12V Output... From a Bike

[ormo]

Ok, this might sound like an odd request but hear me out.

A bit of background: You may or may not have heard of a route called 'LEJoG' - it stands for Lands End -> John o'Groats. It is a route from the bottom of the UK right up to the top (Google 'LEJoG' and the image results will show you what I mean). Me and a friend are going to tackle this route on pedal bikes to raise money for charity (most likely Children in Need).

The problem: We will be taking a SatNav device with us to show us the route (with plenty of maps for backup as well). We need a way to keep the SatNav alive during our trip. It will be charged from a mains socket at every over-night stop, but we need to keep it charged during the day. Most models only allow it to be charged from the mains or from a 12V cars cigarette lighter socket. We need a way to generate a 12V source from our bikes (possibly through some kind of dynamo). I understand completely that it would take immense amounts of pedalling at high speed to get steady 12V, so I thought about some kind of system that collects the low voltage from the dynamo over time, and then gives 12V for a little while. I'm not sure on how long the batteries in the SatNav last and how long it takes to charge them.

The project needs to be as light as possible as we will also be taking camping equipment, video recording devices, bike repair equipment, 2 weeks worth of clothes, etc.

I know how annoying it is for people to demand schematics, so I won't. I'm just asking for a helpful prod in the right direction, maybe a few links.

BTW, PM me if you're interested in sponsoring us (we're thinking maybe £0.01-£0.05 per mile - it's about 1000 miles).

Thanks!

 

[Menticol]

Maybe your SatNav device consumes less than 12V, it I guess it takes the 12V from the car cigarette socket and lowers them to 9V or something like that (I'm just guessing, I dismantled a old GPS that did that).

First, take the Satnav appart, and look the label on the battery. Post th results here. Measuring how much volts and amps does it consume would be great too, you need a multimeter to do that.

(Or check the specs on the manual, if provided)

 

[Mikebits]

How about getting a portable sat nav like this one?
GPS Units

I have an earlier version, the Explorist and I love it. Just takes a couple AA batteries.

 

[kchriste]

I'm not sure on how long the batteries in the SatNav last and how long it takes to charge them.

This is the first thing you need to find out. It may last long enough that you have nothing to worry about. Personally, I would just bring extra batteries with me rather than put up with the extra drag that a generator would cause.

 

[ormo]

Personally, I would just bring extra batteries with me

This would be my first choice to, but many units have an internal battery

How about getting a portable sat nav like this one

I'm having a look, but we're relatively limited in choice because we're looking for companies to pledge us the use of the equipment for the time we cycle

 

[Mikebits]

I'm having a look, but we're relatively limited in choice because we're looking for companies to pledge us the use of the equipment for the time we cycle

This is possible if... There will be news coverage, or internet coverage, or media of some sort. Consider, what would be in it for the supplier of the device? How could you entice them to endorse you? Perhaps a promise to wear their logo on a jersey or something. There are ways. Be creative, afterall it is for a good cause

 

[Mikebits]

One more thing you might do. Send letters to your local Rag (Newspapers) explaining your cause. News people like human interest stories. Also in the letter explain your possible need for certain endorsements.

Doing this would also bring media attention which might also entice endorsers

 

[sundgist]

How about a small solar panel mounted to the bike or top of your rucksack. The sort that maplins sells for charging mobile phones.