Running Front And Rear Bike Lights Off Of The Same Battery Pack

RevDoug

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Jan 8, 2013
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8
I have a bike light in front that runs off of a 7.4 volt Li-ion pack (2S2P 26650’s) and a light in the back that runs off of an 11.1 volt pack (3S2P 26650’s). Is there any way to run both lights off of a single battery pack?


Thanks
 

znomit

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Aug 1, 2007
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See if you rear light will run off the front pack. If it does you can get a splitter cable. Don't try it the other way around without checking with the manufacturer.

BTW thats a crazy amount of battery for a rear light. What is it?
 

RevDoug

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Jan 8, 2013
Messages
8
See if you rear light will run off the front pack. If it does you can get a splitter cable. Don't try it the other way around without checking with the manufacturer.

BTW thats a crazy amount of battery for a rear light. What is it?

Yes it will power the rear light but the output is way too low. I need the 3S2P (or even 4S2P). It is a Whelen Vertex.
 

CyclingSalmon14

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Feb 10, 2014
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I don't even....

Why! You must be blinding everyone, or running all week long?

Is it the whelen rear led light? How much dose it output? I can't see why any led light would need 6-8 26650's? Or did I read something wrong?

My rear light puts out 75 lumens (blazingly bright, almost to much so) for three hours off a 700mah battery.
 

RevDoug

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Jan 8, 2013
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Well, the issue is this:

On the rear light (Whelen Vertex) I get 6 ½ hours on the 3S1P pack. Since I usually ride for 7 hours I need to run 3S2P. It is pretty much a waste of the additional capacity but I’m not going to change how much I want to ride just because my battery only lasts a certain amount. Plus, as the cells age and their capacities drop I’ll need more of the packs themselves. Regarding the front light, I run one of the “1200” lumen China specials in fast blink mode. I’ll get about 4 ½ hours off of the 2S1P pack hence I need to run that as 2S2P to last more than my 7 hour ride.

Is this setup bright? Oh yeah! But as I do most of my riding during the mid-day it needs to be bright. Also, I ride a recumbent trike so I need a bit more help than a typical diamond frame bike.

CyclingSalmon14: No I run the white Whelen in the back as it is MUCH brighter than the red. I’ve been contemplating going with the blue light but there are some laws that I might run afoul of.

So, you can see that I have to carry two separate battery packs both with a huge reserve capacity. If I could run the lights off of a single pack maybe I could combine the additional capacities and get away with fewer total cells.


Any ideas?
 

CyclingSalmon14

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Feb 10, 2014
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Hmm that's a lot of cells!!! Light seem really hungery!

My rear light is still bright but will run 12? Hours if I need it but that's at night, during the day I can understand all that light when on such a low bike.

I do hope you don't run a stobe during the night though! Due to target fixation and just blinding people could be worse than no lights, but during the days not so bad the magic shines flash is very fast stone though, very effective but also annoying but fine during the day I guess.

Amazed how many cells you need to run that rear light! Here in the UK it is illegal to run anything other than red on the rear, although I'm pretty sure no one will actually pull me over if o did.

But good luck sorting your lighting solution out, I only ride with lights in the dark / twilight or if its overcast such as a gloomy day / raining.

For night ridding I'd say your solution may be a tad overkill though ahaha!

Anyways its all about enjoying your ride St the end of the day.
 

RevDoug

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Jan 8, 2013
Messages
8
CyclingSalmon14: I typically don’t ride much past sunset but if I’m caught riding at night, yes, I run the rear in flash mode. I’m going to guess that it is annoying for a car behind me, but is it any more annoying than an emergency vehicle with flashing lights that are brighter than what I run with?

My objective is to be seen and avoided!
 
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