One has to wonder how much current the new LED lamps actually consume.
Yesterday I returned from a ride on my bike that should have consumed
at least a fifth of an 8.8Ah bottle battery, built with the famous Panasonic lipo cells. This bottle battery, supplied with some of their kits by the British supplier of Bafang/8fUN electric motor kits (
http://www.8funbike.com/store.asp/d=5/c=45 ), is known to be more commodious than its official rating, but it would be useful to know by how much. My longest ride is 22km of mixed hills, on which the battery is engaged for half the time going uphill at full throttle with me perhaps adding half the power, and the lamps are on all the time, used as daylight running lamps, and yet I've never managed to deplete this "small" battery fully.
So, on returning I left the battery mounted on the bike with the front and rear BUMM lights shining. Now, by my reckoning, by analogy with a hub dynamo driving a halogen light, and by reading the relevant German legislation which fixed the format of all bike lamps now in general use with tourers and commuters, the lamps between them consume 500mA at 6V, so 3A spot consumption or 3Ah per hour of use. Even a full 8.8Ah battery should be depleted in 3 hours by the lamps alone...
I left the bike standing at 5pm with the lights blaring out loud, and when I went to bed at 3am -- the lights were still blaring out loud, absolutely full power. At this point I abandoned the experiment as these lipo batteries need to be watched near depletion and while charging as they have a track record (in computers, not on bikes) of spontaneous combustion when under stress.
There are only three possibilities:
1. That "8.8aH" battery is monstrously underrated.
2. That "3W total" LED lamp set doesn't consume 3Ah per hour.
3. I made a wrong assumption somewhere along the line of reasoning.
I fancy #2, economical lamps. What do you think?
Andre Jute