As the core component of electric vehicles, batteries are both the most expensive and the most frequently used. Nowadays, many new national standard electric vehicles use lithium batteries, so in this topic, let’s talk about how to charge lithium batteries correctly?
Lithium battery wrong charging method is not only battery damage so simple, but also may cause deflagration or even fire, its serious consequences are the average person can not bear, let’s first talk about the principle of lithium battery deflagration?
The core cause of lithium battery explosion is that the internal liquid vaporization expansion caused by short circuit high temperature, short circuit high temperature will also produce open flame, and electrode liquid is combustible, in addition, lithium battery in the process of decomposition will also release oxygen, which strengthens the intensity of deflagration.
First, part of the causes of short circuits are mainly caused by high and low temperature charging and overcharging.
1. Why does low-temperature charging also damage lithium batteries?
Charging in a low temperature environment, the negative electrode material of the lithium battery will be passivated, and during the charging process, the electrochemical polarization of the negative electrode is significantly intensified, and the precipitated metal lithium is easy to form lithium dendrites, penetrating the diaphragm and causing a short circuit of the positive and negative electrodes. For ordinary low-speed electric vehicle (lithium iron phosphate) lithium batteries, do not charge if the ambient temperature is lower than -20 °C.
2. Why does overcharge cause lithium battery deflagration?
When the battery is overcharged, the excess lithium ions overflow from the positive electrode react with the solution, releasing heat to heat the battery, inducing the reaction of lithium metal with solvent, lithium intercalated carbon with solvent, and a large amount of heat and gas to cause the battery to explode.
If we use a mismatched high-current charger or buy a lithium battery without a BMS intelligent management protection system, it is likely that overcurrent will cause overcharge and short circuit of the lithium battery.
Second, in addition to the above dangerous charging methods, how to charge lithium batteries under normal circumstances?
1. Lithium batteries have no memory effect, can be charged as they go, and the ideal state is shallow discharge shallow charge within 50%, which is conducive to improving the service life of the battery.
2, to avoid lithium batteries in a low-power state for a long time, due to over-discharge and the negative electrode of the SEI film is destroyed, then the lithium battery is basically scrapped, but lithium battery self-discharge is very weak, lead-acid battery long-term placement a month to charge, and lithium battery 2-3 months to charge once.
3. Unplug the charger in time after it is fully charged, and there is no need to trickle charge after the lithium battery is fully charged, but there will be a certain amount of heat generated, if the charger is not unplugged in time, it is likely to lead to overcharge caused by short circuit and deflagration.
Well, do you understand how to properly charge lithium batteries? If you find it useful, you are welcome to like, follow, retweet and favorite!
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