Electronics > Projects, Designs, and Technical Stuff
Automatic Ni-MH battery charger woes
<< < (6/6)
VanMarco:
i do have an lm393 on hand. i still cannot figure why the IC gets so hot.
mikerj:

--- Quote from: dave_j_fan on February 03, 2020, 02:21:44 am ---i would differ here as overdesigning nimh circuit is notneeded

simple resi and capacitor design works well


camelion chargers have very simple design

--- End quote ---

A simple resistor based trickle charger for NiCDs is ok, provided the rate is low enough but trickle charging NiMH cells is not generally recommended unless performed at very low currents (<0.05C).  Certainly you shouldn't be entertaining the idea of full speed charging like this without some method of automatically terminating the charge.
Conrad Hoffman:
It's important to understand the battery technology. Battery U. isn't perfect, but they generally give a good overview: https://batteryuniversity.com/learn/article/charging_nickel_metal_hydride

NiMH needs very good charge termination if you want to charge at a reasonable rate. At odds with that, NiMH doesn't charge well at slow rates, and still has to be terminated at about the correct point. I've owned several different chargers that claimed to do NiMH well, but only the most recent one seems to do well without damaging the batteries. IMO, there's no simple circuit that works well for this- you need a battery charging system, where you have several redundant termination methods.
Zero999:

--- Quote from: VanMarco on February 05, 2020, 03:34:28 am ---i do have an lm393 on hand. i still cannot figure why the IC gets so hot.

--- End quote ---
Add a 2k2 resistor in series with the op-amp/comparator output.
Navigation
Message Index
Previous page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod