That's a good question! I think the answer is "A LOT longer than it'll ever have to". I believe the battery has a discharge time of something like 20 hours. I don't think it would run the headlight that long, but I'm SURE it would last a few hours anyway, and I just clip the little alligator clips from the recharger onto the battery terminals when I bring it in after a night ride. I JUST got back from one, in fact! It's SO much fun riding at night! And that headlight is ultra cool! I like riding at night much better than in the day....esp here in the Chicago area it's so nice and cool out right now. The only thing that I like less is that I can't see my speedo (and now my tach/hour meter). Other than that, night riding is for me!
Warner
OK, warner, you've convinced me. Thanks for doing the research, looks like now's a good time to do it, the days are already getting shorter. Will definitely extend my riding hours. What are you using for a tailight?
I have a planet bikey superflash, but I read that flashing red led's are not legal in all states, But they sure are effective, until a cop stops me they're staying.
geez, warner, are you turning into a bag lady?
That's a good question! I think the answer is "A LOT longer than it'll ever have to". I believe the battery has a discharge time of something like 20 hours. I don't think it would run the headlight that long, but I'm SURE it would last a few hours anyway, and I just clip the little alligator clips from the recharger onto the battery terminals when I bring it in after a night ride. I JUST got back from one, in fact! It's SO much fun riding at night! And that headlight is ultra cool! I like riding at night much better than in the day....esp here in the Chicago area it's so nice and cool out right now. The only thing that I like less is that I can't see my speedo (and now my tach/hour meter). Other than that, night riding is for me!
Warner
I read something about a dimmer in sirjakesus' post, it might be better than buying a new bulb, just turn it down to what you need for a given situation. BTW, I just bought an 8ah battery (6.5 lbs.) and a set of h3 lights 60 bucks from walmart. I don't know if they make lighter batteries in this power range, I'll see if I can live with the weight.battery was only $43I did some more research...and it's sobering! I haven't tested this out in practice, but here's some of the information I found about calculating my battery life for my headlight. The current setup is a 7.5 amp hour battery which is rated based on a 20 hour discharge rate. My headlight bulb is a 55 watt bulb (VERY bright). Here's what I found:
I found this formula for roughly calculating the battery life:
Battery amp hours X 80% divided by amp draw = approx. running time
If this is true, here's how mine works out:
7.5 x 80% = 6 / 4.58 amp draw (55watt light/12volts) = 1.31 Hours
But then I also found that with a faster discharge rate (faster than 20 hours) the amp hours are cut down DRASTICALLY. The example they gave was that if the discharge rate were 1 hour instead of 20 hours, it actually cuts the amp hours in HALF. So for my calculation above, instead of getting 1.3 hours of run time, I'd actually only get .65 hours, or about 39 minutes. Not too much. This is all based on calculations of course.
So, what if I swapped the 55 watt bulb for a 35 watt bulb? It wouldn't be AS bright, but right now it's REALLY freakin' bright guys! Here's the same math applied to the 35 watt bulb (and remember, the discharge rate goes down quite a bit so this calculation is conservative....it should last longer!)
7.5 x 80% = 6 /2.9 amp draw (35 watt bulb/12 volts) = 2.06 hours
And even with the 50% penalty for quicker discharge, this still give me over an hour. I think it would be a good amount more than an hour, but that should be a worst-case scenario.
So now I'll go buy a 35 watt H3 Bulb and see how it works!
Warner
PS - If you're interested where this information came from, here's a link to the site:
http://www.powerstream.com/battery-capacity-calculations.htm
I read something about a dimmer in sirjakesus' post, it might be better than buying a new bulb, just turn it down to what you need for a given situation. BTW, I just bought an 8ah battery (6.5 lbs.) and a set of h3 lights 60 bucks from walmart. I don't know if they make lighter batteries in this power range, I'll see if I can live with the weight.battery was only $43
