Ender 3V2 heater cartridges

I was under the impression that the Ender 3 series printers used a 24V 40 watt heater cartridge but I read an article that says this it to hot and these machines should only use 30 Watt cartridges. A lot of websites including this one sell 40 watt units for the Enders so which ones should be used.

I can’t comment on the E3V2 specifically, but in general, it’s the current drawn by the cartridge that’s the real limit. Draw too much current and you will eventually kill the MOSFET that drives the heater cartridge. The Temperature is set by the thermistor/controller feedback loop. A higher wattage cartridge just reaches the set temperature faster. Since there’s a time delay between when the feedback loop responds to the set temperature having been reached and turns off the power, you end up with an over-shoot. The faster the temperature rise, the higher the overshoot. Temperature drop is governed by the ambient air temperature; airflow over the heating element, heatbreak and heatsink; and how much heat the filament itself absorbs in the process of melting as well as the rate of flow of filament. All of the cooling factors are independent of the heating element, so you heating curve, which should ideally look like a triangle-wave (equal heating and cooling times) ends up looking like a sawtooth (rapid heat gain with overshoot, regular rate of heat loss).

Iv used 40 with no problems

All the ones that I can find for sale seem to be 40 watt. I have sent a info request to Creality, have to see if they respond.