How to charge battery at freezing temperature?

I believe everyone knows that due to the structure of cells and the specificity of the chemistry, the battery cannot be charged below the freezing temperature.

There are still a lot of companies are advertised as "low temperature rechargeable", "low temperature -xx℃ charge" words, Grepow's low temperature series battery can also charge in the environment of minus 20 degrees, how is it done? What about charging in a low temperature environment? In this article, I will tell you how to achieve it.

Why can't I charge the battery in a low temperature environment?

Materials of lithium-ion batteries, such as separators and electrolytes, are organic materials with a low melting point. If the temperature is too high, some negative chemical reactions will occur inside the battery, which will seriously affect the battery life and even safety performance. The key materials of the battery under low temperature conditions: the conductivity of the positive electrode, the negative electrode, the electrolyte, etc. are reduced, resulting in a decrease in electrical conductivity, which will seriously affect the battery life. Low temperature protection is when the temperature is too low, the metal lithium in the battery will deposit, no longer react with the substance, resulting in internal short circuit of the battery, which will cause damage to the battery or cause safety hazard of the battery.

2 ways to charge battery at freezing temperature

Battery charger self-heating charging

This way is rely on a special charger for heating, because it can not be charged normally in a low temperature environment, so the charger heats the battery till the temperature above the freezing point, and then charge the battery. This method is more safe and effective, but it takes longer time, because the charger can only perform small-rate discharge heating in a low temperature environment. Therefore, it will takes around 1 to 3 hours to heat up before charging.

Advantages: Able to charge even when the battery is empty

Disadvantages: Longer charging wait time; Rely on a special charger

Condition by BMS / PCM

The battery with BMS / PCM can provide two functions, one is low temperature alarm, there will be warning when the battery charge or discharge below the setted value, or the protection function, directly disconnect the discharge to prevent damage to the battery caused by low temperature or accident. The second type is to start the low-temperature self-heating function through BMS/PCM. The specifications are can be customized. For example, a 5000mAh battery with self-heating function BMS, will reserve 1000mAh of power in the battery every time it is discharged. Before the battery charging, the BMS will discharge the reserved power to heat the battery until the rechargeable temperature, then the battery will starting charge automatically. These are all based on the settings of the BMS.

Advantages: The waiting time is short, and the reserved power can be customized according to the needs of the ambient temperature.

Disadvantages: The battery's operating capacity will be reduced because BMS will reserve a portion of the power for low temperature charging.
Go view Grepow Custom BMS / PCM Solution：https://www.grepow.com/custom-battery.html

I believe that there are not only two technologies low temperatures. But as far as we know, these two are currently more common for charging batteries and more stable. If there are other ways, please let us know in the comments that we have found that the new method will also be updated in the blog.