Do rechargeable lithium-ion batteries lose charge in the cold?

[Colin H]

Do rechargeable lithium-ion batteries lose charge in the cold, or merely function poorly when cold?

In other words, if a fully-charged lithium-ion battery is stored at -15C for a week, but then warmed up well inside your clothing for an hour or two, will it last less long than if it hadn’t been stored at -15C for a week?

Of course I know that the battery will not function well when it is cold, and I have read just now from a Google search that it is not good for the health of the battery to charge it when cold.

A couple friends have told me that on multi-day trips in cold conditions it is important to keep batteries consistently warm (as opposed to simply making sure they are warm before trying to use them). While my understanding of batteries is primitive, I don’t understand why exposure to cold would cause the battery to lose charge. While I can imagine that long-term storage in cold might not be good for the life of the battery, it seems improbable to me that keeping the battery warm for 3 days of cold weather travel would make any difference compared to just letting the battery be cold in your pack, and finally sticking it deep inside your clothing a couple hours before needing to use it. My suspicion is that these friends of mine are mistaken, and going through extra hassle for no reason.

For context: I am more of a mountaineer/climber than backpacker (although a lot of “backpacking” is often involved!). I sometimes leave civilization with, for example, 3 USB-battery-sticks, 5 rechargeable headlamp batteries, an iPhone, and an inReach. For trips in consistently below-freezing temperatures, I keep my phone deep in my clothing if it is turned on, and same for the inReach. With the battery sticks and headlamp batteries I let them stay cold in my pack, and only warm them up before use. I don’t think I’m losing charge in this way, but am I wrong?

Sometimes I spend some time at a sort of “advanced base camp,” and leave a significant equipment cache there when descending, so as to hike back up with a lighter pack later. If I have a couple headlamp batteries and a battery stick that were fully-charged upon leaving civilization, and that I haven’t used at all up to that moment of descending from ABC, would it be unwise to leave them with my equipment cache? If I come back a week later, and the temperatures have been between -20C and -10C, will the batteries have somehow lost charge (more than they would have during a week of +20C)?

Thank you for any informed insight!

 

 

[Terran Terran]

Mine don’t seem to lose charge. They get down below 0*F. Probably around -20*C, if I’m right.

I have a battery (actually battery banks) on a trike that stays in the garage year round  and another that stays in the back of my truck, running a small fridge. The battery banks are just a bunch of triple A,s joined together with a battery management system. Extremely low temps may damage the BMS. They can be bought with heaters.

I think the chemistry slows down in cold weather which may affect the amperage. A cold battery may lose power faster. It’s not good to charge them in cold weather. They maintain a certain amount of heat.

[Nick Gatel]

“Do rechargeable lithium-ion batteries lose charge in the cold, or merely function poorly when cold?”

They lose capacity — that is amp-hours or watt-hours.

Also some devices cannot be charged (think iPhone) if the temperature is too low or too high. The BMS in an iPhone determines whether or not it will accept a charge. So you want to keep the device as warm as possible and increase the amount of backup capacity in really cold weather.

I have several larger LiFePo4 batteries (48AH and 300AH), which are a little different than the common small Li-ion batteries, but the importance is that Li is similar in behavior in the different kinds of Li batteries. I can use the batteries in cold weather, but they have less capacity that at normal temperatures. The BMS will not allow them to accept a charge if the temperature is under 32°F.

 

[Colin H]

Thank you for the input so far!

Nick, it is not clear to me from your reply if you are saying that the battery has a functional lowered capacity when cold and in use, or has actually lost capacity by being stored cold. Perhaps my original post was not actually worded very clearly. I am imagining 2 scenarios:

Scenario A: A battery stick rated at 3,500 mAh is fully charged indoors, at 20C. It is then placed inside your pocket (where, hypothetically, it stays at 20C), and hooked up to something at a constant output (say, an LED lantern).

