okay, thanks for the info. I mentioned these electric kits to my young brother out of university and he would like to add a ~350 - 500watt wheel motor kit on his bike, along with an A123 pack, for about 15-20 mile range unassisted at maybe 40km/h?

It needs to be a rear hub motor, and have 8 speed cassette with disc brake mounting. I would like for it to be a 36V unit, as that would allow me to run a nice 12S A123 pack.

I have looked around for kits, some are what I'm looking for, but are front only hubs, then some are rear, but no disc brake....etc. Just trying to find the right one!

He will spend $400 for a kit NOT including batteries.

I agree they are seriously beautiful bikes. Really, they would pay for themselves in a matter of a year you drive to work everyday.

I was suspecting they were using the Crystalyte motor, I wonder what they did to it without changing in any significant way. Even the best hub motors are not built anywhere near the quality/performance that we R/Cers enjoy.


Metallover, I have looked at many kits, I keep going back to the Ampedbikes kit for $350, gives you 23mph, maybe 25 with a little extra influence (voltage:smile:), but the one thing I am wondering is if they can take a 8 speed freewheel?

I am also eyeing up the Nine Continent kits, as I can buy these within Canada.

Also, if anyone has any experience with the A123 cells from the Chinese suppliers, let me know how they are, performance, used?, capacity, number of dead cells when purchased, etc.

http://cgi.ebay.ca/20x-A123-3-3V-230...item19bbd8d6c6

Found an article on A123's next gen cell, a 20Ah prismatic. They also said some 4, 6, and 8Ah cells are due to be produced as well? That would be nice for us RCers. It says cost will be drasticall reduced, power density has doubled :intello: and energy density has gone up as well, 50%, on par or higher than LiPo apparently. The 26650 is 100Wh/kg, so 150Wh/kg vs. 140 Wh/kg for Lipo?


The prismatic cell features an increased energy density through new anode and cell designs. New materials provide increased cycle life and energy density. On the cathode side, A123Systems has scaled up its efforts to reduce costs through improved and more efficient processes, and continues to expand cathode development to improve both capacity and energy.

At the cell level, the energy density (Wh/kg) of the new 20Ah cell is 50% greater than that of the old 26650 cylindrical cell (from 2007), while the module level energy density increased by 30%.

Looks cool, I'd really like to see some new A123s come out.


Nice ebikes guys. Question tho, is there any other ways other than the twist-grip unit to interface w/ a esc using PWM?

Basically I'm starting another project, but its going to be a ride-on power wheels for my son. They just use relays to control on/off power supply from the motor to cheap johnson electric motors. I can use a number of old brushed controllers just fine (even inexpensive BL controllers) but I'm trying to figure out a way to interface the foot pedal to the esc using PWM.

http://ampedbikes.com/kits.html

Excellent deal. Great service. Highly recommended.

I'm (afaik) running the same motor and my controller is limited to 20a, altough I am running much more voltage.

I'd rather buy from a Canadian supplier, and there are a couple that I know of in Vancouver so I may as well keep it close. I am pretty sure on this Nine Continental kit w/cycle analyst, $450 CAD. Seems pretty solid of a kit to me. Plus 48 A123 cells (Tech Ex eBay supplier) for $290 shipped for ~340Wh for up to ~20 miles range at 40km/h?

http://www.ebikes.ca/store/photos/NC26R_Fast.jpg

$750 for total system cost, plus a little custom work I might do to make a nice sealed aluminum battery box.

Do the calcs I made look right to you?

Little off topic but...

KTM

Ya, I saw an article on that KTM just last night, looks pretty decent I guess. It's not really clear on how much HP it has, is it 6000W, or what?

Motor effective horsepower 7.4 (10) / 6000 kW (hp) / Umin-1
Motor peak performance 22 (30) / 6000 kW (hp) / Umin-1

I think the second line 6000W is a typo, it must be either 22 or 30hp? That would be quite a bit of power for a small bike like that. I think they could have made a bigger battery pack on it as though, 2.5kwh in an offroad bike seems skimpy. Overall a decent bike I guess, maybe 30 mins of offroading is what you could expect?

You might find this interesting. Built by recumpence, also the maker of this.

A Bugatti has a power/weight ratio of 4.2lbs/hp.

This e-bike has 14 Horsepower and it weighs >50lbs. It has close to 3lbs/horsepower. That is only beaten by the fastest superbikes and indy cars.

http://endless-sphere.com/forums/vie...hp?f=28&t=9534

http://endless-sphere.com/forums/dow...e.php?id=21336

Video
http://www.youtube.com/watch?v=DtcTY...layer_embedded
[youtube]DtcTYmI5tfA[/youtube]

That is what I'm talking about! 14hp is what I want in my ebike (not this one I will build for my brother), but in mountain bike form. So what motors are being used? Brushed?

