battery overdischarge protection circuit

githublink: contains eagle files, arduino sketch code, python code, etc.

When dealing with rechargeable batteries, one faces two voltage limits: over-charge limit, over-discharge limit. When it comes to charging, most battery charging ICs out in the market will deal with it and frankly, I haven’t yet ran into a situation where I need to delicately control the voltage limit when the charging should stop. The battery charging ICs has a few variants when it comes to overcharge limits: 4V, 4.1V, 4.2V are some examples that I’ve seen in the datasheets.

However, when it comes to over-discharge protection the limits are set very low: 2.7V or 3V. Even these protections are only supported in not just “battery charging” chips but in “battery management” chips which tend to be much more expensive. However, what if you want to cut off battery power when the battery voltage gets lower than a voltage limit that is higher than the over-discharge cut-off voltage supported by the battery management chips? Continue reading “battery overdischarge protection circuit”

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SCR

http://www.allaboutcircuits.com/vol_3/chpt_7/5.html

http://wangdol.tistory.com/132

http://blog.naver.com/yjhzzing4699?Redirect=Log&logNo=20165607200

요약
일반 트랜지스터(emitter base collector)와 비슷. ebc 대신 agk 기호사용. a가 +극이랑 연결됨.
G에 전압이 주어지면 A->K 전류흐름. 그 전에는 안흐름
근데 G에 전압이 주어졌다가 안줘도 a->k 흐름은 유지됨.
즉 on 상태가 유지되는 특성. 다른 표현으로는 latching 특성이 있다고 말하기도함.
on상태를 off로 되돌리는 방법은 간단하게 A에 주어지는 전압을 해제하든 해야함.