Kerry at light makes/assembles a solution for this. The trick is to use a cache battery that allows itself to be used at the same time as its being charged.
http://www.klite.com.au/#!love-your-pet/c17i2
This is exactly what I would like. But at the mo, using the sparkfun / adafruit lipo charger, it will only charge the battery at 500mA, if I'm going fast enough to generate 500mA! For a light driven from a single Li-in, I'd want to run the led at at least 1A. So eventually, I'd run out. I can use this for bike packing, as I cant see me riding for all that long at night, so the battery could charge the next day. But for 24hr racing, I'd want a fool proof system where the battery wouldn't run out. Do you think I'm asking for the moon on a stick? I cant understand why it hasn't been home built before.
Edocaster, Thanks for that link, very interesting. Particularly the protection circuits. I haven't yet settled on a 5V reg but I'll have a look at their spec sheets and choose the best one. Inside the 'red box' is just off the shelf components, from adafruit and sparkfun. They work in the 500mA to 1A region, which I think is fine as you aren't going to get any more out of the dyno.
So far..
Protection is sorted with an AC zener with a suitable voltage to protect the regulator. The vener is coupled to a thermoswitch with opens the circuit when it warms up, protecting it further.
Then to the 5v switching regulator.
Then to this
https://learn.adafruit.com/adafruit-powerboost-500-plus-charger/overview . That will provide power to my gps and cache battery. Charge at 500mA, can discharge at 2.4A MAX I think.
Cache battery can charge any USB device once stopped too. (via the powerboost)
All that can be turn off, so the dynamo powers the light.
My main problem area is still the standlight. I'm notdead set on using Martin's circuit 12, I just want one what will work well off road AND have a standlight.
Those coin caps look good, nice and small. Which circuits did you use Edocaster? The one at post 70 or post 89? I'd prefer the one with the caps TBH. I understand that the higher resistance will limit the charge rate. But bearing that in mind, if you have a stop start section where you are relying on the stand light, it could potentially run out. And charging will be at the expense of lumens once you get going again.
I'm still reading through the big thread you linked to on CPF.
Thanks again for your help guys