Ebike lighting and power -- a discussion

[d8veh]

I've just done some calculations on my single Cree XM-L T6. It runs for about two and a half hours on full power and the battery pack is 4 18650 cells, so I'd guess at 5aH regardless of suppliers claims. So, that makes two amps at about 8v so 16watts of LED.
http://www.ebay.co.uk/itm/250914024911? ... 1497.l2649
I'm still waiting for the 3 LEDs Cree XM-L T6 one.......
http://www.ebay.co.uk/itm/160682688338? ... 1497.l2649
but in the meantime I got this one with 3 Cree R5s. It runs off 2 18650 cells. The light it gives out has quite a wide spread and I'd say that it's comparable with a halogen spot-lamp. I haven't yet tested to see how long the batteries last, but I guess 20-30 minutes.
http://www.ebay.co.uk/itm/150642124764? ... 1497.l2649

[hillzofvalp]

I'm liking my incandescent 10W bike light very much. Especially since it was free. I'd like to get a nice LED light second hand... or maybe find a single halogen at a mechanic

[StudEbiker]

I picked up a Dura Micro AC Adapter DM5127 at the local Goodwill this week for a couple of bucks. It has a dual output of 5v and 12v. Could be useful for someone. Here they are on Ebay.

http://www.ebay.com/itm/Dura-Micro-AC-A ... 5d315afcf0

[Joseph C.]

I bought the Magic Shine 1400 lumen 'Mickey Mouse Ear' light. The handle bar mounted light switch is very handy.

I don't suppose anyone could tell me what lumens the light is really outputting? The battery is 4.4amp hours and is said to last 2 and a half hours. If I had to guess I would say about 900 lumens.

[Alan B]

Figure out the watts (volts times amps) and multiply by 90% converter efficiency and then by 70 lumens per watt. That's led lumens, about 70% will make it out the front. So volts times amps times 0.9 times 70 times 0.7 should give a good estimate.

[Joseph C.]

Figure out the watts (volts times amps) and multiply by 90% converter efficiency and then by 70 lumens per watt. That's led lumens, about 70% will make it out the front. So volts times amps times 0.9 times 70 times 0.7 should give a good estimate.

Thanks Alan. As the battery is 8.4 volt 4.4 amp hour and it has a run-time of two hours that should be a draw of 2.25 amps.

Therefore, only 833 lumens out of 1400. Not too bad.

Edit: That also means that the 1600 lumen Magicshine only outputs 870 lumens - assuming the batteries sold with it are 9 amp hours and it lasts four hours on full. Hmmm...

[Alan B]

The loaded battery voltage might be a bit lower, probably 7.2-7.4V.

[Joseph C.]

The loaded battery voltage might be a bit lower, probably 7.2-7.4V.

Don't depress me.

[Alan B]

I bet they're still bright!

I have an SST-90 LED here, unmounted. 4 volts at NINE amps. A 36 watt LED. This one is a couple years old, I'm sure there are bigger ones now. Even this one is pretty hard to keep cool. 2500 LED lumens. Need a temperature sensor on it, only run full brightness when moving fast. Or fan cool it. Or make your handlebar of aluminum and use it for a heatsink.