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# How Long Will the Lights Be On?

01/22/2013 1:04 PM

Anyone know a formula or a good rough estimate of lifetime of a lithium ion battery under load as the temperature drops?

I ride mountain bike year round and already know that when the temps fall into the 20's F, my bicycle lights run about 1.5 hrs on mid setting, while they last 1.5 hrs on high setting when the temps are in the 80's F.

Well, it was 3 degrees F last night, this AM, and now at noon, so I figure 3 degrees max when I ride tonight. How short must I cut my ride to not run out of power for my lights?

I know the sane thing is not to ride when it is that cold - ever meet a sane mountain biker? If you did, he was actually a roadie.

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#1

### Re: How Long Will the Lights Be On?

01/22/2013 1:41 PM

One good, well-designed experiment is worth ten thousand theories.

Turn on your bike's lights and find out. Better that then getting caught in the middle of nowhere and, later, inconveniencing twenty or thirty poor blokes who have to come looking for your frozen behind next day. Then take a spare with you.

I mountain-bike, too, and have nearly made it in the papers because I didn't know the limits of my gear.

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#2

### Re: How Long Will the Lights Be On?

01/22/2013 1:56 PM

Hate to waste a night trying this out. Wanted to ride tonight mostly because it is just 3 degrees F. By tomorrow it will be back into the teens again, and I've done that before.

Of course I carry a spare. I have the only full suspension mountain bike with a full rear rack and very large bag stuffed with socks, gloves, food, as well as the usual tools, in a 3 county area.

I guess I could ride up and down the rural road I live on until the low battery warning starts to blink, but the woods is beckoning and I know I won't stay out of them.

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#3

### Re: How Long Will the Lights Be On?

01/22/2013 2:08 PM

Fess up, it's that adrenalin rush that comes from Living on the Edge, no?

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#4

### Re: How Long Will the Lights Be On?

01/22/2013 2:30 PM

I used to drag race (at a legal sanctioned track - not the street) all summer long until I got too old to do the wrenching anymore - what do you think?

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#5

### Re: How Long Will the Lights Be On?

01/22/2013 2:47 PM

What kind of mountain bike did you race? Mine was a AA fueler. Rail, and very hard to steer. Much more fun after I hooked the chute onto the bike instead of wearing it.

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#6

### Re: How Long Will the Lights Be On?

01/22/2013 2:59 PM

I just did the 5.0 Mustang thing with weekly bracket racing just to keep me sharp on the lights. Not near as fast as a AA/F.

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#7

### Re: How Long Will the Lights Be On?

01/22/2013 3:29 PM

I think I would just get something like this....and keep the battery under my coat, or in a heat pack...

Place of Origin:Guangdong China (Mainland)

Brand Name:OW

Light Source:LED Bulbs

Battery Type:Lithium Ion

Wattage:10

Certification:CCC,CE

Waterproof:Yes

Beam Angle:60?°

Switch Mode:High/Low

Flashlight Type:Camp

Model Number:ow-708

Emitter Type::CREE XMLT6 LED

LED luminous flux::1200

LumensPower::10w

Battery Configurations::Rechargeable battery 4400mAh

Working Time::around 180 minutes

Body Material::Enclosed with aviation aluminum alloy

Switch::End-cap press ON/OFF

Main product dimensions::55x42x45 mm

CREE XMLT6 LED 1200 Lumens:Bike Light & Headlight

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#8

### Re: How Long Will the Lights Be On?

01/22/2013 3:34 PM
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#9

### Re: How Long Will the Lights Be On?

01/22/2013 3:43 PM

Here's another vote for just keeping the pack inside until ride time, and then keeping it in the climate-controlled environment of your riding suit. If the harness isn't long enough, it should be fairly simple to make an extension.

Tom D.

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#10

### Re: How Long Will the Lights Be On?

01/22/2013 3:46 PM

NO NO NO - the modern way is self contained - no wires - 600 brilliant lumens from a CREE LED and the battery is in the light housing, about 3/4" diameter and 4" long - very light - very bright - no wires wrapping round your head tube, stem, etc. One third the weight of what you show. Helmet mounts are real easy now. No wires running down your neck and back. Actually can run 3 lights at once now - 2 on the bar and 1 on the helmet. But as you note - now they get quite cold.

I have 9 similar copies to what you have shown for sale - cheap. Kind of a mini-history of the last 10 years of bicycle light development. Each one a bit brighter, a bit lighter, and a bit cheaper than the previous years offering. The ones from 10 years ago are only 150 Lumens and cost 2-1/2 times what the latest one did.

