Innokin T18E Prism Replacement Coils

The Bottom Dual Coil (BDC) design uses two separate heating wires wound within the coil head, arranged around a central wick. When current passes through the coil, both elements heat simultaneously, creating a larger combined heating surface than a single-wire coil at the same resistance would provide.

The practical effect is more even vapour production across each draw. A single-wire coil concentrates all heat on one point of contact with the wick, which can lead to slight variations in vapour character depending on draw speed and remaining tank level. With two elements sharing the load, each one runs at a slightly lower individual temperature while the combined heat is equivalent or greater. This reduces the risk of localised hotspots on the wick and produces a more consistent draw from the first puff on a full tank to the last on a nearly empty one.

The bottom position of the elements means the coil sits below the e-liquid level in the tank when the device is upright. E-liquid wicks into the cotton from the surrounding reservoir rather than being drawn upward, which reduces the gap between liquid level and wick saturation that causes dry hits in top-coil designs.

The 1.5 Ohm coil runs at 11 to 14 watts and produces a moderately tight MTL draw with warm vapour. At this resistance, the throat feel is comfortable with nic salt e-liquids at 10mg to 20mg. Freebase nicotine at 3mg to 6mg also works well. The draw is noticeably tighter than a restricted direct-lung coil but more open than the 1.7 Ohm option. Vapers who have been vaping for a few months often settle on the 1.5 Ohm as their everyday choice.

The 1.7 Ohm coil operates at 10 to 12 watts and gives the tightest, coolest draw available for T18E-compatible devices. At 1.7 Ohm, the vapour temperature is low and the draw resistance is high, making the physical act of drawing most closely resemble a filtered cigarette. For ex-smokers in their first weeks of switching, the 1.7 Ohm is the more familiar option. The lower wattage also means the coil generates less heat per draw, which extends its lifespan slightly compared with the 1.5 Ohm under equivalent use.

Both options work with 50/50 VG/PG e-liquids, which are the most practical choice for the T18E. Higher VG blends above 60% VG may wick more slowly at these resistances, particularly with the 1.7 Ohm coil at its lower operating temperatures.

Priming a new Prism coil extends its lifespan from the first use. Before installation, locate the small wicking ports visible on the side of the coil body and add two to three drops of e-liquid directly onto the exposed cotton. This pre-saturates the wick before the coil sees heat. Install the primed coil, fill the tank, and wait five minutes before vaping. The first few draws can be taken slowly and at a slightly reduced draw duration to allow the wick to reach full saturation.

Under regular daily use, a Prism T18E coil typically lasts 7 to 14 days. The lifespan depends substantially on the e-liquid used. Simple tobacco, menthol, or fruit liquids with low sweetener content produce the longest coil life. Dessert and custard liquids with significant sweetener content caramelise on the coil wire over time and cannot be cleared by wicking alone. These liquids typically shorten coil life to the lower end of the range.

Signs of a spent coil include a persistent burnt or flat flavour that does not improve after refilling the tank, reduced vapour production, or a gurgling quality in the draw that was not present when the coil was new. None of these signs improve by themselves: a coil that has degraded will not recover. Replace with a new coil, prime it correctly, and the original draw quality returns.