Dongguan City Yuanyue Electronics Co.Ltd , https://www.yyeconn.com
The circuit consists of three main sections: detection, display, and alarm.
Upon connecting the battery under test, the polarity protection diode VD1 and the current-limiting resistor R1 ensure the circuit operates at 12V. The RS flip-flop formed by ICla and IClb ensures ICla outputs a high level due to the action of capacitor C1. This triggers V1 to amplify the signal, pulling in the relay and turning on three parallel bulbs that discharge the load. These bulbs have a total power of 180W, and the discharge current is 5A, simulating the typical power consumption of an electric vehicle during normal driving.
Additionally, the high-level output from ICla allows ICld to pass the 60Hz clock frequency from IC2 to the electronic clock circuit IC3 for timing. IC3 uses the LM8361, a common electronic clock circuit, set to operate on a 60Hz, 12-hour timing cycle. The result is displayed on the corresponding screen. Pressing SB at the start clears the clock, setting it to 12:00 and starting the timer.
When a 36V battery is fully charged, it can reach up to 43V, maintaining around 36V during discharge until the end, where the voltage accelerates. Discharge should generally stop at 32V to avoid damaging the battery. The input of IClb in the diagram is used to detect the battery voltage, as the Schmitt trigger uses a flip voltage of half the operating voltage, which is 6V, making it highly sensitive. Once the detected voltage drops below 32V, the input of IClb flips below 6V, causing the RS flip-flop to switch low and outputting a low signal. When V1 turns off, the relay K releases, stopping the load bulbs from discharging, and ICld stops outputting a high level, halting IC3. The time counted represents the travel time of the battery under normal discharge conditions. At the same time, IClc begins to oscillate due to IClb’s high-level output, and the signal is amplified by V2, causing the electromagnetic horn BL to emit a squeaking sound, indicating the end of the test.
This circuit can be used directly after calculating the voltage divider resistors R3 and R4 accurately, without any further adjustments. For instance, when testing a 48V battery, R4 needs to be replaced with a 10kΩ resistor. For a 24V battery, it can be replaced with a 22kΩ resistor.
Component selection: ICl is CD4093, IC2 is the time base circuit MM5369, and IC3 is the electronic clock circuit LM8361. Other similar components can be substituted. The relay should have a working voltage of 12V and a contact capacity greater than 10A. The electromagnetic horn can be sourced from a quartz clock or replaced by a speaker, though the latter may be slightly bulkier.
Lead-acid battery capacity (life) estimation: A fully charged 36V/12Ah battery can be used for 2.4 hours of detection and discharge, indicating its capacity is 12Ah. Another battery of the same size but with reduced capacity might only last for 1 hour of testing, showing an actual capacity of just 5Ah, indicating it has reached the end of its life. By determining the discharge duration, the true capacity of a particular lead-acid battery can be roughly estimated, providing valuable information for lead-acid battery exchange and maintenance services.