OK to keep batteries in Refrigerator?

[JAW]

According to lesson BU-808 at Battery University ( 25 C = 77 F) the biggest advantage of low temp storage occurs if you store batteries that are fully charged. Batteries stored at a 40% charge show little advantage in storage at low temperatures.
(Pasted from How to Prolong Lithium-based Batteries - Battery University)

Lithium-ion suffers from stress when exposed to heat, so does keeping a cell at a high charge voltage. A battery dwelling above 30°C (86°F) is considered elevated temperature and for most Li-ion a voltage above 4.10V/cell is deemed as high voltage. Exposing the battery to high temperature and dwelling in a full state-of-charge for an extended time can be more stressful than cycling. Table 3 demonstrates capacity loss as a function of temperature and SoC.

Temperature​	40% charge​	100% charge​	Table 3: Estimated recoverable capacity when storing Li-ion for one year at various temperatures. Elevated temperature hastens permanent capacity loss. Not all Li-ion systems behave the same.
0°C	98% (after 1 year)	94% (after 1 year)
25°C	96% (after 1 year)	80% (after 1 year)
40°C	85% (after 1 year)	65% (after 1 year)
60°C	75% (after 1 year)	60% (after 3 months)

 

[WithTheBirds]

[Edited by Moderator]Water damage will occur if you STORE batteries in the fridge. No myth here. If humidity dew point is hit, there will be water condensation. you can't tell when/where that will happen, so its BEST practice NOT TO DO SO. and to add, you prob can't acclimate properly for many situations. Your comment is negligent.

Your seemingly misunderstood what I wrote.

I am not suggesting condensation won't form, it probably will. I am saying that your fear of damage is without basis as any condensation that forms will have low dissolved solids. Corrosion and conductive path issues (the things you might have a legitimate concern about) are of negligible potential consequence.

Acclimatisation will happen by itself in all situations. No idea what your point might be here.....

 

[johnmeyer]

There is so much misinformation and conflicting views on this thread.

No kidding.

Around 5 degrees and at circa 3.86v per cell is the PERFECT condition to store lithium polymer packs. - So yes, in a fridge is absolutely the best place.

Yup.

These guys probably have forgotten more than any of us will ever know about battery chemistry....

How to Prolong Lithium-based Batteries - Battery University

Discover what causes Li-ion to age and what the battery user can do to prolong its life

batteryuniversity.com

I'm an EE, and have always found the information at that site to be spot on. Key pull quotes from that site:

"The worst situation is keeping a fully charged battery at elevated temperatures. "​

​

"The recommended storage temperature for most batteries is 15°C (59°F)."​

​

"The self-discharge of all battery chemistries increases at higher temperature, and the rate typically doubles with every 10°C (18°F). A noticeable energy loss occurs if a battery is left in a hot vehicle. High cycle count and aging also increase self-discharge of all systems"​

​

"Under normal circumstances the self-discharge of Li-ion is reasonably steady throughout its service life; however, full state-of-charge and elevated temperature cause an increase. These same factors also affect longevity."​

This graph comes from that site:

As you can see, the temps found in a typical refrigerator (about 36-42 degrees) are perfect for maintaining the charge and extending the life.

 

[WithTheBirds]

No kidding.
Yup.I'm an EE, and have always found the information at that site to be spot on. Key pull quotes from that site:

"The worst situation is keeping a fully charged battery at elevated temperatures. "​

​

"The recommended storage temperature for most batteries is 15°C (59°F)."​

​

"The self-discharge of all battery chemistries increases at higher temperature, and the rate typically doubles with every 10°C (18°F). A noticeable energy loss occurs if a battery is left in a hot vehicle. High cycle count and aging also increase self-discharge of all systems"​

​

"Under normal circumstances the self-discharge of Li-ion is reasonably steady throughout its service life; however, full state-of-charge and elevated temperature cause an increase. These same factors also affect longevity."​

This graph comes from that site:

As you can see, the temps found in a typical refrigerator (about 36-42 degrees) are perfect for maintaining the charge and extending the life.

I have a suspicion (based only on subjective observation) that while temp dependent capacity loss is a real concern it may not apply to the degree suggested by those numbers.

As with most things LiION chemistry has gradually improved. Quality cells in recent times seem to hold up significantly better than when they first entered the RC hobby.

