How to calculate the battery capacity based on charger and charging time?

How to calculate the battery capacity based on charger and charging time?

The battery capacity is divided by charging current and multiplied by a factor of 1.2, time unit is hour.

Note: The general battery capacity indicated on battery, in milliamperes. The larger value, the larger the capacity. For example: 1200mAh means that the battery capacity is 1200 mAh. At the same time, the charger is also generally marked with a charging current, also in milliamps.

For example: battery capacity is 1200 mAh, charger charging current is 600 mA, charging time is (1200 mA / 600 mA) × 1.2 = 2.4 hours, then the charging time of this battery using this charger is 2.4 hours.

Note: The above calculation method does not apply to new batteries.

The charging time of the battery can be calculated by the formula: battery capacity/charging current *60. If the battery is 2500mA and the charging current is 500mA, you can calculate 2500/500*60=300 minutes. In fact, this is only the theoretical time. It takes longer to charge because the charger is not charged with constant current, that is, as the charging time is longer, the charging current is relatively reduced. Generally speaking, there is no problem when charging for 8 hours. When charging, you can touch the appearance of the battery by hand, there will be slight heat, which means the battery is charging well. The highest charging voltage of 1.2V nickel-metal hydride battery is about 1.4V. You can use a multimeter to check if it is full. In addition, the charger charging section has the same time as the multi-cell battery because the outputs are independent of each other. Take a look at the output 1.2V-500mA*4AA500mA*2AAA, which means that the charger has four independent outputs of 500mA.

The charger voltage is 5V, the charging current is 500MA, and it takes 1 hour and 20 minutes to fully charge.

Since the lithium battery charging control is divided into two stages,

The first stage is constant current charging. When the battery voltage is lower than 4.2V, the charger will charge at a constant current.

The second stage is the constant voltage charging phase. When the battery voltage reaches 4.2V, due to the characteristics of the lithium battery, if the voltage is higher, it will be damaged. The charger will fix the voltage at 4.2V, and the charging current will gradually decrease. When it is reduced to a certain value (generally when 1/10 sets the current), the charging circuit is turned off and charging is completed.

Therefore, according to your description, if your 500mA is tested with an ammeter, your capacity is estimated to be 600mAh (will be smaller than 500*1.33, because the second constant voltage phase accounts for about 20% of the charging time, this process The actual charging current will be smaller). If 500mA is the tag value on the charger. Maybe the actual current is not that big.

If it is accurate, please use the multimeter string on the output of the charger. Record the current every 5-10 minutes (note that it is off). Add the amount of electricity charged in each period so that you can judge the capacity.

Knowing the charging time of lithium batteries, from the difficulty level, the operation problem is not big, and clarifying the source of lithium battery charging time is more helpful to make it more scientific in theory and practice.

The theoretical lithium battery charging time is the ratio of the battery's nominal capacity to current:

Lithium battery charging time (h) = battery capacity (mAh) ÷ charging current (mA)

However, since there is impedance during charging, in order to offset the influence of the impedance, the actual charging time is greater than the above theoretical charging time. In order to make the charging time of the lithium battery meet the actual full power requirement, it is generally based on the ratio of the charging capacity to the battery capacity. The size is set to a factor greater than one, for example when the charging current is less than or equal to 5% of the battery capacity, the coefficient is 1.6.

Lithium battery charging time = battery capacity ÷ charging current × 1.6

By analogy, according to the ratio of the battery capacity of the charging current, the coefficient of the lithium battery charging time is calculated.

1.5 (5% < charging current ≤ 10%),

1.3 (10% < charging current ≤ 15%),

1.2 (15% < charging current ≤ 20%),

1.1 (20% < charging current).

In real life, the lithium battery charging time of portable electronic products is also designed according to the above formula. These lithium batteries generally equip with corresponding constant current chargers. The electric indicator light indicates it's charging, when battery fully charge there will be an alarm signal. Therefore, the consumer only needs to follow the instructions, and no need to worry about charge time for lithium battery for a long time.

The page contains the contents of the machine translation.