The chip on the ink cartridge will show empty even after the tank has been refilled. To restore the chip setting to full it must be reset with an electronic chip resetter.
It is possible to use the refilled tank on the printer even though the chip indicates empty. However, you must always ensure that the cartridge has ink in it while printing. If it does not have ink while printing, permanent damage to the printhead will likely occur. Click here to learn how to disable the ink chip on the printer.
The preferred method of using refilled cartridges will be to use a resetter to restore the chip to behave like a new cartridge.
A reset chip allows the cartridge to electronically function as a brand new one. It will estimate the remaining ink in the tanks during printing and more importantly, when the tank has run out of ink, it will provide a TRUEwarning that the cartridge ink level is low and you should do something about it. This is Canon's patented process of optically detecting true ink levels and is a feature to protect the printhead from damage resulting from printing without ink.
For the cost of the resetter it is a good investment towards minimizing damage to the more costly printhead.
The resetter shown comes with a USB cable and this needs to plug into any USB port during use. This model requires no batteries.
There is also another benefit to the resetter that is largely ignored. It will increase the life of your printer waste ink pad dramatically if used strategically. The best way to use it is to refill and reset ALL cartridges anytime ONE needs to be filled and reset.