 

[Saigondroner]

I have always kept batteries in the fridge. This includes all chemistries, and both primary and rechargeable.

Most condensation issues happens when you take them out, and not when you put them in. Minimizing (or eliminating) condensation is simple: put each battery in a well-sealed plastic bag. If you have a vacuum machine, vacuum pack, but don't let the vacuum go all the way or you could crack the case. You simply want to get rid of air pockets. The sealing and the removal of most of the air reduces to near-zero the amount of moisture that might condense.

Then, when you take them out, let the unopened battery and bag warm to room temperature for 2-3 hours. You'll get lots of condensation on the outside of the bag (if it is warm and humid), but not on the inside.

Resist the temptation to artificially warm it up, and don't open the bag until the package feels like it is up to room temperature.

You can use a point 'n shoot IR thermometer to make sure of the temperature.

Amen! My guess is the fridge in AZ is more humid than outside. SEA is opposite. I have to place a cold bottle of water on a kitchen towel overnight, or risk slight water damage.

 

[gnirtS]

Store in a cool dry place.

In the tropics, the fridge is often the ONLY cool dry place availabe.

 

[BerndM]

I have no idea what the battery colors are on some of these drones, or even if they are mounted on top or below the drone's body, BUT could there possibly be ANY cooling advantage to top mounted dark gray batteries like on the Mavic pro or mavic 2 variety by spray painting their tops in a shiny "chrome" color to reflect as much sun as possible.
Maybe it would help some, maybe it won't. I have no idea. Just a thought.

 

[ElectroBald]

As most of us know, Li Po batteries HATE high temperatures. Here in Arizona, it's almost impossible to fly during most of the day. I keep my batteries in an ice box when I'm flying away from home, or the refrigerator (40° F) when I'm flying at the house. Anyone have thoughts about harmful effects from keeping the batteries a LOT colder than ambient temperature just prior to flight? It just keeps the battery at the end of the flight at a much safer temp.

This is an old myth from the 70s, you will do more damage to you batteries than good.

 

[WithTheBirds]

This is an old myth from the 70s, you will do more damage to you batteries than good.

Your opinion here has no basis in fact. The contribution of increasing ambient temperature to accelerated LiON chemistry aging (specifically increased IR and reduced usable capacity) is well understood and demonstrated.

To the extent you might hope too persevere with your assertion some evidence would prove helpful.

Btw- from my recollection the first LiPO packs didn't enter the RC hobby in any significant way until the mid/late 90's.

 

[ElectroBald]

Your opinion here has no basis in fact. The contribution of increasing ambient temperature to accelerated LiON chemistry aging (specifically increased IR and reduced usable capacity) is well understood and demonstrated.

To the extent you might hope too persevere with your assertion some evidence would prove helpful.

Btw- from my recollection the first LiPO packs didn't enter the RC hobby in any significant way until the mid/late 90's.

I’m not starting to argue with you on this as I have been working in electronics for more than 35 years, and yes I was there in the 70s. freezing batteries has been a discussion (any batteries for that matter) since, and no good has been coming out from any research, unless you work with super-conductor power cell, which is another area. When LiThium-Polymer batteries gets below 10 degrees Celsius, they start to lose their effectiveness and performance. I understand what you’re saying, but you are at the opposite side of the spectrum, neither cold or heat is beneficial for any batteries.

By the way, lithium-Polymer batteries were actually worked on in the 70s, but since they were dry cells, the conductivity was very bad, so they were heated up to increase the passing of current, which would not be a good thing for our RC devices, so gel was added later, probably in the 90s when they were finally used in small devices.....

 

[Saigondroner]

I’m not starting to argue with you on this as I have been working in electronics for more than 35 years, and yes I was there in the 70s. freezing batteries has been a discussion (any batteries for that matter) since, and no good has been coming out from any research, unless you work with super-conductor power cell, which is another area. When LiThium-Polymer batteries gets below 10 degrees Celsius, they start to lose their effectiveness and performance. I understand what you’re saying, but you are at the opposite side of the spectrum, neither cold or heat is beneficial for any batteries.

By the way, lithium-Polymer batteries were actually worked on in the 70s, but since they were dry cells, the conductivity was very bad, so they were heated up to increase the passing of current, which would not be a good thing for our RC devices, so gel was added later, probably in the 90s when they were finally used in small devices.....

