If you've been following these blogs for any period of time, you'll know battery safety is a topic we hammer on time and again. That's for good reason – there's no single element more important to your safety than a properly cared-for and used battery. We're not going to go into how to suggest the right battery for your mod and use in this piece, though that's been covered in these pages before and will certainly be a topic we continue to revisit. 

Here, we'd like to talk about how to monitor your batteries for wear, and how to decide when to replace them. First, if you're using a modern vape mod with replaceable cells, you're probably using flat-topped 18650 batteries (18 mm wide, 650 mm long). While there are some mods that use button-topped 18650s, or maybe 18350s or some other battery type, the advice we'll give here should hold true for all rechargeable lithium ion cells. How long should your battery last?

Typically, a quality first-rate cell from a known manufacturer ( like Golisi batteries) can be expected to last up to 300 charge cycles. That’s under optimum conditions, however, and it assumes you replace your cells when they drop below 50% charge, or about 3.6 volts. If you're using your mod until it dies consistently, you're probably draining your cells down to somewhere between a 3.2 and 3.4 volt charge – expect this to cut the lifespan in half. Still, 150 charge cycles isn't bad. You'll notice after a while that your batteries may not seem to hit as hard for as long, and that cells that used to last all day need to be swapped out after a few hours. If you've got several 'married pairs' that stay with one another for each charge and use cycle, it may take quite a while to get to this point, though if you're relying on just one or two sets of batteries as your workhorses, or if you're not keeping track of your cells and using them in random combinations (i.e. not keeping them 'married') you may start to notice a performance decline after just a few months. This is the first warning sign that it may be time to shop for some more batteries. 

There are a few things other than old age, though, that can contribute to killing a battery. If you ever overtax a cell to the point it's noticeably hot – not a few degrees above room temperature, this is normal, we're talking 100+ degrees of heat – there's a chance that the internal chemistry has failed. You may be able to continue using the vape battery, but there's a much greater chance that further stress will send it into thermal runaway (think exploding chemicals on fire, burning you and anything else in the spray path). For this reason, if you ever overheat a cell, we recommend discontinuing its use immediately. 

Another problem is rips in your battery's wrapper. Basically the entire cell except for the positive contact can be considered a negative contact, so using a cell with a tear or crack in the wrapper could expose you to electric shock or worse. Some people attempt to patch the wrappers of otherwise good batteries with tape or other means, while this is better than nothing it's still risky and can cause your cells to stick in your vape mod. Sleeves of plastic shrink wrap specifically designed for 18650s are readily available if you need to re-wrap your battery, and they're pretty easy to install with the aid of a household hair dryer, so if you want to extend your cell's life we'd recommend tracking some of these down. Inspect your batteries whenever they come out of your mod, and again when they come off the charger. It only takes a few seconds, and if you notice any kind of wrapper tearing, chemical leaking, heat bulge, or other irregularity you'll be able to avoid a dangerous situation before it happens. 

What happens, then, when it's time to say goodbye to your old cells? The chemicals in batteries are highly toxic, and in most jurisdictions it's illegal in addition to unconscionable to just throw them in the trash. Instead, most home improvement stores like Home Depot will have a used battery dropoff just inside the front door where you can safely dispose of them. Failing that, Google 'battery disposal in YOUR CITY' and a host of other options is bound to pop up. Keep in mind this goes for other batteries too, including the alkalines in your TV remote and the lithium-polymer packs in your cell phone. Keep it safe, and happy vapor trails.