DIY - NI-Mh battery charger, no delta-v and no delta-t.

[SilverSolder]

The best strategy for charging NiCd or NiMH cells is d²V/dt² detection. This gives the cells a long life, I'm speaking from experience, my cells have until now survived 1000s of charge cycles without significant degradation. All other strategies that I've seen result in overcharging and damage.

To understand the idea, p.4 of this data sheet helps:

https://pdf1.alldatasheetde.com/datasheet-pdf/view/26117/TEMIC/U2402B.html

Today, you'd let an MCU with associated ADCs run the algorithm.

That seems an interesting principle, haven't seen that before.  Not sure how the low current phase (after d2V/dt2 detection occurs) is handled, is it just a timer or does it still need -dv/dt to stop charging?

[vk6zgo]

Never ever charge batteries w/o current limiting/regulation

There are "batteries & batteries".
Lead/acid "wet" cells have been charged with simple transformer plus rectifier combinations for decades.

[Avelino Sampaio]

Hi

I finally managed to finish the tests and I'm very satisfied with the results. The font I ordered from banggood met the requirements.

I thank the participants for sharing important information and thus contributing to my learning process.

[Avelino Sampaio]

Hi!

I took advantage of the box of an old stabilizer and thus concluded my project.  My eneloop, at the end of the charge, reaching around 1.48v.