Do cold temps affect batteries?
 

As we all know, low temperatures are generally bad for batteries. Has anybody else noticed?
Today, I did a short ride @ 27degF. My headlight started to get drained @ 15 miles, where it usually last almost 25 to get drained.

You are answering your own question. Nothing to add except Yes.

One more, yes, if they are lithium-ion batteries, especially. Lithium is affected by cold temperature.

Depending on the type of batteries, yes there are limit of various sorts. Some you shouldn't charge until they get to a certain temperature if you were operating them in colder temps. And many batteries will deplete quicker as the temperatures go down.

Find the manual for your lights and anything else that uses a battery. In the spec's they probably list those temperatures.

Yes. And dynamo lights are not affected by temperature, as far as I have noticed.

Most people, when they try dynamo lights, ask themselves why they didn't try them sooner.

Yep.
cold causes battery life shrinkage.

I have a Cygolite Hotshot Pro tail light. I get three 20-miles rides out of one charge when it is warm, but only two in the cold.

Mark

You should not charge Li Ion batteries below freezing temperature. But I suspect your light warmed up pretty fast when you got it inside, so it was probably warm enough to charge once you started charging it.

I am surprised the light had roughly 60 percent performance (15/25 miles) at below freezing. I would have expected less than 50 percent.

If you have your phone on during that time and if your phone is not kept warm, if it was running apps and had the screen on, that battery drains fast too.

You can find this info from the manufacturer's web sites. For instance, on the data sheet for the Panasonic 18650 lithium ion battery, you can see that the capacity is reduced at -10C relative to room temperature...


https://cimg0.ibsrv.net/gimg/bikefor...302eb2ea46.jpg

Also note that the terminal voltage decreases with temperature too. If the light cuts off at a certain battery temperature, it will cut off quite a bit earlier in cold temperatures.

Steve in Peoria

I have integrated dynamo, lights, and lithium batteries integrated systems that run year-round, one of them a decade presumably now. They do fine, and that decade-old powers a horn that draws far more current than lights.

Maybe your batteries are just beating the odds. Or maybe they have an internal temperature probe that blocks them from charging when it is sub freezing. I am not a battery engineer, all I can do is relay what I have heard.

I called Peter White a few years back and asked if there was a problem using my B&M Luxos U (now discontinued) headlamp in sub freezing temperatures. If you are not aware, that dyno powered headlight has a pair of built in Li Ion batteries. He said he had never heard that about Li Ion batteries and sub freezing temperatures, so he suggested I would have no problem. But I chose to unplug my dynohub whenever I rode that bike in subfreezing temperatures anyway.

The battery manufacturers are pretty clear and consistent about how they want their lithium-ion batteries treated, and they publish their recommendations on their web sites. This is what Panasonic said when I last checked:


https://cimg9.ibsrv.net/gimg/bikefor...282dd9ceb5.jpg

For this discussion, the key points are that you shouldn't charge them below 10 degrees C, and shouldn't discharge them below -10C.
-10C is 14 degrees F, which is as cold as most(?) cyclists will ride, so it's probably not a big impediment.

For things like standlights, which will be getting charged when the bike is ridden in the cold, it's probably best to use a super capacitor instead of a lithium-ion battery. Interestingly, NiCad batteries are much more tolerant of charging in very cold temperatures, which is what I use in my home-built dynamo lights. Nicads are pretty nearly impossible to buy now, so I expect to switch to supercaps for any future work.

Steve in Peoria (where is it is currently below 0F)

Obviously, there are lithium batteries for cars, and these must tolerate low temperatures, so the technology is there. If you Google around, you can find low-T versions in 18650 such as here.

do they publish any sort of datasheet with performance data or charts?

Steve in Peoria

There are many more offers from the manufacturers than retailers, and it is easier to find any charts with the former, such as here. However, there are now new lithium titanate (LTO) batteries, with specs here, and available cheaply at AliExpress. I think I will swap my current batteries for these in the system of my own construction.

If you are knowledgeable on this sort of thing, do you have any thoughts on NiMH batteries for cold weather?

I use a lot of those for a variety of things. But rarely use them below freezing.

My niece bought a Tesla a few years ago, just before covid. My niece's hubby was telling me that they get very poor "mileage" in winter because there is an internal battery heater that keeps the battery warm in cold weather. He is talking about Portland OR to put "cold" weather into perspective. When I have been there in winter, it was in the 20s and 30s (F) for temps.

I have read that Tesla is switching to a heat pump instead of battery heaters, as it is more energy efficient for maintaining battery temperatures.

But, I do not have an EV, so I can't say any more on the topic. More than half of my miles are long distance trips of several hundred miles, the charging networks are not well enough established for me to consider an EV yet.

Here's the datasheet for the Panasonic AA NiMH.
and one for the Energizer AA NiMH.

