What are the different types of AA and AAA battery?
AA and AAA batteries are the lifeblood of so many electronic devices. They power gadgets from your TV remote to your clock, your grooming gadgets to your wireless keyboard.
But were you aware that there are several different types of AA and AAA? They look the same, but they’re not the same at all.
In this post, we will break down the different types of AA and AAA batteries, and give you an explanation of what makes each type of battery unique.
- Not rechargeable
- Short Shelf Life
- Abundantly Available
The most available batteries on the high-street, alkaline batteries are not rechargeable. Not ideal in the modern world, where the increasing focus is on recycling.
But they are cheap and easy to find, making them a convenient everyday option. Despite having a high energy density, Alkaline batteries have a short shelf life. They will also drain rapidly when in constant use.
Alkaline batteries also often struggle with high-power devices. This is because they cannot produce enough energy at speed. They are suited to low-power devices such as game controllers, television remotes and small toys.
If left unused, alkaline batteries can also leak and cause damage. The Potassium Hydroxide that leaks from alkaline batteries is caustic and thus toxic. 
- Not Rechargeable
- Longer life span
- More expensive
- Effective at extreme temperatures
Another disposable single-use battery, Lithium batteries are a more environmentally friendly option. This is because they outlast alkaline batteries’ lifespan between 8-10 times. 
They perform much better than their alkaline counterparts in extreme temperatures.
At 2 to 3 times the price of Alkaline batteries, Lithiums still represent better value. They are more suited to high-drain electronics such as door alarms and camera flashes.
Lithium is an exceptionally low-density metal. So Lith batteries weigh less than Alkaline batteries. This makes them more suitable for portable items that need lots of power, such as power tools.
Lithium batteries are also safer than Alkaline batteries, as they are non-toxic and don’t leak. Even so, there is a small risk of overheating and explosion. This can occur in the event of a short circuit or other damage. That is why the regs on sending them in the mail are so tight.
- 2,000 cycles
- Degradation quicker than lithium
Lithium-ion (Li-ion) and standard lithium batteries both contain lithium. But there are key differences.
Boasting a 1.5 Volt output, Li-ion AA and AAA batteries are rechargeable and will last for at least 2,000 cycles. 
This makes them more sustainable than their non-rechargeable counterparts.
Unlike the li-ions, the anode of the standard lithium battery contains lithium only. The li-ion anode contains a multitude of materials. This means that the manufacture of li-ion batteries is more complex and expensive.
And although standard lithium has one charge only, that charge lasts longer than a single li-ion charge. So, lithium batteries are still considered useful for certain applications.
And finally, standard lithiums can rest for several years with little degradation. In contrast, Li-ion batteries are no good after 3 years without use.
However, it is worth noting that Lithium-ion batteries do have some safety issues, particularly when charging, so only a dedicated charger should be used. 
Nickel Metal Hybrid Batteries (NiMH)
- Shorter shelf life
- Not great in extreme temperatures
NiMH batteries are the most plentiful form of rechargeable battery. They are the non-toxic replacement for the now obsolete Nickel Cadmium (NiCD) Batteries.
Rechargeable with up to 1000 cycles, NiMH batteries are more sustainable than disposables. But they slowly self-discharge over time, even when not in use. This gives NiMH batteries a shorter shelf life and low use time.
They are suitable for busy high-demand items such as digital cameras. Their use in items such as smoke alarms is discouraged. This is because NiMH batteries self-discharge, usually needing recharging after 90 days.
Recently, new technology has been developed which prevents self-discharging to some degree. These are Ultra Low Self Discharging (ULSD) NiMH batteries. They reduce the self-discharge rate, but this is in exchange for some capacity. 
NiMH batteries also tend not to function well at extremes of temperature. Furthermore, the internal structure of NiMH batteries is susceptible to damage. So take care not to drop NiMH batteries.
Nickel Zinc Batteries (NiZN)
- Long shelf life
NiZN batteries are quick to recharge, inexpensive and have a long shelf life. They hold a charge longer than NiMH batteries but are still subject to a degree of self-discharge.
An important feature of NiZN is a higher initial capacity. So they are excellent for high-demand devices such as camera flashes.
NiZNs are the most recyclable batteries available. The metal components; Zinc and Nickel are easy to separate and reuse. These batteries function well at extreme temperatures and are stable during charging. But they need a special charger to recharge them, adding to the cost.
NiZN batteries are also slightly larger than typical AA batteries. So they can be difficult to fit in the occasional tight-fitting battery compartments.
Nickel Cadmium Batteries (NiCD)
- Useful at high temperatures
- Low capacity
These batteries are almost obsolete since the introduction of NiMH batteries. In fact, NiMH batteries outperform them in most respects. But there are still some conditions where NiCD batteries are still in use. These are mostly applications at high temperatures.
NiCDs are often used in larger power tools, medical equipment and larger toys. They were the first type of rechargeable battery. Yet they have many disadvantages. Cadmium is a toxic heavy metal that must be disposed of in the hazardous waste. Burning these batteries is particularly hazardous. 
If that isn’t bad enough, NiCD batteries have a very low capacity – the lowest of any battery available. They also have a pretty high self-discharge rate. At temperatures of 20C, they discharge at a rate of up to 10% per month. 
- Rechargeable and single-use variations
- Lithium, Li-ion and NiMH
CR-V3s are two AA batteries connected as one 3-Volt unit. They are usually Lithium, Lithium-ion or NiMH batteries. This means there are both single-use and rechargeable versions of CRV-3 batteries . They are used in MP3 players. digital cameras and similar devices.