I was wondering if anyone had any links / info on a dV (change in voltage) based battery charger for Ni-Cd or Ni-Mh batteries.
Ideally I am looking for a simple low cost comparator (ie LM393 or similar) based circuit and want to avoid using a more expensive dedicated battery charger IC solution.
I need to charge 2-5aH battery packs in around 16 hours.
When you charge a Ni-mH or Ni-Cd battey the voltage graph looks like the attached image. I am using a constant current charger.
When the battery charge is full the voltage of the battery drops as is shown in the attached image.
I am wondering if there is a simple way to detect that the voltage differential has turned negative over time so I can reduce my charge current to the battery.
Ideally I want to use a cheap IC based solution, something like a 555 or a LM393 would be good.