Vape Battery and Charger Guide UK: Which Battery Fits and How to Charge It Safely
Vape Battery and Charger Basics
The short answer. Check what kind of battery your device uses before you buy anything. Some devices have a battery sealed inside and you charge them with a cable. Others take loose rechargeable cells, usually 18650, 20700 or 21700, and those need a separate vape battery charger. Match the size printed on the battery to the size your device says it takes. Charge on a hard surface, stay in the room, and stop using any cell that is dented, wet or hot.
This guide is for people who buy vape gear by the box or the pack. It covers which battery fits, how to read the numbers on the label, how to pick a charger, and how to look after cells day to day. Where we know a fact from our own product pages, we say so. Where we are giving a general safety rule, we name the UK fire services and councils it comes from. We have not tested any battery or charger ourselves, and nothing here is a lab result.
If you are new to all this, start with our starter vape kits. Most kits there use a built-in battery, so you can ignore loose cells until you move to a mod.
Built-In or Removable Vape Battery?
A built-in battery is fixed inside the device. You plug a USB cable into the side or bottom and wait. You do not take it out, and you do not need a separate charger. Pod kits and pens mostly work this way.
A removable battery is a rechargeable cell that slides into a box mod. When it runs flat you can charge it outside the device, or swap in a spare that is already full. People who vape a lot like this because a spare cell in a pocket case means no waiting around.
| Type | How it charges | Usually found in |
|---|---|---|
| Built-in battery | USB cable into the device | Pod kits and pens |
| Removable cell | Outside the device in a battery charger, or in the device if the maker allows it | Box mods |
How do you tell which one you have? Open the battery door on the mod. If you see a cell inside, it is removable. If there is no door and only a charging port, it is built in. Not sure? Send us the model name and we will tell you what we know. If we do not know, we will say so.
Some tank-style kits sit in the middle, with a built-in battery and a tank you fill yourself. The guide on topping up a tank covers that side of things.
18650, 20700 and 21700 Sizes Explained
The numbers are measurements in millimetres. An 18650 cell is about 18mm wide and 65mm long. A 20700 is about 20mm wide and 70mm long. A 21700 is about 21mm wide and 70mm long. This is general battery industry knowledge, and the sizes are the same whoever makes the cell.
| Cell size | Approx. width x length | On our site |
|---|---|---|
| 18650 | 18mm x 65mm | Golisi S30 (3000mAh), AWT (3000mAh, 40A) |
| 20700 | 20mm x 70mm | iJoy (3000mAh, 40A) |
| 21700 | 21mm x 70mm | Golisi S35 (3750mAh) |
The size matters because the battery has to fit the tube of the mod. A fatter cell will not go into a slot made for a thinner one. A thinner cell can rattle around in a wider slot, and that can leave a poor connection. Use the size the maker of your mod names.
Some mods are built to take more than one size, and the maker says so. Many are not, so do not guess. A common question is whether a 21700 can go in an 18650 mod. For most mods the answer is no, because it simply will not fit. Check the mod page or the box.
On our site, the Golisi S30 18650 is an 18650 cell with a 3000mAh rating.
For a wider mod, the iJoy 20700 battery is a 20700 cell, also rated 3000mAh. We have not listed which devices each one fits, so tell us your mod and we will check with you.
What the mAh and Amp Numbers Mean
Two numbers on a battery cause most of the confusion. They do different jobs.
The first is mAh, short for milliamp hours. It is the size of the fuel tank. A higher figure means the cell can hold more charge, so it usually lasts longer between charges. A 3000mAh cell should run longer than a 2000mAh cell in the same device, all else equal.
The second is the amp rating, shown as A. This is how much current the cell can give out in steady use without being pushed too hard. Mods that fire at higher power need cells with a higher amp rating. The pairing is the point: the cell has to be able to supply what the mod asks for.
| Number | What it tells you | Check it against |
|---|---|---|
| mAh | How much charge the cell holds | How long you want between charges |
| A (amps) | How much current the cell can give out | What your mod asks for |
| V (volts) | Normally shown as 3.7V on the pages that state it | The mod maker's instructions |
Here is a trap that catches people. A bigger mAh is not always the better pick. Cells are a trade. One that holds a lot of charge may give out less current, and one built for high current may hold less charge. So check both numbers against what your mod needs. Our AWT 3000mAh pair lists 3000mAh, 40A and 3.7V in its title. Our page does not explain the 40A figure any further, so it is worth asking us before you rely on it for a particular mod.
Some of our listings show the mAh but not the amp rating, and some give neither the voltage nor the chemistry. When a number is not on the page, we do not fill it in. We say "ask us".
Vape Battery Pack of 2 for Dual Mods
Many box mods take two cells at once. In a dual battery mod, both cells should be the same make, the same model and the same age. Never mix an old cell with a new one, and never mix brands. The cells share the load, so a weak one drags the other down.
This is why many of our cells come as a Pack of 2. You get a matched pair for one dual mod. The iJoy 20700 listing shows a single cell with no pack size, so check before you order a pair. If your mod takes one cell, a pair gives you a spare.
- Same make, same model, same age in one mod.
- Mark each pair, for example A and B.
- Charge the pair together and use them together.
Keep each pair together. Many people write a number on the wrap with a marker, one pair as A and the next as B, so the two cells always go into the mod together and always charge together.
The Golisi S35 21700 is sold as a Pack of 2, and the page gives 3750mAh as its capacity. It does not list an amp rating, so ask us if that matters for your device.
