I suppose you were correct with this statement, then.
I wonder why, though. Considering the fact that the X230 and X220 batteries are nearly identical (in outward appearance) and also both models’ batteries “clip in” each others’ battery houses.
Is it really about the charging chip’s firmware (if there is such a thing) that has a pre-compiled list of compatible brand/model names for X230, and once it sees a battery model that’s not in that list (such as the 6-cell battery I plugged in from X220 machine) it refuses to charge it up?
Btw, I had confused the cell number of the batteries I had. To clarify, my X220 had a 9-cell battery that I bought later. The X220 and X230 machines came with their own 6-cell batteries. I was using the X220 machine with the 9-cell battery I had bought. Now I have switched my machine to an X230, and tried inserting the 9-cell battery in the X220 into X230. That 9-cell battery isn’t being charged. But the original battery (which is 6-cell) came with the X230 gets charging when the computer is plugged into the wall outlet.
It wasn’t uncommon for the older IBM/Lenovo laptops to only accept whitelisted hardware, I think it’s the same with the batteries. You also can’t replace the Wi-Fi card, and on the older models like the X40 you couldn’t even replace the hard drive.
It can also be dangerous to not use a battery that isn’t fully compatible with the laptop, it could damage the laptop, or worse case burn down your house.