jdunmyer
Posts: 45
Joined: Mon Oct 10, 2016 10:18 pm

Charging interference?

Sat Feb 15, 2020 8:57 pm

My 2017 Bolt w/37000 miles resides in a detached garage (30'X30' pole barn) that has a 60-amp subpanel fed from the 200-amp service in the adjacent building. Subpanel is connected to its own ground rod, sunk into wet soil. The subpanel feeds a Clipper Creek HCS-40 that I upgraded to when I bought the Bolt in December of 2017. Previously, I had 2 different Leafs, charged with a Schneider EVSE. The 2 doors have Liftmaster operators that were supplied and installed by the builder; I wired them to power when I wired the building.

The Bolt was alone in the garage during the "incident". I came out from the house and looked to the garage to see both doors open. This was about 9:00 AM; the Bolt is set to finish charging at 10:00 AM, so charging was in progress. These operators are modern, using the current technology in their radio units. I'm kind of guessing that the charging process emitted RFI that caused the operators to open the doors.

Liftmaster tech support hasn't been of any help, at least so far.

Any ideas?

It appears as though I should shut off the circuit breaker if I leave town...

Entropy512
Posts: 6
Joined: Thu Feb 13, 2020 8:26 pm

Re: Charging interference?

Mon Feb 17, 2020 2:13 pm

That's weird. Any recent garage door opener system should be using rolling code security, which would be impossible to trigger using random interference.

If it's a much weaker system... I remember decades ago, somehow our neighbors managed to select the same exact combo of resistors we did for code selection. Their transmitters opened/closed our doors, and our transmitters opened/closed theirs!

Some of the non-rolling-code systems can now be brute-forced in only 1-2 minutes due to a complete lack of security. https://samy.pl/opensesame/

If you have an older non-rolling system... Replace it NOW.

jdunmyer
Posts: 45
Joined: Mon Oct 10, 2016 10:18 pm

Re: Charging interference?

Wed Feb 19, 2020 10:35 pm

I'm pretty sure that my operators use the rolling code scheme, they're only 6 years old. Again, BOTH doors were opened, so it's not just a single failure.

The operators on the garage doors have a fairly short range, the car has to be within 60-80 feet for them to work. OTOH:, I have a barn with an overhead door and commercial-grade operator that can be opened from more than 200 feet away. Although I don't know the difference, the transmitter looks to be identical to the ones for the garage doors.

Back in about 1969, I was parked in front of a friend's house, who I knew had an automatic door operator. I grabbed the mike on my CB radio, keyed up, and whistled into the mike, changing the pitch as I went. The door opened after a few seconds. In those days, garage door radios operated on the 27 Mhz Citizens' Band, and used a simple tone modulation for "security". It didn't take much to spoof them.

Return to “Technical Discussions”