Setup:
This device has two modes of operation; stand-alone and app mode. First I will cover stand-alone mode. Honestly this device is so simple, if you can’t operate this in stand-alone mode you need immediate help and should stop drinking. In this mode you simply press the lone button on the device and hold it till you hear a beep. At that point the device will start to warm up, then it will automatically start a count down from 5 and tell you to blow. The entire time you are blowing you will hear a beep and you’ll feel a little click when it got a large enough sample to analyze. It will then calculate your estimated BAC and display it on the screen. The device has an auto power save feature which will shut the unit down after about 30 seconds or so. Below are two press images of the stand alone mode and ZeroLine estimate.
App mode is a little bit more complicated to get set up but is still pretty painless. Your first step is to go to your respective app store and download the free app from BACtrack. Once installed you will need to provide your email to register the device and its one year warranty. The next screen basically tells you not to use this to determine if you are safe to operate any equipment. Then the app instructs you to turn the device on. If it isn’t already, you will need to get the C8 into app mode. To enter into app mode, power up the device and then press and hold the lone button until the display reads app mode. It will then immediately switch to SEARCHING. Eventually you will see the phone indicate the device is connected and you can start a BAC reading.
Along the bottom you have a few options. The first gives you access to your historical readings. These are broken up into (3) categories: Mine (All), Mine (Verified), and Friends. Swiping you’ll also be able to see how good your guesses were compared to actual readings and once more will give you a bar graph of where your readings landed. Selecting the Globe icon then launches your browser and brings you to BACtrack Worldview. The “?” mark provides device background and information, and finally the Settings tab allows you to set Data Storage and sharing preferences, see account info, change units, and if needed call an Uber.
Performance
At this point the device is ready to go and all you have to do is tap the pulsating BAC test button. Doing so, the device will warm up and allow you to guess what your BAC reading will be, then it alerts you that you should take a breath and finally will tell you to blow. In just a few seconds the results will be ready and displayed on your device along with the estimated time to your BAC reading reaching 0.000% or ZeroLine.
I had hoped to test this against a police breathalyzer but I found out; at least in the state of New Jersey, many cops don’t have these. As it turns out they are not admissible in court as probable cause for an arrest. That is why you often see officers performing field sobriety tests. If a person fails this they can be arrested under suspicion of DUI and taken for a breathalyzer which is often done at the police station. The reason for this is due to the potential inaccuracy of the devices themselves. As this device clearly states, you need to wait 15 minutes before taking a reading after your last drink. This is due to the residual alcohol in your mouth affecting the reading. This has a huge effect. At the show when I tested this I blew a 0.244 right after a sip of a rum and coke. But about 20 minutes later it was down to 0.043. So this artificially high reading could end up getting an arrest overturned even if it was proven later they were drunk, just because it was considered an illegal arrest.
So with that option out the window the next thing that came to mind was the following. I decided I would test the device by drinking a few beverages then immediately measuring the BAC, waiting 15 minutes to test and then testing every hour or so. Then compare the estimated ZeroLine hour by hour to see how accurate it is. So just after eating lunch I starting drinking beer (Molson XXX) and within an hour I drank four. Immediately after the last sip I measured my BAC and got a 0.166%, just 15 minutes later it was a third of that, reading just 0.054%. Below is a chart of the readings I got over time.
When I discussed this device with a neighbor whom is a police officer; he mentioned that their protocol for using a breathalyzer requires them to watch the suspect for 15 minutes to ensure they didn’t belch as this could cause a higher reading than actual. So when I saw that the 3:45 reading was not lower and in fact my ZeroLine estimate jumped by 45 minutes I thought maybe that is what happened at this point. But if that were the case you would expect the next reading to show a large drop but it didn’t. In fact the next reading showed an elimination rate of 0.013%/hr. which correlates well to the estimated rate of 0.015%/hr. the officer mentioned. So I suspect this plateau was either due to food I ate at lunch and/or snacks I ate later that were affecting the absorption of the alcohol I consumed. Taking that one point out, my average elimination rate came out to be 0.0148%/hr., so it seems the rule of thumb is fairly accurate, and so is this device.
