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Charging frozen

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curtix

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Joined
Feb 12, 2024
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Calgary
I can’t seem to find a good answer to this;

How quickly and how badly will charging a frozen LifePo4 battery damage it?
I found a really good deal on a 100Ah/100A battery. The deal is good enough that, depending on how quickly it will deteriorate and how much capacity will be lost, it may be worth using for the purpose I need it for.
 
1) You Cannot Discharge LFP at temps below -20C.
2) You Cannot CHARGE LFP below 0C. There are exceptions like Yttrium Doped LYFP but they are NOT the norm.
3) You can charge at 0.2C from 0C to 10C temp, then can proceed with 0.5C
 
12v system? 24v? You can wrap the battery in a DC pet warming blanket on a simple thermostat and stick the bundle in a cheap coleman cooler. That will use a little power to get it up above freezing but then it'll be chargable and keep it warm for a good while. Cheap and effective.
 
Rednecktek said:
12v system? 24v? You can wrap the battery in a DC pet warming blanket on a simple thermostat and stick the bundle in a cheap coleman cooler. That will use a little power to get it up above freezing but then it'll be chargable and keep it warm for a good while. Cheap and effective.
Click to expand...
12V but I don’t think I’d have the room for that in the space I need to put it
 
curtix said:
12V
Click to expand...
Steve_S said:
1) You Cannot Discharge LFP at temps below -20C.
2) You Cannot CHARGE LFP below 0C. There are exceptions like Yttrium Doped LYFP but they are NOT the norm.
3) You can charge at 0.2C from 0C to 10C temp, then can proceed with 0.5C
Click to expand...
If there is no low temperature protection you can charge at any temperature you want.
I’m aware of the recommended temperature as is obviously indicated by the nature of my question. As such, I didn’t ask what the recommended charge and discharge temperatures are. I asked, exactly how much damage will occur, how much loss and how quickly.
 
In my RV we often camp when night temps get below freezing (32F). But it will be warmer during the day. So my planning is to add a little external heat and insulate it the best I can.

On my rig I added a RV tank heater pad under the cells - and built a box with plywood around it (top is plexiglass) and finally make a blanket out of the bubble wrap insulation that covers the whole battery. And tried to seal the battery compartment the best I could - but due to its outside location it was limited. The temps stayed in the high 30’s at the battery while the outside lows were mid20’s. Good enough for us - any colder and the wheels move us to warmer places.

Just prevent the battery from freezing, have cold temp protection enabled on the bms and have your charge systems (Victron in my case) not charge if it’s too cold.
 
The reason we can’t really answer the question is because the manufacturer of the cells says if you CHARGE normal LifePo4 cells below freezing you will ruin it. A few posts by people on this site has confirmed that understanding with posters saying they had done it - how long it took don’t know.

My understanding is one charge with a frozen battery will ruin it.

For me the easiest thing is to prevent too cold charging by multiple ways.

You can discharge when the battery is very cold without issues.

Did that answer your questions?
 
curtix said:
How quickly and how badly will charging a frozen LifePo4 battery damage it?
Click to expand...
Problem is it's like asking how long will tires last if you drive on a dirt road. Too many variables, and even if you defined all the variables, there probably isn't enough research to answer it.

Somewhere on this forum is a temperature compensation chart that describes acceptable charging voltages at various levels below zero. I'm won't do the digging, but I've seen it out there. The existence of that chart implies a possibility of acceptable charging below zero with reduced voltage.
 
I guess I find it odd that there isn’t more information about it. Here and anywhere that I can find online.
Two posts above this it was suggested that one charge at too low a temperature will “ruin” a battery but what does that mean? Surely it’ll still take a charge and discharge?
I imagine it will cause a loss of capacity. And I imagine that continuing to charge at low temperatures will further degrade the cells and cause further loss of capacity. But again; how much? How quick?
Let’s start with this question;
If you take a 12v-100ah battery at 15-20% and charge it at -15° to 90-100°, what will be the result?
Obviously no one can say precisely because of variables like cell manufacture etc. but I’m looking for answers somewhere more specific than “It will ruin the battery” and less specific that a 800 page book on the subject
 
