Solenoid Deactivates Arduino on Engage

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Hi all! Working on a little Christmas present here - one of those GPS lock boxes that only work once you get to a certain location.

Included is a sketch of the circuit itself. I have a simple script running to wait one second and then send a high signal to the MOSFET, hopefully engaging the solenoid.

My problem right now is that most of the time, inconsistently, the solenoid cannot make it all the way closed. Midway through the attempt the MicroView just gives up and resets.

I’ve ruled out back EMF from an inductive load because I have not one but two snubber/flyback/freewheeling diodes on the circuit. The signal to the 12v boost converter goes to the protoboard power rails before it goes to the boost converter.

What’s more, when I plug the boost converter into a wall supply and use the battery, the circuit works, and then continues to work for a small while.

This leads me to believe I have an over current issue. Currently working on trying to get a measurement out of the circuit. This is why I upgraded my current limiting resistor to the MOSFET from the usual 1k to 3.3k.

Is there a way I can source more current from the Lipo or perhaps charge up some kind of cap so I can dump it on engaging the solenoid? I believe a cap could work since after plugging the 12v boost converter into the wall it works for a while. I’m thinking maybe a cap somewhere in the circuit is getting charged up…

Thanks so much, and happy holidays!

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Using 2 boost converters in series with the highest current draw item at the end of the chain is the problem. The first converter is being asked for way more instantaneous current than it can provide. A cap on the 5V rail might help stabilize the power, but a large enough cap still is going to draw some big current when it has to charge at startup. I’d suggest using a servo instead of a solenoid, and changing the power source to two LIPO in series (about 7.4V). Use a buck converter or switching regulator for the 5V supply, and power the servo from the LIPOs using a couple of large (5 or 10A) diodes in series to drop the voltage down to 6V. If you must use a 12V solenoid, at least change to the 7.4V setup and power the 12V boost from the LIPOs instead of from the 5V rail.