Torch Batteries & Chargers Explained
By: Dewy Lawrence
There is a lot of misinformation about batteries and charging out there and also a lot of people who just want to know more about how it all works. So I decided that I would put my expertise as a qualified electrician and a battery enthusiast (If thats a thing) to good use and share the knowledge.
I will try to stick to the basics of common torch batteries for now and maybe we can get a little more involved in a future blog. You can skip to the conclusion at the bottom if you just want a basic rundown and my recommendations of what to use.
I will start by saying that technically what we will be talking about aren't actually batteries because a battery is historically something that consists of multiple electrochemical cells connected together. eg. A car battery consists of 6x 2 volt cells to make a 12 volt battery, whereas a AA “battery” is just a single 1.5 volt cell so you would need 2 or more AA cells to make a battery. The word battery has evolved over the years to include traditional batteries as well as single cells. So I will just refer to them all as batteries.
Battery Types
There are 2 main battery types that we can start with before breaking it down further.
Primary Cells - There are non rechargeable batteries such as your AA, AAA, C, D cells, there are hundreds more examples but any non rechargeable battery falls into this category. (There are some chargers that claim to recharge standard AA alkaline batteries but it is not efficient at all and really just a waste of time)
Secondary Cells - These are all your rechargeable batteries such as Lithium Ion (Li-ion) and Nickel-Metal Hydride (NiMH) These can come in all shapes and sizes and this category covers all rechargeable batteries.
Battery Chemistry
I won't go too far into the science of battery chemistry here as I could end up writing for days and there are really only a few that are going to be used in torches and outdoor products. The chemistry of the battery determines the voltage and is one of the most important factors to consider when purchasing a torch. I will stick to the three most common battery types used in torches.
Alkaline
These are your traditional AA, AAA, C, D and 9V Energizer or Duracell type batteries that you will find at the supermarket. They typically produce a nominal 1.5V per cell.
Pros:
- Easy to obtain and can be found all around the world
- Used universally in a lot of devices around the home.
- Fairly small and great for pen shaped torches
- Decent shelf life
Cons:
- Very expensive as you need to keep on buying them
- Very wasteful, as soon as they are depleted they go straight in the bin
- They have a tendency to leak and damage your devices
- They have a limited power output and are unable to provide enough current to power modern high powered LED torches.
- Poor performance in Sub-Zero temperatures
- NiMH batteries are rechargeable and come in the exact same sizes with a higher capacity
Whilst Alkaline batteries do still have place in the modern world it is generally in your TV remote! All jokes aside I do keep a stock of AA and AAA batteries at home as they always come in handy and there are still some very innovative torch companies making torches that use these batteries. Check out the Acebeam M20 for what I believe is the best single AAA torch on the market. Alkaline batteries are great if you are the type of person who will never remember to recharge your batteries but they also very wasteful and expensive and if you forget to take them out they will eventually leak and damage your gear.
If you come across a torch that wants you to use 3 or more AA or AAA batteries in them then I can assure you that it is using fairly old technology and there is something much better out there for you. If you come across a torch that asks for C or D sized cells it is likely only useful as a club to hit someone with.
Nickel-Metal Hydride (NiMH)
These are rechargeable cylindrical batteries but can be made into many shapes and sizes by combining multiple cells into a battery pack. For the purposes of modern LED torches we will talk mainly about the AA and AAA sized versions. They produce a nominal 1.2V per cell.
Pros:
- Rechargeable
- Available in a wide range of common sizes
- Great replacement to use in devices designed for Primary AA and AAA cells
- Good shelf life on the modern Eneloop branded batteries
- Unlikely to leak or explode
Cons:
- Power output is limited and not suitable for some modern high powered LED torches
- Expensive to buy
- Some modern chargers are removing the capability to charge NiMH to save space and money
- Slowly being left behind due to advances in other battery chemistry types.
NiMH batteries a great alternative to use in devices designed to take AA and AAA batteries if thats all you have, but they are still leaps and bounds behind lithium-ion batteries in terms of capacity and power output.
Lithium-Ion (Li-ion)
Li-ion batteries are the pinnacle of modern commercial rechargeable battery technology and there is a reason that Tesla use them in all of their electric vehicles. The cost has reduced dramatically in recent years to the point where they are much more economical than anything else on the market. The inclusion of USB powered chargers and torches with built in charging circuitry has helped boost popularity. Common sizes are 14500(AA), 18650 and the new 26650. Nominal voltage is 4.2V
Pros:
- Higher energy density provides longer runtimes
- Higher voltage and current output means brighter lights
- Rechargeable around 500 times for most common Li-ion batteries
- High output models can produce enough power to drive ultra modern high output LED’s
- The gold standard for modern LED torches and will be around for a long time to come
- Can be charged very quickly when using the right battery/charger combo
- Much greater performance in cold temperatures and can operate down to -40ºC
Cons:
- Some older gear can not use these batteries
- Harder to find in stores than traditional batteries
- So many brands, sizes and different configurations can be hard for a beginner to understand
Li-Ion batteries are the winners when it comes to rechargeable batteries for use in modern LED torches. There is a little learning curve to understand the different sizes and types but we are here to help with that! The 18650 cylindrical cell is the most common size available and is used universally amongst Torches, Electric Vehicles, Power tools and even Vaping (e-cigarettes)
Lithium Primary Cells
I will briefly cover lithium primary cells here as they are a fairly common battery, there a lot of different chemistries that can be used here that will result in different voltages and outputs but I will try to be brief.
