For anyone not aware, there are hour meters that can be installed on spark-ignition engines that only need a single wire put near a spark plug wire to show cumulative hours. The electrical energy going to the spark plug is inductively coupled to the wire, which triggers the meter to count run time. I bought some of these a few years ago and thought they were great. Then they started to fail, some after over 100 hours, but many after only a few hours. Failures I have seen so far are resetting to 0, blank display, and invalid display. I have seen them available from a low of about $5 at Amazon (
https://www.amazon.com/Inductive-Automatically-Tachometers-Motorcycle-Generator/dp/B0C1S6BHC8/) to about ten times as much at NAPA (
https://www.napaonline.com/en/p/SME722500). Some add a tach feature, but they all appear to be the same basic design with variations in color or lettering.
At first I was quite impressed with the little meters. I had assumed that they were using energy harvesting to run the meter since there was no battery to replace. No, taking one of the failures apart, I found that there is a battery, but it is not meant to be replaced, so when it discharges the meter stops working. However, small LCD displays can use only a minute amount of power, so a battery still could last many years. That would be tolerable, but with the random resets to 0 and other failures occurring regularly, they are becoming a big disappointment. I have installed these off the engine and with some padding to reduce vibration, but they are still failing.
Does anyone know of a more reliable hour meter with the simple 1-wire connection? Battery operation gives many more choices of products, but it is not an option unless there is a voltage available to operate it, which is often not the case for small engines. Thanks for any ideas!
