Bests & Worsts Reviews from Amazon

I have some information that I believe will explain why some people, if not all, are having issues with battery life from the ZSE40 4-in-1 sensor. First, let’s talk about what “battery life” means. Is it the time until you see your controller displays “0% battery capacity” (or something like that), or is it the length of time you actually got from a set of batteries before the sensor just stopped reporting anything back to the controller app? It turns out, they are two entirely different matters. I ran a simple experiment where I substituted an inexpensive lab power supply for the batteries in the ZSE40, and then varied the voltage to the battery terminals while observing what my controller app (Indigo 7.0.3 running on a Mac) displayed as “Battery Level.” (Your controller may call it a different name, but the idea is the same: an attempt to tell you, the user, how much juice is left in your batteries.) The results of my measurement were quite surprising. This comments section is not intended for any kind of technical discussion. If I got into electronic terms, most would not understand it and rightly ignore it. I must condense my findings into something simple. But one thing you need to know is how to gauge the health of an alkaline battery. You can do this by measuring its "voltage" using a simple meter. A fresh alkaline will have a battery voltage of between 1.5 to 1.6 volts. As the battery discharges, its voltage will slowly decrease. A half-discharged battery measures about 1.25 volts. When the battery is fully discharged, its voltage will measure about 1.0 volts (some might prefer 1.1 volts). These numbers are approximations, but are reasonably accurate. Next, you must understand how a controller app determines the state of the battery of the ZSE40. It is NOT the app that does the measurement. It is the ZSE40 itself. It reads the batteries’ voltage, computes “something,” and then spits back a value between 0 to 100 to the app that specifies the batteries’ health, as a percentage. This is the number that you all read. From my above description of an alkaline battery’s state of health as measured by voltage, you would think that 100% would translate to a voltage of 1.5 to 1.6 volts, and that 0% would translate to a voltage of about 1.0 to 1.1 volts. You would THINK that, wouldn’t you? Think again. For whatever reason, the hardware and/or firmware in the ZSE40 considers a battery voltage of 1.3 volts to be at 0%. As in “dead battery.” I’m here to tell all of you that an alkaline battery with 1.3 volts across it is quite healthy, having about 60-80% of its capacity still remaining. Yet, the Zooz ZSE40 translates any voltage of 1.3 volts or less as 0% remaining capacity. The sensor tells you to throw away your batteries when they in fact they are still very healthy, and commenters respond with “eats batteries!" You will notice that even though the controller app says your batteries are exhausted, the sensor still continues to work just fine. It only confirms that there is still a lot of gas left in their little tanks, despite what the gauge says! Once you see "0% capacity remaining," you have no idea if your batteries have 80% capacity remaining or 1% remaining. You're flying blind at this point. A last point to be made is that the sensor ceases working when the battery voltage drops to 1.1 volts per cell. This shutoff leaves a bit more battery energy on the table, so it is a bit wasteful, too. This, folks, is why many of you observe short battery life. It is not the fault of the app, it is not a coding error in your app, it is the fault of the ZSE40 sensor for reporting this erroneous number to the app. The app writers can only report the information that the sensor gives it, even if it is wrong. And it is. I give it two stars because while the fuel gauge is thoroughly messed up, the sensors themselves are decent. Zooz should either update the firmware (mine is 16.09, BTW) or should not be shipping a product so flawed. ++++++++++++++++++++++++ For those of you who want a bit more detail, here is how the sensor converts battery voltage (I’ll call it Vbatt) and Capacity remaining (I’ll call it CR, expressed in percent) as the ZSE40 passes it to your controller: CR = (Vbatt - 1.3) * 500 (in percent) or conversely Vbatt = (.002 * CR) + 1.3 (in volts, for 1.3V ≤ Vbatt ≤ 1.5V) So 1.50V or higher reads as 100%, 1.46V reads as 80%, 1.42V reads as 60%, 1.38V reads as 40%, 1.34V reads as 20%, and 1.30V or less reads as 0%. If you understand anything about alkaline batteries, you know that these numbers are complete nonsense, as they paint just about any alkaline as far, far weaker than it really is.