mark barker
New Member
- Location
- Swindon, Wilts
Are you planning on taking a trailer to carry your stuff? If so, how about a small gel battery and inverter? You could charge the gel battery from a dynamo, and power the laptop from the inverter.
Dynamo setup – can I buy or make anything that will output 40w?
- Thread starter marada
- Start date
Page may contain affiliate links. Please see terms for details.
andrew_s
Legendary Member
- Location
- Gloucester
I doubt that the B+M S12 would be up to giving 12W. It's a sidewall dynamo, and the tyre/roller traction probably wouldn't be up to it.
Roller slip was a problem people used to have when trying to run 2x3W halogen off an S6 or a Lightspin.
Roller slip was a problem people used to have when trying to run 2x3W halogen off an S6 or a Lightspin.
Yellow7
Über Member
- Location
- Milton Keynes
I'm an electronics engineer by profession & realise the problems your facing.
The most efficient dynamo is the SON hub dynamo, although, as with most (all?), you only get 6v AC output, this can easily be rectified to give DC (mosfet rectification being more efficient as opposed to standard silicon diodes) but your voltage is still only ~ half of what you need (19v DC), so you then need a DC to DC circuit, modern switch mode chips (Agilent, Maxim [MAX1771]) are typically 90% efficient if external component selection is adhered to as per the datasheet, so you could obtain 19v at ~200mA, so would take aprox 10 hours to charge full, given time it’s a circuit I’d like for my own set-up but limited time prevents such a design be realised.
I’ve recently made an AA battery charger with a 5v USB output (for mp3 charging), there’s a bicycle projects page on my blog, www.wallisonwheels.com maybe in the future it will feature said circuit, unless someone else saves me the time, maybe contact a local technical college to see if any students may be interested as a 'course project', this would prove beneficial to both parties.
Mark.
The most efficient dynamo is the SON hub dynamo, although, as with most (all?), you only get 6v AC output, this can easily be rectified to give DC (mosfet rectification being more efficient as opposed to standard silicon diodes) but your voltage is still only ~ half of what you need (19v DC), so you then need a DC to DC circuit, modern switch mode chips (Agilent, Maxim [MAX1771]) are typically 90% efficient if external component selection is adhered to as per the datasheet, so you could obtain 19v at ~200mA, so would take aprox 10 hours to charge full, given time it’s a circuit I’d like for my own set-up but limited time prevents such a design be realised.
I’ve recently made an AA battery charger with a 5v USB output (for mp3 charging), there’s a bicycle projects page on my blog, www.wallisonwheels.com maybe in the future it will feature said circuit, unless someone else saves me the time, maybe contact a local technical college to see if any students may be interested as a 'course project', this would prove beneficial to both parties.
Mark.
Hi Mark
I have just been looking at your blog and it looks like a really interesting trip. Have you got an exact route planned out yet?
It sounds like a charger like this would come in really useful for you as well. As you are travelling in Africa, Solar power should also be quite efficient, although It would also be great to have the dynamo as you can never have too much power to charge all your gadgets. You mention maybe building something with 19v at 200mA. I wonder if it would be possible to say go for 19v at 700mA or would that be asking too much? I know the Ewerk can output 1.5A, however it is only 13v, but nevertheless 1.5A sounds like a lot?
I have just been looking at your blog and it looks like a really interesting trip. Have you got an exact route planned out yet?
It sounds like a charger like this would come in really useful for you as well. As you are travelling in Africa, Solar power should also be quite efficient, although It would also be great to have the dynamo as you can never have too much power to charge all your gadgets. You mention maybe building something with 19v at 200mA. I wonder if it would be possible to say go for 19v at 700mA or would that be asking too much? I know the Ewerk can output 1.5A, however it is only 13v, but nevertheless 1.5A sounds like a lot?
Well weight is not really an issue, my laptop only weights 1.5kg and as I am not racing the weight is insignificant. As I said before I don't really like smart phones / PDA. I think my laptop is perfect for the job with a real life 10 hour battery life and only consumes about 8.5 Watts per hour. Also I much prefer to be self sufficient for power. I think it is cheating when you are camping in remote places to then go looking for mains power!
CopperBrompton
Bicycle: a means of transport between cake-stops
- Location
- London
Phones/PDAs are pretty hopeless for blogging if you want to include photos. You need to resize photos (and maybe crop them, if you're taking them while riding as I do), and typing on a phone - even with a decent physical keyboard - can't compare with even a netbook.
I wonder how remote you are planning to be? A netbook typically gives 5-6 hours battery-life, so if you're planning to use it for say 45 mins a day, a single overnight charge would last you a week. Could you find power (a friendly householder willing to let you plut it in overnight) once a week? Might be a lot simpler and cheaper.
I wonder how remote you are planning to be? A netbook typically gives 5-6 hours battery-life, so if you're planning to use it for say 45 mins a day, a single overnight charge would last you a week. Could you find power (a friendly householder willing to let you plut it in overnight) once a week? Might be a lot simpler and cheaper.
