Commuter build

[Skippic]

Please don't laugh, but I'm considering a complete change.

2nd hand DH bike.
A small rear DD motor.
LiPo or A123. (high voltage, small capacity, mounted either in the triangle or somewhere in front)

I just figured if I where to get a bad FS bike for $150 I might as well go for an old DH for $300-$500.


Moral: if you think you want a very efficient and light bike, you don't, you want a heavy tire burning monster ^^.

 

[Pure]

I don't think anyone is going to laugh at you. Change your mind as often as it takes until you are happy with the final decision. Heck I wouldn't care if you went with a cheap Curry, as long as you are happy with it.

 

[GCinDC]

Yo skippic,

it was great having you come by my stable and chat about ebikes. i want to follow up with a summary here, so others can provide help.

you rode my bike in speed modes 1, 2 & 3 and thought mode 2 would be fine: ~ 30mph top speed, low torque.

your commute next year at home will be 6 miles, flat, bike path.

you are getting a kona stinky donor.

you would like a rear DD motor, but ideally smaller (stealth) and lighter than the 9x7 9C.

so the questions I wasn't able to answer:
- how much battery/amps do you need to go 30mph?
(check out swbluto's simulator, btw)

- is there a smaller DD (non geared [ie noisy]) hub motor that you can push ~2kw (or whatever you need for 30mph) through?

as i mentioned, you will want a new motor that easily adapts to disc brakes.

and you will really have to decide if 30mph is really your top speed. you may think it is now - as is perfectly normal :lol: - but it may change :lol: - in fact most here would bet on it :lol: but don't let me influence you. :lol: you will want to pedal. (and you should get a 7spd 11T freewheel, btw so you can go into high gear (like mine was stuck in))

now, let's find some jumps in DC... what model is your (non electric) DH bike again?

 

[Skippic]

Hey Greg,

thanks for your help. I was very surprised at the performance of your bike, especially the acceleration.

My Kona Stinky just arrived!

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At the moment I'm thinking:
Battery:
LiPo 20s2p or A123 2 x 12s2p from cell_man - I understand the A123 would have 1/2 the capacity, but it should be more or less indestructible so I would feel just as confident with it
Motor:
I wanted something like the Crystalyte 400 series, they should have 44mm disc mounts according to http://www.ebikes.ca/store/store_motors.php
But considering they are pretty old design, the HS3540 might be a wiser choice.
Should I buy the bigger, heavier and noisier one? I have no need for brisk acceleration, just a decent top speed.

The DH bike is the Sette Vexx:
http://www.pricepoint.com/detail/20243-018_SETVB9-277-Bikes--/Sette-Vexx-DH-8-Inch-Dual-Suspension-Mountain-Bike.htm

 

[ambroseliao]

That Sette Vexx is one beautiful bike. I had Emil over to the house but didn't have enough time with him to have him test ride my TF. I drooled over the Vexx the whole time and thought it a great candidate to put a motor on it.

 

[dbaker]

Custom A123 pack for the triangle?

 

[dbaker]

What bike trails are you going to ride on your commute?

 

[GCinDC]

me too! i rode it while he rode mine. doesn't respond to pedaling so much. :lol: :lol: tried as hard as i could to bunny hop it and only got an inch of air at most... :lol: P L U S H ride. and the front forks make mine look small. really wide handle bars tho! we're talking about meeting up and taking it over the 5' drop. he says it doesn't look like much.

 

[GCinDC]

What bike trails are you going to ride on your commute?

yeah, he's been thinking saddle type, like yours, so i was hoping to hook you two up. i thought he should see your faith build. he doesn't commute here, but will get a full container when it's time to return to the EU, and then his commute will be 6 mile trail... i told him about your experiences w/ agro bikers, even at 6AM, not liking being passed... lol.

 

[ambroseliao]

Emil,

That bike looks great for an ebike conversion. Where did you get it?

Ambrose

My Kona Stinky just arrived!

 

[Skippic]

Hi dbaker, GC, Ambrose,

My commute is 6miles each way flat ground, no stops, charging on both ends.

My idea was to go 30mph, but after testing GC's bike it doesn't seem that much. I probably could go up to 40mph.

As for batteries, 95% I'll use A123.

At the moment I'm looking for a small diameter rear DD with disc mount. What are my options there?

The Stinky is from eBay for $450 with shipping. It's small enough for my wife to ride it as well

 

[TonyReynolds]

Skippic,

Cherck out my build, if you haven't already:

http://www.endless-sphere.com/forums/viewtopic.php?f=3&t=30723

It's very similar to what you're proposing and was sourced from cell_man. So far I'm very pleased, with a couple small caveats.

The triangular A123 battery is performing very well. The controller cell_man included with the kit has a direct plugin for a CA, which is on teh way from cycle9.

My bike is very stealth. Most people wouldn't know it was electric unless they saw the throttle.

Gear drive motors will have a smaller diameter than DD, for a given output.

