Does anybody use a dynamo to charge up a phone/gps etc?

[andrew_s]

My idea is to land at Seydisfjordur and head north....

You are aware that the only ferry route to Seydisfjordur is from northern Denmark?
Routes others have used, such as joining the boat in the Shetlands/Orkney, no longer run.

 

[simon_brooke]

You are aware that the only ferry route to Seydisfjordur is from northern Denmark?
Routes others have used, such as joining the boat in the Shetlands/Orkney, no longer run.

Yes, I know. It's a bit of a bummer, but there it is. My choices are fly to Denmark, boat to Seydisfjordur, or plane to Keflavik, internal flight to Egilstadir. I've done western Iceland (although given time I'd love to go again); I really, really want to see the east fjords, and I also want to camp north of the arctic circle.

I don't mean to put you off but just to prepare you, the climb out of Seydisfjordur is a tough one. The ascent to the top is 650m (2,132.ft) of hard climbing and the road is steep and most of it is of a gradient of 1 in 10! It was our first introduction to Iceland and it nearly put my wife off Iceland! Fortunately Iceland isn't all like that, what time of year I you hoping to go?

No worries, I have training climbs of that magnitude (although mainly tarmac - the map says that road is tarmac...). My aim on the first riding day is to get to a wild camp above Ketilstadhir, but I could just stop at Egilstadir if I'm not going well, and that would be a very short stage. I am kind of hoping to get to the arctic circle for June 21st, but appreciate that still pretty early in the season. My outbound route is all coastal and should be OK, not so certain about coming back towards Grimmstadir (but I can always abort that and go back the way I came).

Planned route here.

Apart from the climb out of Seydisfjordur I imagine I'm going to get serious grades crossing the ness north of Ketilstadhir, and I've really no idea of the profile between Thvera and Grimstadir, or on the N1 south and east from Grimstadir. I'm aiming to do about 60km a day average, when on a tour in Scotland I'd aim to average 100km/day. I'm aware that weather is likely to make some days essentially unridable, and I've deliberately not planned for two successive nights of wild camping - I will stop at hostels and campsites where I can.

 

[Rohloff_Brompton_Rider]

to do what the original op asked is really simple and relatively easy. dynamos generate ac batteries need dc. the bit you need in the middle is called a 'bridge rectifier'. these can be bought from places like rs, farnells etc etc. it comes with 4 prongs. 2 in and 2 out. the 2 ins are connected to the wires from the dynamo. the 2 outs are connected to the batteries. i had something like this set up 10 years ago and ran converted cateys with halogen bulbs in for 4 or 5 years and never had to charge the batteries. it was just plain ugly to look at. now that lights have moved on since then i haven't bothered this time round. but its a good idea to use the batteries as a stored energy source to use where you like.

 

[andrew_s]

What batteries were you using?
The bridge rectifier is simple enough, but the problem is normally not cooking the batteries. The 0.5A that a hub dynamo will charge them at is a high enough rate to cause damage by overcharging, and if you are charging by riding time it's going to be virtually impossible to keep track of how much charging is required.

 

[Rohloff_Brompton_Rider]

this is true, i didn't have one but a zenner diode could be used. it's a long time ago but i remember the batteries were nimh from rs in an ip65 enclosure (6x3inch). i cannot remember the brand of dynamo (also non bottle type) but it was fastened at the back of the seat stay between the bottom rear forks (i.e., where the mudguard fastens). it was also in constant contact with the tyre. i think it was only six volts and i was running a pack of 12v so over cooking wouldn't have been a problem. it's a while since i've done any electronics in anger but i'm sure that there are voltage/rectifiers combination's now.

 

[andrew_s]

A 12V pack from a bottom bracket or bottle dynamo is reasonable, but hub dynamos are perfectly happy giving their half an amp at 18 or 20 volts provided you are riding fast enough. Also, the sort of constant voltage charging you would get from a zener is really only suitable for lead acid batteries. Any voltage cut-off low enough to prevent damage would also be low enough that a NiMh wouldn't charge significantly.

Anyway, to revert to the original subject, Busch & Müller are about to start selling a power supply unit for dynohubs that will take care of it all for you - the

 

[simon_brooke]

Nice! But, at 139 euros, not cheap.

I've been experimenting with this. Without the 'supercharger' panel (which makes it a lot cheaper) it is adequate to keep my phone charged in reasonable daylight; with the 'supercharger' it would comfortably charge another device as well, and the 'supercharger' is perfectly happy on top of my trailer.