This depends how much power it uses, how often you use it and what to of e-liquid you use when you do! When should you change them?
Generally speaking, the less power your coil uses the longer it's going to last! But this will also depend on how much you use it: e.g. how much liquid you vaporize with it! There are a few key things that will determine how long your coil will last which we'll list below:
- The Wattage It's Run At: Essentially, the more power your coil requires the less time it will last for. This usually relates to the resistance (ohmage/Ω) of your coil. If it's less than 1.0Ω it's going to use more power and probably last around 7-10 days. If it's more than 1.0Ω it's going to use less power and probably last 10-21 days. This is a very rough guide, but the general rule is: more power, less time. Of course, if you run your coil above it's recommended wattage (which we don't recommend at all!) it's going to last even less time. Too much straight away and it won't even last a second!
- How Often You Use It: Like tires, the more you use coils the less time they're going to last! In terms of ml a coil will vaporize before it needs changing use 100ml as a very rough guide regardless of resistance. The sooner you get through the amount of e-liquid before you coil needs changing, the sooner you're going to have to change it!
- What Type Of Liquid You Use: It's no secret that some liquids are 'coil killers' (we're not going to name any names, but you know who you are!). Generally speaking if the liquid is a bit 'misty' and/or very sweet it's going to reduce the lifespan of your coil significantly! If you want the most out of your coil try and go for a clear (not necessarily colour, more how easy it is to see through it) liquid that doesn't taste like a bag of sugar!
Finally, when should you change them? You'll know you coil is coming to the end of your life in two stages. Firstly, the flavour you've been getting since you changed to a fresh coil will start to deaden. If you're familiar with your liquid, you'll know what it should taste like: these flavours will start to become less pronounced (if you're trying a new liquid that you're going to be using a lot, it's always a good idea to try it first on a fresh coil then you'll know what it should taste like!).
The second stage is when the flavour goes and you start getting a cottony, burnt or metallic taste coming through. At this point your wick is gone and it isn't able to effectively deliver e-liquid to your coil. This is similar to a 'dry hit' (where when changing the coil you inhale under power with no e-liquid on the wick and get a strong metallic taste: see here how to not do this!). You might get this once where - for some reason - not enough liquid has got to your coil (maybe because your tank was left at an angle where there wasn't any liquid getting to your wick so it dried out): this isn't necessarily the end of your coil. Make sure your wick is wet and try again. But if it keeps happening then stop using your coil and change it as soon as possible! It's always good to have at least one spare coil for this exact reason because you really don't want to be using it once it's gone!
If you can see into your coil you can also usually tell by the colour of your wicking material (the stuff that was once white!). Once your coil is done it's usually a dark grey colour: black and you've gone too far! Don't just look at the inlets on the side of your coil to see what colour your wick is, to check it properly you need to see down into the inside of your wick!