stationary Bicycle Dynamo for recharging battery 3

[TheCreator]

I've got a battery Lithium-ion, 12 hours life, 68Wh.
I'm going to use a bicycle to get around, but I'll be in remote areas so need some way to recharge it.
Solar power is inconsistent.
I've decided to use the bicycle chain removed from the rear wheel and attached to a dynamo, with a little stand for keeping the bicycle stationary.

Being a novice with electronics I need some advice.
I've read that a blocking diode is required to stop the battery from powering the dynamo.
Do I need a specific type of dynamo, for my battery?
How long will it take me to recharge this battery - is this a realistic idea?

 

[MikeHalloran]

You need a speed increaser anyway, so it would make sense to leave the chain as is, and run the dynamo from a small friction wheel, maybe an inch or two in diameter, on which the bike's weight rests while it's in the stand.

You will be astonished at how fast you will get tired.



Mike Halloran
Pembroke Pines, FL, USA

 

[TheCreator]

Yes, I was considering that I might need to pedal for 8 hours in medium-high gear.
But I won't be doing cycling during the day, just some light walking.
The days I do cycle will be to get to a civilised area with power supply and then take a bus/train to my next remote location.
I'll also have two batteries, so can use one say for a day or more. Do a half charge (perhaps not ideal for the battery life), and use the second battery while recharging the other.
I could charge in evening, then finish in morning (after 4 hours sleep).
I'm quite fit so this would not be a significant challenge.

Thanks for the info.

 

[jraef]

If you are really serious about this, you can have your wheel hub replaced with a Dynamo Hub (with appropriate apologies to Frank Zappa I hope). That way you only need to carry a simple wheel stand. This company also sells a good regulated USB charger that deals better with the varying voltage input.

http://www.sinewavecycles.com/produ...ce=googlepla&gclid=CI-w_J707cECFU9k7AodSVAAAw

"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington

 

[racookpe1978]

I biked for many years as a daily commuter since we had only one car.

Just running those simple two little 10 watt light bulbs (no LED's!!!) was a real drain.

yes, you can get energy out. It will be real energy, and I hope you feel better doing it. It will be emergency short-term power if you have a power failure.

But it will not be enough for anything but emergency re-charging of very, very small appliances like a cell phone or radio.

A portable outside solar panel (to prevent theft!) (1 meter x 1 meter, or 2 ft x 4 ft at least) hooked to a simple re-charging circuit inside re-charging a deep-cycle 12 V battery will give better results over a two or three day period. Add a 12v/120 volt AC converter to recharge/use a few simple 120 v loads.

 

[TheCreator]

Thanks, but I won't be trying to recharge as I cycle around.
It will be in the evening after a days light walking.

I've found this which I believe may suit my needs:

http://pedalpowergenerator.com/products/belt-drive-bicycle-generator-systems/

 

[MikeHalloran]

You have to demount the tire to install the belt.
I wouldn't want to do _that_ every day.


Mike Halloran
Pembroke Pines, FL, USA

 

[LionelHutz]

There is an older book that details how to build exactly what you want. I believe it was called "Home Power Dynamo". I have a copy at home but won't be there until Saturday to check the title and information.

With just a quick look at the part you linked, I would say you will need to add a major amount of mass to the outer diameter of the bicycle wheel for it to be usable. You need momentum in the system to smoothly transition between pedal pumps.

 

[TheCreator]

Well you see, I won't be riding every day, I'll only ride from a town/village to a very remote location.
At remote location, I can set up my bike for recharging over 1-3 days (where I will be walking around, without the need to use the bike).

Well I did kind of want something where I could simply unhook the chain and move it over to my dynamo - quick relase wheel is easier than deflating the tire & removing the outter rubber.
So long as it works.

 

[TheCreator]

Here is some more information that I've found out.

I need it for a 68Wh battery (12 hour life), how long do you think it
would take me to charge?

This depends on how strong you are. The average person can do about 120
watts per. Hr. this is 120/12=10Ah.

If I multiply my batter 68Wh by its life 12 hours, then this
equals 800 roughly.
Average person can generate 120Wh, I can
probably go a bit higher. Do you think this is correct?

 

[LionelHutz]

The book is called "The Homebuilt Dynamo". It's quite detailed, right down to magnetizing the ceramic material. I quickly looked through it and the author added a 139lb flywheel built with lead weights to smooth out the charging. The book also claims about 100W is possible.

 

[TheCreator]

The weight of the dynamo I'm getting is 15kg.
Thanks.

 

[IRstuff]

I hope you noticed LH's reply that you could possibly get 100W, which means that it would take you a minimum of 68 hr to recharge your battery, assuming you drained into completely empty. Note, however, given the inefficiency of the charging process itself, your recharge time might be significantly more than 3 days to recharge.

But have you looked at off-the-shelf systems, like:

http://www.econvergence.net/The-Pedal-A-Watt-Bicycle-Generator-Stand-s/1820.htm

Its weight appears to be only about 2/3 that of your dynamo, and it includes an inverter and the hardware to connect to your bicycle.

TTFN
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[IRstuff]

oops, I read and calculated that wrong, 68Wh is probably about an hour or so.

Given that it's only 68Wh, it seems to me that it would be far easier to carry spare batteries. 14.8V LiPO batteries with 5 Ah capacity only weight about 0.5 kg, so given your weight allotment for the generator, you could carry 30!!! LiPO batteries.

TTFN
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