I've installed a custom kernel over another one without installing the rom first twice, and both gave a bugged behavior so I try to remember to always install the rom first.
My test of the battery depleting are done.
I've tested the kernels PureCAF X1 EAS and IceCold r4.2 , because the I/O schedulers list of PureCaf is too poor.
If the battery started to deplete much sooner than with KangarooX 4.4, it started abnormally late and slowly.
The Antutu Stress test normally draws about 10% of the battery, but it drawed only up to 3% with both kernels.
As the delay before the battery start to deplete vary from a few minutes to a few hours with KangarooX.
I still don't know what this bug from from, perhaps one of my apps because I had an Automate flow that only monitored the WIFI, but it make the WIFI to enabled automatically, an unexpected behavior that could exists on the battery level too, as I have two apps that monitor it.
Finally, I'm back to a full Pie setup. It prevents to limit the battery charge but it reports the real charge level, in more of allowing to install the last version of the kernels instead of being stuck to a prehistoric one