Author Topic: Front Light  (Read 2881 times)

Zed43

  • prefers UK hills over Dutch mountains
Re: Front Light
« Reply #50 on: March 15, 2019, 10:30:04 am »
Because you overestimated how long they would last
Or because it got much colder, which can have a big effect on the output of batteries. I once got a Garmin 820 down to 2% charge in just over 2 hours at slightly below zero; it normally lasts 3-4 times that long.

mattc

  • n.b. have grown beard since photo taken
    • Didcot Audaxes
Re: Front Light
« Reply #51 on: March 15, 2019, 10:34:47 am »
The most obvious failure mode of battery lights is the batteries being dead when you don’t want them to be. Because you overestimated how long they would last; underestimated how long they need to charge; lost track of which batteries are full and empty; because the plug came loose when they were meant to be charging; because they switched themselves on in your bag; etc.

This entire category of failure has no equivalent in the world of dynamo lights.
Yes; I'd say every one of these could happen on PBP. Not WILL happen - but things worth ruling out, all other things being equal.

I've certainly seen someone (on a 600) surprised that their new power-bank had no charge in it. As for the other issues, I've probably had most of them at some point!

(but I do still use battery lights a lot!)
Has never ridden RAAM
---------
No.11  Because of the great host of those who dislike the least appearance of "swank " when they travel the roads and lanes. - From Kuklos' 39 Articles

simonp

  • Omnomnomnipotent.
Re: Front Light
« Reply #52 on: March 15, 2019, 11:12:32 am »
I have the Ixon Iq Speed (two) and the main issue is the batteries need refreshing when used infrequently. I'm tempted to try replacing them with a 7.2 or 7.4V Li-ion pack (or two so I have spares). These will hopefully hold their charge better when not in use.

4-cell packs with 5000mAh capacity would be lighter than the standard packs.

zigzag

  • unfuckwithable
Re: Front Light
« Reply #53 on: March 15, 2019, 02:16:25 pm »
The most obvious failure mode of battery lights is the batteries being dead when you don’t want them to be. Because you overestimated how long they would last; underestimated how long they need to charge; lost track of which batteries are full and empty; because the plug came loose when they were meant to be charging; because they switched themselves on in your bag; etc.

This entire category of failure has no equivalent in the world of dynamo lights.

none of these failure modes is applicable if the light is fully charged before the event, shows the burn time remaining and lasts way longer than required. fit and forget.
even on the tcr (two weeks) i didn't need to charge the lights on the go; topped them up once in a hotel.

Re: Front Light
« Reply #54 on: March 15, 2019, 09:11:21 pm »
What are the night light burn time estimates for the 90 hour 80-90 hour riders?  I am guessing I need around 21 hours with the lights on but this is a wild guess.  What are other riders on the board planning for?

Front Light
« Reply #55 on: March 15, 2019, 09:21:11 pm »
About 9 hours per night


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SPB

Re: Front Light
« Reply #56 on: March 15, 2019, 09:55:40 pm »
I guess it depends on whether you think you'll sleep mostly in the day or at night, and whether you want to allow for running lights to help you be seen in any rain or morning mist.

I was thinking of ensuring I have at least 40 hour run times if I take battery lights, in the hope that would give sufficient contingency to cover worst case.

simonp

  • Omnomnomnipotent.
Re: Front Light
« Reply #57 on: March 15, 2019, 10:20:35 pm »
You need to allow for having lights on in poor visibility as this is a PBP regulation.

Re: Front Light
« Reply #58 on: March 16, 2019, 02:32:49 pm »
Dynamo lights are probably more reliable than battery lights, as there's less to go wrong, but it might happen.

How do you make that out?  There's far more to go wrong with a dynamo generator than a battery light.

I was talking about the light itself, in a paragraph where I'd already separately considered the reliability of the generator and wiring.  Obviously the system is only as strong as its weakest link[1].