For my use in standlights, NiMH doesn't look like a good choice because the manufacturers only provide specs for charging at or above 0C. They are a bit more particular than nicads in terms of continuous charging, but that's not hard to accommodate.

As for discharge characteristics, Panasonic does have specs for temperatures down to -10C. No graphs or info on how much the capacity is reduced, though.
Energizer only specs discharge down to 0C, so I don't know if they are being conservative or if their batteries are less suited for cold than Panasonic. The datasheet does include the admonition "NOTE: Operating at extreme temperatures will significantly impact battery cycle life".

Energizer does provide more generalized info on NiMH batteries in their NiMH Handbook.

In general, all batteries operate by the use of chemical reactions to generate electron flow. Chemical reactions occur slower in cold temperatures than in warm, so it's to be expected that performance will drop when things cool off. Super capacitors offer better performance in the cold (although I haven't checked the datasheet...), but have to be much, much larger to provide an equivalent amount of energy.

Steve in Peoria

Thanks.

FYI - I prefer rechargeable batteries, thus I am not considering buying Lithium AA or AAA batteries. But, my camera owners manual specifically says for cold weather use Lithium AA batteries. And suggests having a spare set that is in a warm pocket. So, if I needed to have working batteries in very cold weather, I would try those out. My camera uses Li Ion batteries, but has an optional adapter to use AA batteries.

I switched to dyno on my fatbike after I had 2 hotshot taillights die on my 7 mile commute. It was 5F though.
It's possible I left one on the bike all day, don't recall.

I used to have a Canon point & shoot camera that used two AAs. When I used nimh AA's, it would quickly shut down in cold weather. My newer Canon Powershot p&s uses a proprietary lithium battery and it seems to tolerate cold temperatures quite well. A typical scenario is when I'm out on XC skis....

https://live.staticflickr.com/65535/...38c693_c_d.jpg

I'm not sure if the lithium performs better than NiMH, or if the difference is due to the lithium having a nominal voltage of 3.7V versus the nominal 2.4V of the two AA NiMH of my earlier Canon. I suspect both used similar technology circuitry that had similar minimum voltage requirements.

I do like the idea of having a AA adapter for a camera! It would be nice to have a cheap alternate power source when needed. ...although... I imagine that the adapter costs about as much as a spare lithium battery?

Steve in Peoria

Rechargeable Lithium (Li Ion) cells don't really like cold weather. Ask any EV owner living in a cold climate.

Lithium "Primary" cells (non-rechargeable) are a great option in cold weather.

All the best

Barry

It was a night-to-day change in winter for my bike power circuit when I swapped 5 NiMH batteries for 2 LiPo, I think, and this was not due to the nominal voltage as lights were operating well enough even when undervolted by 1V or so. I was worried I would blow my circuitry at the nominal 7.4V as it was a drop-in swap. However, all went well. With NiMH, the winter standlight operation was worse than a capacitor backup. With LiPo I can go on for hours in winter w/o the dynamo and honk w/o lights dimming. I chose LiPo over Li-ion due to its flatter discharge curve in my memory.

Count me as one of those people. I think it was 2016 or so when I got my first Dynamo but I first looked at them back in 2011-2012 and said "nah too heavy, too this, too that". Silly me. Now with the Supernova M99 Pro DY light I have essentially a car headlight with high beam ability powered by my front wheel moving from my pedaling is there anything better? Granted the light isn't installed yet but soon will be

My spouse bought a 2023 Tesla in August of 2023. The cabin heater is a heat pump. The car heats and cools the battery automatically, and it will preheat the battery before we drive if we tell it we are going to drive it. I don't know if it uses the heat pump to warm the battery. It also cools or warms the battery when we charge, depending on the conditions.

So with extra machinery and software, you can use these batteries in cold weather, but all of that comes at a cost. It's not a cost that makes sense for a bicycle light.

I was really surprised when my niece's hubby told me how much worse their Tesla performed for "mileage" in near freezing temperatures compared to normal temperatures, but for them the car works great as a primary commuter. They have a gas car too for longer trips. I think the one with the short commute drives the gas car, the longer commuter drives the EV. But longer trips, they tried that once in the Tesla and had trouble getting it charged without spending a lot of time and effort to do so.

I am retired, so no commuting. I average about 4000 miles a year in a vehicle, buying any vehicle that is new makes no sense, the warranty would end before the oil needs changing. And more than half my vehicle miles are on trips of several hundreds of miles, so an EV makes no sense for me. Most of my in town trips are on a bicycle. (Exception, as I type this it is minus 9 degrees (F) outside, not biking anywhere this week, we had something like 20 inches of snow last week.) I do not have a heated garage to store an EV with it's battery inside in this kind of weather. The 19 year old Volvo will do for my dentist appt today.

