# Newb Bicycle Question



## MinasIthil (May 31, 2014)

I'm a newbie here, so nice to meet you all. 
I love bicycles and cycling, and have been members of related forums. Most of them recommend this forum as the go to place for headlight solutions.

This is what I want to know. Dynohubs have been the number one choice for the majority of the professional cyclists that I have talked to. With today's technology, super-capacitors can continue to power your headlamps even when you are not pedaling.
My questions are these:
1. Are there any super-capacitors that can power a 1,000 lumens light for 5 minutes without pedaling?
2. Would it be significantly safer if I add voltage regulators, or is it basically unnecessary?


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## Edocaster (Jun 6, 2014)

Well, I don't know about dynohubs being recommended by 'professional' cyclists - most sports cyclists don't use them! But if you mean by experienced non-sports riders, yep, there are many fans. I'm not an expert, but from what I know:

1) You can power a light by supercapacitor for 5 minutes, but not at 1000 lumens (not unless you had a pretty enormous supercapacitor). A 1.5F 5.5V coin-type supercap could probably do 15 lumens for five minutes, with the right circuit. That's enough to be seen by at night.

2) DIY headlights tend to rely on the LEDs themselves to take all the available current from the dynamo (typically about 500mA), and the voltage won't rise above whatever the LEDs need. For a commercial product though, I'd imagine that overvoltage protection would be fitted as standard, to deal with situations such as a break in the circuit.


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