Some mods use external chargers; You remove the 18650 batteries or what have you, and put them in a separate USB charger. Those are not what we’re going to talk about here. This post is about mods and batteries that are charged via USB.
Hopefully it can provide some clarity, and maybe rid us of a few misconceptions about the technology involved.
There are basically two styles of USB powered mod chargers; the Ego/cigalike style chargers that come with smaller non-replacable batteries, and the integrated chargers found in box mods and certain tube mods. But before we go into all of that, let’s clear one thing up …
Your wall wart is not a charger
It’s just a dumb voltage regulator.
Pictured here is a USB power supply, aka USB wall adapter, aka USB wall wart, aka USB “charger”.
This is not a charger. People commonly refer to them as USB chargers, because they use them to charge things with. Yes, it sounds logical, but it is an unfortunate misnomer.
People will read about battery chargers, and believe that it applies to their USB wall warts. It rarely does.
The actual battery charger, which we will soon have a closer look at, is tailor-made for a specific type of battery. It monitors the battery as it charges, and limits the charge current in order to protect the battery. A good charger will shut down when the battery is full.
The USB power supply, on the other hand, has one job, and one job only: To put out a direct current at 5 Volts. It will try to do this from the moment you plug it in, to the moment you unplug it. It does not know, or care, about your battery. That is simply not its job.
Like all devices, the USB power supply has its limits. Some can only output a maximum of 0.5 A (500 mA), just like the typical USB 2.0 port in your computer. Some can output 1 A (1000 mA), which is closer to your typical USB 3.0 computer port. Others yet can provide 2 A, or even more.
It is important to note that a USB power supply rated at 2 A does not always output 2 A. It can if it must, but that is for the load (the charger) to decide.
So how about that USB charger?
They come in two flavors.
Ego/cigalike style charger
These screw into the battery. Different batteries come with different chargers. Because the charger is specially made for the specific type of battery, it is very important to always use the correct charger for the battery. If you ignore this, the battery may catch fire or explode, and you may lose your house, your car, or worse.
A word of warning: If you buy the cheapest starter kit that you can find on some online auction site, you risk getting a criminally unsafe charger with it.Some of these products are house fires waiting to happen.
As long as you get your batteries and chargers from reputable vendors, and make sure to always use the correct charger for the battery, you should be OK, though.
What do you mean you don’t see a charger in this picture? Oh, you’re right. The charger is hidden inside the mod, right behind that micro USB plug.
The good news here is that the charger is the correct charger for the battery. The manufacturer certainly made sure of that. Well, almost certainly. Crap products are always being made. Staying away from them is up to you.
The bad news …? There is no bad news. The charger doesn’t take up much space, it typically weighs less than a gram, and most importantly, you don’t have to think about it. This is about as safe and convenient as it gets.
This type of charger is common in box mods, but you can also find them in some tube mods.
What does this all mean for me?
Can I use my XYZ wall wart to charge my mod?
Probably yes. Remember, the USB power supply only provides 5 VDC to the actual battery charger. As long as it does this right, and the actual charger does its job right, everything is dandy. BUT here are a few things to check:
- Is your USB power supply of decent quality? Is it made by a reputable manufacturer?
- Does it actually output 5 VDC (like any well behaved USB power supply should)? Have a look at it. Does it say “Output: 5 V DC”? Then you should be good to go. If it says “Output: 12V AC” or something else, it doesn’t adhere to the USB standard, and you should not use it for anything other than its originally intended usage.
- Some USB power supplies made for pads and other high power devices are able to switch from 5 VDC to higher voltages, e.g. 12 VDC, depending on what is plugged into it. If you have one of these, how much do you trust its auto-sensing capability?
- If the battery charger for your mod is capable of charging at 1000 mA, you probably want to use a USB power supply that can provide at least 1000 mA. If you use a significantly smaller power supply, it will become a bottleneck and slow down the charging. It is better to use a slightly overpowered power supply, than an underpowered one. More on why below.
But someone said “You cannot use this or that USB adapter”
Some people advocate using an underpowered USB power supply (e.g. no more than 500 mA), because in the event of a charger failure, there is a chance that an underpowered power supply may limit the damage it causes.
However, running an underpowered wall wart at full tilt for hours on end comes with its own problems, like introducing ripple to the charger or simply running hot. Both of which increase the risk of failure in the first place.
Normally, the best practice is to run your equipment within its specifications. That means that you should use a USB adapter that is rated for at least as much current as your charger will draw.
- Wikipedia: Battery charger
- Wikipedia: Common external power supply
- Wikipedia: Ripple
- Wikipedia: USB
- Wikipedia: Voltage regulator
- Battery University
- E-cigarette-forum: Batteries and chargers
Yeah, well, you know, this is just, like, my opinion, man.
Do with this information as you will, and take the responsibility for your own safety. If running your equipment within spec actually causes it to fail, blame cruel fate, not me. If you feel that it’s safer to ignore everything I’ve said, knock yourself out.