A dynamo light doesn't have a battery compartment, which means it doesn't have a method of opening to access the batteries, which is subject to wear and stress, while compromising the waterproofing (or, in the case of external battery packs or rechargeable lights with non-replacable batteries, electrical connectors subject to frequent mating cycles).  It doesn't have spring battery contacts.  And it generally doesn't have an afterthought of a quick-release handlebar bracket to go wrong, either (semi-permanent attachment is the order of the day, which usually[2] makes for simpler, better-engineered, attachment methods like nuts and bolts).  And of course there aren't any batteries to fail or simply be insufficient for unexpected conditions.

Which isn't to say it can't fail in ways that are common to both battery and dynamo lights - water ingress or vibration damage to the electronics or optics, for example - just that it's avoided a whole load of other points of failure by having less to go wrong.

That said, the most common battery light failure modes are down to human errors which - while cumulatively significant in day-to-day use - are unlikely to be an issue for long audax rides (eg. not planning sufficient battery charge for a ride, damaging or failing to secure lights properly when removing them for security reasons, or just not bringing removable lights with you).  The always-ready nature of dynamo lighting is advantageous on a commuting or touring bike, but irrelevant for something like PBP.


[1] In a dyanmo system I'd say that was the wiring.  In a battery system I'd say that was the user.
[2] Emphasis on the 'usually'.  There are some decently-engineered battery lights that get this stuff right.  Dynamo lights and battery lights with external battery packs have something of an advantage in that they have less mass for the mounting to support.


5 minutes in (almost) any french supermarket will yield a temporary,cheap but not necessarily high quality, solution to battery light failure which could be quickly put in place. You can bin the broken ones if saving weight is a consideration. Broken dynamo lights can be cured through the same route but the installation side will be longer and more fussy (or you revert to the battery alternative, again more fussy to install, depending on how much wiring you want to remove or immobilise with cable ties). In the end failure of either system need not be a game killer unless happening late at night (outside shop hours!) when you don't have a sleep margin to fall back on (which of course under Murphy is exactly when it will happen  :'(  )

mattc

  • n.b. have grown beard since photo taken
    • Didcot Audaxes
Re: Front Light
« Reply #59 on: March 16, 2019, 02:48:16 pm »
The most obvious failure mode of battery lights is the batteries being dead when you don’t want them to be. Because you overestimated how long they would last; underestimated how long they need to charge; lost track of which batteries are full and empty; because the plug came loose when they were meant to be charging; because they switched themselves on in your bag; etc.

This entire category of failure has no equivalent in the world of dynamo lights.

none of these failure modes is applicable if the light is fully charged before the event, shows the burn time remaining and lasts way longer than required. fit and forget.
even on the tcr (two weeks) i didn't need to charge the lights on the go; topped them up once in a hotel.
What zigzag means is:
"Only an unprepared fool would experience any of these failures on their big ride of the year."

... but fortunately he is too polite to write that :)
Has never ridden RAAM
---------
No.11  Because of the great host of those who dislike the least appearance of "swank " when they travel the roads and lanes. - From Kuklos' 39 Articles

Re: Front Light
« Reply #60 on: March 17, 2019, 11:08:05 pm »
What are the night light burn time estimates for the 90 hour 80-90 hour riders?  I am guessing I need around 21 hours with the lights on but this is a wild guess.  What are other riders on the board planning for?
Broadly (times of sunrise and sunset of course vary with date and longitude) there's 10 hours between sunset and sunrise (just after 9pm to just after 7am). Fuller value (90 hour) riders will ride for all of Sunday night and for good parts of the next 3 so that's 40 hours of lighting required, less the time one plans to spend stopped in the dark, but plus a buffer for using lights during daytime when poor visibility so warrants.
But sometimes a less powerful setting will suffice (in a group and not leading) and this can reasonably be taken into account.
https://app.photoephemeris.com/?ll=48.390290,-4.486280&dt=20190820010700%2B0200&z=13&spn=0.04,0.15&center=48.3903,-4.4863


Re: Front Light
« Reply #61 on: March 18, 2019, 12:02:53 am »

 less the time one plans to spend stopped in the dark,

This is the actual question. 