Scenario B: the battery stick rated at 3,500 mAh is fully charged indoors, at 20C. It is then left outside (in a drybag) for a week of winter conditions, at say roughly -20C. It is then placed in your pocket for a couple hours, reaches a temperature of 20c, and then remains in that pocket (where, hypothetically, it stays at 20C) and is hooked up to the same LED lantern.

The question is whether the battery will cease to power the lantern after less time in Scenario B, compared to Scenario A.

In other words, I am not asking about how the battery capacity is affected when the battery is cold and in use. I am asking if exposing the battery to cold somehow lowers the capacity BEFORE the battery is in use.

Thanks!

 

 

Scenario B:

[David D]

I was curious about this a while back, and found this at the time

“The lithium batteries are also good at low temperatures but they don’t like being cold for long periods of time. If cold soaked at 5 deg F for an hour, they still have 95% of their normal capacity. Allowed to cold soak overnight they only have 50% of their capacity.”

[Jerry Adams]

You stated the question clearly at the beginning.    The distinction between A and B is confusing to us humans for some reason.  It’s also confusing, the difference between battery life and battery lifetime to use Rex’s terms.

https://www.dnkpower.com/myth-or-fact-lithium-ion-batteries-self-discharge/#:~:text=When%20a%20lithium%2Dion%20battery,or%20stored%20in%20suboptimal%20conditions.

“Lithium-ion batteries self-discharge at a rate of around 0.5-3% per month,depending on battery chemistry,enviroment,BMS etc. Strikingly, they discharge very fast while they are still fully charged. For a fully charged lithium battery or lithium cell, then it will lose 5-10% of its charge over the next month until it reaches 80% state of charge. under SOC of 30%-80%, the battery has most steady performance, around 0.5% or even less self discharging rate.

However, when you use a lithium-ion battery at low temperature or high temperature, it will discharge at a much higher rate. You can feel if your phone get hot, it dies quickly. like said previously,You can expect the self-discharge to typically double for every 10C rise.This is because a lithium-ion battery will fast discharge when it comes out of it’s best performing enviroment of 5-45°C degree. So, This means that if your device or battery temperature is too high or too low, the battery dies extremely fast.”

reading that entire page, it was a little confusing to me whether they were talking about A or B

I think they pretty clearly said that storing battery at high temperature will increase self discharge.  I’m not sure about cold temperature, but if so, not as much as high temperature.

I think more significant is a battery quickly loses charge until it gets down to 80%.  Is that better or worse at cold temperature???  If it was worse at cold temp, then it would more quickly get to 80% but then discharge more slowly.

Some other things about temperature you didn’t ask about:

I tried to turn my phone on once when it was much below 32F but it wouldn’t power up, displayed a message saying it’s too cold.  So I put it in inside pocket and just left it there when I wasn’t looking at it and used phone without problem.

Charging is more sensitive to cold.  You lose efficiency below 50F.  Below 32F you can permanently damage the battery.  A phone would protect you from this and just not turn on at 32F.

If you operate the battery at temperatures approaching 32F, and the phone lets you, the battery will run down faster.  Keep it in an inside pocket.

If you operate the battery at higher temps, the battery will run down even faster than cold temps.

Hmmm… one could do an experiment – charge a battery, wait one month, discharge using a power meter to see how many Wh it has.  Repeat, storing it in the freezer for that one month.

[Terran Terran]

https://www.canbat.com/how-to-store-lifepo4-batteries/

[Jerry Adams]

That’s for LIFEPO4 batteries intended for RVs.  Might be different than phone and USB power banks and …

They say :

Recommended storage temperature: -5 to +35°C (23 to 95 °F)
Storage up to 1 month: -20 to +60°C (4 to 140 °F)
Storage up to 3 month: -10 to +35°C (14 to 95 °F)
Extended storage time: +15 to +35°C (59 to 95 °F)

But they don’t say why.  And they say the discharge rate is 2% per month which is different than the 0.5% given in that other source.

