I am currently using a dynamo powered headlight. I have a bright battery taillight separate from the dynamo. The batteries are rechargeable, but I often forget to charge them.

I want to convert by taillight into a dynamo powered one. I pretty much know what to do except for the capcitor. I found an old capacitor in my large collection of spare parts.

Please look at the picture closely


I have some questions:
1. Has anybody ever open these types of capacitors up? I'm afraid of opening mine.

2. I know that this is AC powered.
How can I quickly convert this to DC?

3. This capacitor was designed for high voltage, so it is dangerous. How would I design it to only discharge 8 volts and 3 watts to power my 20 lumen taillight for about 1-5 minutes?

Thank you very much