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Fast Charging
Many customers want to charge their batteries fast and ask us about a "faster charger".
We do not recommend to charge a lithium ion battery faster and normally do not want to offer any "faster charger". A faster charger is actually a charger with larger charging current. Unless you really need to charge a battery faster, otherwise, it is a very bad idea to charge a lithium ion battery fast. Here are some reason:
1. Fast charging a lithium ion battery will short the battery life time. Below graphic shows some life time comparisons for using different charging current to charge a lithium ion cell:
2. Fast chargers may only charge a battery to 70 and 80 percent, can not fully charge a battery. Fast-charging creates a lag between voltage and state-of-charge that increases the faster the battery is being charged. This can be compared to a rubber band lifting a heavy weight. The larger the weight, the wider the lag becomes. The ultra-fast charge forces the voltage to the 4.20V/cell ceiling quickly while the battery is only partially charged. Full charge will occur at a slower pace as part of saturation.
3. Fast chargers using large current, which may generate more heat, cause fire if the cells are not made for fast charging. To make cells accept large charging current will need change cell design, make cell density lower. So for same capacity, the battery weight will be heavier and size will be bigger.
Guidelines Regarding Chargers
If possible, charge at a moderate rate. Fast charging always causes stress.
Fast charge fills the battery only partially; a slower saturation charge completes the charge. Unlike lead acid, Li-ion does not need the saturation charge but the capacity will be a bit lower.
Do not apply fast charge when the battery is cold or hot. Only charge at moderate temperatures. Avoid fast charging an aged or low-performing battery.
Do you really want to charge your lithium ion battery fast? Think again.
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