How to suck a battery ? : )

Thread Starter

q12x

Joined Sep 25, 2015
107
I've made this Shortcircuit Tester, using a passive buzzer. Basically i made a driver for the buzzer, and a regulator for the driver.
Circuit link here: https://www.deviantart.com/q12a/art/dBenzin99-ziub-28-Shortcircuit-Tester-846979932
But now i want a way to "suck" the voltage from the battery, when it will go down under 5V.
I believe it will work (lower) until the battery will go down to 3V, but lower than that, the buzzer will become silent.
I want to "suck" the rest of the remaining 3V, until i will completely deplete the batery, not 1mV to remain in it.
I imagine it will work with a boost converter or a joule thief. But im very unsure of these circuits because i never build one.
What do you suggest? Thank you !
 
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crutschow

Joined Mar 14, 2008
25,108
Once a 9V non-recharagable (alkaline or zinc) battery gets to 5V (less than 1V/cell) there's no significant energy left in the battery.
It's just a waste of effort to try to extract the little that's left.

Of course the LM317 regulator set for 5V will not regulate below about a 7V battery voltage.
 

Thread Starter

q12x

Joined Sep 25, 2015
107
What is the battery type? Draining a rechargeable one down too far may permanently damage it.
Good point, I didnt think to mention. The battery as shown in image i provided (you must zoom in), is an Alkaline 9V single use battery.
I intend in the future to buy a 9V rechargeable one. For now, i test how long this simple one will hold with my little circuit. Then 0.5V or 1V stop/limiter should be placed in the draining circuit i suppose. Hmm... very interesting point you bring.
 
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