Introduce a TL431 battery chargers

Introduce a TL431 battery chargers
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The battery exceed the battery voltage, and its life expectancy will be greatly reduced.
Here introduces a simple recharging circuit, it USES the three adjustable voltage shunt type TL431 chip (IC1) as a major adjustment device. When the same phase input feet (REF) voltage less than its internal benchmark voltage (2.5 V), TL431 cathode K output high potential, make the relay keep in releasing the state, charging to continue. Conversely. When the battery voltage over the threshold voltage circuit. Make REF voltage more than 2.5 V. TL431 cathode K low potential output. Relay suck close, charging circuit disconnect, charging to stop. TL431 plus a few external components charging control circuit. Because have a reference voltage TL431 in-house. So TL431 more instruments have a lagging effect, namely the comparator ceiling and floor difference.
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When the battery voltage up to more than the threshold voltage, relay RL1 suck close, the contacts N/C will be charging circuit disconnect, LED1 by flashing lights. At the same time, provide a lag path R3, to control the release of relay voltage Vr. Vr can work out by next type: Vr = Vref... (1 + R1 | | R3 / R2). | | R3 type of R1 for R1 and R3 of parallel value, namely (R1xR3) / (R1 + R3).
When the battery voltage is lower than release voltage, TL431 cathode (K) voltage close to the battery voltage. Relay keep in releasing the state. Charging to continue and LED1 not hair flash. Until the battery recharging voltage exceeds the threshold voltage Vt, LED1 again issued flashlight, charging to stop. R5 to limit the charging current.