Well Grand Poobah, explain to me why the bloated,poorly stored LiPo outperforms the same battery that drops to zero midflight.

 

[WithTheBirds]

I’m not starting to argue with you on this as I have been working in electronics for more than 35 years, and yes I was there in the 70s. freezing batteries has been a discussion (any batteries for that matter) since, and no good has been coming out from any research, unless you work with super-conductor power cell, which is another area. When LiThium-Polymer batteries gets below 10 degrees Celsius, they start to lose their effectiveness and performance. I understand what you’re saying, but you are at the opposite side of the spectrum, neither cold or heat is beneficial for any batteries.

By the way, lithium-Polymer batteries were actually worked on in the 70s, but since they were dry cells, the conductivity was very bad, so they were heated up to increase the passing of current, which would not be a good thing for our RC devices, so gel was added later, probably in the 90s when they were finally used in small devices.....

Your timing is out- you can check if you like but I will say with confidence the first LiION cells were developed to the point they were commercially viable in the early 90’s.

You are confusing performance in use with storage. Yes, LiION current delivery is reduced at lower temperatures, this is particularly evident below 10 degrees C as you have said. It is also a fact that elevated storage temperature reduces usable capacity and increases internal resistance. The effect isn’t trivial when coupled with higher SOC. A cell at or close to 100% SOC will loose close to 20% capacity (over 12 months) if stored at 25deg C. The same cell will loose less than 5% at 0 deg C. Higher at higher storage temps the effect is significantly greater.

Yes, keeping the packs at or close to 40% SOC for storage will negate most of the benefit of storing at lower temperatures. However to say keeping the battery in the fridge will cause harm is simply not true.

 

[johnmeyer]

As an EE, I always look to actual testing. Here is one example:

How to Prolong Lithium-based Batteries

It talks about the effects of storage charge percentage on the Li-ION battery longevity (50-60 percent for long-term storage can almost double the life compared to storing them fully charged).

It then talks about storage temperature. Scroll down just 2-3 pages and you'll find a graph along with this statement:

"Elevated [storage] temperature hastens permanent capacity loss." ​

The tests went all the way down to 0° C (almost the same as a cold fridge). If the batteries were almost totally discharged (less than 40% charge), keeping them cold didn't bring much improvement in capacity after they were later fully re-charged, but if they were closer to fully charged, storing them in a cold environment improved their ability to recover their full capacity when re-charged.

The capacity loss from storing at high temperatures was permanent.

There are several things in this thread that keep popping up where people keep confusing freezing (i.e., below 0° C) a Li-ION battery, with putting it in the fridge, which is cold, but above freezing.

Freezing is bad, but chilly cold is good.

There is also confusion about operating temperature vs. storage temperature. As anyone who has taken high school chemistry knows, chemical reactions happen more readily at higher temperatures. So, if you store your batteries in the fridge (as I have done for fifty years), you need to warm them before using. This is well-known by anyone who has tried to start a car in sub-zero temperatures and found that their old battery suddenly doesn't have enough juice to turn over the engine.

Finally, some of you who own EVs already know that, in cold weather, the car's computer will actually use some of the battery energy to pre-heat the battery compartment in order to get them to a temperature where they can put out all of their energy. Years ago I had dinner with the founder of Tesla, Martin Eberhart, and he told me in great detail about the computations used to determine how much energy to use for this process: too much and you waste your precious charge, too little, and the car won't operate.

Finally, here is one more citation:

Lithium Rechargeable Batteries

Here's the key quote:

At a 100% charge level, a typical Li-ion laptop battery that is full most of the time at 25 degrees Celsius or 77 degrees Fahrenheit will irreversibly lose approximately 20% capacity per year. However, a battery stored inside a poorly ventilated laptop may be subject to a prolonged exposure to much higher temperatures than 25 °C, which will significantly shorten its life. The capacity loss begins from the time the battery was manufactured, and occurs even when the battery is unused. Different storage temperatures produce different loss results: 6% loss at 0 °C (32 °F), 20% at 25 °C (77 °F), and 35% at 40 °C (104 °F). When stored at 40% – 60% charge level, these figures are reduced to 2%, 4%, 15% at 0, 25 and 40 degrees Celsius respectively.​

 

[WithTheBirds]

As an EE, I always look to actual testing. Here is one example:

How to Prolong Lithium-based Batteries

It talks about the effects of storage charge percentage on the Li-ION battery longevity (50-60 percent for long-term storage can almost double the life compared to storing them fully charged).

