If you're going discrete for more power I suggest NFETs with high pulse current capability such as IRFP3206 units. You can drive them with pnp bipolar transistors or NPN emitter followers and I'd use a 28 pin PIC micro to sequence the whole thing cleanly with dead time to prevent possible shoot thru. You should check the ESR of the batteries with an ESR meter so you know the size of the current pulse.
BISS type bipolars are optimum as Switching bipolars go.
One day I'm going to have to do this for Forklift 2V Lead Acid cells and that's how I"d do it as the PIC can also allow voltage sampling to actually optimise which cells get the charge balancing.
Thanks for links to charging information, but I have covered existing products and understand the charging properties very well.
This is about making a particular piece of test equipment.
I am not really up for a cell charging discussion, perhaps when the equipment design is further progressed!
I am using Picaxe 28x2 for the experimental stages.
Coded Several Types of Sequence to cover tests.
In regards to higher current replacement for relay.
Every second person suggests I use MOSFET, but no one has been able to demonstrate how it would be done with real components for this task!
Not suggesting it is the case with everybody, but many people suggest MOSFET because they know it has been done.
With no idea how to do it.
I thought it might be done with Bi-Directional P-Channel MOSFET/Power Switch per Cell.
https://www.mouser.com/ds/2/427/70785-241024.pdf
Using the Switches only for flow from Cap to Cell, but having the benefit of sourcing or sinking in one package?
Designing it correctly for the job is the problem!
Any voltage drop would need to be compensated, the we would need a source and sink version for each cell.
As with my previous questions?
Are you up for giving me an example?