AA/AAA - These primary lithium cells will give you the best runtime of any AA/AAA sized battery, but they are very expensive and you can get nearly the same performance from Eneloop Pro NiMH batteries which are rechargeable and much more cost effective. These do have an excellent shelf life and are great to keep in storage in case of an emergency.
CR123A - These were originally designed for film cameras but were taken in by some torch manufacturers in the late 1980’s. They are still used in some law enforcement and military situations where the increased cost is set aside due to the convenience of just throwing the old battery out and using a new one. A lot of torches that use 18650 rechargeable batteries are able to be used with 2x CR123A batteries as well. Another advantage is that they can be found fairly easily around the world due to their earlier popularity in film cameras.
Charging
Charging comes down to a few charger types and is fairly easy to understand. Most modern chargers have adjustable charging bays and can fit most of the common sized Li-Ion batteries in them. I could go into a lot more depth here but the basic concept of battery charging is that the slower you charge them the longer they will last you.
External 240V/12V Chargers
These are the most common types of battery chargers and are available as universal chargers which can charge both NiMH and Li-ion or as single chemistry chargers that can only charge one or the other. They range in size from being able to charge a single cell up to 8 cells and beyond. Some come with 12V car adaptors and some are mains powered only.
External USB Chargers
These are the newest charger type and are quickly becoming the most popular as they are very convenient due to the fact that they can utilise any USB port for charging and you can even use a power bank to charge in the field. Some of the newest ones can even act as a power bank and utilise your spare batteries to charge your other USB devices. You are limited by the 2.1 amp output supported by USB but there some modern chargers with 2 USB inputs that can charge up to 6 batteries at once. Check out the Queen Ant by XTAR for this functionality. USB chargers are generally limited to charging either Li-Ion or NiMH batteries but not both.
Internal USB Charging
A lot of modern LED torches are moving in this direction, they come with a built in Micro USB or USB C port so you can just plug in your smartphone charger and you never have to remove the battery. They generally utilise the same batteries as other torches so you can still carry spare batteries and swap them out as required. There are some that use built in batteries but these are generally smaller torches such as keychain sized or compact head torches. The only real downside here is that very large torches utilising multiple batteries may charge a little slower than when using an external charger due to the limited power output of USB ports, but some are already moving to the newest USB C standard which can provide plenty of power to charge them at full speed.
Proprietary USB Charging
This type of charging uses a dedicated magnetic charger that comes with the torch and attaches to the base of the torch, they generally charge via USB. This is great if you are buying a gift for someone who will probably only own one good torch. But if you lose the charger you need to either buy another one from the same brand or charge your battery in an external charger. The the problem here is that whilst the batteries are often the same size they are not universal and you would need to buy an exact matched battery from the manufacturer of the torch if you want to use the included charger. It also limits you because these torches are all side switched due to the tail switch location being taken up by the charging area. The Olight brand commonly uses this method and they make some great torches but it really does lock you into the brand which may or may not be OK depending on your individual circumstances.
Capacity and Power Output
1000mAh = 1Ah
Battery capacity is a fairly simple concept to grasp. It is measured in Milliamp hours (mAH) it just means that a 1000mAh battery can output 1000mA of current for one hour before needing a recharge. So the higher the mAh rating of a battery the longer it will last. There are some other factors to be considered here but that is the basics of battery capacity.
Power output is a little more complicated. We can have 2 18650 sized batteries both rated at 3400mAh but one can output 20A of current continuously whereas the other can only output 6A of current continuously. (The high output batteries are generally called IMR batteries) This is only important when using them in very high output torches that need to operate at a higher current to produce the required amount of light. If you tested both of these batteries in a normal torch that only draws 6A of current they would both have roughly the same runtime. So before you spend big dollars on IMR batteries its good to check if you actually need them to power your torches.
Conclusion
As you may have figured out I am a big fan of both Li-ion batteries and USB charging methods. The advantages are the increased runtime and power output of lithium batteries and the convenience of being able to charge your batteries using any available USB port. If you are somebody who owns a lot of different torches and uses them regularly you will likely benefit from an external USB charger such as the F2 from Nitecore but if you really only want to own 1 or 2 torches you might be better off with a torch like the EC50ii from Acebeam that has an inbuilt micro usb port and removes the need to own an external charger.
The 18650 battery size is the most popular amongst torch manufacturers and it will likely stay that way for years to come due to the convenient size and also continued use by Tesla in electric vehicles means they will keep getting cheaper and the supply is unlikely to dry up anytime soon.
This is by no means a fully comprehensive explanation of batteries and chargers and I have left out a lot of different types of batteries and stuck with the most popular and relevant information.
Please feel free to get in touch if you would like any more information or have anything else you would like to hear about in terms of torch batteries.