adjustable low voltage cutoff with automatic reset

[markdi]

interesting circuit

it will shut off your device/flashlight before damage occurs to your battery from over discharge.

resets automatically

http://www.siliconchip.com.au/cms/A_102095/article.html

 

[markdi]

better link- whole article I hope

http://www.siliconchip.com.au/cms/A_102095/article.html

 

[BatteryCharger]

Both links are the same. /ubbthreads/images/graemlins/smile.gif Looks pretty cool, I wish I could buy one of those already put together somewhere.

 

[bikeNomad]

Re: adjustable low voltage cutoff with automatic r

Depending on the cutoff voltage you need, it may be easy to use one of the "power supply supervisor" chips like the DS1233AZ-10 (which I happen to have 200 of for some reason) to monitor voltage against a fixed cutoff (in the case of this chip, 2.8-2.97V). It's a 3-terminal device (VCC, GND, !RST), and it's got an internal pull-up resistor, so it can directly drive a BJT or FET to switch loads.

These have a 350msec timeout on reset; this may cause a useful 3/second warning flash when the batteries get near to cutoff.

So (assuming that you're using 3 Ni cells, or 1 Li cell) you could make a 2-component switch-off circuit (1 SO-223 part, 1 SO-23 part) with one of these and a logic-level N-channel FET.

There are also Li cell protector ICs that protect against over-discharge.