1.5v dry cell battery

　　Battery charger circuit diagram

　　Battery charger circuit diagram - LM317 voltage regulator forms a constant current source to provide 50mA charging current for the S01-S06AA battery box array. Each battery box is connected in series with the LED and is connected to a shunt resistor. When the battery case contains a battery, the LED lights up during charging. Multifunctional battery charger (1)

　　The LM317 voltage regulator forms a constant current source to provide 50mA charging current for the S01-S06AA battery box array. Each battery box is connected in series with the LED and is connected to a shunt resistor. When the battery case contains a battery, the LED lights up during charging. Each battery box is connected in parallel with the LED through a 5.1V zener tube.

　　Battery charger circuit diagram (2)

　　There are two different opinions on whether alkaline batteries can be charged. Some say it can be recharged and the effect is very good. Some say it should never be recharged, as the battery instructions warn of the risk of explosion. In fact, alkaline batteries are indeed rechargeable, and the number of recharges is generally about 30-50 times.

　　In fact, it is due to the mastery of charging methods that leads to two completely different consequences. First of all, there is no doubt that alkaline batteries can be recharged. At the same time, in the battery instructions, it is mentioned that alkaline batteries are not rechargeable and charging may cause explosion.

　　This is true, but note that the word "may" cause an explosion. You can also understand it as a disclaimer of self-protection statement from the manufacturer. The key to charging alkaline batteries is temperature. As long as the battery can be charged without high temperatures, the charging process can be completed smoothly. The correct charging method requires the following points:

　　1. Small current 50MA

　　2. Don’t charge 1.7V, don’t discharge 1.3V

　　After some people tried charging, they categorically said that they could not charge. The reasons for problems such as no charging, short power use time, leakage, explosion, etc. were mostly due to problems with the charger. If the charging current of the charger is too large, it will far exceed 50ma. For example, the charging current of some fast chargers is above 200ma. The direct consequence is that the battery temperature is very high and it is hot to the touch. It may leak or explode in serious cases.

　　Some people use nickel metal hydride rechargeable battery chargers to charge. Low-end chargers do not have an automatic charging stop function. Long-term charging may cause the battery to overcharge and cause leakage and explosion. Better chargers have an automatic charging stop function, but the charging stop voltage is generally set to 1.42V for nickel-metal hydride rechargeable batteries, while the full voltage of alkaline batteries is about 1.7V.

　　Therefore, if the voltage is too low, it feels like it cannot be charged, and the power usage time is short, and it has no effect. Another thing is that not charging the battery means not waiting until the battery is completely dead before charging. If you do this, no matter how good the battery is, it can only be charged three or five times, and the effect is poor.

　　It is generally recommended to use Nanfu alkaline batteries with a voltage of not less than 1.3V. Therefore, if you plan to charge alkaline batteries, you must have a qualified charger with a charging current of about 50ma and a charging cut-off voltage of about 1.7V. Take a look at your home charger.

　　There are special chargers for alkaline batteries on the market, so-called patented products. In fact, it is a simple circuit with a charging voltage of 1.7V and a current of 50ma. Using the existing parts LM358 and TL431 on hand, I made a simple circuit that automatically stops charging when the cut-off voltage is 1.67V. The cost is only two yuan. For reference by interested friends.

　　Related instructions:

　　Alkaline manganese rechargeable battery: It is developed on the basis of alkaline zinc manganese battery. Due to the application of mercury-free zinc powder and new additives, it is also called mercury-free alkali manganese battery. This kind of battery can be recharged and used dozens to hundreds of times without changing the discharge characteristics of the original alkaline battery, which is relatively economical and affordable.

　　Alkaline zinc-manganese battery, referred to as alkaline manganese battery, was successfully developed in 1882, developed in 1912, and was put into production in 1949. It was found that when KOH electrolyte solution is used instead of NH4Cl as the electrolyte, there are major changes in both the electrolyte and the structure, and the specific energy and discharge current of the battery can be significantly improved.

　　Battery charger circuit diagram (3)

　　In the circuit, diodes D1 to D4 rectify the AC input, and capacitors C1 and C2 filter the DC. L1, C1 and C2 form a π-type filter to attenuate differential mode conduction EMI noise. Are these transformers E-sheild with powerIntegrations? The combination of technologies allows this design to easily meet the EN55022 Class B conducted EMI requirements with sufficient margin without the need for Y capacitors. Fireproof, fusible, wire-wound resistor RF1 provides critical fault protection and limits inrush current generated during start-up.

　　Figure 1 shows U1 powered by an optional bias supply, which reduces no-load power consumption to less than 40mW. The value of bypass capacitor C4 determines the amount of cable drop compensation. A value of 1µF corresponds to compensation for a 0.3Ω, 24AWG USB output cable. (10µF capacitor compensates for 0.49Ω, 26AWG USB output cable.)

　　In the constant voltage phase, the output voltage is regulated by switching control. The output voltage is maintained by skipping switching cycles. Regulatory voltage can be maintained by adjusting the ratio of enable to disable periods. This also allows the converter's efficiency to be optimized over the entire load range. Under light load (trickle charging) conditions, the current limit point is also reduced to reduce the transformer flux density, thereby reducing audio noise and switching losses. As the load current increases, the current limit point will also increase, and fewer and fewer cycles will be skipped.

　　When no more switching cycles are skipped (the maximum power point is reached), the controller within LinkSwitch-II switches to constant current mode. When the load current needs to be further increased, the output voltage will decrease accordingly. The drop in output voltage is reflected in the FB pin voltage. In response to a drop in the FB pin voltage, the switching frequency will decrease linearly, resulting in a constant current output.

　　D5, R2, R3 and C3 form an RCD-R clamp circuit to limit the drain voltage spike caused by leakage inductance. Resistor R3 has a relatively large value to avoid drain voltage waveform oscillation caused by leakage inductance. This prevents excessive oscillation during turn-off, thereby reducing conducted EMI.

　　Diode D7 rectifies the secondary and C7 filters it. C6 and R7 work together to limit transient voltage spikes on D7 and reduce conducted and radiated EMI. Resistor R8 and Zener diode VR1 form an output dummy load, which ensures that the output voltage at no load is within acceptable limits and ensures that the battery is not completely discharged when the charger is disconnected from the AC mains. Feedback resistors R5 and R6 set the maximum operating frequency and output voltage in the constant voltage stage.

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