Batteries in the cold
 

I know this is an electronic/lighting question and there's a forum for that there's more traffic here so I'll ask it here.

The last couple of mornings it's been like -14, -17*C. The battery life on my rechargeable lights--all of them, as well as my camera, have been shortened considerably. The funny thing is once I got into work and they've had time to warm up they continued to work, and even the low-charge warning signals stopped flashing. The camera--same thing.

So what gives? Is this normal and is just accepted? What can be done to mitigate, if anything?

I've noticed the same with my Bright Eyes head light, the tail light doesn't seem to effect it. In the winter it only last 4 days versus 5 in the summer.

Yes, it's completely normal. Most if not all chemical reactions slow as temperatures drop. This includes batteries. It's one reason cars are harder to start in bitter cold.

If you do a net search for something like cold battery performance you find tons of info.

Ahh, that sucks!:mad:

Batteries are powered by chemical reactions. Cold temperature slows the rate of those reactions, and can raise or lower internal resistance depending on the battery type and design. This can lead to low voltage and higher or lower than normal discharge. So then, further depending on your battery and its circuitry and the programming used to ascertain its status...it's a crap shoot.

But generally speaking, cold weather diminished battery performance.

I ride down to 10F and I don't notice it so much in my current lighting set-up which is LEDs and Lithium batteries, both rechargeable and single use), but I do notice it in my phone, which is also lithium battery powered, but I usually carry it in a holster on my hip. I don't know if the cold reduces the charge as much as it says, or if the circuitry is fooled by some other temperature related issues. Either way, when the phone goes into low battery mode out in the cold on a commute, it usually returns to normal as it warms up.

In the old days my main headlight was a halogen bulb driven by a rechargeable lead-acid battery. That battery was definitely affected by the cold. And my cellphone...well, I didn't have one until 1997.

So, I was right to bring my charger to work today. It is -26C/-15F this morning. I'll let the battery warm up over the next hour or so, then charge it.

You may not need to charge it, just bringing it into the office will warm it up so it'll have more power available when you start home.


In the normal course of things, I replaced several of my extra blinkies this year. It's getting harder to find decent lights that at least pretend to be weather resistant, so I've got at least one rechargeable blinkie on each commuting bike. I've already found it more of a hassle to take each one off the bike, bring it in, and recharge it weekly, as opposed to tossing a couple new alkalines in every 4-6 weeks. Not looking forward to finding out what really cold weather is going to do to the rechargeables.


Of course, my primary dyno lights just keep going, and going, and going...

My lights on my studded tire bike go in my pocket until I need them.. (here it has not snowed , on the coast at sea level ,

( but it is icy on the passes over the Coast range [1600 feet on US 26] I don't live there but we have to go over that, or US 30 to PDX..)



Mountaineering head/helmet lights have long cords so you have the batteries warmed by your body heat

keeping them in a pocket, under your parka.





.....

Not a bad idea to just buy another charger and leave it at work. :thumb:

In winter, I generally bring battery lights indoors when I'm not riding, just so they will work better (at least until they cool back down to the ambient temp.) I'm eager to build up a dyno wheel for my fixed-gear (primary commuter) so that I will have fewer battery lights to futz with. :)

+1,

Also consider that batteries produce a bit of heat as they discharge. So if you insulate them with something like bubble wrap, and store them indoors, they may stay warm enough to function well all the way home.

If you opt for some kind of full time insulation of the battery case, don't forget that it might make sense to remove it in the Spring.

I'm not as smart as you think, I only have the one charger for this type of battery (a block of 4 18650s). Normally, I can get 3 weeks out of a charge but it has been 2 weeks, 1 week of commuting (last week) and most of this week in the garage (lows of -15C/5F to this morning's -26C/-15F) so I decided to check the battery condition today for this afternoon's ride home in dusk and nearly dark conditions.

I've wondered about the few Tesla owners here in town: the closest major city to us (Toronto) is 4hrs/380km south and it would not be surprising if these owners would want to go there every once in a while or more often. The reported range is 400km so with either heater or A/C on at different times of the year, I don't know how they would do it (in their Teslas). About 2hrs south of us is a small town of Parry Sound that a lot of people will stop at as a halfway point but I'm not aware of any charging stations there (but then, without a Tesla myself, I don't really need to know).

