Dissimilar batteries:

I've researched this & was unable to find a satisfactory answer. This relates to lithium technology batteries. Suppose I had many batteries, some lipo, some lifEPo4 some lithium ion, would there be a way to create an isolating circuit so as to join all the like batteries in a pack, or packs, then somehow join the like packs of batteries together with the other packs, isolating them, perhaps with diodes, through some junction without the inherent danger one faces when joining different batteries? For simplicity, let's say 6s2p lipo, 6s2p lifEPo4, 6s2p li-ion, each pack isolated with a diode to keep the flow towards the load & away from the other packs and series the packs for approx lifEPo4 22.1+ lipo 22.6 + li-ion 21.6 46.3volts. the different voltages & different chemistries would be dangerous just to combine, and would lessen the voltages if one attempted that, I'm thinking of some way to isolate the packs from each other,directing the flow of electrons ONLY toward the load. Obviously the packs would have to be charged separately.

I use a 30 amp 5 pin automotive relay to isolate 2 batteries a 4s 220ah lifepo4 and a 312ah 3s li-ion battery. The main battery is on the normally close pins of the relay and aux battery is on the normally open pins. When the relay is activated it switches from one battery to the other.
The switch happens quick enough that if I have lights on, they either brightens or darkens as they switch from one voltage to the other. I use this so that my solar controller can charge one or the other battery, not both at the same time. It works pretty good and I didnt need a diode or capacitor.

Switching between packs is the easiest. Paralleling packs with the same voltage using diodes comes next. You can also diode parallel packs with different voltages, as long as you accept that one will drain before the other, each one has a low voltage cutoff, they're charged separately, the load can handle the voltage range, and each battery can handle the current alone.

You could also parallel the outputs of DC/DC converters, one for each battery, to get the same output voltage from them all. The converters must be able to function in parallel. Maybe you can even parallel non-cooperative converters with diodes, I don't know.