At Lidl, the German supermarket that trades all over the UK and Ireland, they're still selling a whitish ovoid a bit more than an inch across which is a rechargeable battery for giving mobile devices a boost. It is rated at 1Ah, 1000mAh. It is itself recharged from your computer, or any USB charger. It therefore has two USB ports, one to charge it, on for it to charge a mobile device. €6.99 here, probably a fiver in the UK.
In our dynamo drive recharger circuit this egg battery is ideal to provide a load for the regulator, and also to provide an additional layer of security for your devices in case you make an oops with pot on the main board. It is not essential to the scheme we have worked out, but, as Peter pointed out, it performs a very desirable function in the belt and braces department. That the rechargeable battery in that format is desirable in itself on a bike is an added plus.
Together with the pre-built board that I recommended above (choose one of the two I recommend to suit your existing skills and tools), that is everything you need to charge mobile devices from your hub dynamo. Not bad for a tenner, considering what BUMM charges for the E-Werk, and extra for the buffer battery too, especially considering how crudely the E-Werk and buffer battery are presented.
Andre Jute
