LeftieBiker said:
Some people have added AC to their garages. I don't think this makes financial sense.
If Nissan sold a "battery temperature moderator" that would reduce battery heat while the car was parked in the garage for the hottest 3 months of the year, and it cost $15 a month, for only the months when used, I guess you'd pass on it as 'not making financial sense'...?
I admit this is more complex that my first thoughts.
A vent might cost $15 total, and for some garages would reduce temperature by as much as a window mount AC could. Also, adding insulation to the garage doors $30 to $90, can help a lot. Probably want to do this with the AC options as well. Might also want to add insulation to the walls and roof.
A window mount AC costs more than $15 per month. Depending on size, anywhere from $130 to over $400, depending on size, efficiency and sound level. Then the monthly cost to keep the temperature below a setpoint: such as 25C, which would range from $45 per year for the smallest units and your three month of use to perhaps $600 or more for really hot places. That is going to vary a lot by climate, and also by how large and how well insulated the garage is.
So how do the two options compare for improving battery life?
Ships are safe in harbor, but that's not what ships are for. If you leave the car in the garage, this is the best case for the AC option. If you drive the car, go someplace for a short time, then return, the battery might stay close to the garage temperature. The AC option will look better. If you work, then go do things in the evening, the battery might stay closer to the outdoor temperature, and there would be less gain from the AC and the AC is mostly cooling an empty garage during the hot part of the day.
So let's look at the first driving pattern. If the outside temperature is averaging 35C (that's way hotter than you) and the garage and battery temperature is 25C, then battery capacity loss would be half as fast for calendar loss. Assume the battery is ~$8000, and would last without AC for 8 years/100k miles at an average temperature of 25C (should actually do rather better in your climate). With the AC, calendar loss would decrease, but cycling loss would continue. So perhaps the battery might last for 12 years/150k miles. So the yearly battery cost might decrease from $1000 to $667, perhaps enough to pay for the AC. Maybe.
If you are in a climate where you would just miss the warranty replacement, and you can AC the garage for less than $333 per hot month, and your driving pattern is the drive somewhere then return soon, car is mostly in the garage, then it might make sense.
If your climate will get the warranty replacement, then you would miss out on a free battery.
If your climate is cooler, then the battery is going to last the average life of the car, 11.5 years.
If you commute to work, the AC is mostly cooling an empty garage.
A vent and some insulation probably pays off, unless you miss a warranty replacement battery.