I store my bike in the mudroom. The temperature in there over night is probably around -10 if the temperature outside is -17 like it was this morning, so I was behind the eight ball already even before leaving the house.

My lights, and camera, all use the universal USB chargers, so no problem finding those. I've got five outlets attached to my computer for just such a purpose.

I was surprised my bike light was always low on power lately, when commuting back. Then it hit me...

My commute is about 30 minutes. However, last few winter days that average became something like between 1 1/4 and 1 1/2 hours due to really bad road conditions. So I thought I was commuting 30 minutes while in reality it was of course much longer! Had too much fun :-)

Yes, this is another argument in favor of dynamo lights. Of course, they're not perfect, and they're not for everyone, but I love mine. They've proven to be more reliable than I expected them to be.

I've never had a problem with Lithium. It is cold resistant (unlike other battery types that just quit working at those temperatures).

My batteries are either inside or in the garage, so they are well within their normal operating temperature when I start out, then they do generate their own heat and do fine when using them.

As far as cars go, I did find that I lost 30% range in the winter, which is significant. Part of that is just keeping the car warm. I can't say that I have noticed a decreased range for my bike stuff, but I don't tend to stay out quite as long when it is well below freezing, so it hasn't been an issue.

And yeah, those temperatures (-17c) are pretty extreme for a battery.

Other known workarounds include moving away from the frozen tundra.

Its colder on your side of the hill than on the coast.. (just through there Monday)...

Shrinkage happens to batteries too. Letting the batteries warm up before charging is a good idea, it allows for longer lifespan of the batteries too.

Now you tell me! :mad: I took it off right when I got home and plugged it in.

used to wrap my magicshine battery in bubble wrap & stuff it in a water bottle, covered it w a plastic sandwich bag & secured w two rubber bands. wire just went out down the side then up to the light. probably only need steady-on setting for one of the trips & light enough outside for the strobe setting which uses less power?

https://www.bikeforums.net/attachmen...6&d=1264590735

Well, yes but,... typical use case for a motor vehicle, which is taken into account at the design stage, is not only the battery but the entire drivetrain must be functional when conditioned down to -40 degrees (assuming all components are within their operational spec limits).
That means the battery must be able to crank the engine over, and the ignition (and electronic fuel system, considering vehicles produced in the last 4 decades), must be able to function at a level sufficient to start the engine.
This becomes tricky when the battery is impaired by the cold, at the same time the lube oil is tending to congeal, resulting in very slow cranking and severe voltage dips on each compression stroke. BITD when I was involved in this stuff, that meant the ignition and fuel had to function down to 6 volts (in the case of a 12 volt system).

Great info, thanks. I don't think most people (not talking about people in this forum, but in the general public) realize how well cars start these days.

Tell that to my Iphone. Had a soccer game last night. Left the office at 100% charge, and after riding to the field still had something in the 90's (It was in my pocket, under a couple of layers). During the game it was basically sitting out, and I think it was probably around 30F (-1 or -1C), for the hour long game. When I went to check it afterward, it showed a whopping 1%.

Got home and plugged it in, and it began charging from 93%, sooo... maybe it's just reading 1%, because of the cold, but it could maintain that 1% for a long, long time?

Up in deer camp last month when my Iphone was in the pack all day I tried to charge it in the car and got a "too cold to charge" message. I had to stuff it in a mitten with a hand warmer to even charge it.


In the late fall and winter I bring my battery inside the house at night to stay warm. My helmet too after the first few times I put on a cold helmet and start remembering to bring it in.

was reading safety warnings for a car battery charger I got yesterday. one of the warnings was never charge a frozen battery. they didn't say why but there's probably a good reason. was gonna take it out of my kids car, bring it inside to charge it overnite. but the warnings about gas clouds & explosions, etc had me doubting the idea. eventually my mechanic said he'd go check it out & it was probably the starter anyway