PEDAL POWER AND A GPS
I suppose this follows on from a thread in the clubroom a while back on the topic of chargeing phones, gps's etc on the bike.
In the latest CTC mag there is a bit about a guy who toured in France using a powered while he rode GPS toy. Between his dynohub and the GPS was a bit of electronics marketed by an outfit called pedalpower+. I looked up this bit of kit and it is made in Australia and retails in Europe at circa €120.
I may be missing a trick here, but all I think would be needed to achieve the same is a rectifier and a 5V regulator. Those bits plus a few connectors etc could be put together for about a fiver by anyone capable of using a soldering iron. If I was using a hub dynomo, I would be tempted to give it a try.
Reg Oakley
Seems like someone has already done what I envisaged. http://www.instructables.com/id/bicycle-dynamo-rectifier-and-regulator/#step1 .
Ray Carlson
Reg I've been looking at the same thing and followed the same route as you; the Australian gizmo, bottle dynamos, and dry batteries etc. I have also been looking at making a charger (not wanting to part with £100 plus) with bits from Maplin. As you say the bits are cheap enough but there is one thing that I'm still looking in to and that is the USB voltage. It's certainly 5v dc nominal but I think it should be 5.5v and as yet I've not found regulator that has that value.
Bottle dynamos seem to be 6v ac 3W as standard, so a rectifier is needed. Therefore by Ohms law would give a current of 500mA and in theory would charge a 1000 mAH battery in 2 hrs. However we then start hitting complications. If the regulator is set to 5v then the time taken to fully charge the battery would be infinite as eventually there is no voltage difference to create a current. So I guess that with 5.5 v the battery could be charged to near 100% in practical terms but it would still take well in excess of the 2 hrs, probably nearer 6 hrs allowing for losses.
I'm guessing at the moment, but I'm sure that a workable solution could be arrived at for less than £20. I'm going to follow this through to see where it leads.
I did also think that a few AA batteries and suitable voltage regulation would be cheaper for the one off trip a year. However because of the high internal resistance of dry cells the current would be low and the speed of charging might be too long for anything but an emergency device.
There's a lot of helpful information on YouTube etc. Anymore thoughts Reg?
Or am I talking a lot of old rubbish? :-(
Reg Oakley
No Ray you are not talking/writing rubbish. If you go onto the CTC technical forum and have a look around, there are a number of diy battery and phone chargers.
Most do seem to be built around 5v regulators. Which i believe is the USB specd voltage and should be OK for keeping a phone alive---just if continuously running a gps application.
Reg Oakley
This is a dead simple solution that uses 4 nimh cells to act as a reservoir and also stabilisation. http://www.candlepowerforums.com/vb/showthread.php?242082-Charging-portable-equipment-from-a-bicycle-hub-dynamo&s=590e4e2188e7db2b14697ed2583faf4f&p=3085764#post3085764 .
Not sure if you can overcharge a nimh if running without an external load on the circuit though.
In the latest CTC mag there is a bit about a guy who toured in France using a powered while he rode GPS toy. Between his dynohub and the GPS was a bit of electronics marketed by an outfit called pedalpower+. I looked up this bit of kit and it is made in Australia and retails in Europe at circa €120.
I may be missing a trick here, but all I think would be needed to achieve the same is a rectifier and a 5V regulator. Those bits plus a few connectors etc could be put together for about a fiver by anyone capable of using a soldering iron. If I was using a hub dynomo, I would be tempted to give it a try.
Reg Oakley
Seems like someone has already done what I envisaged. http://www.instructables.com/id/bicycle-dynamo-rectifier-and-regulator/#step1 .
Ray Carlson
Reg I've been looking at the same thing and followed the same route as you; the Australian gizmo, bottle dynamos, and dry batteries etc. I have also been looking at making a charger (not wanting to part with £100 plus) with bits from Maplin. As you say the bits are cheap enough but there is one thing that I'm still looking in to and that is the USB voltage. It's certainly 5v dc nominal but I think it should be 5.5v and as yet I've not found regulator that has that value.
Bottle dynamos seem to be 6v ac 3W as standard, so a rectifier is needed. Therefore by Ohms law would give a current of 500mA and in theory would charge a 1000 mAH battery in 2 hrs. However we then start hitting complications. If the regulator is set to 5v then the time taken to fully charge the battery would be infinite as eventually there is no voltage difference to create a current. So I guess that with 5.5 v the battery could be charged to near 100% in practical terms but it would still take well in excess of the 2 hrs, probably nearer 6 hrs allowing for losses.
I'm guessing at the moment, but I'm sure that a workable solution could be arrived at for less than £20. I'm going to follow this through to see where it leads.
I did also think that a few AA batteries and suitable voltage regulation would be cheaper for the one off trip a year. However because of the high internal resistance of dry cells the current would be low and the speed of charging might be too long for anything but an emergency device.
There's a lot of helpful information on YouTube etc. Anymore thoughts Reg?
Or am I talking a lot of old rubbish? :-(
Reg Oakley
No Ray you are not talking/writing rubbish. If you go onto the CTC technical forum and have a look around, there are a number of diy battery and phone chargers.
Most do seem to be built around 5v regulators. Which i believe is the USB specd voltage and should be OK for keeping a phone alive---just if continuously running a gps application.
Reg Oakley
This is a dead simple solution that uses 4 nimh cells to act as a reservoir and also stabilisation. http://www.candlepowerforums.com/vb/showthread.php?242082-Charging-portable-equipment-from-a-bicycle-hub-dynamo&s=590e4e2188e7db2b14697ed2583faf4f&p=3085764#post3085764 .
Not sure if you can overcharge a nimh if running without an external load on the circuit though.