Re: Front Light
« Reply #62 on: March 19, 2019, 12:26:09 pm »

 less the time one plans to spend stopped in the dark,

This is the actual question.
Since you implicitly ask, for me: 12 hours on nights 2 and 3 (10 hours sleeping), aiming to finish at sunset on Wednesday (Sunday 1830 start). My (separate battery 4.4Ahc 252g) light (130g) will run for 24 hours on low and 5 hours on high. I will carry one spare battery, and not expect to use it.

frankly frankie

  • I kid you not
    • Fuchsiaphile
Re: Front Light
« Reply #63 on: March 19, 2019, 12:56:56 pm »
Broadly (times of sunrise and sunset of course vary with date and longitude) there's 10 hours between sunset and sunrise (just after 9pm to just after 7am). Fuller value (90 hour) riders will ride for all of Sunday night and for good parts of the next 3 so that's 40 hours of lighting required, less the time one plans to spend stopped in the dark, but plus a buffer for using lights during daytime when poor visibility so warrants.
But sometimes a less powerful setting will suffice (in a group and not leading) and this can reasonably be taken into account.
https://app.photoephemeris.com/?ll=48.390290,-4.486280&dt=20190820010700%2B0200&z=13&spn=0.04,0.15&center=48.3903,-4.4863

I think 40 is a huge overestimate.  Yes it's 10h per night and you may ride 4 nights and yes the roads can be very dark (no-one's mentioned this - the rural roads are much darker than typically in the UK, and have fewer markings - white lines and so on - so bright lighting options are a must).  But subtract sleep AND controlling/feeding times from nights 2, 3 and 4 if you must, and you're unlikely to ride more than 5 night hours on each of those nights. 
For dawn and dusk and lit roads I would strongly commend using separate visibility lighting at the front, and this would probably save at least 2 more hours per night on your main lighting.
 
Last (and 7th) time Sheila rode PBP she was on a fairly slow schedule, she packed batteries for 20 hours of main lighting (3W LED, with an option to run 2 at once) and came back with some batteries unused.  Separate visibility light at the front was key.  Modern lights with their multi-levels may change that strategy a bit but you still need two main lights for redundancy, however multi-talented your main light is.
"This is a complex subject, with a need for more than one highlighter pen."

Re: Front Light
« Reply #64 on: March 19, 2019, 03:26:59 pm »
Just dug out my old spreadsheets from 2011 & 2015 and I have it at 19.7 & 21.2 hours of actual night riding.

I move along at around 21 km/h on long rides and take about 87 hours.  I don't rush through controls and only sleep proper (4 hour stops) on the 2nd and 3rd nights, after which I catnap at every control.

I've never noticed any difference in speed, over the years, whether I use dynamo or battery.  I am 15 stone, so any weight difference is largely irrelevant. I've only ever had one light fail on a ride and that was a battery powered B&M Ixon IQ (the contacts are rubbish).

Re: Front Light
« Reply #65 on: March 19, 2019, 05:29:56 pm »
Fuller value (90 hour) riders will ride for all of Sunday night and for good parts of the next 3 so that's 40 hours of lighting required, less the time one plans to spend stopped in the dark, but plus a buffer for using lights during daytime when poor visibility so warrants.
I think 40 is a huge overestimate.  Yes it's 10h per night and you may ride 4 nights . . . . But subtract sleep AND controlling/feeding times from nights 2, 3 and 4 if you must, and you're unlikely to ride more than 5 night hours on each of those nights. 
For dawn and dusk and lit roads I would strongly commend using separate visibility lighting at the front, and this would probably save at least 2 more hours per night on your main lighting.
 
. . . Separate visibility light at the front was key.  Modern lights with their multi-levels may change that strategy a bit but you still need two main lights for redundancy, however multi-talented your main light is.
"I think 40 is a huge overestimate." I agree - see above.
"you may ride 4 nights . . ." Question was asked for fuller value riders who will finish after the 4th night.
"subtract sleep AND controlling/feeding times from nights 2, 3 and 4 if you must, and you're unlikely to ride more than 5 night hours on each of those nights." See above "less the time one plans to spend stopped in the dark". So that's 10 plus three lots of 5.
". . . Separate visibility light at the front was key." Expect all riders will have one - they'll need the discipline and effort to conserve the main light when there's an opportunity. Headtorch in back pocket/bag as well.