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Discussion Starter · #1 ·
I have a DiNotte 200L that I really like most of the year, but with temps hovering around zero Fahrenheit my 2 cell battery dies in approximatley 30 minutes at the low setting! This is not acceptable... The battery is approaching a year old with perhaps 40 charge cycles on it, but I had this problem when it was nearly new, so it seems to be a weakness of the Li-ion battery.

So, what works better? Should I get a AA version of the DiNotte? Which batteries do better in the cold? What do the Idita-bike guys use??

Thanks,
Tom
 

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Discussion Starter · #3 ·
pinkrobe said:
Interesting! I have a Li-ion pack that gets left on my bike outside 5 nights/week in the winter, and I've had no issues with it dying prematurely. Low temperatures are in the -30 range.
Wow, how long are your run times? What size battery are you using?

I emailed DiNotte, and they acknowledged that run times will be shorter during cold weather, but seemed surprised by 30 minutes on low power. They suggested I insulate the battery.

Tom
 

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Longfellow Mafia said:
Wow, how long are your run times? What size battery are you using?

I emailed DiNotte, and they acknowledged that run times will be shorter during cold weather, but seemed surprised by 30 minutes on low power. They suggested I insulate the battery.

Tom
The pack is a 4400 mAh [maybe 4800?]. Run times are in excess of 4 hours between charges, running a triple Cree Q5 light via a bFlex [achesalot design] at max power. Note that I don't run the light for 4 hours continuously. It's typically on for 30 minutes at a time, twice a day [my daily commute], 5 days a week for 5 months/year.
 

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Helmet or bar mount? If it's on your helmet you could use the longer chord to keep the battery in your jersey pocket while you ride.

Have you tried running it inside to confirm it is a cold-weather issue and not a weak battery?
 

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If you run any battery in heavy cold it will have dramatically decreased capacity. NiMH and NiCd are the worst by far.

Li-ion is better but will still suffer.

Use the long cable and keep the battery in next to your body where it will stay warm.

At 0F, most batteries are taking a pretty big hit at that point. NiMH is speced to operate to about 0C (32F) and Li-ion is spec'ed to operate at -20C or just about 0F. Either way, if you freeze the electrolyte, then you will have it hardly operating at all anyhow. So don't store them at very cold temps like that.

J.
 

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What about wrapping your battery in some kind of insulation. Batteries have an inherent resistance, which should translate into a bit of heat being generated when they are driving a load. Google for "foil bubble insulation". It's pretty thin and seems to work in our chicken coop pretty well.

The other option might to be to add a string of around 6 quarter watt resistors, of 10 ohms each across the terminals of your battery. If you encase the resistors in heat shrink tubing and bury them in the insulation wrapped around the battery, they will provide about 1 watt of heating. That should help keep the battery warm. You might want to add a switch to the resistor string, so you can turn the heater off.

Later this winter, when it gets good and cold overnight (we get down to around -10 F many mornings in mid January), I want to run some tests of battery self-heating in an insulated enclosure. And I want to try adding some kind of resistive heater to see if I can improve performance at cold temperature.

I'd try to keep the battery indoors when not using it. And having a battery in your pocket if you have a light on the handlebars is a bad idea. It might keep you attached to the bike when you didn't want that.

Mark
 

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Basically, I'd do what winter search and rescuers, mountain climbers, and winter campers do - get a long cord and keep in next to your body. That technique that is based on long experience in critical situations. The batteries are not going to produce enough heat to make a serious difference at 0F.

To get the best performance out of the batteries, you need to get the temperature up over 40F - that's a 40 degree difference that needs to be overcome.

J.
 

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Discussion Starter · #9 ·
I've been using it bar mounted, but I store the battery indoors between uses. And the battery lasts much longer at warmer temps, so I know it isn't simply a weak battery. My commute is about an hour to hour and a half, depending on conditions. I may go with a helmet mount setup so I can store the battery in my pocket, or I may try insulating the battery in one of those portage packs that sit at the seattube/toptube junction.

Thanks everyone for your input!
 

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This thread has inspired me. For years I've tried to insulate my battery for winter rides without much luck. Last year I tried encasing the battery in 6mm packing foam and using a chemical heating pack...It might have given me about another 10-15min run time but that was it. I like the idea of putting the battery next to your body. Undoubtedly that would work if you have a long enough cord and some way to hold the battery close to your body without being too uncomfortable. However there are problems you are sure to encounter with the cord.. It would make getting off the bike a bite not to mention what might happen in a fall or if you had to suddenly bail. Considering that, I don't think I'll try it with a bar mounted light. When I get back to work tomorrow I'm going to borrow one my employers remote wired thermometers. Then I'm going to try the insulated pack once more only this time I will put the remote sensor in with the battery. I'll put the pack on my balcony and simulate riding conditions using a fan. I'll try different levels of insulation to see what happens. I'll use my Dinotte 4xAA pack first because it was more sensitive to cold, then I'll try the Dinotte 4 cell Li-ion and compare. I'm not saying I'll do a run time test, I just want to see how long it will take before the temperature drops. It might take a while to do these comparisons so be patient. I'll post up with the results as I get them. In the mean time feel free to post your ideas for insulating the battery.
 

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HuffyPuffy said:
Removed my post, probably a dumb idea (was to use a thermos bottle or bento box).
...not as dumb as you may think. I was considering a thermos bottle as well. What I generally did in the winter was to put my battery in one of my old neoprene battery bags. Like I said before, most of the time, this really doesn't help that much. One of the reasons is probably because the bags hook right up next to the top tube. Main tubes act like giant heat sinks so probably best to keep battery away from metal as much as possible. In keeping with that thought I dug out an old Blackburn under-the-seat bag. The bag zips close and has lots of room for foam insulation. Unfortunately, the 7 day forecast in my area shows a slight warming trend. I would like temperatures below 0 degree C. for the testing. I could use my freezer but than I wouldn't be able to use a fan ( wind chill is very important ). Looks like I might have to wait till Wednesday before I do a test.
 