Actually, to be fair this thing has a power to weight of more like 16lb/HP if you actually have someone riding it!

Hey, that gives me an idea, R/C controlled ebike! :mdr:

He's using two Astro 3210 brushless motors Astro makes them for ebikes by request. He's using CC HV110 controllers and lipos too. Check out the second page of the thread for pics. The first 4-5 pages are worth a glance.

That's cool. How much are the Astro motors? What controller would he have used? .......NVM, I searched and found it: $400 not bad!

http://cgi.ebay.com/A123-cell-2300ma...item2a066e4733

I am wondering if these are a good buy? They are obviously genuine A123's, and they are a decent(ish) $8/cell, which I wouldn't mind paying the extra bit if I know what I am getting. I keep thinking $400 is alot for a battery for it, but then I remember that if you would buy a purpose built ebike battery, you are looking to pay $500-$600 for the same range, and then the cells they are no match for an A123 based pack... very inexpensive in the long run.

At least 2000 cycles @100% DOD x 20 miles range = 40,000miles/65,000km Then even after this point, the pack would most likely still be around 80% capacity, still perfectly usable IMO. $400/40,000miles = 1 cent per mile of battery cost over the life time.

Metallover, could you tell me what your ebike consumes in Wh/mile? What speed, and whether you pedal or not?

Here is all of the data you would ever want to know about my bike
http://spreadsheets0.google.com/ccc?...A26RsYfg&hl=en

I get about 40wh/mi when I don't pedal much and drive like I stole it. I have gotten under 25wh/mi before, with lots of pedaling, and if I can get this controller modded I will lower the amp limit from 20a to 10a which should get me 25.5wh.mi without pedaling.:mdr: I'll also be able to remove the amp limit for twice the power.:intello:

Here's some AWESOME e-bike prediction software. It's worth the trouble of downloading it.
http://www.endless-sphere.com/forums...119810#p119810

Currently the bike can do 35mph pretty regularly. I've gotten to 38mph on a long flat and 39.5mph down a hill. This is with the 20a limit; raising the limit won't help my top speed tho.. With a 10a limit it will decrease my top speed to around 25mph.

On long rides I pedal as much as I can. I can get 15mi not pedaling and going full out all the time, so when I stay in town I usually don't pedal.

To me they look like the 3220 motor?

http://www.astroflight.com/images/3220_1.jpg

Could be either motor really? Looks like they have good idle current too, good for an ebike for sure... now if someone could throw that in a hub with a planetary gear drive, you are flyin!

Metallover, okay thanks for the info, but how fast are you cruising at when you get 40Wh/mile? :wink: This is for my brother, who says he doesn't need to go that fast, 40km/h (25mph) is fast enough, which I think is the top speed of the Nine Continents kit at ~36V, no?

I asked Cell_man at Endless-Sphere about the 15Ah cells, so a 12s pack should be 550Wh and at ~16Wh/mile that I am seeing kit suppliers say a bike will do at 35-40km/h, should be a good 30+ miles range. The large pismatic A123's are a good price of $2.5/Ah, or $38/15Ah cell,

Have you ever tested at various speeds and recorded the Wh/mile, say, in 5 km increments?

Hi guys,The chain drive is a better idea,especially on an mtb with suspension.You need the weight suspended.If its hub mounted it makes it hard to do much,the wheels drop as soon as you get any air under them,making the bike handle awfully.

Wheelies rock with a rear hub?

When I get 40wh/mi I am usually crusing at... 30-35mph. :smile:

My general guideline is that if you keep the average non-geared hubmotor e-bike to 25mph you should get around 25wh/mi without pedaling.

I don't know how fast it would go at 36v.. I got around max 25mph on 44.4v lipo with a 26" rim. Pedaling would probably get you to 25mph on 36v with the 9c, but you would be looking at about 20mph w/o pedaling.

Play around with that e-bike prediction software some and you'll see some better numbers.

Okay, are you using the "fast" version or the regular version hub motor? THe fast version uses the 2806 motor instead of the 2807. But I think I would rather get the 2807 and run a higher voltage of 48V.

bumsnogger, yeah I would have to agree with you one that, if a good belt drive or something could be made I would much rather have external drive than hub driven. Suspension would feel like garbage for sure, unsprung weight is very critical in a good handling vehicle, be it car or bike.

I've got the 2807, aka 9x7, aka the slow one. Plug the fast one into the ebike prediction software and see what you get.. I think the fast motor is made more for people who want to run 36v.

Yeah, and the 2806 26" kit I think gets to 25mph on 36V? Is that right? I have having a hard time finding much info on speeds for the different kits.

