Less than 2%. After the batteries are combined in parallel and series, the capacity will be lost 2-5%. The more batteries there are, the greater the capacity loss. Lithium batteries can be assembled if the difference in capacity, internal resistance and voltage does not exceed 2%. When coupling ternary lithium batteries that need to be calculated, the voltage cannot differ by 0.001 volts. If the battery operates at 1C, the operating current of a 1000 mAh lithium battery can reach 1A, so the internal resistance difference cannot be greater than 1 milliohm.
The series connection method of Pacific Automotive Network means that the negative electrode of the first lithium battery is connected to the positive electrode of the second lithium battery, the negative electrode of the second lithium battery is connected to the positive electrode of the third battery, and so on, untilUntil the required voltage is reached, the voltage of this connection method is the sum of the voltages of the cells connected together, and the capacity is the capacity of a single cell, and then the protection is connected to the output.
For example, a 12V battery requires three strings (taking ternary materials as an example), and a 24V battery requires seven strings.
The parallel connection method means that the positive electrode of the first lithium battery is connected to the positive electrode of the second cell, the negative electrode is connected to the negative electrode, and so on, until the required capacity is reached. is reached. The voltage in this overall method remains unchanged is the voltage of a single cell, and the capacity is the sum of all battery capacities.
Notes on series and parallel connection of lithium iron phosphate batteries:
1. Do not mixdifferent brands of lithium iron phosphate batteries, different capacities or new and old lithium batteries. . Choose those with consistent performance. Replace all batteries when they are low. When lithium battery packs are used in series, the same type of battery must be used. Pay attention to the polarity of the battery. If the polarity of a battery is reversed, the voltage of the entire battery string will be reduced instead of increased.
2. If different capacities or old and new lithium batteries are mixed, leakage, zero voltage, etc. may occur. can occur. This is because during the charging process, the difference in capacity causes some batteries to overcharge and undercharge. During discharge, some high-capacity batteries are not fully discharged, while low-capacity batteries are overdischarged. In such a vicious circle, the battery is damaged and leaking or has low (zero) voltage.
3. Generally, lithium iron phosphate batteries need to be matched when used in series and parallel. The corresponding standards are: lithium battery cell voltage difference ≤ 10 mV, lithium battery core internal resistance difference ≤ 5 m, lithium. Battery cell capacity Difference ≤ 20 mA.
4. Remove the lithium battery protection circuit board and check whether the battery protection circuit board can be used in series or parallel circuits. For example, if it was a 4.2V protection circuit board and it was connected. series to 8.4 V, then the battery protection board. The card can no longer be used.
(Images/Text/Photos: Pacific Automotive Network Calling the Beast Q&A)