Best, Tony

 

[Skippic]

Tony,

the geared MAC at 48V was my first choice, but it's not silent. Therefore I decided to up the voltage to 72V and get a small DD, something like the Crystalyte 408.

I'm hoping someone here can help me find a small rear DD with disc mount, capable of doing about 30-40mph for 20min. I would welcome it being water and future proof.

Some of the other aspects of the bike would be:
1. easily removable battery mounted on both sides of the frame just above the fork
2. Arduino instead of the CA, for about the same price I should be able to make something much more flexible (I want to have have have the EU legal mode on it and other options to play with)

 

[TonyReynolds]

Tony, the geared MAC at 48V was my first choice, but it's not silent. Therefore I decided to up the voltage to 72V and get a small DD, something like the Crystalyte 408.

The MAC at speed makes almost no noise; I can hear it a little at startup. I realize that the DD motors are for all intents and purposes silent, and your needs may drive you that direction, but I did want to correct the point that for the MAC motor at least (not speaking of eZee, BMC 9C or others), the noise of the gearing isn't that bad.

The 250W geared motor on my wife's iZip Via Rapido makes A LOT of noise in comparison.

I went with the geared motor to get a smaller package for stealth, weight and to eliminate the cogging effect for freewheeling.

TR

 

[Skippic]

After studying more all current products and prices I'm thinking:

12 x 4s1 5000mAh 20C Lipo from hobbyking @ $23 for a total of 24s2p and $300 with shipping
http://www.hobbyking.com/hobbyking/store/__18631__Turnigy_5000mAh_4S1P_14_8v_20C_hardcase_pack_USA_Warehouse_.html

methods' "wife kit":
2810R 9C laced into 26” rim (6x10 windings)
36V – 72V 25A controller with IRFB4110’s and 100V caps - upgraded to 40A
Large screen direct plug-in CA
Split-twist throttle
$370 shipped to the lower 48
http://www.endless-sphere.com/forums/viewtopic.php?f=31&t=31146

3 x 8s New Zephyr "Lite" BMS Kits without charge controller @ $45 for $135
http://www.endless-sphere.com/forums/viewtopic.php?f=31&t=34495

And a comfortable seat for about $50.

The batteries will be plugged into each BMS 2s2p (much cheaper than 8s and they also come in a hard case).

According to various sources the 9c 2810 should give me close to 40mph at full charge 24s. I don't believe I need more than that, nor would it be safe. On the other hand the bike will have nice hill-climbing and acceleration without heating up much.

The Zephyr Lite BMS makes sure the batteries stay balanced and my capacitor charger knows when to stop.

My idea is to have an easily removable battery back, that will slide in from the front (just above the fork) and go almost to the seatpost. It will include the BMS and my portable charger. This way I can park my bike at work and go inside with just the pack. It can be charged almost anywhere and according to simulations the charging current @ 220V should be at about 3.37A average with 50Hz spikes up to 10A. In order to minimize the damage to the battery I'll probably leave 2 charging options, the already mentioned at 1/3C and a slower one at about 1/16C (I expect to use about 1/2 charge each way and will have 8h to recharge). This way the pack should be foolproof and unless the BMS fails I should know if something is wrong.

My target is to have a reliable bike, speed and price are secondary. With the 9c slow wind I should be off to a good start. If the battery pack/BMS/charger combo works well all should be good.

Total price:
$455 - Kona Stinky (eBay)
$300 - Batteries (hobbyking)
$135 - BMS (GGoodrum)
$370 - Motor + CA + Controller (methods)
$30 - Charger (me)
$40 - Doc's torque arms (Doctorbass)
$100 - materials (I'm only counting stuff I'll put on the bike)

$1430 - Total
+ materials I have bought and will never use $300 + countless hours ^^

 

[GCinDC]

According to various sources the 9c 2810 should give me close to 40mph at full charge 24s. I don't believe I need more than that, nor would it be safe. On the other hand the bike will have nice hill-climbing and acceleration without heating up much.

come by tonight and pick up mine. if you like it, you can have it for $75. note that you really should relace it, since it was the moron lace job (and consequently hard to pump up), and that it might need new connectors, and only takes a thread on disc, which you can also have if you want. you can borrow a controller to test it.

i still am confused by the choice in the motor. how far do you need to travel again? you're getting it cause you think it's the most efficient to get to 40mph? maybe, i don't know. i'd consider the mac again... above 30mph, all you hear is wind anyway... and since you'll be on a bike path, you can just not accelerate when passing others...

 

[GCinDC]

so you rode my comfort bike w/ a 9C 6x10 and then my GT hs3540, both @ 80V, identical controllers. what did you think of each?

you were pretty happy after the first, right? but you looked like this after the second!

note that the bike ate probably 3x as much current w/ the latter...

as i said, i've got some 4s packs, so we can try them at 24s if you want, later this week..

and you can use the welder whenever you want..

 

[Skippic]

Thanks a lot for everything!

I was convinced of getting the 9c 6x10, but the second ride "unconvinced" me. Well it was not just the second ride. Already on the first one the top speed was much lower than your 9c 9x7 I rode way back in summer. The HS and the 6x10 felt similar going up a steep hill, but on flat there is no comparison.

