This graph above is from this past Saturday (4/23/22) as I was about to attempt my Level2. I used this altimeter 5 times last year and that was all (hence flight #6).
I placed the rocket on the rail and turned on my main altimeter (not pictured), waited for beeps, and then turned on this easy mini #6221 for a back-up and listened for beeps. All seemed well with both so I proceeded to install the igniter. I was on one knee with one hand on the nozzle of a J275 and I was inserting the igniter.
Suddenly there were two very loud "pops" and I couldn't get the (EXPLICATIVE) away fast enough. So after the gathering of everything, then the long walk-of-shame up the hill, I unpacked and pulled out the E-bay. Sure enough, the back-up easy mini no longer had charges. It had just fired the main and then the apogee charge while on the rail. Graph above (flight #6).
So I already had the motor reload in the case, and I'm not sure I could make it to another launch until June, so I decided to take a chance and go with a single armed and active altimeter. Mind you, the back-up altimeter #6221 was left in the rocket and went along for the ride - no charges attached. At this point I wanted to see if it would repeat the error/issue. Back to the pad and up on the rail she went. Altimeters switched on and all beeped the same as the first try. 3,220 feet later and I passed L2 cert.
Same temps, same breeze, same high cloud cover, even same orientation on the launch rail (lugs to the south side) as nobody else launched between my attempts.
Below is a graph of that next flight (flight #7) from that same easy mini #6221 maybe 45 minutes later. Battery voltages read the same. Only difference was that there were no initiators wired in to the back-up and no black powder in the charge wells. I don't trust that easy mini anymore - or the 2nd one I have. Such a shame, too. Only 7 flights.