I. Lead-acid battery charging method
Currently, most electric bicycles in China use lead-acid batteries. Although lead-acid batteries have disadvantages such as heavy weight and short cycle life, they also have advantages such as low price, resistance to overcharging and over-charging, and good safety. Below, we will teach you how to charge lead-acid batteries.
1. Choose the right charger. When charging lead-acid batteries, it is best to use the original charger, as this will reduce wear and tear on the battery.
2. Charging environment: The charger generates heat during battery charging, so the battery should be placed in a well-ventilated, open area. Never cover the charger with any object while charging, as this can easily damage the charger and battery, or even cause a fire.
3. Charging time: When using lead-acid batteries, get into the habit of charging them on the same day you use them. Do not wait until the battery is completely drained before charging, so as to avoid shortening the battery life due to "deep discharge". If a fully charged battery is not used for a long time, it should be charged once a month.
Friendly reminder: Do not charge the battery with it upside down.
Three common charging methods for lead-acid batteries:
1. Pulse charging
This is a simple and economical method. The low-voltage AC output from the transformer secondary is rectified into pulsating DC (without filtering) to charge the battery. This method has a large charging current and a fast charging speed. The disadvantage is that when the grid voltage fluctuates, the charging current also fluctuates. It is easy to cause the battery temperature to rise and the electrolyte to be lost due to the large charging current, which can lead to battery damage. Therefore, this method is rarely used for maintenance-free sealed lead-acid batteries.
2. Charge with constant current
To prevent excessive temperature rise inside the battery and excessive electrolyte loss, the charging current is set relatively low, requiring a longer charging time. On the other hand, if the charging time is too long, overcharging will occur. To prevent damage to the battery due to overcharging, an overcharge detection or timing circuit is required.
3. Constant voltage charging
Both theory and practice have proven that constant voltage charging is safe when the charging voltage is below the upper limit of the charging voltage. Even if the charging time is very long, there is no danger. If necessary, the battery can also work in float charging mode.
II. How to repair lead-acid batteries
We have provided a comprehensive overview of lead-acid batteries, giving a general understanding of their structure and operating principles. A lead-acid battery consists of positive and negative plates, separators, electrolyte, battery case, and connecting strips.
The repair methods for lead-acid batteries are as follows:
1. Battery series connection repair method
This method is used when the nominal voltage of a single battery cell is below 12V. For example, commercially available rechargeable emergency lights often use 6V 4Ah batteries. The tester's single-channel output is 12V. In this case, two 6V batteries can be connected to the tester for desulfation repair (Note: Appropriate charging and discharging currents should be selected based on the battery's nominal capacity).
2. Battery parallel current sharing method
If the battery voltage rises rapidly during the repair process, the charging and discharging current should be reduced. In this case, the two batteries can be connected in parallel to a single tester circuit, with the charging and discharging current reduced to half of the original; this method also works well.
3. Output Combination Method
This method can be used for batteries that have been stored for a long time or have severe self-discharge and sulfation, when water replenishment and charging are not effective enough. This method is more effective for severely sulfated batteries. When using this method, it is best to choose a charging current of 5A. Because of the superposition of repair functions, the negative pulse current is greater than the positive pulse current. Choosing 5A is to compensate for the resulting cancellation of charging current.
4. Output Parallel Current Increase Method
If the battery being repaired has a large capacity, such as exceeding 20Ah, it may be necessary to increase the charging current. In this case, two or more outputs of the tester can be connected in parallel to the battery being repaired simultaneously to enhance the charging current. In actual tests, it was found that, depending on the battery type, when testing with a T1000 digital multimeter in DC 20A range, the current after connecting the two outputs of the tester in parallel to the battery gradually increases to the sum of the two output currents.
5. Parallel desulfurization output method
For batteries severely sulfated that have shown little improvement after repeated repairs, a method can be used to enhance desulfation by connecting two parallel testing instruments with their repair functions simultaneously to the battery being repaired. This method is not easy to master. The instruments should be connected in phase; otherwise, the desulfation current will weaken. This can be assessed by monitoring whether the voltage and current increase.
