# 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.

- [Original product page](https://bargainpostbox.co.uk/product/fireangel-fa3820-portable-carbon-monoxide-alarm)
- [View offer](https://bargainpostbox.co.uk/visit/fireangel-fa3820-portable-carbon-monoxide-alarm)
- Market: UK
- Language: en-GB
- Currency: GBP
- Brand: FireAngel
- Model: FA3820
- Price: 16.20 GBP
- Previous price: 25.99 GBP
- Discount: 38%
- Price checked: 2026-11-12T15:10:21.271Z
- Rating: 4.6 / 5
- Reviews: 3499

Prices and deal status are the latest recorded data, not a guarantee of availability. Confirm the price and availability with the store.

## 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.

## 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.

## 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.

## Before you buy

- 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.

## In the box

- 1 carbon monoxide detector with sealed battery (Included)
- 1 manual (Included)

## 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.

## Customer feedback

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.
- Positive themes: 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.
- Negative themes: Some customers find the beeping extremely loud.
- Mixed feedback: Feedback varies on whether the alarm is appropriately audible or excessively loud.
- Mixed feedback: 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.

## Alternative options

- [FireAngel FA6813 Portable Carbon Monoxide Detector/Alarm, 10 Year CO Alarm \| 1-Pack, Battery Powered Carbon Monoxide Alarm for Home & Travel, CO Alarm Detector Monitor for Caravans, Campervans & Cars](https://bargainpostbox.co.uk/visit/fireangel-fa6813-eux10-portable-carbon-monoxide-alarm)
- [FireAngel FA6812 Digital Carbon Monoxide Detector for Home, 10yr CO Alarm \| 1-Pack, Portable, Battery Carbon Monoxide Alarm for Home & Travel, CO Alarm Detector Monitor w/Screen for Campervans & Cars](https://bargainpostbox.co.uk/visit/fireangel-fa3820-portable-carbon-monoxide-alarm)
- [Kidde K5CO Carbon Monoxide Detector Alarm with 10-Year Sensor Life \| Battery Powered, 2 x AA Batteries Included, Wall Mount or Free-Standing, 85dB, Kitemarked to BS EN 50291-1](https://bargainpostbox.co.uk/visit/fireangel-fa3820-portable-carbon-monoxide-alarm)
- [FireAngel FA3322 Digital Humidity & Carbon Monoxide Detector/Alarm for Home \| 1-Pack, 10-Year Sealed Battery Carbon Monoxide Alarm for Home, Travel Humidity, Temperature, CO Alarm Monitor for Campervans](https://bargainpostbox.co.uk/visit/fireangel-fa3820-portable-carbon-monoxide-alarm)
- [Kidde 2030-DCR Compact 10 Year Life Carbon Monoxide Alarm with AA batteries](https://bargainpostbox.co.uk/visit/fireangel-fa3820-portable-carbon-monoxide-alarm)
- [FireAngel FA3313 Portable Carbon Monoxide Detector, Carbon Monoxide Alarms for Home, 10-Year Sensor, Replaceable Batteries, Travel CO Monitor, 1-Pack](https://bargainpostbox.co.uk/visit/fireangel-fa3820-portable-carbon-monoxide-alarm)
- [Carbon Monoxide Detector, 10 Years Sealed Battery, Carbon Monoxie Alarm, With Temperature and Humidity Detection and LCD Display, Carbon Monoxide Alarms for Home](https://bargainpostbox.co.uk/visit/fireangel-fa3820-portable-carbon-monoxide-alarm)
- [Carbon Monoxide Detector, 10 Years Battery Carbon Monoxide Alarm, CO Alarm with Test/Silence Button,Carbon-Monoxide-Detector Comforms to EN 50291 Standard](https://bargainpostbox.co.uk/visit/fireangel-fa3820-portable-carbon-monoxide-alarm)
- [Kidde K10LLCO Ten Year Longlife Carbon Monoxide Alarm with Sealed Lithium Battery](https://bargainpostbox.co.uk/visit/fireangel-fa3820-portable-carbon-monoxide-alarm)
- [2 Pack Kidde 2030-DCR Compact 10 Year Life Carbon Monoxide Alarm with AA batteries](https://bargainpostbox.co.uk/visit/fireangel-fa3820-portable-carbon-monoxide-alarm)
- [2 Pack Kidde 7DCO Portable Digital Display Carbon Monoxide Alarm for Travel, Holiday, Caravan, Boats & Home - AA Battery Powered](https://bargainpostbox.co.uk/visit/fireangel-fa3820-portable-carbon-monoxide-alarm)
- [WisuAlarm Carbon Monoxide Detector, 10-Year Figaro Sensor, 10 Year Battery, Carbon Monoxide Alarm, CO Alarm with LCD Display, Test/Silence Button, EN 50291 Certificated](https://bargainpostbox.co.uk/visit/fireangel-fa3820-portable-carbon-monoxide-alarm)

