Disclosure: I received a mix of free sample and loan units for the purpose of this review. I received no payment and was not required to write a positive review.
Back in November, I tested a couple of personal breathalysers that are sold as morning after protection – devices to use to ensure you are not over the limit the next morning after an evening of drinking.
Both devices appeared to work acceptably, but their varied results and poor specified accuracy (+/- 25% at the legal limit) made me wonder about their credibility and worry that they might give drivers a false sense of confidence as to whether they were legal to drive.
These fears were heightened when I discovered that a standard-issue police breathalyser – the kind police use at the roadside – retails at around £800. Even a cut-down version of this device with all the extra police functionality removed still costs £300; more than ten times the £25 cost of the more cheaper of the two AlcoSense breathalysers I originally tested. When there is this much price difference, there must be a compromise somewhere.
Breathalysers Test 2
Thanks to UKBreathalysers.com, who supply and calibrate breathalysers for a wide range of public sector, business and private customers, I was able to borrow three further breathalysers, including a police-specification unit, to test against the AlcoSense Lite device I tested previously. I did not include the cheaper AlcoSense ONE unit in this test as in my opinion its very low cost and lack of mouthpiece make it little more than a toy and certainly not something I would trust if my driving licence was at risk.
Dräeger 6510 (Standard UK Police model)
The Dräeger 6510 is the standard model issued to UK police for roadside use. In the USA, the 6510 is approved for evidential use – i.e. readings from the 6510 can be used in court in evidence against you. In the UK, I believe that evidential readings are usually taken via a further test on a machine in a police station or via a blood test.
- Cost: Approx. £800
- Specified accuracy: +/- 1.7% of measurement value
- The 6510 measures the precise amount of breath blown into the machine (1.7l) and has a fuel cell sensor – the most accurate and reliable type of alcohol sensor.
The AlcoDigital 3000 uses the same hardware as the Dräeger 6510 but lacks some of the additional software and calibration facilities required by the police. This enables it to be sold more cheaply without sacrificing the accuracy of the device.
- Cost: £300
- Specified accuracy: 1.85% of measurement value
- The 3000 has the same volumetric sampling and fuel cell sensor as the Dräeger 6510
AlcoHawk Slim 2
The AlcoHawk Slim 2 is a low/mid-range personal breathalyser. It uses a cheaper, semiconductor sensor to measure alcohol and does not measure the amount of breath blown, only the flow pressure, which enables it to ensure that the breath is supplied in one continuous breath.
The Slim 2 is approved by the Department of Transport in the USA as a screening device. This means it can be used to check for the presence of any blood alcohol but the result from such a test cannot be used as evidence in court – a further test on a more accurate device would be required for this. In the UK, this type of device is not used for any law enforcement purposes.
- Cost: £50
- Accuracy: +/- 20% at 1.25 times UK limit
AlcoSense does not reveal much about the technology in its breathalysers on its website, but according to its official specification, it was the least accurate (and cheapest) device in this test.
When it comes to breathalysers, it seems that you get what you pay for.
- Cost: £34.99
- Accuracy: +/- 25% at UK limit
Test Results: What Did I Learn?
I learned quite a lot about breathalysers from this test, but by far the most important and surprising thing I learned was about how different people’s bodies handle alcohol differently. I’ll come back to this shortly, but first let’s take a look at how the breathalysers coped with the testing.
My testing was conducted over several days, allowing me to try several different drinking scenarios. It’s a tough job, but someone has to do it!
I have not included details of what I drank in this test as everyone reacts differently to alcohol and comparisons between people are not relevant. What’s important is the results I achieved and the variation between them.
My first test was conducted over the course of an evening’s steady drinking (7pm-11pm) with a meal. The instructions for each of these devices say that you should not perform a test less than 20 minutes after drinking, so all tests were carried out after a break of at least 20-30 minutes from drinking. I also conducted a test 6 hours after drinking (simulating an early morning start) and 9 hours after drinking.
I have converted all readings into a % figure showing how close to the UK limit the results are. 100% equals the UK legal limit. I did this because not all the machines use the same measurement units, making comparison difficult without doing some maths.
|Time||Dräeger 6510||AlcoDigital 3000||AlcoHawk Slim 2||AlcoSense Lite|
|6 hours later||23%||14%||38%||25%|
|9 hours later||0%||0%||0%||0%|
The results from the two cheap personal breathalysers (Slim 2 and Lite) were less consistent than those from the 6510 and 3000. This highlights their unsuitability for use in a work environment, where someone’s job could depend on the outcome of a breath test.
The two cheaper devices are also likely to become less accurate with age – the more expensive units should be serviced every 6-12 months. Doing this will maintain their accuracy.
Important Lesson: People & Alcohol
People often ask how much they can drink and still remain under the limit. The answer is that everyone is different and that there is no safe amount. My testing proved that how true this is.
On a second evening, my wife and I did the following:
- We had exactly the same amount to drink, glass for glass, over exactly the same period
- We also had exactly the same meal during that time
Half an hour after we had both stopped drinking, we both used the Dräeger 6510 to preform a breath test. The results were surprisingly different:
- Me: 37%
- My wife: 57%
We repeated this with a similar result on a different evening – so it wasn’t just fluke.
These devices are primarily intended for use the morning after to check that you are below the legal drink drive limit. The only amount of alcohol you can safely drink before driving is none.
In the case of the AlcoHawk Slim 2 and the Alcosense Lite, I would not personally want to use one to safeguard my licence, due to the limited accuracy of these devices. After all, even if the AlcoSense Lite is working correctly within its specification, it could give a reading of anywhere between 75% and 125% for someone at the UK drink drive limit.
The Dräeger 6510 and AlcoDigital 3000 gave me more confidence, although I was a little surprised that they did not read more closely together at times. If you need something for business use, you should be considering something of this kind to ensure that you can take multiple, accurate readings at all times.