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#11

### Re: How Long Will the Lights Be On?

01/22/2013 4:06 PM

So I guess a bigger battery is out of the question?

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#12

### Re: How Long Will the Lights Be On?

01/22/2013 4:12 PM

Good one - looks a lot like my wife's e-bike. They need to do a bit more work on them. Twenty fives pounds of battery to go 25 miles or less, generally much less, is a bit disheartening. That actually looks like a good solution for her bike so she can go as far as I do.

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#14

### Re: How Long Will the Lights Be On?

01/22/2013 4:27 PM

25 miles! I don't even like to drive that far in the car.....This opti thing looks cool...

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#13

### Re: How Long Will the Lights Be On?

01/22/2013 4:14 PM

http://data.energizer.com/PDFs/temperat.pdf#page=3

http://media.duracell.com/media/en-US/pdf/gtcl/Technical_Bulletins/Lithium%20Technical%20Bulletin.pdf

Should have left them on earlier today in the cold to see how long. Then recharge them for your ride. Above is data that may help.

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#15

### Re: How Long Will the Lights Be On?

01/22/2013 4:28 PM

Very good. If I interpolate correctly and assume properly, it appears that the lithium batteries do not fall off as steeply as the old nickel metal hydide batteries did below freezing. And, it looks like if I can get 1.5 hours at 20 F, I should get more than 1 hour at 0 F. (looked like a 10% drop in this range) So if I ride 45 to 55 minutes I will be safe. (probably a good limit for exposed facial skin too) Beyond that and I need to watch the battery monitor light real closely and stay near home too. (that's a problem with these lights - once the battery monitor light starts, the end is real close)

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#16

### Re: How Long Will the Lights Be On?

01/22/2013 4:48 PM

Also keep in mind that those specs, as with any specs, speak of what to expect generally. They won't help you if your specific unit is for any reason an outlier - whether because of age, manufacturing variations, quality of materials used, unsuspected damage or whatever. Thing is, you don't own a general unit, you own a specific unit that may or may not be representative of what you see on that sheet. Not normally a concern, say, in balmy weather but, given your present temperatures? Test it. Find out. Your unit may perform quite differently under those specific conditions and until you test, you simply don't know. Don't bet your health on what that spec sheet tells you. Even NASA knows better! That's why they test the crap out of everything before declaring it adventure-worthy. Except of course for Hubble Space Telescope Mirrors. Good thing they had some sharp bikers on hand, ay?

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#17

### Re: How Long Will the Lights Be On?

01/22/2013 5:02 PM

Yeah - but I am running three specifics, not just one, so there is a good possibility if one is below specs, then one is better than the average spec. I can ride out of the woods this time of the year on one light if need be, because below 20 degrees the grease in the bearings gets so thick, you peddle quite a bit slower than in warmer weather. No 15 mph on flat dirt now - just about 5 mph is good - won't over run the light from one unit at that speed. Add to that the ice and packed snow we have on the dirt right now....

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#19

### Re: How Long Will the Lights Be On?

01/23/2013 3:16 AM

When there is snow/ice, you will need less light to see clearly due to reflection from the ground. Try using one light, and keeping the second as back-up for when the first gets low.

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#20

### Re: How Long Will the Lights Be On?

01/23/2013 7:57 AM

I envy you - too cold for me here at zero degrees F. I stop when it gets around freezing...too damn old to bike in the winter anymore Too slippery as well, my old body can't take the dumps anymore. Only 3 months to wait. I agree with the idea of a test. Don't see why you can't ride and if the batteries are still good when you get back, leave them on until they die. If they die on the ride use the spares.

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#21

### Re: How Long Will the Lights Be On?

01/23/2013 8:06 AM

Have to have at least 2 - one on the bar for the road ahead - in snow, you really have to "read it" or you will go down even with studded bike tires. Low mount gives the details of the snow much better than a high mount. Then there is one on the helmet for 180 degrees of visibility. When in the woods it is very good to be able to see what that deer to your side in the woods that you just scared is going to do - run away or right in front of you. Never hit a deer yet, but have come close. Then when our coy-dogs up here start howling, well it is just nice to know where they are, even if they won't attack you.

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#18

### Re: How Long Will the Lights Be On?

01/22/2013 5:11 PM

Oh yes - Specsmanship. It happens. Other folks make these products, too, and as with other kinds of products it is often that case of: "They Wot Gots The Best Specs, Wins."

