Seeking advice for a very particular use case

jever98

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Hi there,

I'm seeking the forum's wisdom to figure out the best way to tackle a very specific use case:

I will be doing a cycling ultra race next year that lasts about 35 hours. We are alternating between two riders and riding through two nights.

In total, I need good lighting for on road riding in the mountains for a total of 16 hours. Out of those 16 hours I need strong lighting (I would guess 800lm or more) for about 12 hours to allow us to ride as fast as possible and not get sleepy. As we are racing, I don't want a very bulky or heavy setup.

Currently I own a Magicshine 872 and and 808E, whicch I could install on each of the two bikes I will use. The challenge I see is that I cannot recharge the battery packs in our follow car, as there don't seem to be 12V car chargers available (maybe I'm wrong here?).

I would very much appreciate advice on how to solve this riddle best. Some ideas I have been kicking around in my head:
- Find a torch with >2.5h run time on high, with changeable batteries
- Buy a bunch of cheap battery packs on Dealextreme (about $10 each)
- Find a way to charge the battery packs I have in the car

Thanks in advance for your help!
Jever
 

peter yetman

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Just thinking outside the box here. Have you thought about getting an inverter for the car? This would give you a mains voltage supply in the vehilcle. As the load for your charger wouldn't be too high you could get a small one which wouldn't cost too much.
p
 

vadimax

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Yes, you are wrong :) Here you are: Xtar SV2. It comes with a car 12V cable. And don't forget the "CPF8OFF" code for 8% off the price ;)
 
Last edited:

jever98

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Thank you both for your answers!

The inverter idea seems very good to me. A 150w inverter is about €20 on Amazon, so that should do. They can put out 150w. The Magicshine charger states that it pulls 1.8A at 8.4V, so about 15W if I'm not mistaken? There should be plenty of spare capacity to charge then.

@vadimax: the link you included seems to be for individual cells. The battery packs I have look like this.
 

angerdan

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So you need light for 12h without recharge?
This would mean more than 160Wh capacity (800lm @80lm/W, 10W).

Li-Ion has the best energy density, so better stick to anything with 18650 cells.
Instead of charging an battery pack during the ride, think about precharged 18650 cells which can be changed during driver exchange.
Possible with this battery case and enough protected 18650 cells (better with button top for easy recognition of polarity):
www.dx.com/p/pannovo-b-c04-water-resistant-4-x-18650-battery-pack-case-for-bike-lamp-black-254957
 

nbp

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When I crewed for a friend who did some 24 hr ultra events he had a bike light that was powered by some sort of generator hub on the bike wheel. As long as he was moving he had light. I believe he had another light or two as well. Are there any such generators available nowadays, perhaps newer more efficient ones? The advantage obviously is no dealing with batteries at all.
 

peter yetman

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I reckon if he's as much of an anorak about his bikes as we are about our lights, a generator may slow him down with added drag.
But good wheeze.
P
 

nbp

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That's why I asked, there may be some specifically for this purpose that create minimal additional friction. Plus, youre going to waste time stopping to swap batteries or whatever anyways, maybe adding a few seconds worth of friction isn't a big deal. When I did more distance cycling years ago it was a lot easier to just keep going. After 50 or 75 miles stopping and getting off makes it doubly hard to get back on. And these guys are going a lot farther yet. I dunno, it was just an idea from what I saw in the past.
 

jever98

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Thanks to all for the inputs, it's really helpful.

Regarding hub dynamos: yes, they exist. Shimano and Son make them, they put out between 3 and 6W. Unfortunately it's not really an option, as I would have to rebuild race wheels, cable up the bike, etc. It would cost hundreds of Euros and indeed be slower ;).

At the moment I am leaning towards a solution with a light head installed under the Garmin out front mount, a bit like in this picture (disregarding that it's a torch - couldn't find a better picture).
4169AP410nL.jpg


Torches without external battery packs that give light for >2.5h before recharge seem to be quite big and heavy, which might overload the garmin mount and not work well with a gopro adapter (from what I hear). I could then recycle my old light heads that have been sitting around (Magicshine MJ872 and MJ808E). For my riding buddy we could get some relatively simple light heads in the 1000 Lumen class. I would hope that with 4 battery packs we manage to get through the nights. The first night is only about 4h, the second night 10h, but in both cases there is a segment we have to ride together.

I still have 2-3 battery packs from Magicshine that are probably crappy, but will test them out.

Two questions for the experts, if I may:
I read around a bit and am struggling to come to a conclusion on which light heads to buy for my friend: Ituo XP2 is nice, but expensive. I was wondering if we could get away with something like a Yinding 900 for our relatively simple application and the fact that we won't use the lights much outside the race. Any other recommendation is also welcome.

In terms of battery packs, it seems there are plenty cheap ones out there that are crappy. I can buy something custom made from a place like enerpower.de (6800mah for 30 Euros, 10200mah for 40 Euros, using Panasonic NCR18650B cells). Is it worth getting those types of packs? I.e., would I get significantly more runtime out of them? I struggle to tell online what a good or a bad battery pack is.

Thanks again for all the advice,

Jever
 

vadimax

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znomit

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