How to make a lithium battery 3.7v liter 9v circuit? What is the circuit diagram?

A 3.6V lithium battery with very low standby power consumption is converted into a 9V boost circuit

Homemade lithium battery 3.7v liter 9v circuit

The schematic diagram of the charging device shows that the maximum output current is 20A and the maximum charging voltage is 80V. It can be adjusted from 0V, so it can charge batteries of various specifications, and can also be used for battery packs or series batteries of the same specification. The group is charged, for example, up to 5 12V batteries connected in series can be charged at the same time. Charging the series battery can shorten the length of the connection, reduce the line loss, and facilitate the connection, so the work efficiency can be greatly improved.

As can be seen from the figure, the transformer T provides the operating voltage for the double base tube V1, the double base tube V1 and the corresponding peripheral components form an oscillator, and the oscillation frequency can be controlled by RP1, RP2. In this circuit, the values of RP1 and RP2 are quite different, so in actual operation, RP2 can play a coarse adjustment function, and RP1 plays a fine adjustment role. This is especially important when charging a single battery to avoid damage to the battery. The oscillation pulse generated by V1 is isolated by VD3, and the thyristor VS is triggered. The magnitude of the charging current and the level of the voltage depend on the output pulse of the oscillator, that is, the oscillation frequency. R5 is the sampling resistor, and its size depends on the ammeter. If the current meter has a sampling resistor, R5 can be omitted. R6 and C2 are damping elements for protecting the meter head.

The actual selected component parameters are shown in the figure. The transformer T has a power of 5W and an output voltage of 24V. If the output voltage is less than 0~80V, the maximum current is less than 20A, and the other pair can be used. The base tube can also be replaced with a thyristor with higher trigger sensitivity. Special attention should be paid to: the phase line and the neutral line should be connected according to the figure; in actual operation, the battery must be connected before the power can be connected; after the charging is finished, the power should be cut off before the battery connection is removed. The disadvantage of this machine is that it has a large interference to the power grid. If conditions permit, a high-power filter can be made to reduce the interference to the power grid.

Homemade lithium battery 3.7v liter 9v circuit

The picture shows the lithium battery fast automatic charger circuit. Lithium batteries can be charged at high currents, but the maximum charging voltage of a single-cell lithium battery cannot exceed 4.2V. If it exceeds 4.5V, it may cause permanent damage. The discharge voltage of the lithium battery must not be lower than 2.2V otherwise it will cause permanent damage. This circuit uses the LM3420-8.4 dedicated lithium battery charge controller. When the battery pack voltage is lower than 8.4V, there is no output current at the output pin (OUT) of the LM3420, and the transistor Q2 is turned off. Therefore, the voltage adjustable regulator LM317 outputs a constant current, and the current value depends on the value of RL.

The LM317 has a current rating of 1.5A. For larger charging currents, the LM338 or LM350 can be used. During charging, the battery voltage will continue to rise. The battery voltage is detected by the input pin 4 (IN) of the LM3420. When the battery voltage rises to 8.4V (two lithium batteries), the output voltage of the LM3420 output pin 1 causes the Q2 control LM317 to switch to the constant voltage charging process. Stable at 8.4V, after which the charging current begins to decrease. After the lithium battery is fully charged, the charging current drops to trickle charging.

When the input voltage is interrupted, transistor Q1 is turned off, the battery pack is disconnected from the LM3420, and diode D1 prevents the battery from discharging through the LM317.

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