Negative Delta V Detection Circuit

That op amp will make a fine comparator.
reference voltage* onto one input (say +)
Voltage to be monitored onto - input.
If - input goes below + input, the output goes high.
You can add positive feed back to romove jittering between states.
Google op amp comparator or op amp positive feed back.
Those 324s are nice fellahs to play with.
The un used op amps should have + input joined to their output or upto supply to stop 'em oscillating,.
There must be tons of op amp tutorial on the web.
Have fun..

* can be a simple potential divider, pot, reference voltage chip, zenner etc.

Del

The un used op amps should have + input joined to their output or upto supply to stop 'em oscillating,.

Shouldn't be (- input), your Catness?

Unity gain buffer...ok

Yeah, been looking at stacks of Op-Amps and similar. Am I looking in the wrong place with a peak detector circuit as my reference voltage? I can't figure out how to link together the peak battery voltage and also monitor the voltage drop of that same battery at the same time.

Or is it as simple as I think it is with using a peak detect circuit on one part of an op-amp (+) for the reference voltage and using the other part of the Op-Amp (-) for monitoring the voltage of the battery and switching either high or low once a drop has been detected in comparison to the (+) pin? I think a diode may come in handy to seperate the + and - pin from each other too as both will be linked to the same battery if I use what I just mentioned.

Nah, I don't think you need a peak detector...
Personally I'd charge at 2 rates, both based on current measured across a series resistor. I'd switch between them when the voltage on the pack exceeds a certain level.
But to answer your question, you could monentarilly shut off the charger and measure the voltage on the pack, and compare it with your reference votage.

But you probably don't need to, just compare the voltage on the pack (or a proportion of it for convenience, scaled down by a potential divider or pot) with your reference.
(A simple timer could switch off the charger for a second every minute...but this is all over complication)
I'd still do it the simple way...but hey I appreciate that you are experimenting and learning...after all I messed about with battery chargers and series regulated power supplies to learn about this stuff....many years ago.
Mmmmm huge birds nests of discrete components.
Del
(BTW while working on this stuff watch out for people creeping up behind and clapping their hands)

Food for thought. Thanks. I will run a simulation or two to see how I can mix things up. No punn intended. Will post later what I think will work.

...and yeah, I am all too familiar with birds nests and goblins behind my back

I also like to build practical circuits from simpler common parts. But sometimes it is just easier to buy the right part for the project. For best results in battery charging applications, I prefer to use an ASIC from a one of the major suppliers. Here is one example from MAXIM

http://www.maxim-ic.com/quick_view2.cfm/qv_pk/1666

A Google search will turn up several more. Good luck with your project.

Yeah, saw those during my search last few weeks. The 712 and 713 are ideal but too pricey from Maxim and other places. The 712 is ideal for what I intend to construct, but at around $10 each, will be out of my budget, as I would need a hundred of them. Also looked at many other types from other manufacturers and was still out of range from my hip pocket.

Figured of imitating those microcontrollers with the parts I have in abundance. Thanks for the best wishes on my madness