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Messages - fixitsan

Pages: [1]
1
Home Brew / Re: New build underway
« on: November 09, 2012, 01:58:13 AM »
Needs must, as they say

They're light and cope with at least a 1C discharge.

Been too busy with work to move things forward but hope to get into it soon

2
Home Brew / Re: New build underway
« on: October 12, 2012, 10:42:26 PM »
Well, my gearbox arrived this week
http://www.ebay.co.uk/itm/221128973244?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2648

Inside it is in excellent condition. It looks like it's 5 speed.
I'll probably rig it down to be two speed, or maybe three if it needs it.

Not sure how I'll actuate it, I'm hoping to make an automatic mechanism, but I can go with a foot pedal if i have to. It has a ratchet and pawl indexing system, the ratchet is on the lever arm but no pawl, the pawl must be on the missing lever.


3
General Discussion / Re: Newbie help!
« on: October 07, 2012, 02:58:32 PM »
A lot will come down to cost, and how lucky/patient you are in finding good deals.

I would take a look here http://www.evalbum.com/ , click on the search tab and go to 'motorcycles'. Then just look at what everyone else is achieving and what you can realistically expect.

Lets say the bike uses 120Wh/mile at 60mph. The classic Austin Mini car uses 10HP/7.5kW at 60mph, figure on a bike using less than that. How much less is down to aerodynamics and rolling resistance. Say you achieve 6kW power requirement. (I suspect that is too high a figure, but lets see, for example, how you might approach specifying your components)

You need to break down that 6kW into battery power.

Because P=IV (Watts = Amps x Volts), lets say you have a 60V pack, then Amps = 6000/60 = 100A

This means you need a battery pack capable of delivering a sustained 100 Amps. for good acceleration, you can expect 350Amps, or more.

So start looking for batteries which will support a 100Amp discharge rate, and allow short duration pulses of 350 or more Amps.

So what about the motor ? Typically, on a single speed bike, gearing is set to about 5:1 via the sprocket ratios.

To get 60mph from a tyre on an 18" wheel with 5:1 gearing, expect a motor rpm in the area of 4000rpm.

So you need to be looking at a motor which can give you 6kW (maybe less) at 4000rpm.

there are some other things to be considered too. Because P=IV, you can see that for any value of P(in watts) that as V increases, I decreases, in other words more Volts, fewer Amps.
This is important when it comes to wiring. Higher voltage wiring doesn't need to carry quite so much current, so the wiring doesn't need to be as heavy gauge at high voltages as it does for low voltages.

Using 60V/300Amp as the example, while your cables ought to be able to withstand 300Amps for at least short bursts, if yiou rearrange the battery to deliver 120V then the cable only needs to be good for 150Amps  (assuming the current will be limited by the controller or some other device - fuse)

Another important aspect to consider is the power losses in the cables due to cable resistance. Every cable has a resitance, and the power lost in any cable is proportional to the resistance times the current squared, Ploss = R x I^2. Easy to see from this that keeping the current down and voltage up high that yoiur connectino and cabling losses can be reduced significantly (never eliminated completely though)

4
Home Brew / New build underway
« on: October 06, 2012, 06:47:28 PM »

Bike1 by fixitsan2, on Flickr


bike2 by fixitsan2, on Flickr



This bike was bought for £65. It's a 1990 FZ600 Genesis. It was located on the Isle of Skye and because it was sold as 'buyer collect' it attracted very few ebay bids. It had an engine, carbs and exhaust header, which I got £120 for when I sold them on  :) After paying for the fuel to collect it I still had money left over.




motor by fixitsan2, on Flickr
The motor is from a piece of industrial equipment, or a golfcart. The motor plate has been all but removed but from what info I have found on it, it is probably 36V-48V


fueltank by fixitsan2, on Flickr
The tank is in good condition and might become a housing for the electronics.


Allbats by fixitsan2, on Flickr
Boxes of batteries


Each box above contains one of these.

archoscharger by fixitsan2, on Flickr
They are designed to be travel batteries to power an ARCHOS media player, rated at 10Ah


fz600 049 by fixitsan2, on Flickr
Inside, all the components just slot together, allowing for easy modification


dismantled by fixitsan2, on Flickr


2cells check by fixitsan2, on Flickr
I am thinking of fitting two cells into one alluminium case, the case offers lots of protection and still provides an airgap around each cell.



