coreyaudia7

Hi Everyone,

During the past week the keyless/convenience mechanism has been failing to unlock or lock any of the doors on my Audi A7 when I first walk up to it in the morning. Funny thing is, I can still unlock the trunk of my car using this feature no problem. However, once I drive the car for a while, the feature starts working again and I can unlock/lock my car doors.

It's been pretty cold here in Chicago, and I was wondering if that could be the issue? The issue also occurs with my spare smart key and the batteries are fine on both the spare and main keys. I plan on taking it in soon to the dealership, but was wondering if anyone else has had this issue before? Why would it work after I start my car but not when I first walk up to it in the morning?

Thanks for any advice!

tenspeed

It could be that the battery voltage is low. Cold ambient temperatures, age, and using the car for short trips could cause it. My ancient Optima will trigger the "Low Voltage" alarm on my radar detector when it's frigid.

coreyaudia7

When you sayow voltage are you referring to the key itself or my car battery? I just bought the car a few months ago so I'm assuming it's not that. Thanks for responding!

fkaufman

Battery capacity (how many amp-hours it can hold) is reduced as temperature goes down, and increased as temperature goes up. This is why your car battery dies on a cold winter morning, even though it worked fine the previous afternoon. The standard rating for batteries is at room temperature - 25 degrees C (about 77 F). At approximately -22 degrees F (-27 C), battery AH capacity drops to 50%. At freezing, capacity is reduced by 20%. Capacity is increased at higher temperatures - at 122 degrees F, battery capacity would be about 12% higher.

As the temperature of the car battery drops, the voltage level of it will also drop. Once the engine started up, the alternator will generate the appropriate voltage level and supply it to all the car circuitry.