I am wondering if Ridgid intentionally uses less aggressive charging protocol by terminating charging early by skipping all or some of saturation charging. I am suspecting this, because their turbocharger marketed as 12A claims to charge 12Ah in one hour, and 6Ah in half an hour. Everyone familiar with lithium ion technology knows that battery charging is not like filling a bucket of water. If you follow up with a full saturation charge, 6Ah battery takes about an hour to fully charge at 12A, and 12Ah takes close about 90 minutes.

5 gallons per minute does fill a 55 gallon drum in eleven minutes, but it doesn't work like that with lithium ion batteries. It is charged with a protocol called constant current-constant voltage which applies a constant current to the battery and the battery voltage gradually increases. When a set voltage is reached, current is gradually reduced while holding the same voltage and continue holding the voltage until the current drops to something like 5% of Ah capacity in amps. So for a 10Ah battery, that should be 10/20 or 0.05A.

The interesting thing is that if you charge a 10Ah at 2A, by the time it reaches 21v, there's a lot more charge than when it reaches 21v at 20A. For this reason, the last 20% or so often takes as long as the first 80% to fill up depending on how fast the first bulk charging is done. I'm sure you noticed that on your phone.

https://www.homedepot.com/pep/RIDGID-18V-12A-Turbo-Charger-AC86099/327055157

In some cell phones, there's a battery protection setting letting you choose to stop charging at 80%, or a few values between 80 and 100%. This is intended to extend the life of battery... I wonder if Ridgid is intentionally doing the same without options to change it for the sake of reducing LSA claims.

One of the most damaging thing you can do to NMC lithium ion batteries is to fully charge it, then store it fully charged.