And then we have the Official Testing Labs' results. Trivial example: You buy a new car. On every new car is what I like to call a bullsheet: It tells you how many miles per gallon your car will never get, according to Some Testing Lab® located in a nondescript wooden shed out behind Santa's workshop. It, too, is manned by elves, but ones who've been banned because of their not having, shall we say, a well-rounded sense of proportion.

You get the idea.

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#22

### Re: How Long Will the Lights Be On?

01/23/2013 8:16 AM

Just for the record - it was 2 degrees F and I made it 55 minutes - lights still on - me, well, too cold and tired. That crunching sound you hear on cold days as you drive your car though snow is the tires quickly freezing to the surface from the pressure - well guess what - same things happens on a bike and that sure makes the rolling resistance grossly high. Add to that the thickness of the grease in the bottom bracket and wheel hubs and 3 miles feel like 10.

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#23

### Re: How Long Will the Lights Be On?

01/23/2013 9:28 AM

Not up to Batttery Perfornace these days due to Age of rider !! Too old to ride in the woods at night! Especially in the Cold!

However, one thought, I have never had a problem with Grease slowing me down, whatever Bike I was riding and I used to have many. There ought to be a grease that you can use which is suitable for low temperatures. And water as well!

Good Luck, glad that you got home safe!

Keep riding!

Sleepy

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#24

### Re: How Long Will the Lights Be On?

01/23/2013 9:41 AM

Not worth changing grease for the one night it drops to 0 degrees F. I do thin what is stock, with a bit of thin oil, and it is fine in the standard temps around 20 F. Did have one incident where I didn't change the grease in the rear hub - cassette type - and the pawl stuck causing me to free wheel all the time. Rather embarrassing 3 mile walk out, not to mention the pain that hit when I first jumped on the pedals after coasting and they just spun freely. Top bar on that bike was like the good old days - crotch height.

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#25

### Re: How Long Will the Lights Be On?

01/23/2013 9:59 AM

It probably all depends on the LI formulation of the cells you may have.

We have in our high altitude balloon experiments have been using simply the Energizer LI batts (AA size) for years with great results! Yeah the ones you can get at any store.

They re rated at 2200 mah capacity, and tolerate cold better than any cell we have ever tried, we need to down rate them by only 10% in our flights, and we are talking VERY cold here like 50 to 60 BELOW C !!!!

Video from one of our flights,

http://youtu.be/HJ0IT4ZwtSo

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#26

### Re: How Long Will the Lights Be On?

01/23/2013 6:31 PM

I ride my converted MTB to commuter bike all winter long in Wisconsin. But my low temp cut-off point is 9 degrees F with low wind conditions. Takes me about 40 minutes to ride from work to my home. I don't use LI batteries in the 3 white LED lights I have up front and 1 red LED in back, just AAA NiMH. I notice a drop in the run time of about 15 to 25% on the NiMH bateries. But it's really hard to confirm this because I can't repeat runs because the temperature conditions are never the same. What to you use for gloves? I use snowmobile gloves with liners and my fingertips sometimes get very cold.

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#27

### Re: How Long Will the Lights Be On?

01/24/2013 8:10 AM

Yeah - the old lights with NiMH really dropped off as temperatures fell. Glad we have the Li-ion ones now. I usually stop at 5 degrees F, but just had to go a bit lower one time. Didn't repeat last night, when the temps went down as low.

The gloves I use are a bit surprising as they are not very heavy, but warm. Be aware though that I am not an average biker, as, despite my cycling year round, have a bit higher body fat to lean ratio than a Tour rider. Actually, I am closer to an NFL defensive lineman. Ever read Dirt Rag? - I am very close in build to Gene Tierney. So I suspect my extra padding helps. I am using Bellwether gloves. They look like the gloves you see sold for conditions in the forty degree range, but I use them all winter. I limit week days to 1 hour, but will be out for 2 to 3 hours on Saturdays and Sundays and my hands never get cold. We see temperatures in the mid to low teens here most of January.

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#28

### Re: How Long Will the Lights Be On?

01/24/2013 8:57 AM

Let me correct my last response to you - it is Maurice Tierney at Dirt Rag - thought that name looked wrong when I wrote it. Anyhow, in the Cydesdale class as he used to say when he wrote for the magazine - now he just sits back and does and occasional review.

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