First time Tesla owner with a new-to-me 2019 X here! I found a lot of "fob kills batteries" threads and wanted to add some data, not complete, but something.
I was getting low battery warnings after about 5 days or so, using absolutely genuine Panasonic 2354 batteries with date codes within the past year.
I have a mobile service appt soon and will likely get this fob replaced under warranty, otherwise I'd tear in and do component level troubleshooting.
Of the two fobs, using a Fluke DMM and the same battery:
Good Fob:
-Installed battery, voltage holds steady at about 3.2v
-After removing battery then measuring resistance across the battery terminals (- lead to -, + lead to +), reading holds steady at 3.2Mohms
-Allowing fob to sit w/ no battery or DMM leads for 30 seconds, resistance reading still 3.2Mohms
Bad Fob:
-Installed battery, voltage drops 0.001v every 1-2 seconds
-Removing battery then measuring resistance across the terminals shows about 2.6Mohms
-Allowing fob to sit w/ no battery or DMM leads for 30 seconds, resistance reading falls to ~1.9Mohms and slowly crawls back up to 2.6Mohms. This is the tell.
Both fobs will draw about 5-10mA when transmitting button presses, no real difference there.
Bad fob has a continuous current drain for sure. Maybe a filter cap with out of spec leakage or something similar, just enough to be a problem but not enough to be a problem today. It's low enough that I wouldn't suspect a digital circuit problem but you never know.
I was getting low battery warnings after about 5 days or so, using absolutely genuine Panasonic 2354 batteries with date codes within the past year.
I have a mobile service appt soon and will likely get this fob replaced under warranty, otherwise I'd tear in and do component level troubleshooting.
Of the two fobs, using a Fluke DMM and the same battery:
Good Fob:
-Installed battery, voltage holds steady at about 3.2v
-After removing battery then measuring resistance across the battery terminals (- lead to -, + lead to +), reading holds steady at 3.2Mohms
-Allowing fob to sit w/ no battery or DMM leads for 30 seconds, resistance reading still 3.2Mohms
Bad Fob:
-Installed battery, voltage drops 0.001v every 1-2 seconds
-Removing battery then measuring resistance across the terminals shows about 2.6Mohms
-Allowing fob to sit w/ no battery or DMM leads for 30 seconds, resistance reading falls to ~1.9Mohms and slowly crawls back up to 2.6Mohms. This is the tell.
Both fobs will draw about 5-10mA when transmitting button presses, no real difference there.
Bad fob has a continuous current drain for sure. Maybe a filter cap with out of spec leakage or something similar, just enough to be a problem but not enough to be a problem today. It's low enough that I wouldn't suspect a digital circuit problem but you never know.