I've ordered the 24s2p Lipo and BMS kits for now. The motor question remains open. If possible I'll epoxy the torque arms and we can continue making tests on my bike. I'm especially interested in getting the rear disc brake working (unlike your bikes).

As for tires, Maxxis Hookworm 2.5?

and you can use the welder whenever you want..

Be careful what you say or I'll end up living in your garage! I'm always thinking of how to do things because I don't have a welder.

One last thing, your comfort bike feels dangerous, the GT much better, but there is no way I would think of jumping with it

 

[Skippic]

At last I'm making some progress, I ordered 12 4s Lipo packs.

Glued Doc's torque arms:

Soldered 1/3 of my BMS:

It took me about 6hours to solder it because I made a mistake and soldered a different value resistor array.

I'm having some doubts about the wheel alignment:

If the wheel is centered exactly where the motor is, it will be offset by about 1/3" or 8mm.

Another more important question is if I can move the motor towards the center. I definitely need more space for the disc brake and am willing to sacrifice speed wheels. I understand one way would be by grinding off a part of the fat portion of the axle opposite the brake and stacking washers on the other side. If anyone knows where I can find threads for modding a 9c to get more space for the brake, please let me know.

And the last part, battery pack:

The idea is to have a battery pack with BMS and charger always connected together. It must be easily removable and once in place it shouldn't move.

Here is how I imagine it:

The BMS will be on each side between the batteries. The empty central part is meant to accommodate the charger. Everything will be covered by black bag fabric.

The controller will fit in the triangle, just below the battery.

 

[GCinDC]

all while sick w/ cold? nice.

your charger freaks me out. how many amps will it push? cause your lipos are rated for 2c charge, right?

also, i'm not sure you need angle supports for each layer of batts. lipos are happy to get stacked together, at least in 2-3 levels... what will you be making that frame with?

ps. i hope you didn't glue my axle on on there...

 

[Skippic]

all while sick w/ cold? nice.

I couldn't do anything else so I had the whole weekend to play around.

your charger freaks me out. how many amps will it push? cause your lipos are rated for 2c charge, right?

The charger should be OK, I'll begin a new thread on it a post the link. But it should have like 3.4A on average with spikes possibly up to 8A @ 50Hz. The battery has max charge rate at 5C x 10Ah. So even 8A will only be 0.8C or 16% of the maximum allowed. What I'm afraid of is the pulsating which might damage the battery. Say it deforms slightly when receiving a high charge and goes back to normal when it's not charging. With normal charging that would be one deformation cycle. With this one it's about 540,000 cycles for a full charge. So the question is if there is any deformation or not.

also, i'm not sure you need angle supports for each layer of batts. lipos are happy to get stacked together, at least in 2-3 levels... what will you be making that frame with?

I agree with the angle supports. Probably too many. Those are 1/2" aluminum angles and only 1/16" thick. The initial idea was to use less, but bigger size. What do you mean by frame?

i hope you didn't glue my axle on on there...

Yes I did! I didn't realize the pressure pushed out a lot of epoxy. Luckily I was checking if I positioned it right and had a chance to clean it before it hardened. Otherwise there would have been no way of taking it off without destroying the axle.

Questions:
Any threads on modding the 9c to accommodate a bigger disc caliper? - I really like the Hayes I got with the bike.

Have you got some 1/16" aluminum sheet? I need a letter size sheet to fill out the frame triangle below the battery.

 

[GCinDC]

yeah, i really think you need a proper lipo charger, even a cheapie for small packs, even if you bulk charge 90% of the time. someone else please tell him...

otherwise, i have to recommend you get lifepo4... no disrespect... :lol:

i've got rolls of 16" flashing, brown on one side, white(?) on the other, if you're interested, otherwise most hardware stores have some sheet.

dbaker's got a brake for folding it properly, tho i haven't heard from him in ages and it's making me nervous.

feel like replacing the halls on that 9x7? PIA wiring job, and not that you'll need the upgraded phase wires pulling 20A...

 

[Skippic]

Charger thread:
http://endless-sphere.com/forums/viewtopic.php?f=14&t=31384&p=522736#p522736
(cheap and ugly) - I don't really care that much about the price, but I want it to be automatic and able to withstand everyday transport with the pack, hence no cooling fans.

feel like replacing the halls on that 9x7? PIA wiring job, and not that you'll need the upgraded phase wires pulling 20A...

You think that 9x7 is ever gonna work again? Maybe sensorless? Do any halls work? If you tell me which halls and suggest adequate wires I can do it.

 

[GCinDC]

You think that 9x7 is ever gonna work again?

thing was barely used. looks great compared to my other cooked ones. i have spare halls somewhere. not sure i'd trust any there. had too much trouble diagnosing it. getting them thru the axle is sure the be the messy part.

 

[Skippic]

Have you ever tried a sensorless controller? I'm always thinking about it... I don't care about standing start. Although I read they have problems at high speeds too.