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Ok, this is what i am doing,
i am making my own 12v lighting system to go on my bike (the human powered one) cause its dark in the morning when i go.
I want to use a 12V 20W 51 mm Halogen dichromic globe.
You can power these with an SLA battery but these are big and bulky.
So what i was thinking is using AA Ni-MH batteries. 2800 mAh.
So here is the question how many of these batteries would i need to get about 90 min run time?
Thanks
Paul
Theoretically you should get about 1.6hours if the batteries are full (10 batteries in series to produce 12v)
20 watts = 1.666666666 amps therefore 2.8 amp hours should give you about the above.
You would do better to double up with two banks of 10 series parallelled and give you a better run time but could be a bit of a sod come charging time.
At current prices that would be about $100 worth of batteries.
Would a little gel cell be a better option strapped on a carrier rack or under the saddle somewhere.
Paul,
Don't reinvent the wheel, go to The Fat Hippy's Website for a complete rundown on making bike lights as you describe.
He's got the coolest, cheapest light design, using a chrome towball cover as a case all held together with stainless hose clamps, and a bit of a discussion on batteries too!
I've seen a few using burgler alarm batteries, strapped to the seat post like this: http://www.users.on.net/~fathers/alternative.htm. Have a poke around anyway!
Cheers,
P
:D
Thanks
Yes i have seen the fat hippy lights and was working on that design, just thought i could do an upgrade on the batteries. I found 16 AA Ni-MH batteries on ebay for $45 delivered.
Paul
We used to have dynamo's rubbing on the tyre
Throwing out a blazing 5 watts of dimness as I recall from my youth, haven't seen them in a while.Quote:
Originally Posted by ptc
I also remember my old bike, same steel as used in the Sydney Harbour Bridge, felt about the same weight too.
Mine was a Rudge.
Aaaaahhhggggg, I remember them, mine was a raleigh, and before that 'something' Miami 5 speed racer, real state of the art in the early 60's, and before that the old Sturmy Archer (3 speed) ball bearing gears (correct me on spelling if it's wrong)
Mine had the Sturmy Archer A leather sadle and sadle bag
The bike was Black.
And on the old Malvern Star, when I was about twelve, we had a hill near our place where if you pedalled at about 150rpm in top gear on the Sturmey Archer, you could blow the bulb on the headlight! :oo:Quote:
Originally Posted by ptc
P
Used to do that on hill near our place called Olivers Hill. Got booked once for doing 65 MPH instead of 35MPH going down there.Quote:
Originally Posted by bitingmidge
The magistrate gave me a warning.