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handwarmer

What about using one of these hand-warmers. It will be 45-50 C in 30-60 minutes. It could be put down in a neoprene bag with the battery. A heavy solution, but cheap.

It works so that you snaps the inner metal coin and the liquid crystallize. It must be cooked to be used again.
 

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I used to have some of those handwarmers, and I'm sorry to say they were a disappointment. Useful heat didn't last nearly the 45 minutes claimed, and if they weren't used fairly soon after being reactivated, they would "go off" on their own and be useless when I needed them.

Better might be something like these. I've used then in my mitts while skiing on sub-zero days for years. They work dependably and stay warm for hours. It's a mystery how these little bags of salt, iron filings, and vermiculite generate so much heat (rapid oxidation?) but they do work great. They need air to work, so something like a thermos or sealed plastic box wouldn't work. But if they work inside a glove they should work in a seat or handlebar bag or camelback. There are a number of brands and can be found at sporting goods or ski shops for about $1 a pair.

JZ
 

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JimZinVT said:
I used to have some of those handwarmers, and I'm sorry to say they were a disappointment. Useful heat didn't last nearly the 45 minutes claimed, and if they weren't used fairly soon after being reactivated, they would "go off" on their own and be useless when I needed them.

Better might be something like these. I've used then in my mitts while skiing on sub-zero days for years. They work dependably and stay warm for hours. It's a mystery how these little bags of salt, iron filings, and vermiculite generate so much heat (rapid oxidation?) but they do work great. They need air to work, so something like a thermos or sealed plastic box wouldn't work. But if they work inside a glove they should work in a seat or handlebar bag or camelback. There are a number of brands and can be found at sporting goods or ski shops for about $1 a pair.

JZ
Jim, I afraid those are the very type of warmers that I have tried. I think the problem is that they require a good supply of oxygen to work. I think it's the very reason that they don't work so well in my winter shoes as well. If you are wrapping the battery up so tight that air can't get to it, the warmers aren't going to work that well. Another potential heat loss area that I almost forgot about is the cord itself. Since it is connected directly to the battery it will act like a mini heat sink. For bar mounted lighting I'm beginning to think that a good strategy might be to carry a back-up battery close to your body and rotate it with the exposed battery when you think necessary. It would be a PITA but it should get longer run times. Not sure I would be willing to do that though, the PITA factor is a little too high for me. Another idea just popped into my head as I was sitting here. I wonder if self-contained systems have an advantage in the winter? Since the battery is connected directly with the LED/ heat sink/ light head, is it possible that the radiated heat from the heat sink bleeds off a little to the battery? If so maybe torches have an advantage in the winter that I never considered. In keeping with this line of thought, If I were a DIY'er , I might considerer building a light with the heat sink next to the batteries for winter time use..( now wouldn't that be a good idea :idea: ) While I was writing this post I did a quickie test with my MTE P-7 torch. I attached a digital thermometer to the half-way point on the torch ( close to the battery ). After about 10-15minutes the read out was around 91'F. Very close to body temperature! ( test done inside with a fan on it ) I'm not sure how this would translate over to actual winter use but it is encouraging. I guess this means when it gets cold again I'm going to have to do a run test with the torch just to compare it with more normal ride temps.
 

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Cat-man-do said:
Jim, I afraid those are the very type of warmers that I have tried. I think the problem is that they require a good supply of oxygen to work.
They do make a version specifically for use in the low O2 environment of a shoe....we spend a lot of time pulling them out of the rental boots at the ski shop :prft: But they are designed for lower heat output, so they don't burn the toes....probably not warm enough for our needs.

Cat-man-do said:
While I was writing this post I did a quickie test with my MTE P-7 torch. I attached a digital thermometer to the half-way point on the torch ( close to the battery ). After about 10-15minutes the read out was around 91'F.
Hmmm....maybe a neoprene "sock" for the torch, to retain some heat? (exactly opposite of what we're usually trying to achieve :lol: )

JZ
 

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Interesting. I wonder if the Li-ion batteries (18650's) in the torches I use are lasting well in cold temps (30's) due to the heat from the emitter being right there and keeping the battery warm???
Maybe 30 degree temps are not cold for some of you, but I am not hitting the trails at night if it drops below freezing. Brrrrrrrr!
 

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JimZinVT said:
They do make a version specifically for use in the low O2 environment of a shoe....we spend a lot of time pulling them out of the rental boots at the ski shop :prft: But they are designed for lower heat output, so they don't burn the toes....probably not warm enough for our needs.

Hmmm....maybe a neoprene "sock" for the torch, to retain some heat? (exactly opposite of what we're usually trying to achieve :lol: )

JZ
Yep, ten minutes after I made the post I was thinking the same thing....:thumbsup:

gmcttr wrote: ...It's called pipe insulation and is available in a variety of diameters at any Lowes/Home Depot/Menards, etc.
Yep, worth looking into...and then there's the ol' reliable...old inner tubing....

SkUG wrote: ..why not put the battery pack on the toasty warm light?
...Don't think that didn't cross my mind as well..:D ..The Dinotte 4cell Li-ion would sit nicely on top of my 600L. In order to make it work though you would need to have some sort of custom-made enclosure ( so the heat wouldn't just blow away ) What I need now is some sheet Neoprene and some DIY sewing skills! :D
 
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