A27/MN27 Battery Equivalents and Replacements
A27/MN27 battery is a small, cylindrical, non-rechargeable battery, commonly used in car alarms, remote controls, garage door openers, glucose and blood pressure monitors, telecommunication devices, headsets, toys, etc.
According to the IEC standard, this battery label is 8LR732, since internally, it consists of 8 (eight) LR732 (or LR632) batteries connected in series.
A27 Battery Features and Specifications
Most common labels for this battery are 'A27 battery' or 'MN27 battery', but it is also commonly known as 27A, A27BP, G27A, GP27A, L828, etc.
A27 battery dimensions are 8.0 mm in diameter and 28.2 mm in length (0.315 x 1.110 inches) and it weighs around 4.0 - 4.5 grams.
Since it internally consists of 8 (eight) LR732 (sometimes LR632) alkaline batteries, A27 battery features a nominal voltage of 12.0 volts, a nominal capacity of 20-22 mAh, and cutoff voltage of 6.0-8.8 volts.
Actual capacity depends on the cutoff voltage of the device being powered by A27 battery and can be even 25+ mAh.
For example, Energizer A27 battery features a typical capacity of 27 mAh when being drained down to 6.0 volts using 20 kΩ load at 21°C.
Also, when the same Energizer A27 battery is being drained using 20 kΩ load, at 21°C, its runtime depends on the cutoff voltage, which is given in the following chart:
|Cutoff Voltage||8.8 Volts||7.2 Volts||6.0 Volts|
|Runtime||49 hours||54 hours||55 hours|
Note: Energizer A27 battery datasheet may be downloaded from the Energizer Official Website in the form of the Energizer A27 Datasheet PDF file.
A27/MN27 battery is a relatively common battery manufactured by several most reputable brands and it shouldn't be a problem to find it in local hardware stores or online shops.
Since it is an alkaline battery, its storage/standby life is 3-4 years, sometimes even more.
A23 vs A27 Battery
A23 and A27 batteries are two very similar batteries, sharing similar dimensions and internal structure.
While A27 battery features dimensions of 8.0 x 28.2 mm and internally consists of 8 (eight) LR632/LR732, A23 battery features dimensions of 10.3 x 28.5 mm and internally consists of 8 (eight) LR932 batteries.
|A23 Battery||A27 Battery|
Both batteries feature a nominal voltage of 12 volts, but due to the larger internal volume, A23 features larger capacity (on average, 50-60 mAh vs 20-22 mAh).
Some devices that are intended to be powered by A23 battery also feature small plastic battery adapter, being able to hold A27 battery in place of A23 battery - this allows the user the greater flexibility in finding the required battery replacement, but if the device is regularly used, A27 battery will drain much faster than A23 battery.
AAAA vs A27 Battery
AAAA are small, cylindrical batteries featuring dimensions of 8.3 x 42.5 mm and a nominal voltage of 1.5 volts.
A27 battery may fit the AAAA battery compartment regarding their diameter, but fortunately, they are too short to be used as a direct replacement due to the difference in length (42.5 vs 28.2 mm).
We say 'fortunately' since the voltage difference is huge (12V vs 1.5V) and such voltage difference may destroy the device intended to be used by AAAA battery.
Note: Some devices, for example, many Pen LED flashlights are being powered by 2 (two) AAAA batteries stacked one behind another for the battery pack featuring dimensions of 8.3 x 85 mm and a nominal voltage of 3.0 volts. Stacking 3 (three) A27 batteries in the same battery compartment is physically possible since it creates a battery pack featuring dimensions of 8.0 x 84.6 mm, but with the nominal voltage of 36 volts! Such voltage difference will for sure destroy any Pen LED flashlight or any similar device intended to be powered by AAAA batteries.
For short, AAAA and A27 batteries are not compatible in any way.
A27 Battery Safety Issues
Just like any other small and shiny object, A27 battery may get swallowed by a child or pet.
Modern batteries don't contain heavy metals like mercury and cadmium, but they are nonetheless dangerous, especially 12V batteries, which may cause heavy internal injuries and burns due to the electrolysis.
If A27 battery gets swallowed, call the local emergency center immediately and act according to their instruction.
That is the reason why most brands package their A27/MN27 batteries using so-called 'pets and kids safe packages' which is sometimes hard to open even by adults - but, better safe than sorry...
Long Story Short: If your device is powered by A27/MN27 battery and You need a new one, go for the A27/MN27 battery of some reputable brand.
If you happen to find out a plastic battery adapter holding A27 battery and after checking the device's documentation You find out that your device supports the use of both A27 and A23 battery, consider getting a good A23 battery which has the nominal capacity 2-3 times larger than A27 battery.
Again, don't swap AAAA and A27 batteries, that is an accident waiting to happen ...