now, sucking juice at 2KW without a BMS or any cell level monitoring. It can be safe if you know what you are doing, and your pack has sufficient capacity to slow things down or self-balance between parallel cell groups. The worst case is the battery bursts into flames. If the bike isn't around anything flammable, even that isn't a big deal.
 
I've never had a bike with a BMS of any type.

I've only used power supplies for charging lipo for the last couple years.

If you know what you're doing, and have well designs packs with good cells, it works out great. If you're a newb, you're gonna burn down.
 
Luke, since you are pressed for time, why not make up some bead locks like the off road guys use? Might fix it entirely!
 
hillzofvalp said:
See, I don't know if I could get away with lipo on a college campus. Currently I would be charging my bike in a brand new apartment complex on the 2nd floor... what a disaster that would be.
Click to expand...

So you better turn in your cellphone, pda, and many laptops that use Lipos such as Apple, and those dangerous Ipods and Ipads. Not safe in your building.

Use a balancing charger if you want to be extra safe. Run a few cycles on your batteries before installation to make sure you didn't get a bad one. Use fuses in appropriate places. Not a problem.

How many laptop fires have you had??

Back to the awesome race preps!
 
Yeah, the point is the difference in engineering between my laptop/cellphone battery and one that I would tamper with myself. When I punctured a little psp battery I was scared shitless. As I understand it, though, lipo will make my 29er a race ready machine.
 
hillzofvalp said:
See, I don't know if I could get away with lipo on a college campus. Currently I would be charging my bike in a brand new apartment complex on the 2nd floor... what a disaster that would be.
Click to expand...

Surely college is exactly the place where things blow up in the pursuit of knowledge?
 
Theres a very large difference between a 1S1P system, such as in most phones and portable devices, and a 24S1P system. Your phone inherently monitors cell level voltages since its identical to the pack voltage. With a 24S setup, you have 24 cells that have potential to wear unevenly due to temperature effects, poor construction, charge methods, overcharge, underdisharge, etc... Monitoring the total pack voltage lets you know very little about the individual cell voltages. Should one start to get weak or go out of balance, things tend to get exponentially worse. The biggest issue is if a cell should go FAR over 4.2V or into reversal. Theres not much you can do about mechanical impact aside from protect from it. The RC pouch LiPo isn't terribly resistant against impact damage, whereas your phone/laptop/tablet is designed with such instances in mind.

I would be slightly concerned about bulk charging a 24S1P system. Having two or more cells in parallel really helps things work themselves out, but basic understanding of the chemistry is always beneficial.
 
Luke, regarding your rear tire issue...Its purly a function of el-cheapo single walled rims. The purty red single walled suck mart rims were disaters. thaey couldn't even be trued all the way.
I relaced them for bmx project & the hookworms blow off the beads Just mounting the wheel after inflation...I havn't treid them on a decent double wall rim yet. I have the same problem with 24"wheels...shit rims be-get shit performance.
See you saturday.
 
Luke my friend you are going to need bead-locks for those tires. And I would run pirelli's if I was you do the work now you have just a bit of time! 8)
 
Alan B said:
This discussion doesn't belong in Luke's race thread.
Click to expand...

+1 there's enough noob lipo propaganda all over the site without adding more
here, that said..Bulk charging and no BMS FTW...


Thud said:
Luke, regarding your rear tire issue...Its purly a function of el-cheapo single walled rims. The purty red single walled suck mart rims were disaters. thaey c
Click to expand...

Agreed, it is a true challenge to mount hookworms on the double walled rims i use, took me
15 minutes a broken tire lever plus 3 more levers to get the f*ckers on, i dread getting
a puncture, reminds me need to pick up some sliiime...

KiM
 
I will be searching for a good quality double wall rim tomorrow then. Thanks for the tips guys.


On the bright side, i went from 24t motor sprocket to 19t, and the motor runs a good deal cooler now. Controller runs a bit cooler as well, and the bike comes off corners with more punch.

As it sits, here is the current state of things:


Things that I'm 100% happy with:

Battery.
Frame.
Motor performance and temp (new gearing setup makes the motor run MUCH cooler)
Controller (mega PITA to setup, but feels really damn good at this point.)
Geometry.
Throttle feel and control.
Brake lever feel.


Things I'm marginally/OK with:

Brakes DID fade on me twice now in practice, pads were smoking heap the second time. I'm going to put some racing pads and high temp racing fluid in the system and see how it performs.
Front fork is more flex than I want. I'm going to see if I can run some all-thread through the fork body and put a little clamp load on it.
The rear wheel feels flexy when cornering hard.
Motor position causes foot to bump once in a while when transitioning which pedal is up weaving through corners (but it's a mild complaint).