This whole subject is confusing with contradictory or confusing information

[Sam Farrington]

Use of Petzl Core batteries during all months in the year has not produced any noticeable declines in winter more than in summer.  However, you may be correct with respect to measuring some greater decline in the winter.  In all seasons, it has been sometimes necessary to recharge, and in use for over a week even in the summer, a second Core battery, fully charged, is carried separately in a small case.

Granted, this has not been the case with other Li batteries, which have sometimes left me in the dark at awkward and dangerous times.  And note that the lamps are usually turned off when sleeping, and not used much in daylight.  Once in a while, planning fails, and the headlamps need to be used for meals.  Again, this is so infrequent as to have no noticeable effect.  For long distance hikers in the winter, or with extended peak bagging for weeks, it is no doubt a different story.

[Jan Rezac]

That’s an interesting question, I’d like to know the answer too.

The cold temperature must only slow down the chemical processes in the battery, so the self discharge should be even lower than at higher temperatures. On the other hand, the cold can possibly cause other issues I’m not aware of. Maybe the electrolyte can freeze and change the structure irreversibly?

It would be, however, easy to test experimentally at home. Just put a battery bank in a freezer for a week, warm it up and measure how much charge it delivers to a phone.

[JayC]

I live in a very cold place, and have not noticed any of my Lithium Ion USB batteries losing much of their charge when stored at pretty cold temps – -20f to sub -40f.  I have had Lithium Ion USB batteries on long winter trips, and so long as they are warmed up before using them I haven’t noticed any degradation in their charging or any noticeable loss of charge.  I wouldn’t expect this to be a big deal, but YMMV.

[Steve S]

Some lights have real on-off switches, while others have microprocessors waiting for a signal. I have a headlight in my car for occasional use. I quickly learned to place a piece of stiff paper under a battery contact.

I don’t have a basis for comparing summer and winter rates of drain, but I suspect it would be higher under cold winter conditions.

[Nick Gatel]

Nick, it is not clear to me from your reply if you are saying that the battery has a functional lowered capacity when cold and in use, or has actually lost capacity by being stored cold. Perhaps my original post was not actually worded very clearly.

Its capacity is lower when used in cold weather. A fully charged battery will have X amount of energy stored in it at room temperature. Take it out into really cold weather and will have less capacity — that is it will deliver less energy (watt-hours or amp-hours).

I’m not a scientist but a field guy with experience. From what I have read, the lithium ions move around much slower in cold weather, thus reducing capacity — think of all those Teslas in winter weather with greatly reduced mileage range when it gets cold.

[Terran Terran]

A lithium battery will produce a small amount of heat. For extreme conditions, they have self heating batteries.

[Jerry Adams]

I did an experiment with a Brunton Lithium Polymer battery.  Kind of an obscure one, possibly different than other lithium batteries, but I don’t normally use it so it was available for an experiment.

Charged, immediately discharged with 1 amp load, produced 9.28 Wh according to one of those USB meters Rex mentioned.

Charged, stored for 12 days in the freezer (nominally 0 F), discharged – 9.06 Wh – so it lost 2.4% of it’s charge.

Charged, stored for 12 days at room temp (nominally 72 F), discharged – 8.82 Wh – so it lost 5% of it’s charge.

So, the answer is, it actually loses less charge if it’s stored cold.

One experiment, weird lithium battery, no check to see if it’s repeatable or just random variation from test to test…

[David D]

Hey Jerry, thanks for testing this.  Was the test in the cold?  LI performance worsens when used in cold, vs stored in cold and used room temp.  Estimates from cars is about 10% reduction but batteries in our gear will differ +/- depending on chemistry and construction, and storage effects are temporary:

https://www.recurrentauto.com/research/how-temperature-affects-ev-range

[Jerry Adams]

I discharged at room temp for all three tests, just trying to answer the original question, does the temperature of storage make any difference

[Jerry Adams]

I always try to look at data from observations that go beyond the original question

If I lose 5% of capacity in 12 days, then it would make sense to charge a battery within a few days of a trip if the battery has just barely enough capacity for that trip

I normally charge up a battery when I get back from a trip, and then maybe it’ll be a few weeks before my next trip, at which point it could be down 10% or even more.  If I do that, I should charge it back up just before the trip

[Steve S]

Jerry, how long after the battery was removed from the freezer did you start the discharge test? Was the battery at ambient temperature when the test started?

