I have made some observations about my own Prius Prime issues in cold weather and wanted to share these with other owners. I am not going to claim everyone else will have the same experiences. I only want to share my own experiences: 1) My car has the feature where you can lock and unlock the doors simply by putting your hand inside one of the front car door handles. In temperatures lower than 23-degrees, these door sensors will NOT function if the key fob battery is less than 90% of power. You can use the buttons on the key fob to unlock the doors, providing the key fob battery is above 70%. In cold weather (Temps below freezing), the key fob batteries will only last 2-6 weeks, depending on where you store the key fob (the colder the temps, the shorter the battery life). Always keep a pack of brand new key fob batteries available for these really cold mornings or you could be stranded. 2) If the keyfob battery is below 70% of it's power, and the outside temperature is below 30-degrees, the car will often not sense the presence of the key fob inside the car. The simple solution in these cases has been to remove the keyfob battery for 10-seconds, then put it back in. After about 30-seconds the car will start. Another option is to put a brand new battery in the keyfob and it again becomes reliable for another 2-6 weeks in cold weather. I guess the cost of the key fob batteries has to be included in the overall cost, operation and eco-friendliness of the vehicle. In stormy, snowy weather, I have to turn off all of the outside driving and parking sensors. Otherwise my dashboard gets lit up, and constantly dings with repeated warnings about sensors not being available. In hindsight, I do not believe this is the best vehicle to own in these extreme weather conditions where temperatures fall below freezing for a large percent of the year.
Not sure how a fob would get that cold being it’s usually in a pocket and indoors when not in use. How do you display the battery charge level?
Were you thinking that you needed the key fob to have a battery before you can operate the vehicle? As weeks go by, and we slowly inch toward the end of winter, things will warm up. When we get warmed up to 30F temps I will try some of these things. But so far in 20F to -20F temps, we have not experienced any of the issues that you are having. I just turn off the car. I am not aware of any method to individually turn off 'outside driving and parking sensors'. My wife drives a Prius and I drive a Prius, we love them here in Maine.
Last month we went through a week of overnight temperatures below -30F. The 12V battery wasn't impressed, but the sensors didn't have any problems.
Humm, something is amiss. For 3+ years I never had to change the battery of the fobs. I live in an area where it gets much colder than 32F, often sees sub-zero, but never had a problem with keyless entry not working or car not starting. Those coin battery does not drain faster in cold temperature, in fact, it last longer in cold. In any case, the outside temperature is irrelevant. In most cases the fob is in my pocket, so the temperature is pretty close to my body temp may be slightly lower but nowhere close to be below freezing.
