Drivers who usually keep test records with a phone and app can easily lose results on days when the battery is dead or they left the phone behind. A personal breathalyzer is a device that measures your breath and shows the result on its screen, and app connectivity is just one way to store or review that result. Not having your phone does not make the test result itself disappear.
What matters is not memorizing just the number, but recording right away what information appeared on the screen. In particular, the unit of the number, when the test was taken, and whether the test finished normally are hard to reconstruct from memory later. If you set aside a sheet of paper or a small notebook and write down what you see as close to the original as possible as soon as you look at the screen, you can keep up your self-check routine even on days without the app.
First determine whether the device can test on its own
Not every app-connected product works the same way without a phone. For example, DATECH's AF-40BT is described as a dual-mode product that supports both standalone use and app use. This product has a display and device memory, so even on days without your phone, you can note down what you saw on the screen.
On the other hand, if the manual or official information for the product you use does not clearly state that standalone use is supported, it is better to check that product's conditions of use than to look for an improvised way to operate it without the app. Whether the phone is connected and whether steps in the test procedure can be skipped are separate questions. If the device screen showed an error or an incomplete test indication, do not record it as a normal result even if a number was visible.
Write the unit and time next to the number
The purpose of the memo is not to produce a detailed report, but to keep you from misremembering what the screen showed later. So it works well to put the device, test time, number and unit, and screen status together on one line. If you write only the number, you cannot tell whether it was in %BAC, ‰, or mg/L, which makes comparison itself difficult.
| Memo item | How to write it | Why you need it later |
|---|---|---|
| Device | Write the name of the device used or a label of your own | Keeps it from mixing with results seen on other devices |
| Test time | Write the date and time you actually checked the screen | Lets you tell it apart from the time it was transferred later |
| Screen result | Write the number and the unit on the screen as shown | Reduces misreadings of numbers without units |
| Screen status and travel | Write the normal completion, error, or incomplete indication and the travel method you chose | Lets you review the result and your actual decision process together |
The official information for the AF-40BT gives display ranges for %BAC, ‰, and mg/L. However, there is no need to convert units in your memo on a day without your phone. Copying the format shown on the screen exactly reduces calculation errors and the influence of memory. If other notices appeared on the screen, such as battery or calibration alerts, adding them briefly after the result keeps the context when you interpret that day's result.
A one-line memo in a hypothetical situation
Suppose, for example, that a person about to go to work the morning after a company dinner used the device without their phone. The screen showed a result number and unit, but right after the test they were busy getting ready to leave and tried to remember just the number. The facts observed here are "at what time, on which device, a result in which unit was shown" and "whether the screen showed normal completion or some other notice."
Interpretation does not mean deciding from one reading whether you can drive. In the memo, write what you confirmed on the screen and your actual travel choice, for example "March 8, 07:20, personal breathalyzer A, number and unit on screen, normal completion indication confirmed, used public transport." If the result was unclear or there was an error or incomplete indication, one possible action is not to guess and fill in the number, but to write "result could not be confirmed, did not drive." The completion criterion in this situation is not recalling the exact number, but having the memo record what the screen showed and the choice not to drive or the alternative travel method used.
Even if you transfer it to the app later, do not change the test time
Once you can use your phone again, you may want to add the record to the app. However, whether manual entry is available differs by product and app, so use only features that are actually supported. If manual entry is possible, it is best to record the original test date and time and to mark it as a manual record transferred later.
If you record the time you entered it in the app today as if it were the original test time, you may misread the time elapsed after drinking or the order of your travel choices when you look back at the records. Even without a manual entry feature, a paper memo serves well as a record. Keeping its source clear as a manual paper memo, rather than making it look like an automatic app record, reduces confusion.
Leave uncertainty visible rather than filling in blanks
If you left out the unit or cannot remember the exact error message, it is better not to fill the blank with a value you think you remember. Fill it in only when you can confirm it from the history stored on the device or the user manual, and if you cannot confirm it, leave it as "unit unconfirmed" or "status unconfirmed." Showing what you could not confirm helps your next decision more than making an incomplete record look complete.
Paper memos can also contain personal information, such as test times and travel details. Even if you build a checking habit with your family, you can consider keeping the memo in a set place rather than leaving it out where several people can see it, such as on the dining table or in the car. What family members should ask of each other is not to compare readings, but something closer to an agreement that on days when a result is doubtful or cannot be confirmed, they will choose a travel method decided in advance, such as public transport, a designated driver service, or riding with someone, instead of driving.
A memo is not a permit to drive but a record that supports your judgment
Results from a personal breathalyzer and paper memos are reference information for reviewing your own condition. The fact that a reading was recorded does not lead to the conclusion that you may drive, and when you feel different from usual or find the result hard to trust, a more conservative travel choice is needed. If you plan to drive the next day, deciding on an alternative way to travel the day before means that even when you have no phone or your records are incomplete, you will not treat driving yourself as the default option.
The core of a short memo is the "number," "unit," "time," "screen status," and "actual travel choice." If you write these five down the moment you see the screen, you can clearly tell which is an automatic record and which is a manual memo when you later compare them with app records or review your testing habits.
※ Self-check results from our products are provided as reference information only. Actual enforcement standards and testing methods may differ by agency and equipment, so self-check results may differ from enforcement results, and the company accepts no responsibility for enforcement results.