I am thinking about the fast version as it would allow the bike to hit 30mph maybe on 44Volts (14s 15Ah A123 prismatic), and still have enought range to make it useful.

You're right but most who use the hub drive do it to keep the CoG down

That's true. and quietness.

When you are onroad a full suspension bike with a hubmotor is pretty dang smooth. When offroad... I guess it isn't so good. Larger tires and better suspension would help, but yesterday during my offroad adventure the vibrations from the bumps made my forearms hurt like no other. Ouch!

Here's the 2806 on 36v.

http://i345.photobucket.com/albums/p.../th_ebike1.jpg

Okay, thanks for the post, so I would guess on:

14s A123/45volts for a 45km/h or 28mph

15s A123/48volts for a 48km/h or 30mph

Pretty well 1mph/Volt for the 2806 on a 26" rim.

Here is where my pickle is, I would like to make it a 14s pack for the sake of charging, have it a split pack of 2x 7s packs on a dual pack charger, straight forward right. BUT, I would like to run 48V for the extra speed or range, but I don't like the idea of charging 3x 5s packs split charge.

Now unless someone here knows of a 15s A123 balance charger available, then sure 15s is the way, otherwise, it's 14s. I will not be using a BMS (waste of money IMO).

You could charge a123s straigh off a power supply and the pack would stay balanced. Ebikes, especially with hub motors seeing around 20a max, and a large capacity pack capable of 100s of Amps, don't even make these cells sweat. Look around on ES and see what they say about the a123 cells.

I dont balance charge my turnigy pack, although I balance them every five runs orand; they are never off by much. I charge them in a 6s 6p configuration...

The only thing you really need is a lvc. Hobbycity has a few alarms, I love the voltage and temperature monitor. Check the balance ever couple weeks with a voltmeter and balance charge if needed, but with a123s you should be ok.

Well traditionally I have never balanced charged my A123 packs (checked my A123 thread?), but those are small R/C packs, not much cost in them... this is a $550 battery (still cheap compared to lipos!), I am not sure if I want to risk it, you know?

Unless the tolerances are even better than M1's, then sure I might go for a PSU charge. I know I will at least put balance plugs on obviously just for checking cell voltages if I didn't use balance charger.

I asking cell_man what he thinks.

Cost of these 15Ah A123 prismatics:
$2.50/Ah x 15Ah
= $37/cell
= $0.77/Wh

For a 48volt pack:
16s1p pack - 720Wh - 51.2V nominal/15Ah rated
$592 + shipping

Rough calculations: @40km/h (25mph) conservative calcs, hypothetically if you drove 30 miles a day, using 100% DOD.

30 miles range (w/o pedal assist)
2000+ minimum cycle life (to 80% OC) - 100% DOD
= 60,000 miles minimum life mileage
=$0.01/mile over minimum life expectancy
=+$0.002/mile of electrical power bill @ 9 cent/KWh (the rate I pay in SK, Canada)

Pretty dang cheap transportation if you ask me. At the discharge rates you see with an ebike, these batts should last alot more than 2000 cycles if the pack is built properly.

Metallover, what are the capacities your Turnigy packs now? How old are they?

I am using six 6s 5ah packs for a total of 10ah 66.6v. My pack is 666wh and yours is 768wh.

4 of my packs are 22 cycles old and I got them in january, so 4 months now. The other two packs are a couple months older and have 5-6 more cycles on them making for around 30 cycles on them.

I figured that I need to ride about 4500 miles on my bike the pay for it's initial cost in gas.

Here's another guy's gas/money log that you might find interesting - http://spreadsheets.google.com/ccc?k...WN091VHc&hl=en

Very interesting. Your guys gas is so cheap! (relatively) We pay over $1.10/L here which is pretty much $4/US gallon... I guess this ebike will pay for itself faster here then. :neutral::smile:

Really, we pay more for everything here, gas, food, cars, everything... liquor! 24 beer is $48 here.

Yeah just checked the prices and a 24 pack of coors is $17. :na:

Cost of living is lower here, but so are the wages... South Dakota has $16.53/hr average for full time work.

#$% you!!! :whip: Although Coors = :no:


I don't know the average full time wage, but our minimum wage here is ~$9/h IIRC.

Well I did a speed test, on a flat hard packed gravel road I was able to hit 54km/h (33.5mph) on the MTB under my own stength, not bad. My brother can hit 50km/h (31mph) So when electric he definitely wants to be able to hit at least 45km/h, and with pedal assist, 50km/h I'm sure.

I think I am going to stick with a 14s pack, as that allows using a balance charger like the 720i I already have. He wants to sell me on a BMS, but I don't feel it's necessary at all. I might as well get a 8s pack for my lawn mower to save on shipping as I was going to get some of these for it sooner or later.