## Add-ons

- [FireAngel FA6620 Optical, Battery Powered Fire/Smoke Alarms for Home \| 1-Pack, 10-Year Battery Smoke Alarm Detector, Replacing FireAngel ST-622/ST-620, Fire Alarms for Home](https://bargainpostbox.co.uk/visit/fireangel-fa3820-portable-carbon-monoxide-alarm)
- [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](https://bargainpostbox.co.uk/visit/fireangel-fa3820-portable-carbon-monoxide-alarm)

## Images

![FireAngel FA3820 Portable Carbon Monoxide Alarm, 10-Year Sealed Battery — 1](https://bargainpostbox.co.uk/i/ibOQkMHT4t22dGHHY6SQeTXBoOG--bWRip7yPkOfBMOES_hEfLPTSwxpnq4MbOYw3BpFiSkRmpNwBRebyc_jBOK6-tH05VF81b9uB2lCBYv7DUnRqFaH6Qi3.jpg)

![FireAngel FA3820 Portable Carbon Monoxide Alarm, 10-Year Sealed Battery — 2](https://bargainpostbox.co.uk/i/_2rIy_bgsvOFEfi7f0Z2aMN27Ep1D3HeYH8gWicdlP3d6ADM8TX93M9_98OmPJsVd7QhpYG6EuYlSQIFff7SopfrR_2B5KcnW6715fUwMK_qlKskmRjV905R.jpg)

![FireAngel FA3820 Portable Carbon Monoxide Alarm, 10-Year Sealed Battery — 3](https://bargainpostbox.co.uk/i/qkInEZicrxKzpWNkoD1qLBC5d72GpNp7I0TzrpM7ef2Fh8N27Ys4Uuld-OOQKx18CALfnDtSUmp9f90R2SUf2lNTkLjWjzqnsqT4gLlw9L06bN7mqcF4X3ce.jpg)

![FireAngel FA3820 Portable Carbon Monoxide Alarm, 10-Year Sealed Battery — 4](https://bargainpostbox.co.uk/i/KYAseCDnWqYAgRTDOp5Qrs8pw23pF1CBFVcy3zoZiwZAAN2ycpWyP0ha29NJ-hb0bGSuMik22sGXUfILaMa6eVEIhvQoSguukIgzqpski2nWSjv3LlSDO2Db.jpg)

![FireAngel FA3820 Portable Carbon Monoxide Alarm, 10-Year Sealed Battery — 5](https://bargainpostbox.co.uk/i/BF2Sr0BqEDS-pWFNK7cJ43KnfMpeptjvc3MkpCG69gOBJV4n2CGXnfZarMI_M2aIdhO8htWFhBCHeQEoRQoX4gbgqvxnxdiqAsvfTrLnEgK231vDP1TviUmK.jpg)

![FireAngel FA3820 Portable Carbon Monoxide Alarm, 10-Year Sealed Battery — 6](https://bargainpostbox.co.uk/i/-15D2dqN5YAECoFnK1z59g9K6T_xM4GUhqxo0WNmeLu9U4p3ta5QyEV0HlcA5I5RgbY36WC_mSCC9VBb3VsEf54mJ0M8azEJN2A5BX7piRejPH6elJRJKCda.jpg)

![FireAngel FA3820 Portable Carbon Monoxide Alarm, 10-Year Sealed Battery — 7](https://bargainpostbox.co.uk/i/9h9PoBYgavEhkP6vN2mRdxetu4Zgpslb5DsDlzSQ8SYQemC1jEcsoXTgOf3n8GsYS2BFC9lKo_vkYbQQoqfFpu0R5OLqg0MpBMKucZ89xY3TU-9uq3GNERXJ.jpg)