FireAngel FA3820 Portable Carbon Monoxide Alarm, 10-Year Sealed Battery

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Product guide

FireAngel FA3820 Portable Carbon Monoxide Alarm, 10-Year Sealed Battery

The FireAngel FA3820 is a portable carbon monoxide alarm with a sealed battery claimed to last the alarm’s 10-year life. Its electrochemical sensor, audible and visual alerts, and free-standing or wall-mounted options suit home use and travel, while customer feedback is mixed on battery life, loudness and reliability.

At a glance

Manufacturer claims four audible chirps with a flashing red CO light for an alarm, plus an amber visual pre-alarm instruction to ventilate.
The manufacturer describes a sealed, tamper-proof battery intended to last the alarm’s lifetime, with a warning when replacement is due.
Alarm memory is described as showing a red CO light after a previous activation.
Listed for free-standing or wall installation and described for domestic premises including caravans, motor caravans and boats.

Price

£16.20Save 38%

Reference price: ~~£25.99~~

Price checked: 12 Nov 2026

View offer

Often bought together

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£12.98

FireAngel FA6720-R Heat Alarm/Detector for Kitchen with 10-Year Battery | 1-Pack, Heat Detector for Kitchen, Fire Alarm for Home, FireAngel HT-630 Replacement

£14.99

Pros and cons

Pros

Compact, lightweight design and free-standing use make it easier to take between home and travel locations.
The claimed pre-alarm and visual warning provide an additional alert alongside the audible alarm.
Alarm memory can indicate a previous activation when the user was away.

Cons

The sealed battery is not replaceable according to the product description, so a battery-life issue may require replacing the alarm.
Customer feedback includes reports of very loud beeping and of some units not lasting the claimed 10-year period.

Technical specifications

22 specifications

Identity
Brand	FireAngel
Model	FA3820

Power and battery
Power configuration	Battery Powered
Battery claim	10 year battery
Battery type	Sealed-for-life lithium battery

Detection and alerts
Sensor type	Electrochemical
Alarm	Audible
Alarm sound level	85dB(A) at 3m (minimum)
Supply voltage	3V DC
High-sensitivity mode threshold claim	180 ppm

Dimensions and installation
Dimensions listed	3.3D x 12.5W x 6.7H centimetres
Weight listed	95 Grams
Installation	Wall / free-standing

Materials and protection
Material listed	Plastic
Colour	White

Operating environment
Operating temperature	-10 °C to +40 °C
Operating humidity	30 - 90% RH
Storage temperature	-20 °C to +50 °C
Storage humidity	30 - 90% RH (non condensing)

Use and approvals
Stated use	Domestic premises, including static and mobile homes, caravans, motor caravans and boats
Approval claim	BS EN 50291-1:2018 and BS EN 50291-2:2019
Warranty claim	5 year manufacturer's warranty.

What to know before buying

Listing details to confirm

The 10-year battery life is a manufacturer claim, while customer feedback is mixed on battery duration and unit lifespan. The listing also describes standard alerts and a high-sensitivity pre-alarm mode, so distinguish the mode-specific early warning from the main alarm behaviour. Follow the product manual for siting, installation and response to an alarm.

What’s in the box

Included

1 carbon monoxide detector with sealed battery
1 manual

Who is it for?

A good fit for

Buyers seeking a portable CO alarm for domestic use, including caravans, motor caravans or boats.
People who want a sealed-battery alarm with audible and visual warnings and free-standing or wall installation.

Less suited to

Buyers who need a replaceable battery or a digital CO reading, neither of which is specified for this model.

FireAngel FA3820 Portable Carbon Monoxide Alarm, 10-Year Sealed Battery · photo 2 — Additional product photo 2

Customer reviews on Amazon

4.6 / 5 · 3,499 ratings

5 stars78%78%
4 stars15%15%
3 stars3%3%
2 stars0%0%
1 star4%4%

Customer feedback highlights ease of use and perceived value, but reports are mixed on battery life, loudness and reliability. Some customers praise the sealed battery, while others report rapid depletion or units failing well before the claimed 10-year life. Buyers who rely on a portable alarm for home or travel should weigh the compact, audible-warning design against this variation in reported experience.

Positive themes

Customers describe the detector as easy to set up and use.
Customers say it is good value and an important addition to the home.

Negative themes

Some customers report the battery depleting quickly or units failing before the claimed 10-year life.
Some customers find the beeping extremely loud.

Mixed feedback

Feedback varies on whether the alarm is appropriately audible or excessively loud.
Reports on reliability and battery life differ, despite the sealed-battery lifespan claim.

Frequently asked questions

How long is the battery intended to last?

The listing claims a sealed battery intended to last the alarm’s 10-year life. Customer feedback is mixed on battery duration, so treat the duration as a manufacturer claim rather than a guaranteed outcome.

Can it be used without wall mounting?

Yes. The listed installation options are wall-mounted or free-standing.

What alerts does it provide?

The manufacturer describes an audible alarm with a flashing red CO light and a high-sensitivity pre-alarm with an amber warning and a visual instruction to ventilate.

Is it suitable for travel?

The listing describes it as portable and suitable for domestic premises including caravans, motor caravans and boats.