I can't believe how economical these cells are, they have the power, the A123 toughest we have come to expect, the cycle life, and best of all they are now energy dense as lipo. $0.75/Wh Is cheap as chips once you think how long they last.

Those cells are very good for the price. The only problem is a battery management system, but that is a problem for all larger packs.


Glad to see others getting into the "hobby". It is a lot of fun, and is quite cheap transportation.

They are GREAT cells, I can't believe I never heard of them before. Each cell is 400 g, 48Wh , that makes them 120Wh/kg, decent.

Their new 10Ah cell that will be coming out this year they say will be ~140-150Wh/kg, apparently.

I will not be running a BMS for it, it will be balance charged and it will be in a hermetically sealed battery enclosure (at least that is the plan) made fom machined black poly block, with handle formed into one end for easy carry. I am not running BMS because I really don't think it's necessary, for these reasons:

-They are A123 cells..... come on
-Will be balance charged, so you will see any cell that would be out of wack
-Discharged typically 60% DOD

The guy I am buying from says they are rated 15 year life, and 7000+ cycles @ 80% DOD. Cheapest battery over it's life compared to any other battery by far, by far.

On the topic of charging: A simple way to do it would be to use a transformer that, when rectified and filtered, has ~5v higher voltage than the max voltage of the pack you are using, set up a constant current charge circuit (pretty simple), and then use a comparator IC that shuts off the charger at 3.6v/cell. It won't have the CV charge phase, but from what people say, very little charge is done at that point anyway.

So, if you are running 14s packs, that's 50.4v. Add 5v (to account for current source dropout) for 55v. The Y23695 3 in the link above would be ideal; wire the primaries in parallel and the secondaries in parallel, use bridge rectification, around 0.5F capacitance (can use an inexpensive car audio cap). The 40v AC output would be around 56v once rectified and filtered, and would provide over 10A charge rate. Add the CC source and cutoff circuits and be done with it. Balancing, if desired, can be done using multiple balancers, just overlap a cell on each so they are in sync.

Of course, this doesn't have cell count protection, but since it will be used just for a single application, it's fine.

That sounds like a good idea actually... although half the stuff you said went over my head (source current dropout? :neutral::mdr:)

I checked out the transformer, 15lbs is quite heavy, but it's not moving anywhere, who cares I guess. IF this were to be used I might want to get the BMS then as I takes care of balancing while being charged. 10amp charge sounds really nice, as it will be charged on a 720i at about 9amps, each side, so you have to do that twice. Looking for a dual output charger that can charge 7 cell packs... why not a 710i DUO, Hyperion?


Also, for another idea for emergency charging, say you are away from your charger and don't want to use your own effort to bike back (far away), I was thinking a small charging circuit built into the battery case. I was thinking just a couple amps at the most with a built in AC socket with protective rubber plug with a PC AC cord somewhere on the bike stored away.

By CC dropout, I mean: The CC source circuit will consist of a voltage regulator configured as a CC source, and it has ~1.5v dropout, coupled with the V drop on the current programming resistor of 1.25v. The extra voltage is just a little extra to prevent the pass transistors from saturating when the cells are close to 3.6v (which would reduce the current) and to account for any deviation in supply voltage. Transistors by themselves could be used as a CC source, but their values do change with temperature and current, so a V reg is a better idea for consistent operation.

And actually, I made an error on the previous post. That 15lb transformer would actually be good for closer to 20A. So, you could either use that at 20A, or use a smaller (and lighter/cheaper) transformer for 10A. But as you said, the "base station charger" will probably stay in one place so moving it around is irrelevant. And for a small 2A on-bike charger, a similar idea could easily be made under 5lbs that will do the same thing.

Sure, you can use a Duo or whatever, but unless your charging station is located where the bike is (my R/C stuff is in my basement and my bike would be in the garage), it will be a PITA to move the charger, PS, and assorted cables around. Not to mention the charger/PS setup will be substantially more expensive.

Okay, gotcha. Are you sure it could do 20A? I see 12.5 amps on the spec sheet for the 40+40 model. EDIT: Oh, the transformer must be center tapped? That is why you would get effectively double the current, correct? I am really gonna consider this idea for charging it.. btw this is for my brother so he is gone to University in fall so he will need his own charger, but for now it's the 720i.

The battery will be easily detachable from the bike by means of rare earth magnets built into the enclosure, and on the bike.

Wait, isn't Sine = 0.7x something, so how do you get more than the average voltage when rectified and filtered? Shouldn't the voltage be pretty close to the AC voltage? Or am I missing some current formula that has to be factored in?