This is due to battery being charged 100% in warm environment, then taken to a colder place. Make sure to charge to 80% if you go to a colder place.
Reason: the warmer the battery temperature, the more capacity it can hold.
If the battery has been charged at 100% at 24⁰C, then the temp goes down to 15⁰C laptop powered off, the excess capacity has to go somewhere.
I’ve never heard that before, and it doesn’t seem to make sense. Batteries will often heat up while charging, and then they would obviously cool back down after charging. So if I’m in a 20C room and the battery heats up to 30C while charging, it’s going to cool back down to 20C after it’s done charging. If simply cooling down after being charged to 100% would cause a battery to swell, then every battery that heated up a bit while charging would swell as it cooled down, and that doesn’t seem to happen.
From my understanding, colder temperatures will slow the chemical reactions in the battery and increase the effective internal resistance. This makes them have a lower effective capacity, simply because they cannot produce as much current at a given charge level, and will experience a greater voltage drop at a given charge and current draw. So you cannot safely discharge them as far, and the safe charge and discharge current are reduced as well. But the concept of some of the capacity having to go somewhere as they cool is a new concept to me.
But just because something doesn’t make sense to me doesn’t mean it’s not correct, lol. Do you have any links or references to info about this phenomena that I could read? I’d love to learn more.
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OMG, so much no. It’s defective or has been damaged.
You can’t do that by moving from a warm to a cold room, not matter the state of charge.
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This is not happening form one charge. It takes a while…
I broken quite some batteries for my RC planes/drones before realizing that.
I’m not knocking your lived experience, but the banging about and general wear and tear on an RC battery back is far far worse than what should be going on inside a laptop 
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Are you sure the move to colder temps while fully charged is what was causing your RC batteries to swell? If it is something that happened to your batteries slowly over time, is it possible there was some other cause? For instance, if you stopped charging your batteries to 100% and they stopped swelling over time, the reduction in charge level may have been the fix, regardless of the temperature swings after charging.
I only ask because I’ve never heard of this before and nothing about the chemistry seems to suggest that this would happen. It seems that any lithium battery that heats up while charging would cool down after and swell if this was the case. So, forgive my skepticism. I’m happy to be proven wrong and to learn new things. If you have an idea why this happens, or know of something folks could read about why this would happen, I’d love to read it.
I am sure, yes. And I’m not the only one having see that.
The reason this happens quite often with RC guys is that they charge their batteries inside (house) temperatures, then go outside even at 0^C, put the replacement batteries on the tarmac and go flying. At these temperatures, the battery temps go down very fast.
Over time, all our batteries started to “inflate”. That’s when we started to check things like internal battery resistance etc. at different temperatures.
Check my private FAQ (where I wrote it down), and eventually the links to the discussion forums still work. You’ll see there that there is a also a large discussion taking place regarding the actually capacity of batteries.
And, just FYI, I have kept statistics on my RC Batteries for a time, and yes, every time I went flying in cold weather and charged the batteries at max, the started to inflate.
In the end, I actually only took as many batteries with me as I could put into my jacket. Under the jacket, they remained warm. From this time on, I didn’t have any more batteries inflating.
Using a battery in cold weather after charging it in a warm environment is not a problem. Charging a battery while it is cold is what damages the cell.
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It warms up a little, but not much.
When discharging the batteries, where my RC Planes pull around 70 Amps, they get hot, yes. Charging? Even at 2C (2 times the capacity. My 5Ah batteries, I charge with 10A) it won’t really heat up. +1 or +2 ⁰C.
I have a charger that lets me apply a temp sensor to the battery to measure the battery. And at a variance of 2⁰C it would reduce the charging power.
Heavy discharge of a cold battery is also hard on them, so is it possible that keeping the batteries warm before actually putting them in use made the difference, and not so much simply letting a charged battery get cold?
Sorry, I think we’re kinda derailing this topic. The main thing is that @bob_bowser should start a ticket and be careful with the swollen battery to avoid puncturing it or anything like that.
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Never do that, that’s why I have telemetry on board. With LiPo batteries, the voltage will tell you when to come down.
And yes, @bob_bowser should send a mail to support for that.
I meant heavy discharge, as in a high current rate. Applying a heavy load to a lithium battery while it’s cold can be hard on it. Charging while cold can be hard on a battery too.
I didn’t mean that you were running the batteries down to too low of a voltage.
Ultimately, in the case of the 61Wh battery in the FW 13, I think the main contributing factor with swelling batteries has been determined to be leaving the batteries at a state of 100% charge for an extended period of time. For instance, someone leaving the laptop plugged in most of the time. Because of the volatile nature of the chemicals when sitting at a maximum state of charge, a battery will degrade or “age” much more quickly when sitting at 100%, as compared to sitting at a lower state of charge. Apparently, this is particularly degrading to the cells used in the 61Wh battery.
