Answering your cycling questions

The actual battery can be taken off and on the bike at leisure.

Unfortunately the regulator - which wires into the dynamo is where the problem will lie. The wires are merged with the dynamo light wires and attached to two little plugs, which attach to the dynamo. You could almost certainly source the plugs very cheaply and this would give you the result you want. However you would then lose the ability to have both the dynamo light and the battery merged and attached at the same time - you would need to switch between the two.

If the manufacturers sold the regulator separately for around a tenner then that would solve the problem. Maybe they are reading this?

I have set up between two bikes. I got 2 short lengths of ordinary lighting cord and cable tied to each bike with spade fittings on each end so that I can move my dynamo hub wheel between bikes as well.

Yes, this should be possible, you'd have to call our special orders team to ask about whether we can order the extra wiring for you, their number is 0870 164 4036.

Everything is supplied.

It took me five minutes and that's only because I am over cautious.

If you look at your dynamo you will see a little plug where the wires go in for the light.

You simply unplug this, merge the light/battery wires and plug it back in.

connected this to a shimano dynamo hub and it was pretty straight forward. similar difficulty to fitting a bicycle computer. A bit fiddly and you might need wire strippers if you want the cables to be just the right length and avoid any slack. Also some additional cable ties are handy to keep the wires all nice and tidy.

Yes, I use the device with my iphone 4 with no problems. Note that you have to use the small adapter provided (labeled 'ipod')

Yes, it can be fitted to a Brompton with a SON hub - I have done so without any additional wiring or tools - just a few cable ties. System is working well. The only minor niggle is that the system can't be disconnected as you are advised to keep it charging all the time, presumably to stop too much power going to the regulator unit without any output. I am considering putting in a small inline switch to one of the wires feeding the regulator so that I can switch the feed off. The connections to the SON are in the form of bare (stripped) areas towards (but strangely not going all the way to) the end of the wires - these can be held in place simply by trapping them with the existing spade connectors feeding the lighting system.
Removing the battery / charger unit is easy, but removing the regulator is not due to both the connections to the spade connectors and zip ties holding the unit in place on the fork. I see this as a design flaw - I would prefer both units to be combined into a single unit that could be quickly removed.

I don't know the technical ins and outs of this, but I think you might be pushing it to charge anything more than a mobile phone.

Yes