[MENTION=203914]Tourist in MSN[/MENTION], my spouse owned two cars, a Prius for commuting and a Honda Element for hauling. They died about a month apart. She replaced both with the Tesla. It's big enough for hauling construction supplies, but it's not as convenient for hauling bikes as the Element. I'll eventually get a bike rack. I don't plan to buy any motor vehicles. Maybe in the next year or two, I'll get an e-bike.

Anyway, electric cars aren't for everyone, but it's working out well for us. The car is never inside. It's disappointing to see the battery drain when it's not even being driven, especially in the cold, but everything has its downsides and cost of doing business. I've heard maintenance costs on this car are not actually low: the tires are expensive, and she already damaged one and needed to replace it. I hear body work is super expensive. But fuel costs, even in the cold, are lower than a gas car. We have a hookup on our barn at our weekend house, so we "fill up" there cheaply. We have solar panels, so electric costs are quite low there. But that's 95 miles from our home in the City. She's found that Tesla Supercharger stations work well for her when she's en route somewhere, usually in New Jersey. I think they charge up to 40 cents per kwh. Charging in Manhattan is stupidly expensive for the energy, and they charge for parking, too. Lucky for my spouse that she doesn't need to charge in Manhattan.

Last night, we drove from the weekend house to our apartment in Manhattan. It was about 24ºF. We went from 91% charged to 46%, and that's worse than usual, but we can live with it since it's really not expensive. The battery is 75 kwh in theory. One cool thing is that when we plot the trip on the navigator, it estimates the amount of energy left in the battery at the end of the trip. It is extremely accurate. When we set off, it estimated 46%, and that' was exactly the result.

It might work a heck of a lot worse in lower temperatures.

Teslas are becoming viable for an increasing number of people, partly because of the extensive charging network. I see taxis in the City that are Teslas. Taxi drivers wouldn't be driving them if they didn't make economic sense.

I do not disagree with anything you said.

I used to work with a co-worker that had a long commute, much on a freeway with a Prius, she claimed about 50 miles to the gallon in summer but only about 35 in winter.

I suggested to my sister that she get a EV when the rebates got really good. She never drove more than 40 or 50 miles per day, no long distances. She did not listen to me, she bought a Subaru EV (made by Toyota) that had no incentives because it was made in Japan. But she loves it. Her kids told her to get Tesla instead, but I am glad she did not. I am hearing that Tesla repairs after the warranty is up are really costly. Other brands (Ford, GM, Toyota, etc.), have lots of aftermarket body parts and other parts available for them from lower cost manufacturers, but it is my understanding that Tesla is the only source for parts. If I am incorrect on that, please correct me.

On parts, for a quick example, I had a Land Rover D2. My OBD2 code reader suggested that I needed a new part under the hood. On one of the internet forums, someone was saying do not buy the Land Rover part, and do not buy the cheaper aftermarket part from a Land Rover supplier. Instead buy this part for a Hyundai from Amazon, it is the same part. I bought the $25 part from Amazon instead of the $100 aftermarket part or the $200 Land Rover part, and it was identical, worked great.

In my community, the taxi company that I usually used when I needed a ride was one that used Prius cars, and those Prius cars had a bike rack on the back of them. Last time I took a taxi was to and from the airport for my 2019 bike tour, my S&S case (with bike) and a checked bag fit in the Prius trunk, along with the carry on bag. A few years ago they switched to Teslas but soon after that they went out of business. I suspect a big part of that was covid. I do not know if the switch to Teslas was part of that or not, that was at about the same time. I am sure that Uber was part of that too, as somehow Uber escaped the same kinds of regulations that a taxi company had.

We are way off topic here, if we continue we should do private messages.

Wife and I have been using EV's for running around town and commuting for 9+ years.
During most of that time the manufacturers were over estimating the residual lease value, meaning an EV lease could be as low as $150/month, (for 3yr, 15k/yr).

We saved a bunch of money and thoroughly enjoy EVs.

"Anyway, electric cars aren't for everyone, but it's working out well for us. " :thumb:

Barry

Shrinkage in the cold! Last weekend we spent 30 hours with no power and 10F temps starting with arctic wins. Shrinkage could not be verified because we all wore way too many layers! Outdoors, indoors and in bed.

And seriously, the batteries I've been using for bike lights since they first came out are the DuraCells. I haven't ever done tests but have found through experience that even in very cold weather I get decent light life and almost always one last ride on a light that is dying unlike just about every other alkaline I've use that after the previous ride simply didn't work. But - that was with the old "stupid" batteries, The new smart ones need their full voltage for the computers to work. (This seems to go for just about everything digital. I have a box of DuraCells with 2/3ds to 3/4s of a charge according to my battery check that work just fine for the old flashlights for a little while.)

This observation about the DuraCells applies to the AAA, AA, C and Ds. I don't think it applies to the coin size batteries like the 2032s.