[Jerry Adams]

yes.  I waited a couple hours, pretty sure it was warmed up

and, if I didn’t it would have produced less power so it would have appeared to lose more power, but it was less

 

[Eric Blumensaadt]

I have a BLUETTI AC200 MAX LiFePO4 “solar” battery I use car camping to charge my 2 wheel drive (yep) 2 battery e-mountain bike. I

In turn the BLUETTI is charged by a roof mounted 220 watt Off Grid TREK solar blanket (from Canada,

BTW). Yes, together the “system” cost was eye watering but hey, I can use it in home black outs – or so I tell my wife.

So I have 3 large lithium batteries to keep in the 90% charge range but my garage seldom gets below 32 F. so I’m not concerned about their “health”.  Yeah, the E-MTB does not get quite the normal range on cold days but I lose only about 10% of normal 60 mile range, whether its the 60 mile range on paved roads or the 35 mile range on rough mountain trails. That’s in the high 30s F. to hight 40s F.

[Nick Gatel]

So I have 3 large lithium batteries to keep in the 90% charge range but my garage seldom gets below 32 F. so I’m not concerned about their “health”.  Yeah, the E-MTB does not get quite the normal range on cold days but I lose only about 10% of normal 60 mile range, whether its the 60 mile range on paved roads or the 35  mile range on rough mountain trails. That’s in the high 30s F. to hight 40s F.

This sounds about right. Li batteries, from what I have read, lose 5% to 10% of their capacity in colder weather. So it one had a 10 watt-hour battery it could run a 1 watt device for 10 hours at room temperature. In cold weather the battery could only run the device for 9 hours. Lead-acid is more like 20% loss in cold weather. But you can charge them in cold weather, whereas most Li batteries cannot be charged below 32° F unless you are using a self-heating  LiFePo4battery.

Also there are several kinds of Li-ion batteries. They all contain lithium but use other minerals in the construction. Some are safer than others. LiFePo4 batteries aren’t as dense as other types, thus fairly safe and mostly used for larger static installations, like RVs.

Years ago, when Eveready started making Lithium AA batteries, I switch from alkaline for my headlamps and have been very satisfied with the cold weather use.

[David D]

The battery efficiency reduces the available power (Wh, mAh) that can be drawn from battery when compared to the power rating thats stated on the device, which is the charge needed to fill it.

Devices range in efficiency from about 65% (lower cost Ankers) to closer to 90% (claimed) for pricy batteries. The spec can usually be found with some digging but it’s the industry’s dirty little secret.

[Todd T]

This whole question wouldn’t even come up if the industry used sensible terminology.  As David D alludes, the subject batteries don’t really lose capacity in the cold, they lose efficiency.  (To nitpick David, though, Wh and mAh are not measures of power but of energy [or proportional thereto].)

[David D]

I’ve been doing a lot of research to pick out a new headlamp for very cold temps, and looked into battery capacities vs temp again.  Manufacturer’s rarely spec their performance below freezing, but after a long investigation, I’m pretty confident these are in the ballpark:

• Disposable Eveready lithiums (available in AAA, AA, CR123A) are the most-cold tolerant but expensive.   ~ 75% rated capacity at -20C @ 1amp draw
• Li-Ion are the next best for cold, ~ 60% rated capacity at -10C, 50% rated capacity at -20C, ~ 25% rated capacity @ -40C
• NiMH are not good in cold, ~ 80% rated capacity at 0C, 20% rated capacity at -20C. My experience with the Energizer NiMHs is in line with this
• Alkalines aren’t recommended below freezing

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