Electric bicycle battery detector - power circuit - circuit diagram - Huaqiang Electronic Network

The circuit consists of three parts: detection, display and alarm.

When the battery under test is connected, the polarity protection VDl and the current limiting resistor R1 are sent to the three terminals for voltage regulation to 12V for the circuit to work. The RS flip-flop composed of ICla and IClb causes ICla to output a high level due to the action of C1. The V1 is amplified to make the relay pull in, and the three parallel bulbs that discharge the load are turned on to discharge. The total power of the three parallel bulbs is 180W, and the discharge current is 5A to simulate the power consumption of the electric vehicle during normal driving.

ICla output high level also allows ICld to allow IC2's 60Hz clock frequency to be sent to the electronic clock circuit IC3 timing. IC3 uses the common electronic clock circuit LM8361, which is connected to 60Hz, 12 hours timing state. The result is directly displayed by the matching display screen. Press SB to clear at the beginning, the electronic clock will display 12:00 and start timing.

When the 36V battery is fully charged, it can reach 43V, and it will remain at about 36V during the discharge process until the end of the discharge will accelerate. Generally, the discharge must be stopped when the voltage is low 32V, otherwise the battery will be damaged. One input of IClb in the figure is used to detect the battery voltage, because the Schmitt trigger uses a flip voltage of half the operating voltage, that is, 6V, which is very sensitive. When the detected voltage is lower than 32V, the input of IClb will flip below 6V, causing the RS flip-flop to turn low and output low. When V1 is turned off, the release of the relay K causes the load bulb to stop discharging, and the ICld is always output to a high level to stop the IC3. The time counted is the travel time of the battery under normal discharge conditions. At the same time, IClc starts to oscillate because IClb outputs a high level, and the signal is amplified by V2 so that the electromagnetic horn BL emits a squeaking sound to indicate the end of the detection.

This circuit can be directly used after the voltage divider resistors R3 and R4 are accurately calculated without adjustment, and the battery of other voltages can be detected. For example, when testing a 48V battery, you only need to replace R4 with a 10kΩ resistor. When detecting a 24V battery, you can replace it with a 22kΩ resistor.

Component selection: ICl is CD4093, IC2 is time base circuit MM5369, IC3 is electronic clock circuit LM8361, and other types can be used instead. The relay selects the working voltage to be 12V, and the contact capacity is greater than 10A. The electromagnetic horn can be used in one of the quartz clocks, or it can be replaced by a speaker, but it is slightly larger.

The lead-acid battery capacity (life) is estimated as follows: A fully charged 36V/12Ah battery can be used for detection and discharge for 2.4 hours, and its capacity is 12Ah. Another battery with the same sufficient capacity can only be used for 1 hour of detection. Its actual capacity is only 36V, 5Ah, and it has reached the end of battery life. Therefore, by detecting the length of the discharge time, the true capacity of a certain lead-acid battery can be roughly determined, which has a reference role for the lead-acid battery exchange maintenance service industry.