This is an interesting thread.
I would hazard a guess that charging a battery to 100% in the warm, then going outside to cold, then drawing high power from the battery…
Is probably a pattern that might never have been tested, so maybe no one has proof about what happens.
But someone in this thread has spotted what they think is a pattern leading to swelling.
I would be interested to see actual manufacturer test results for these scenarios.
I don’t think 50~60C is the optional performance. Li-ion battery typically safe to discharge -20~60C, discharging at 50C gives very little headroom to prevent overheating and it actually decreases achievable discharge C rating. From what I read from battery datasheets and battery tests. When discharged at room temperature(23C) at the max rated C, the battery reaches max allowed discharge temperature right at empty.
So I believe that you should discharge (or charge) at room temperature whenever possible to preserve best longevity and performance.
I use capacity (after calibrating the current sensor) to estimate flight time. If I have a charged 1500mAh battery and I’ll land the drone when it consumed 1250mAh, regardless of the voltage. When using full throttle or turning tightly (common on racing drones) the voltage dips to 3.1V~3.3V per cell even at start, which feels like the battery can’t hold any longer but the remaining capacity is there so the battery is far from empty. The voltage will come back to 3.6~3.7V after landing with an almost exhausted battery.
It is getting off topic, but:
The battery voltage will be lower with lower temperature, and that reflect in the telemetry.
The reason you come down (using the voltage gauge), is that the onboard ESC will cut power to the engine when a certain voltage level has been reached, diverting the remaining power to the rudders.
I tend to use 5000mAh on my large planes. And when I really make the zazou in the sky, the batteries are burning hot when I take them out. Because I take out 16 times the C rate of the battery 80Amps out of the 5Ah power pack. Drones (with 4 rotors) usually don’t do that. Except if you build your own drones and size the motors + battery accordingly and you know at what voltage the “autopilot” will force a landing, hence you are pro-active on how you will fly and handle the batteries.
From experience, flying in 5⁰C will reduce my flight time by 1/3 compared to 25⁰C on planes or 4 motor drones. But on the plane, I can go to the limit, as I glide down (Warbirds have very good gliding ability). The Drone just goes down as fast as possible reducing damage while doing it.
Exactly. This is due to the slowing of the chemical processes due to the decreased temperature. I bet you would also agree that the voltage will drop a bit more under the same load when the batteries are cold vs. when they are hot.
I think the main reason this conversation started is because of your claim that batteries swell because if they are fully charged and then cool down, they have less capacity and that energy has to go somewhere. But the reduction in “capacity” isn’t like a physical reduction in the ability to hold “energy” and therefore, the “extra” energy has to go somewhere. As a battery cools, the chemical process slows, decreasing voltage and increasing the effective resistance of the cells, thus reducing their performance. This is what causes the capacity drop. It’s not an actual, physical loss of capacity, it’s just a reduction in usable capacity. There isn’t a physical reduction that requires “excess” charge to go somewhere. In fact, it would make more sense to say that if a battery is fully charged when cold, and then warmed up, it could be hard on the battery, because the increase in voltage might stress the battery. But going the other way doesn’t seem like it should harm the battery.
That right there tells me there is more going on here. Excess heat and excess strain on a battery can cause the chemical breakdown that releases gas inside the battery. This gas is what causes a battery to swell up. If a battery is pushed hard when cold, it’s harder on it than when it’s warm. I would say it is far more likely that your batteries are no longer swelling up simply because you keep them warm before pushing them this hard.
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No. I never stated that.
I said that, if you charge a battery in a warm environment to 100%, then take that battery to a cold environment, the chemistry will not be able to hold the same charged capacity.
The excess energy will have to go somewhere and that energy goes into inflating the battery (only thing that can happen).
As far as I know most batteries can’t be safely charged below 0 Celsius, for below 5 to 10 depends on battery chemistry, charging should be slowed. At room temperature expect rated charging and discharging performance
I disabled that function on the inverter as I can always cut power to the motor by reducing throttle input to zero. I used a dc-dc converter(MP2307) to convert 14.8V to 5V for the receiver and servo motors to work. A large dip of voltage due to high throttle at initially low temperature doesn’t affect handling that much.
I think the conclusions are:
Low temperature, low performance, higher power demand increases wear. Good longevity for storage.
High temperature, low longevity even when not in use. Good performance due to low internal resistance. Charging still wears down faster compared to mid temp.
Room temperature, good longevity and good performance.
If the environment temperature is changing rapidly, keep the battery charge near the middle to avoid damage
Lol. You literally said it in the first post, and just said it again. You said that when the battery cools down it has a lower capacity, and the excess energy has to go somewhere.
We’ve both said our pieces. I think we’re just going to have to agree to disagree on this one. Cheers!
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