Dear Bonny, Yulla, 蘇元瑜 ...
Thank Bonny's effort to carry the parts and get us all together on phone.
Wendy's idea is great to take photos and records for our bike gen.
Instead of using email to keep our record, do you think we should startup a virtual space like a blog or a simple website so that we can add and share our information, BOM, photos etc. about this project of building a Bike Gen easily and systemically.
I started to use Dropbox but I do not know whether there is other simple way like Google Doc to keep and share information and ideas for a project like this.
If possible, I wish Wendy can help to re-organize or re-edit our emails as a start.
I would send some hand drawings of simple wooden structure for Yulla reference soonest.
Please kindly comment ... thank you all.
BikeGen RPM calculation for your reference:
quoted from : http://www.kenkifer.com/bikepages/touring/gears.htm
If you have a 27-inch wheel or 700 C wheel, you are in 27-inch gear. If you have a 26-inch wheel, you are in 26-inch gear, and so on. Now let's shift gears until the sprocket in front is twice the size of the one in the rear, say a 52 chainring in the front and a 26 cog in the rear. What gear is that? Well, 52/26 X 27 = 54, so if you have 27-inch wheels, you are in 54 inch gear. This gear is the equivalent of having a direct drive bike (such as the old high wheeler) with wheels 54 inches in diameter. If you then change gears in the back, so that you are on a rear cog of 13 teeth (the equation is 52/13 x 27 = 108), you now have the equivalent of wheels 108 inches in diameter.
Suppose our bike has 26-inch wheel and has 52 teeth in the front and 26 cog in the rear, that is equivalent direct wheel 52 inches (52/26x26 = 52). Suppose the wheel diameter of car alternator is 3 inches, then the ratio 52/3 =17. The average cadence of bike cyclist or RPM of pedaling is 100 to 150 , then the RPM of our car alternator is activated 17x100 = 1700 to 2550
Alternatively , with higher gear ratio of front teeth and rear cogs, our car alternator to generate high power or Ampere current with easier pedaling , if our bike should have gear ratio 22 instead of 17. On other words, our car alternator rotates 2200 RPM at cadence of average cyclist 100.
If we have 27-inch wheel bike , the gear inches is changed to 52/20 x 27 = 70 , the ratio of bike and alternator is 70/3 = 23 , the RPM of car alternator of average cyclist pedaling 100 is 2300 .. then we can expect DC current output 10A or 120Watt ( at 12Volt DC ) without much effort.
We can make a table of bike wheel inches, Gear inches, Pedaling RPM and output Current in Ampere after our BIKEGEN prototype be built... for reference.
Dear Bike Team fellows , especially YC ... Keep up your good work!
Thank you and happy weekends
Lawrence at Hong Kong
Dear YC ...
According to successful examples on Internet, the output of the alternator is determined by two factors : the RPM and the field resistance.
The field resistance effect on the output current is quite linear at high RPMs, while at RPMs below 1200 and a resistance about 10 ohms kills nearly all of the current output.
A resistance between 5-8 ohms proved to be the optimal field resistance when in average human pedaling RPM rate 100, resulting alternator RPM 1500 to 2500 depending on gear ratio 15:1 to 25:1 of bike used.
Let's find out the optimal field resistance of our BikeGen this Thursday
Thanks and best wishes
Dear all, I sketch a picture last night after we met yesterday. See attached. I think we can make a good bike generator. The picture is about the adjustable alternator base of the bike generator. It use convenient materials. Wood bars, angle steels, screws and bolts. At the rear end of the bike rack, we make a wall (in yellow) with wood bars. The alternator will be fixed on the inner island. The island can be pushed away by “pushes”. So, the belt connecting bike wheel and alternator can be easily tied and pushed to get right tension. Wings are angle steels fixed to wall to ensure islands stay on ground. Fins are angle steels that support the island consists of 2 wood bars (in blue). A “push” screw is sketched in the middle, with its head fixed and pushing island, tail stretching into a hole on wall. The bolt on the screw tail end can push the island away from the bike wheel to gain belt tension. Good things about it is that we can duplicate it with convenient materials. It is fun that I only use kid’s color pens to FINISH the design. ;-) B.R. ----------------------------- Chairman, csie@MUST Y.C. Chang
Please note when you build the BG stand the car alternator must locate properly to rotate clockwise as see from the wheel.
I will draw in detail later
Up to now, to my understanding, the Bill of Materials (BOM) is as follows:
1. Invertor 400Watt 12VDC - 110VAC (Wendy and Thomas)
2. 87" V-Belt (Wendy and Thomas)
3. 12VDC Voltage Regulator (Wendy and Thomas) may not needed as there is regulator built-in alternator
4. Bike (Grace)
5. 12Volt 90Amp Mitsubishi car Alternator (Lawrence)
Parts not ready yet :
1. Solid Wood, nails, screws ... etc. for the wooden structure to hold the bike and alternator ( Yulla please help for the details later)
2. Car Battery ( borrow from car owner for trial )
3. Multimeters ( borrow if possible)
4. toggle switch to turn on and off the "Field" of alternator to start the generator
5. Red and Green indicator to show the operation of charge and discharge of battery
6. 12V 5A DC power supply to charge battery and to test power consumption of laptops (borrow if possible, may not need if car battery is fully charged from car )
I heard from a car repairer today. Only some older Honda alternator go counter clockwise.
Now, almost all car alternators work clockwise.
When we face the alternator wheel, the wheel must rotate clockwise in order to produce electricity.
Yet, we did both ways yesterday. It seemed that the alternator needs inspection.