It then talks about storage temperature. Scroll down just 2-3 pages and you'll find a graph along with this statement:

"Elevated [storage] temperature hastens permanent capacity loss." ​

The tests went all the way down to 0° C (almost the same as a cold fridge). If the batteries were almost totally discharged (less than 40% charge), keeping them cold didn't bring much improvement in capacity after they were later fully re-charged, but if they were closer to fully charged, storing them in a cold environment improved their ability to recover their full capacity when re-charged.

The capacity loss from storing at high temperatures was permanent.

There are several things in this thread that keep popping up where people keep confusing freezing (i.e., below 0° C) a Li-ION battery, with putting it in the fridge, which is cold, but above freezing.

Freezing is bad, but chilly cold is good.

There is also confusion about operating temperature vs. storage temperature. As anyone who has taken high school chemistry knows, chemical reactions happen more readily at higher temperatures. So, if you store your batteries in the fridge (as I have done for fifty years), you need to warm them before using. This is well-known by anyone who has tried to start a car in sub-zero temperatures and found that their old battery suddenly doesn't have enough juice to turn over the engine.

Finally, some of you who own EVs already know that, in cold weather, the car's computer will actually use some of the battery energy to pre-heat the battery compartment in order to get them to a temperature where they can put out all of their energy. Years ago I had dinner with the founder of Tesla, Martin Eberhart, and he told me in great detail about the computations used to determine how much energy to use for this process: too much and you waste your precious charge, too little, and the car won't operate.

Finally, here is one more citation:

Lithium Rechargeable Batteries

Here's the key quote:

At a 100% charge level, a typical Li-ion laptop battery that is full most of the time at 25 degrees Celsius or 77 degrees Fahrenheit will irreversibly lose approximately 20% capacity per year. However, a battery stored inside a poorly ventilated laptop may be subject to a prolonged exposure to much higher temperatures than 25 °C, which will significantly shorten its life. The capacity loss begins from the time the battery was manufactured, and occurs even when the battery is unused. Different storage temperatures produce different loss results: 6% loss at 0 °C (32 °F), 20% at 25 °C (77 °F), and 35% at 40 °C (104 °F). When stored at 40% – 60% charge level, these figures are reduced to 2%, 4%, 15% at 0, 25 and 40 degrees Celsius respectively.​

You can forget any chance of a liPO freezing in a fridge/freezer. The electrolyte would need to be at or close to -40 deg C.

Your laptop example is good and aligns with what I revealed earlier. That close to 20% at 25deg C capacity loss increases to 35% at 40 deg and a whopping 40% at 60deg (in just 3 months). Easy to see how some laptops have fragged batteries so early in the service life. Especially those that get thrown in a bag without powering down.

The good news is storing at low SOC largely negates the benefit of taking beer out of the fridge to make space for batteries. The difference between 25deg and 0deg C for a 40% charged pack over 12 months is only 2%...

 

[PAW]

I have no idea what the battery colors are on some of these drones, or even if they are mounted on top or below the drone's body, BUT could there possibly be ANY cooling advantage to top mounted dark gray batteries like on the Mavic pro or mavic 2 variety by spray painting their tops in a shiny "chrome" color to reflect as much sun as possible.
Maybe it would help some, maybe it won't. I have no idea. Just a thought.

I think that's a good question. Hate to interrupt this electrifying confabulation by you brainiacs, but is there any merit to BerndM's supposition?

 

[Dizzy1971]

You should NEVER store batteries (any type) in the refrigerator... that was a myth.

When once removing from the fridge they will begin to condense and water damage can begin to cause damage.

Store in a cool dry place.

Yep darn skippy! Don’t put batteries in a fridge,it’s just not a good idea.

 

[Saigondroner]

The vote is in!! Do what u like ;-)

 

[WithTheBirds]

The vote is in!! Do what u like ;-)

I think more accurate assessment might be do what you like without fear and with the opportunity to understand the benefits.