Parallel connecting LFP batteries of different IR

For batteries of the same or similar IR, it’s considered best practice to diagonally connect load tap offs as shown in option A diagram below, but what is the best approach to manage paralleling of batteries with significantly different IR?

I have Lishen 272Ah cells with a spec sheet IR of 0.12mOhm and wish to add Eve 304Ah cells with spec sheet IR of 0.5mOhm, a difference of 4X. From the illuminating posts of @RCinFLA i understand this is because the Eve cells have a thicker electrode design, so I am concerned that in normal parallel connection with the Lishen cells the Eves will share less of the load.

Would alternative B below (having the load connections both connecting to the higher IR battery) offer advantages in keeping these cells closer to the same SOC, or am I way off track?

I would try both ways and compare.

sunshine_eggo said:

I would try both ways and compare.

Click to expand...

And report to back, I'm interested in empirical testing

Even if they don't share current equally, it's not a problem. When you hit the upper or lower knee the lazy one will get dragged into doing the work.

hwy17 said:

Even if they don't share current equally, it's not a problem. When you hit the upper or lower knee the lazy one will get dragged into doing the work.

Click to expand...

Yeah I completely agree and I have no qualms about paralleled cells discharging at slightly different rates then catching up later in the discharge curve, but with potentially a 4X IR mismatch I am thinking the imbalance in this case might be more than just “slightly” different and hence giving some thought to evening things up a little by arranging the connecting leads to compensate a touch.

But the advice from others to try it both ways is not a bad approach of course and I can measure the current with a clamp meter in the intermediate cable between each positive or negative pole so see what percentage of load current each battery is supplying. I guess I was just trying to save myself work and time by asking on here in case people have solved this problem before

A is better, not B.

Remember internal resistance is largely inverse of capacity. Hopefully that can explain why A is better in a way that makes sense as you wouldn't do B instead of A just because a battery is smaller.

Also those spec sheets IR aren't real. The Eve is a lot lower than that. Expect the eve to actually be lower due to the larger capacity.