I'm working on a project for my Moped. I'm looking to add an additional headlight to the bike, it will be used at a weekend house for fun.

My problem is that I'm trying to find the cheapest, yet effective way to make this work. My research so Far has led me to the following equation: For 12v systems

Headlamp Bulb rating 55W $40

Motorcycle Battery autozone 14 ah 12n14-3a battery $46

35w/12v= 2.9 amps (draw)

14AH/20hrs = .7 amps @20, 1.4amps @10, 2.8amps @5

12v Battery charger $40

So If I buy a motorcycle battery, hook it up to a car fog light that is rated 35W I can use it for about 5 hours and then recharge it overnight

and during the next day (battery will be removable). If I want to put back what I use during the night, then I reverse the math, say, I need a charger

that can deliver 1.4 amps over 10 hours charging time, and the battery must be able to accept this much.

What specs wil list this if it is a correct assumption for charging? I've also read about deepcycle batteries, sounds to me like they are used from full charge to discharge

rather than cranking. Is this a necessity or will the motorcycle battery suffice.

So I'm looking at adding a headlight for about $120. Could I make this project cheaper with some compromise, I'm thinking:

Moped headlight 25w $15

6V charger $20

But how many AH would I need in a 6v battery? is it 25w/6v= 4.1 amps draw 21ah/5= 4.2 So I need to find a 6V battery with 21ah, so for the same wattage, as the 35w fog light I'd need a 30ah 6v. I see 4.5 ah 6v's for 20 bucks, so I would need 5 6v , which then costs 100bucks, so I'm break even at 135, infact I loose 10w of lighting.

Does anyone know where to get cheap 6v batteries, they seem close to 12v prices in the bottom range, or they seem small, but I cant find the rating

I hope the post isnt too long or with too many questions all at once.

I'd like to make sure I'm thinking about this problem correctly.

thanks