Venom 2-4 Cell AC/DC LiPo Charger

No, I'm not confused at all. I have tried to use such a charger before I wised up, and it could state 20 amps, it will still only push 3, no matter what because it only has 40 watts. It takes 100(101) watts to charge my 6500 SPC and SMC packs at 1C, that is around 30 mins from storage voltage. Like I mentioned before, if you have lots of time, a whole lot of time, you can get by with a very low power charger, but why would one?

"watts can back it up" is easy to determine via the UL rating. Ergo, declared "amps" is part of a larger analysis of the device. "will want to charge at close to 16 volts" I sense confusion? 16v is the nominal target voltage of a 4s, while you charge you are pushing amps. Yes your math is right, but subjective in the system. w = v * a is correct, but IR (load) is huge, a product of the system -- mostly battery. A firehose does you no good when you have a drinking straw in the the mix. Depending on the quality of your battery, tolerance for abuse or how high your >> amp << rate is for the charge, and the integrity of the charger you need to remember how the numbers are not black and white. On top of that consider the watts available for the power supply (AC) to support the charge. Things are not quite a one-to-one analysis. My EE is rusty on AC TBH.

The amp rating is meaningless unless the watts can back it up. That is what is important in a charger. It states 2s-4s, a 4s pack will want to charge at close to 16 volts. The electrical math says the volts divided into the watts will give you the amperage rate. 40 / 16 =2.5. I don't know if you tried, but a straight charge on a 4s pack like an ebuggy pack(5000-6700 mah) will take close to a couple hours at that rate. That isn't a balance charge, which is really what should be done each time. You can add another hour or more for that. Since this charger maxes at 3 amps any pack over 3000 mah (3 amps) will have to be charged at a less than 1 C rate also. Most 2s car packs are 4000-5000 mah It seems this charger is more in line for charging drone packs which are typically a lot smaller in capacity.