2batsinstalled by fixitsan2, on Flickr


I have over 150 of the batteries. 3.7V 10Ah = 37Wh each, a total of about 5.5kWh

I tested a few stacks of 4x2500mAh (how the packs are made up) at 1C discharge and they warm up to about 25 degrees celsius. At 2C discharge they warm to over 35 degrees celsius, so I'm going to stick at or below 1C.
I'm thinking of making a low capacity buddy pack of high discharge rate lead acid or NiMH, or even LiFePo.

The only controller I have goes up to 36V at 400A.

I have a homebrewed design for a battery monitor (works at cell level), using microcontrollers and an lcd display which I also hope to install

I also have a gearbox on it's way from a vintage Villiers motorcycle, but won't have any idea what it's like until it arrives. It has axially aligned input and output sprockets which is going to allow me to offset the motor position, because at the moment when the motor output sprocket
aligns with the rear wheel sprocket the motor overhangs the right side of the frame by a few more inches than on the left.

a tally of the cost so far.....
The bike has more than broken even.
The full load of batteries was £250
The motor £30
The controller £40.

I also have a good selection of contactors and so on to make pack breaks, which eases charger wiring problems because each Archos pack has it's own competent charger which requires a 5V input. I have some 150Amp 5v supplies I can incorporate, but might need to add a pack break to prevent common line shorting. Each small charger board can put out upto 1.4A so a charge time of 7 hours looks possible. I'm keen to retain each small charger board because it provides an inherent battery balancing mechanism, effectively the whole pack is top balanced every charge.


At the moment I'm only waiting for the gearbox to arrive so that I can decide if it is useful before I decide on how to link the motor with the wheel.

I would like to go the HV route, even the AC route, but I can easily modify whatever I make from what I have here so maybe in future I will go that way with it, when the right components become available at an affordable price.

Chris


5
General Discussion / Hello from a new Scottish member
« on: October 05, 2012, 01:09:56 AM »

EDIT - Bike details on this forum now
http://electricmotorcycleforum.com/boards/index.php?topic=2431.0

Hello folks,

I've been working on building an EV for a while, collecting large motors and batteries for a car project which just went nowhere due to a lack funds. I'm a biker and my old 32 year old Kawasaki KZ550Ltd (imported fom the US 20 years ago by previous owner)  was looking in a sorry state so I was thinking of making it an EV, but, it still had inherent value as a collector's bike and that was sold last week.

On my driveway, waiting for me to find the time to work on it for over a year, is a Yamaha  FZ600 (engine and carbs already removed and sold by me last year to turn a profit ( Yeah !)

Bateries, not very conventional, are li-poly cells, from a utility product. 2500mAh cells stacked 4 together in parallel to give 3.7V 10Ah packs, each with a small charger board. I've tested them to 1C discharge without a problem. I think in total I've got enough to make a 2.4kWh pack. (60V-80V probably). Hoping to charge it from 5Vdc because I've got a 150Amp 5V supply doing noting at all, but i am keeping that decision open for now, i'm flexible on that solution. I also have my own BMS (monitoring) design i draughted up a couple of years ago, and hopefully the minichargers fitted to each 4 cells will help keep the pack top-balanced

Thinking of buddying up some lead acid or NiMH cells, or supercaps in parallel to the mainpack to protect the lipoly's from harm caused by really big discharge spikes. ideally i'ld like to use lipoly's capable of 40C  discharges but, I haven't won the lottery yet !

The motor is an old series DC golfcart motor,36V,  with a suitable 200Amp controller.

I reckon I can get into the ballpark, somewhere, enough to give me my weekend runaround bike, perhaos a solar panel on the garage roof to charge it during the week to make it free to run. All being well I would probably look to going down the AC route and possibly Thundersky (or whoever they're called now) Lithium cells.

I'll get around to taking some pics and documenting as I go. Need to clean the garage up first but then I'm good to go !

Cheers
Chris

(located about 20 miles west of Edinburgh)





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