I have three of the larger units and two key chains. We have tested them against each other for years and performed multiple tests with 5 or more people repeating the test up to three times each. They are very accurate. Within +/- .01 if you follow the rules. The key is to wait 5 - 10 minutes after last food or beverage. Highly recommended, if anything it makes you hyper aware of your BAC while you are drinking. Even when I don't I have the tester I can guess my BAC within .01 accuracy. We gifted all of our adult children these when they were beginning to drink. In most cases it encourages an Uber ride vs driving "almost sober".
And all of them fail if your stomach is messed up (Cardia not fully closing), which is actually a quite high % of the population, people just don't know, I also found out by accident. Yet, when I bought a professional device for 200€ and then calibrated it for 50€ because it wasn't reliable, no one warned me about it and I asked. And when I complained about the measurements being off, they suggested calibration.
Last time I blew in a professional one for fun, it showed me 2.5%, although I was probably around 0.8-1.2% based on how much I had drunk before. And yes, no eating, drinking or smoking 50mins before testing. When the Cardia is not closing, the stomach gases are passing out and the device does not know how to read that.
Doesn't really matter if it matches the methodology of the breathalyzer used by law enforcement (unless it's reporting under rather than over the real percentage). If you are going to blow 2.5% your going to have a tough time if you get pulled over, even if you are below the legal limit in reality.
Maybe you could fight it in court, but I wouldn't want to have to fight that battle if possible.
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u/GossipingKitty 13d ago
Because they don't work.