Alkaline Cells protection

Discussion in 'General Electronics Chat' started by Mandropov, Jul 5, 2004.

  1. Mandropov

    Thread Starter New Member

    Jul 5, 2004

    I'm currently design a Ni-MH charger, and I'd like to protect it from a Alkaline batteries charging.

    What the best way to implement the protection?


    Mikel (
  2. mozikluv

    AAC Fanatic!

    Jan 22, 2004

    the best protection for your nicad charger is YOURSELF. a charger will never distinguish what kind of battery it is charging, whether rechargeable or non. it will even charge your car battery. :p :D :eek: :rolleyes:
  3. Dave

    Retired Moderator

    Nov 17, 2003
    I'm with mozikluv on this one, it is a case of the operator using the charger correctly. If you do not with it to used for charging Alkaline batteries, make sure you place a warning on the unit where anyone who uses it (other than yourself) knows.
  4. Mandropov

    Thread Starter New Member

    Jul 5, 2004
    It's been a long time since I visited this forum. More than 5 years are passed since I asked a question here.

    For anybody interested in a solution, here is an answer: the way to detect Alkaline batteries in charger is monitoring its charging curve (constant current charge) during first few minutes. Even with a low charging current applied, the voltage on Alkaline battery will rise to its initial value (mature cells), while Ni-MH cell' charging curve will rise very slow (almost unchangeable during first 2-3 minutes with a low charging current). Then, if the voltage is raised immediately, the charging process should be terminated. Otherwise, the charging battery is probably Ni-MH. Low current for few minutes into Alkaline battery shouldn't damage it (i.e. the battery wouldn't leak). Of course, such a charger should be controlled by uCU (or very complicated discreet HW).
  5. tom66

    Senior Member

    May 9, 2009
    Thanks for posting the solution!

    I have a battery charger which when you put in alkalines shuts off in about 2 seconds. So maybe there's a faster way of doing it? Perhaps it is just detecting the relatively high cell voltage of 1.5V, and relying on your described method for determining if it's an alkaline for voltages lower than 1.5V.
  6. marshallf3

    Well-Known Member

    Jul 26, 2010
    Thing is I've got devices that don't even start signalling for alkaline battery replacement until they get down to 1.3V or less. My guess is that Mandropov's suggestion is correct so 2 seconds isn't always going to be long enough to detect that.