bike lights Bicycle light batteries - My pet project

[Lamber]

Ever since I had a battery failure on the 2017 Trans Baviaans the topic of bicycle lights started to interest me.

 

An electrical engineer by trade - I figured that this cannot be as complicated and expensive as the market seems to suggest. Over the last 4 years (on and off) I have tested the good, the cheap and the ugly when it comes to batteries for endurance riding. 

 

My findings have led me to build my own prototype and yesterday I finally came to testing it with known parameters. For the first test, I have used the Extreme Lights Endurance light which seems to be most used light for the rides that I have mentioned above. My test setup includes a GoPro with sequence shooting at 60 second intervals within clear view of my G-Shock which was used for timing.

 

Extreme Lights claim 40+ hours' run time at the 200 Lumen setting when used with their 5200mAh battery - I am using the same Lumen setting but my battery is designed to produce 6800mAh at the same voltage.

 

My test is 24 hours in and things are looking good thus far - I will keep posting on this thread for anyone that is interested. After the test is completed I will share some findings which may or may not be informative/trivial.

Edited April 6, 2021 by Lamber

[DuncanCT]

Are you using the 18560's or a different cell? Do you need a BMS system for battery packs for lights?

[leon_pro]

Having a fan blown over it will reduce the heat of the battery and head unit.

If you simulate riding conditions.

[Zebra]

Subscribe, since I am busy with a 5 x 18650. REPACK (oldBlackburn quality) setup myself.

Chris

[Jewbacca]

The light needs air flow to cool it doesn't it?

 

Temperature will also make a huge difference. I remember the first race I ever did in the snow and ice. I couldn't understand why my head torch was going flat every 4 hours but in SA I could use the same set of batteries for 2 nights.

 

We have made quite a few different battery packs in the past to try to eek out hours on Expedition Adventure Races.

 

I even went full on and got a dynamo hub and light. The connector was fidgety in the wet and It was annoying to put together with cold, tired, clumsy and gloved hands.

 

Good luck. I settled on a small 1000 Lumen Max light mounted on my helmet (so it's always looking where I'm looking) with 4 settings and can generally run 1 battery for a whole race. (2 or 3 nights out on the bike). 

 

It's fun to play with stuff like that. After a few years though I got bored of DIY and now I just buy a spare battery or 2 from extreme lights when one futts out. 

 

I hope your solution works. We had mixed results re weight vs gain 

[Hairy]

very interested ... back in the day we used to make night lights out of PVC tube, alarm or motorcycle batteries and downlights.

 

then got to work with an engineer who was developing LED night lights when LED's were becoming a thing, but have lost interest over the last couple of years.

 

I do have a light I dug out the other day that is needing a new battery source, so this would be fun to watch what you are doing.

[Shebeen]

Ever since I had a battery failure on the 2017 Trans Baviaans the topic of bicycle lights started to interest me.

 

An electrical engineer by trade - I figured that this cannot be as complicated and expensive as the market seems to suggest. Over the last 4 years (on and off) I have tested the good, the cheap and the ugly when it comes to batteries for endurance riding.

 

My findings have led me to build my own prototype and yesterday I finally came to testing it with known parameters. For the first test, I have used the Extreme Lights Endurance light which seems to be most used light for the rides that I have mentioned above. My test setup includes a GoPro with sequence shooting at 60 second intervals within clear view of my G-Shock which was used for timing.

 

Extreme Lights claim 40+ hours' run time at the 200 Lumen setting when used with their 5200mAh battery - I am using the same Lumen setting but my battery is designed to produce 6800mAh at the same voltage.

 

My test is 24 hours in and things are looking good thus far - I will keep posting on this thread for anyone that is interested. After the test is completed I will share some findings which may or may not be informative/trivial.

That's not a proper test, you will be just looking at how to overheat the unit. The guy who started extreme lights(Hannes?) did this properly about ten years ago, his thread might still be here somewhere. They did a huge amount of battery testing.

 

Also, bike lights are complicated and expensive? You must be really new in this game!

[Lamber]

Are you using the 18560's or a different cell? Do you need a BMS system for battery packs for lights?

 

18650s yes.

 

No BMS for three reasons:

 

1. Price - seeing as I am only using 4 cells, a good BMS would cost the same as the cells thus not worth the money

 

2. BMS is good for display but none is needed for the system, i.e. no place for the software to report to which goes back to issue 1.

