Issue with the new heating cartridge of my 3D printer

Recently I had an issue with my heating cartridge, and I decided to change it.

For my Anet A8, I needed a 12 V 40 W one. I ordered it but I received a 15 mm length instead of 20 mm length heater element, but as the characteristics where the same I thought that it should not be an issue!

When I finally tried it, it was not able to reach the commanded temperature. It's like 175 °C instead of 195 °C.

I don't understand why it's harder for the newer heating cartridge to reach the commanded temperature, is the length important even if it's the same power (12 V and 40 W) ?

• Try to measure the resistance - does it have the expected 3-4 Ohms for a 40W 12V cartridge?
– towe
May 27 '20 at 12:15
• It might be the wrong cartridge May 27 '20 at 12:24

If it is a 24 V, 40 W cartridge, operating at 12 V, then the effective power would be $$40[V] \times \frac{12[V]^2}{24[V]^2}=10 [W]$$. This might be too low to reach the temperature. It is best to check the resistance of the heater element with a multitester; it should be about 4 Ω for a 12 V heater cartridge and about 14 Ω for a 24 V heater cartridge.