The local Meijer's department store here has a 50% sale on Rayovac products. I bought up a Rayovac universal smart charger and 12 NiMh 2500mah AA batteries (they also have 9volt, C & D cell rechargeables at half price. I got the smart charger for $10.50 and the batteries for $9.00. I'm using the AA's in some hokeyspokes I bought for night commuting.
Seeing that the rechargeables are less than $1 a battery, I'm thinking about replacing my 12 volt, 5ah SLA (which weighs about 4 lbs) with a NiMH battery pack.
My commute runs about 1 hour, although I like the idea of a longer battery life if I should decide to go on a longer night-ride. I use a 9LED taillight which uses about 1.3 watts, a 10 watt low-beam, and a 20 watt high-beam. I do not use the high and low-beams together.
So, how would I go about building a NiMh battery pack for my 12 volt lighting system? If I could make a battery pack that would fit inside a waterbottle, yet later separate the batteries for use in my charger, that would be great (the charger can recharge 9volt, AA,AAA,C, & D cells)