curtix said:
I guess I find it odd that there isn’t more information about it. Here and anywhere that I can find online.
Two posts above this it was suggested that one charge at too low a temperature will “ruin” a battery but what does that mean? Surely it’ll still take a charge and discharge?
I imagine it will cause a loss of capacity. And I imagine that continuing to charge at low temperatures will further degrade the cells and cause further loss of capacity. But again; how much? How quick?
Let’s start with this question;
If you take a 12v-100ah battery at 15-20% and charge it at -15° to 90-100°, what will be the result?
Obviously no one can say precisely because of variables like cell manufacture etc. but I’m looking for answers somewhere more specific than “It will ruin the battery” and less specific that a 800 page book on the subject
Click to expand...

Just buy one, discharge it, put it in the freezer and then charge it and see what happens.

Report back.
 
curtix said:
OMG could someone please come in here and actually answer the question? Or even address the question? Please!
Click to expand...
There is no data for what you ask.

You will just have to decide if you want to be the only guy out there doing this and if it ruins the battery, can you afford to buy a new one?

I have started to “Not fix something myself I can’t afford to pay someone to fix or accept the total loss if I screw it up.” I worry less now.

If this answer does not work, I will make something up for you.
 
curtix said:
I guess I find it odd that there isn’t more information about it. Here and anywhere that I can find online.
Two posts above this it was suggested that one charge at too low a temperature will “ruin” a battery but what does that mean? Surely it’ll still take a charge and discharge?
I imagine it will cause a loss of capacity. And I imagine that continuing to charge at low temperatures will further degrade the cells and cause further loss of capacity. But again; how much? How quick?
Let’s start with this question;
If you take a 12v-100ah battery at 15-20% and charge it at -15° to 90-100°, what will be the result?
Obviously no one can say precisely because of variables like cell manufacture etc. but I’m looking for answers somewhere more specific than “It will ruin the battery” and less specific that a 800 page book on the subject
Click to expand...
That’s because it’s not done. As was mentioned, go for it and let us know how it works out for you.
 
I made a video trying to charge an LFP cell below freezing (at -17C):


While there was no initial damage, the issue was also that I couldn't get any power into the cell because of increased resistance. Normally the power supply would go into C.C. mode and dump whatever it could into the battery, but that didn't happen.
 
O
chrisski said:
There is no data for what you ask.

You will just have to decide if you want to be the only guy out there doing this and if it ruins the battery, can you afford to buy a new one?

I have started to “Not fix something myself I can’t afford to pay someone to fix or accept the total loss if I screw it up.” I worry less now.

If this answer does not work, I will make something up for you.
Click to expand...

😆 Of course there’s data. In 2024, the idea that there’s no data or that no on has done studies on the effects of charging LifePo4 at below freezing is absurd on its face.
I can’t really address the last part of your reply because I have no idea what you’re saying actually.
 
Last edited:
upnorthandpersonal said:
I made a video trying to charge an LFP cell below freezing (at -17C):


While there was no initial damage, the issue was also that I couldn't get any power into the cell because of increased resistance. Normally the power supply would go into C.C. mode and dump whatever it could into the battery, but that didn't happen.
Click to expand...
Interesting. I expect damage and loss of capacity but inability to charge is not something I would have guessed.
Thanks for the only actual answer so far.
 
This is not the video I was thinking about, but I'm sure you can find more videos like this.

 
Wjen the electrolyte reaches 0C, it changes and causes crystals to form, changing in this condition flat out destroys the cells.

Most likely the outer cells would fry, then the in er banks would be overcharged, and thw bms would disconnect...

If the battery was frozen solid entirely below 0C, all the way through, and was then charged, all cells would die.

This is what i have read on here.
I do not have experimental knowledge.
 
I have some some lab data on this. We were paid to evaluate cell replacements for a now discontinued cell. This will be lighter on details than I'd like because of it being private paid testing. At 15F the damage can be as high as 16% SoH after 10 Charge and discharge cycles at 1C/1C. Results vary greatly depending on cell types however with 2%-16% of SoH loss after 10 full cycles. Cold weather rated cells were sub 1% of SoH loss. Beyond 15f it becomes pretty much impossible to push power in and out of normal cells.
 
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