dynamo but with rechargeable lights strategy?

[robotfury]

So I can just about afford a PD8x, Plug III, and Cinq5 power pack buffer battery but not a light, such as the Revo or kLite bikepacker pro.  So I would be using the dynamo to charge/support my GPS and charge rechargeable lights such as a Nietrider Lumina 750 or LM Urban 800.

Just wondering if anyone uses this method? I was told that charging the lights from a dynamo takes a while and that I will never get the charge to full on the 750 or 800 if I run them until they are empty and then try to recharge from the dynamo.

Can I recharge these lights from a dynamo? Do I need a cache batter to do that?

[bmike-vt]

What do plan to do with the cache battery? For 1/2 the cost of the plug you could get a Sinewave. Or you could ditch the plug and get a light and charging solution in one with the Luxos U.