Things I'm STRONGLY displeased with:

Tires. They slip, they are wearing out in under 10 miles of practicing, they get flats randomly from rolling part way off the bead and pinching the tube. They ROLL CLEAR OFF the bead in hard corners and you crash... NOT COOL.

Rear wheel feels very noticeably flexy, and it's single wall, which may be a big part of the tire falling off the bead issue. I'm going to try to get a new double-wall strong 24" downhill bike rim and re-lace that hub into it tomorrow, and see if the tires stay on the bead that way.




Overall, it feels like a machine that will hold it's own against the 200cc 4-stroke bikes with million gear transmissions that I'm going up against. I think it's going to be a hell of a good race, and I'm damn excited!
 
Before you lace it up, put the tire on there and see how hard it is to put on. If it's too easy, it'll probably come off easy too. Might save you the time of relacing if it's not gonna change it.

Better yet, bring the tire to wherever you're gettng the rim from, and try mounting it on there first, before buying and going home with it.

If possible, mount the whole thing, inflated tube and all, then drag it hard sideways with your foot on the rim and see what happens. It's not as much sideload as you'd see in a hard turn, by far, but if it comes off with just that, you'll know it's not gonna work.
 
It's 2am on the West Coast USA, but surely you're not sleeping this close to the race? :D

Hookworms come in single-ply and dual-ply. You definitely want the dual-ply ones for extra sidewall strength. A Stealth Bomber owner from the Bronx tried the single-ply 24"s and hated them but loves the dual-plys. He's 220 lbs on a 115 lb bike. I've never tried the single-plys myself, but you're going to need all the tyre strength you can get!
 
I found my hookworms to be a long lasting commuter tire but i dont like them that much for hard cornering... a wider rim will flatten out the tire a bit more and help in this dept.. double walled rims with high side walls is absolutely the way to go ( sunrims Rhyno or BFR comes to mind, if you " have " to stick with bicycle grade stuff :eek: ) it's a total bitch to get the tire on but it WILL stay on i'm confident of it..

I would never put a tire and tube on a loose hoop, it would egg out real bad and be a royal pain to true up afterwards..
 
Ypedal said:
double walled rims with high side walls is absolutely the way to go ( sunrims Rhyno or BFR comes to mind ) it's a total bitch to get the tire on but it WILL stay on i'm confident of it.
Click to expand...
+1
Sun/Ringle "Double Track" and Sun/Intense "Mag 30" are a pain in the a$$ when it comes to changing tyres

Get some thick DH tubes too
 
Ypedal said:
double walled rims with high side walls is absolutely the way to go ( sunrims Rhyno or BFR comes to mind, if you " have " to stick with bicycle grade stuff :eek: ) it's a total bitch to get the tire on but it WILL stay on i'm confident of it.. .
Click to expand...

I use the sunrims myself themz the ones i had a bitch of time getting the HooKWoRmS on...

KiM
 
i use the sunrim rhyno lite and have had similar problems getting beads on and off. The kenda kinetic tires i had at first are all ready notoriously hard to get on, and then the rims made it nearly impossible; cool the rim, warm the tire is my advice. 6 tire wrenches this year have died to my rear rim... I also work with the walmart/canadian tire bikes, and I'm not surprised that your tires are pealing off at all to be honest; I bet once you get a better rim the problem improves. I'm thinking you're right about those tires not really being suitable though. Is the relation ship with force on the tire while cornering linear or exponential when considering speed/weight?
 
I like to lean waaaaaay over in turns, so I tried a good range of bike rims for the hookworms to minimize sidewall flex, and settled on the Alex DX-32's. The arey 38mm wide, which spreads Hookworms into a good patch and minimizes sidewall ballooning.

I used to have problems mounting hookworms until I saw the KY method. Lightly butter the inside of that last bit of bead with the slippery stuff, and tire slips right on.

-JD

RM7524.jpg


4883a042cd76fef13d01d7b10f2c5b99.jpg
 
You must log in or register to reply here.

Similar threads

M
Building my first trailer - dropouts vs through frame etc.
2
Replies
31
Views
2,289
MitchNotMitchell
M
E
    • Like
Eldridge Axial Flux Motor/Generator
Replies
19
Views
4,738
Logic11
L
S
    • Like
Ride1Up 700 Series: An upgrade journey
2 3
Replies
53
Views
6,819
slaphappygamer
S
S
    • Like
Xtracycle Edgerunner electric conversion with Grin All Axle v3 and SuperHarness
Replies
2
Views
5,297
smitty2k1
S
B
YZF 2007 Electric conversion
2
Replies
49
Views
7,078
BenBenBen
B
Back
Top