 

3. Vibration. The less components I use, the less chance of damage to components.

 

The only circuitry involved is a small PCM, this seems to be the industry standard.

[Lamber]

Having a fan blown over it will reduce the heat of the battery and head unit.

If you simulate riding conditions.

Thanks for your comment and good point.

 

After 36 hours neither the head unit nor the battery radiates any heat - my assumption is that this is due to the low lumen setting. As soon as I test for the next (higher) lumen setting I will make use of the fan as you suggested.

Edited April 6, 2021 by Lamber

[Lamber]

The light needs air flow to cool it doesn't it?

 

Temperature will also make a huge difference. I remember the first race I ever did in the snow and ice. I couldn't understand why my head torch was going flat every 4 hours but in SA I could use the same set of batteries for 2 nights.

 

We have made quite a few different battery packs in the past to try to eek out hours on Expedition Adventure Races.

 

I even went full on and got a dynamo hub and light. The connector was fidgety in the wet and It was annoying to put together with cold, tired, clumsy and gloved hands.

 

Good luck. I settled on a small 1000 Lumen Max light mounted on my helmet (so it's always looking where I'm looking) with 4 settings and can generally run 1 battery for a whole race. (2 or 3 nights out on the bike). 

 

It's fun to play with stuff like that. After a few years though I got bored of DIY and now I just buy a spare battery or 2 from extreme lights when one futts out. 

 

I hope your solution works. We had mixed results re weight vs gain 

This ties into Leon's comment above and valid point thanks. 

[Lamber]

very interested ... back in the day we used to make night lights out of PVC tube, alarm or motorcycle batteries and downlights.

 

then got to work with an engineer who was developing LED night lights when LED's were becoming a thing, but have lost interest over the last couple of years.

 

I do have a light I dug out the other day that is needing a new battery source, so this would be fun to watch what you are doing.

Thanks Hairy, that was obviously waaay before my time 

 

I'm just as interested to where this might lead. I won't be dabbling in LEDs just yet (although I have a solid background in working with industrial LEDs) as I would like to get the battery side of it sorted first.

 

36 hours in and no smoke yet...

Edited April 6, 2021 by Lamber

[Cois]

How do you balance the charging of the cells?  I know that is the number one killer of notebook batteries.

 

I bought a load balancing charger (they use it to charge cells for RC cars) that we rigged to charge a light (LED) that my wife drop tested and broke.  So we replaced the batteries with old notebook batteries that are still useable and changed a few things to load balance the batteries.

 

I once started working on building a battery pack and got the load circuit to charge 6 batteries at a time, but I know you do get bigger load balancers.

[dave303e]

my only 2c- a few years back we could buy bike light batteries that were built in a bottle shape. They were massive batteries. But it was nice to have a single battery unit that you could mount in a bottle cage and be done for a whole expedition race...

[DieselnDust]

At the 200lm setting the battery and head unit isn't going to overheat and static cooling is sufficient. I've left my nightlightning endurenz burning for hours in a tent at 24hr races and it's cold to the touch at 200lm setting.

 

The LED driver board is what is going to influence the efficiency of the battery usage.

For battery repacking I use international power products in milnerton. She just repacked my Lupine 13A.hr li ion battery.

My 20 Yr old HID lamp still burns with a real 1000lumen output for 6hrs.

The popular brand lights... No thanks. Over stated light output and ja well say no more

[DieselnDust]

Thanks for your comment and good point.

 

After 36 hours neither the head unit nor the battery radiates any heat - my assumption is that this is due to the low lumen setting. As soon as I test for the next (higher) lumen setting I will make use of the fan as you suggested.

You will need to look at the required drive current for the LED and the surface area of your heat sink. There should be a curve for the LED that provides the required area for the Amps drawn. This is your starting point. Each LED model has a sweet spot along this curve when it performs best.

[Frosty]

very interested ... back in the day we used to make night lights out of PVC tube, alarm or motorcycle batteries and downlights.

 

then got to work with an engineer who was developing LED night lights when LED's were becoming a thing, but have lost interest over the last couple of years.

 

I do have a light I dug out the other day that is needing a new battery source, so this would be fun to watch what you are doing.

My first Sabie Shenanigan race was done using a PVC pipe, halogen light bulb, push button switch on the top of the pipe, and a battery cable tied to the bottle cage. The pipe had a few holes on the sides and open at the rear for air flow/cooling. Weight wasn’t an issue back then, as much as 26” wheels had tubes and tyre liners.