Choosing a Vape Battery Charger
A good vape battery charger does a few simple things. It stops when the cell is full. It checks each slot by itself. It shuts down if something looks wrong. Those are the features worth looking for.
- Stops by itself when the cell is full.
- Checks each slot on its own.
- Shuts down on a fault, such as a short circuit.
Count the slots first. Two slots suit a pair of cells for one mod. Four slots suit a busy household or a small stock of spares. Check which cell sizes the charger accepts, because some are made only for a few.
Here is what our own pages say. The Nitecore Ci4 charger has four slots and, according to the page, handles 3.7V and 4.35V batteries. The page also mentions voltage monitoring, protection against charging for more than 20 hours, a flame-resistant build and automatic temperature control. It does not list the charging current or the cell sizes.
The Golisi O4 charger is another four-bay unit. Its page lists 18650 among the sizes it takes, short-circuit protection, over-current protection and reverse-connection protection, and a 2A charge setting that drops as more bays are used. It lists a pouch in the box.
| Charger | Slots | Safety features on the page | Not stated |
|---|---|---|---|
| Nitecore Ci4 | 4 | Voltage monitoring, 20 hour charge cut-off, flame-resistant build, temperature control | Charging current, cell sizes |
| Golisi O4 | 4 | Short-circuit, over-current and reverse-connection protection | Screen |
| Efest Lush Q4 | 4 | Stops at full charge, over-discharge, over-voltage, short-circuit and reverse polarity protection | Cell sizes, power input |
Whichever charger you pick, use the cell sizes it names. If the page does not say whether your size fits, ask first.
Charging and Carrying Batteries Safely
These rules come from UK fire services, councils and trading standards, not from us. Greater Manchester Fire and Rescue Service, Essex County Fire and Rescue Service and Derby City Council each publish vape battery advice, and their points line up closely.
- Use the charger that came with the device, or one the maker recommends. Derby's advice with the Chartered Trading Standards Institute (2020) says not to use a phone or tablet charger for a vape.
- Charge on a hard, flat surface that does not burn, uncovered, and not on a bed or sofa. This is Greater Manchester Fire and Rescue's advice.
- Do not leave a charging device alone. Essex fire service tells people to stay nearby so they can spot overheating. Manchester and Derby both say not to charge overnight.
- Unplug once the battery is full.
- Keep spare cells in a plastic case, away from coins and keys, because metal touching a cell can cause a short circuit.
- Keep batteries out of hot cars and direct sun, and away from radiators.
Look at your cells now and then. If one is dented, torn, wet, leaking or gets hot while charging, stop using it. The councils and fire services say not to put damaged or dead batteries in a household bin. They go to a household recycling centre or a battery recycling point. Check your own council's page for the nearest one.
Heat is also one reason a pod can taste harsh. If your pod kit tastes off, our burnt taste guide goes through the checks, and a low battery is one of them.
If you use a box mod, the same rules apply to the cells inside it. Browse the vape box mods and read the maker's battery instructions for each one.
Vape Battery Wholesale for Regular Buyers
If you buy cells regularly, buying a few packs at once can save you reordering every few weeks. It also gives you matched spares. Our vape battery packs page lists everything we currently carry in one place.
Our vape battery wholesale pages do not show a bulk price table or a minimum order for cells, so we will not quote one here. Send us what you want and we will confirm what is possible. Do not assume a discount applies to batteries until we say it does.
One tip for anyone ordering several packs. Date them when they arrive. Use the oldest pair first, so no pair sits unused for months. Keep unopened packs somewhere cool and dry.
Vape Battery Charger Bulk Orders
Chargers are easier to stock than cells because they have no wrap to damage and no pairing rules. Even so, a charger bulk order is worth planning. Think about how many slots you really need, and which cell sizes your own mods use.
For a household with several mods, a four-slot unit covers two pairs at once. For one mod, a two-slot unit is enough. You can see all of ours on the vape battery chargers page.
The Efest Lush Q4 is a four-slot charger. Its page says the slots are monitored independently, that it stops at full charge, and that it has protection against over-discharge, over-voltage, short circuit and reverse polarity. Current is 0.5A for four cells, 1.0A for two, or 2.0A for one. The page does not list the supported cell sizes, so ask us before you pair it with a particular cell.
Store spare chargers in their boxes, in a dry place, with the cables wrapped loosely. Check the plug and cable for damage before every first use.
FAQs
Which battery does my vape mod need?
The one the mod maker names, in the size they name. Check the manual or the battery door. If you cannot find it, send us the mod name and we will tell you what we know.
Can I use a 21700 battery in an 18650 mod?
For most mods, no. A 21700 is wider and longer, so it will not fit a tube made for an 18650. Only use a size the mod maker lists.
Is a higher mAh battery always better?
No. A higher mAh usually means longer between charges, but the amp rating decides whether the cell can supply the power your mod asks for. Check both numbers.
Can I leave a vape battery charging overnight?
Fire services say no. Greater Manchester Fire and Rescue advise against leaving a vape charging while you sleep, and Essex fire service says to stay nearby while it charges.
What is the smallest vape battery wholesale order?
On the cell pages we checked, most come as a Pack of 2, and one 20700 listing shows a single cell. We do not show a minimum order for batteries, so ask us if you want more than one pack.
How should I store a vape battery charger bulk order?
Keep the boxes in a cool, dry place away from direct sun. Leave each charger in its packaging until you need it, and inspect the cable and plug before first use.
Do I need a charger for a built-in battery?
No. A device with a built-in battery charges through its own port with a USB cable. A separate charger is only for loose cells that come out of the mod.
