I'm sure this question has been asked over and over again. But, my case is a bit special.

For a bit of background, I currently have a fenix BT-10 for commuting. Recently there has been some road construction that has forced me to ride on a dirt road in the dark. I now know that the measly 350 lumens coming out of this light aren't enough.

I'm very electronically inclined. I love to build robots and other small electronics projects.

I was debating using a battery backup battery (12V, roughly 2.5x4x4inches) in a waterproof container to power my lights, using various voltage regulators to get the voltage to what's needed for various lights. Designing such a simple power distribution board would be extremely easy for me.

The advantages of using a battery with a power distribution system:

• I can use any light I'd like
• It'll work just as well when it's raining.
• Full brightness standing still.
• Don't have to worry about it messing up my tire.
• Cheap (I already have all of the parts.)
• Don't have to rethread wheel (hub dynamo)
• Can use battery to power heated gloves (if necessary.)
• Reliability. It's a battery, those usually ARE people's backups.
• Can use it to heat it's own compartment (if necessary) to deal with cold days.
• Could possibly use it to charge things (devices) (not that I'd ever do that, but it's possible.)

I'm not going to use a hub dynamo for a few reasons. Cost and complexity. This is going on an OLD bike. It's not worth it to rethread the wheel. And I don't feel like spending 2-300 bucks on a decent hub dynamo.

I did notice today that the tires I installed on the back of this bike have the ridges to work with a bottle dynamo.

Therefore, if I got a CHEAP bottle dynamo, the ones that like to blow up bulbs. I could simply regulate it and use it to charge the battery, but not to power the lights. (Sure it'd technically be doing a bit of both, depending on how I made the circuit.) It'd still have to deal with the bottle dynamo potentially ruining my expensive studded tires however.

As for weight, this battery isn't much more heavy than a normal book I'd tote back and forth from work to home, so that's not an issue.

Thoughts? I could use any normal 12V bulb/housing made for dynamos (which are generally extremely cheap!) Or I could power my 5-6V bike lights (that normally run off of 4 AAs). Voltage regulators are extremely cheap (even the high power ones.)

EDIT: I also ENJOY doing projects like this, so even if it's not perfectly practical, I may still do it.