...a rare bike-related post from me, as I rarely buy anything new and stick with what I have!
I have just dug up an ancient CatEye Sunrise that was old when I bought it through the forums for 20 quid ages ago. The only image I can find of one is here: http://www.realbiker.ru/Graphics/BikeHardwear/Electric/LightOn/3.jpg
Unsurprisingly, the battery is now totally dead and even when I last used it, it didn't have much of a charge and weighed a ton. But the lamp's a good size, gives decent light, the battery pouch is decent and (at this point) is expendable, so I am thinking of using it on my commuter bike full time.
But what kind of battery can I replace it with? I am a complete battery numpty. At the moment it's fitted with a:
Sunrise Rechargeable Battery
LCR6V3.4S (6V,3.4Ah/20HR)
Constant Voltage Charge
Voltage Regulation
cycle use: 7.3~7.5V
standby use: 6.8~6.9V
initial current
less than 1.36 amperes
Would this do it: http://www.batterydoctor.net.au/p/73686/panasonic-6v-34ahlc-r063r4pu.html Is there anything lighter than lead?
Right now I have a 30 min commute and only use lights one way, so if I could get away with charging only once every week (or less!) I'd be pleased. I'd also like to change the bulb from the 6W version to the 10W version (which will obviously suck up more juice). There aren't LED drop in bulbs to replace the GH24 halogens, I suppose.
Or am I just trying to polish a dog turd at this point?