The job yesterday was to test the alternator. Not done yet!
The whole story need to be restated after we manage the alternator, the battery, the bike stand.
The BG stand depend heavily on the bike we choose. We will suggest how to make a good stand.
Still some work to be done…
From Lawrence 4/3/2012
Just got the parts:
LED indicators 24V
Push switch 10A 600V ...
from Lawrence 3/15/2012
We changed to use car alternator instead of DC magnet motor used in the example of pedalpowergenerator.com, so we do not need to use blocking diode anymore to prevent battery current flow into the motor when speed slow-down.
Car alternator has built-in diode bridge and regulator to convert generated alternate current into DC current so blocking diode and
Charge Power Controller 10A 12V/24V
are not needed.
Our BG is not working yet, so I just suggest parts and spec. as follows:
1. used bike 7 gears or more
2. used car alternator 12VDC
3. Lead acid 12VDC car-battery 50AHours
4. BG stand
5. v-belt 87"
6. 400watt 12VDC to 110VAC inverter
7. toggle switch 4Amp
8. Resistor 24Watt 0.5ohm
9. Indicator Red and Green 24 Volt ( charge and discharge)
10. A pair of jumpers or copper wire with red and black clips to connect the alternator and the battery 10A ( about one meter )
11. one fuse and holder 8A (protection)
12. multimeter (voltage and ampere meter)
Please check if they can prepare all parts in Nageria, especially the used car alternator and battery because they are heavy.
Thank you and best wishes
My friend just donated one car battery for us.
I'll get it this weekend. He will get it fully charged.
So, on Sunday, I'll take all the stuffs to Yulla's place.
See you on next Tuesday noon.
Thanks for the car battery donation.
We should keep the car battery always fully charged otherwise will shorten the life of battery as the density of acid will increase after discharge. It is not recommend to leave a car battery idle over 2 weeks.
If possible, lets take the battery out of the car after the construction of wooden stands.
Thank you and best regards
From: Sam Lu
場地的部分，清大還在找可用的實驗室，如果 MUST 有場地，那就再好不過。
三個學生的聯繫方式我們都有了，他們也 standby 等我們找他們，
我建議是先找出這 project leader (Lawrence?)，由這 leader 負責此事之後續進行。
project 進行過程中，只要將我們加到 cc list 即可，以免有時會狀況外 ;-)
如果都沒人願意當 project leader, 那我建議 Lawrence, Yula, 還有那三個清大學生，
先見個面交換一下意見，討論一下這 project 該如何進行。也可請其中一個學生
負責規劃該 project 之進行。 What do you guy think?
2012/2/29 Wendy Lu :
> Dear Yulla, Can you let us know if you've found a place (or classroom) for
> the bike assembly?
> Dear whomever travels to Taipei, can you please let Grace know if you can
> help bus her old bikes to Yulla's place?
> And dearest Sam, do you think if we should have those 3 students involved at
> this stage? If so, can you check with Alice if they prefer to find a place
> to work on the project at NTHU or they don't mind to come to MUST to work on
> the project.
> Thanks for the join effort to bring electricity to the needed,
From: Sam Lu
我們應該是先做出原型 (prototype) 出來 (when will it be ready to demo?)，
除了，Lawrence 之外，還有誰要參與(Yulla?) 這項計畫?
---------- Forwarded message ----------
From: Hsiao-tsui Chang
Subject: [無國界工程師] 坦尚尼亞志工團：孔明車
To: Sam Lu
Picture posted on https://picasaweb.google.com/LabdooScrapbook/BikeGeneratorEWBTWN#
我將主導發電車的整合與測試。預計下周五(3/16)下午清華同學可以來明新，如果Lawrence 3/16不方便，另一個時間是下周二(3/13)9:30am到2:30pm(我請吃便當)。當然，如果 Lawrence或是關鍵parts不能配合，我們就再延後一些。
誰能列出一個PARTS列表與availability check? (其實我連哪些是關鍵PARTS都還不熟!)
另Lawrence希望下星期可以找時間下來和大家碰個面。但因他實行ECO，一切以腳踏車代步(?是嗎)，所以希望可以安排在白天囉! 所以元瑜，可以麻煩你協調一下! 你可以直接和Lawrence，Yulla橋時間，或需要我也可以告訴我! 時間訂了告訴我一聲，我也想見見大家喔!
According to the examples found on Internet the ideas of bike gen work ... what we do not know is the power output, the efficiency, the power duration of laptops ... with the cheapest and available parts found ... we got to measure all data such as volt and amp output before installation if our workshop can setup with some tools
If all parts are available, we can start to make the wooden structure first then the prototype can be expected within a week or two with some adjustments
I am now doing bike tours in TaiTung and will go to check the car alternator Friday
Thank you and regards
From: Wendy Lu
Thank you so much Sam,
I personal believe it will be nice to have team work to build this prototype.
Sine we are just building ONE PROTOTYPE to proof the concept, and the video Lawrence showed us proved the bike idea works. The only challenges the bike team faces will be how to replace with the parts which can be find easily everywhere, especially good if the parts can be found in the third world countries, and also maximizes the output.
It will definitely help if more brains are put together to think how to best improve the design.
What do you guys think?
My only concern is the delivery schedule need to be solid...
Lawrence, if Thomas helps bring back the parts next week, and Yulla provides a space for you and NTHU students to work on the bike, can you estimate a date for the first prototype to be delivered? (I believe it will take more than one iterations to come up a efficient final design:)
A good bike generator solution will benefit not only millions of kids...
From: Thomas Li
Values and Philosophy
Terms & Conditions
Glits (under development)