I have P2, P3 and P4, but in practice use P2 and P3. They are decent in general but over time drain power just sitting idle, so it is a bit a pain to remember to recharge them ahead of any situation when you need to rely on them. Above 3 cells I move to a huge power bank by a little known brand off AliExpress, with 8 cells, that can power my laptop, soldering iron, small drill, etc. The latter has USB-C and an outlet for which the voltage can be set manually.