Guess Again? The Worst and Best spot in a car to keep a light.

The safety of keeping Lithium batteries in automobiles has been discussed in several threads here on the BLF.
Safe temperatures have been quoted for various cell makers.

- New Data Run at the Bottom -

I thought it might be fun to see just how hot the most likely storage spots might get during a hot day in Texas.

The official temperature hit 113F.
My car thermometer hit 115F on the way home – with a cloud blocking the sun part of the time.

I setup a data logger with 3 probes and set it to take a temperature reading every 5 minutes.
Make a guess which one is:

Under the Driver’s Seat
The dashboard Glovebox
The center Console

The test subject is a dark gray 4 door Toyota with a black interior.
I got the logger going in the house and then I ran some errands.

I parked the car in full sun on the east side of my office building at 11:32am.
I had all the windows up and didn’t open the car till I went home at about 5:25pm.
Using an infrared thermometer I pulled the following temps.

Time - - - - - Dash _ Asphalt, Roof
11:32am 118, 141, _ NA
12:43am 135, 167, _ 165
01:45pm 156, 170, _ 185
02:45pm 156, 157, _ 192
03:45pm 148, 156, _ 181
04:45pm 117, 115/156, 112

At 4:45 the car was in the shade of the building.
The two asphalt temps are taken in shade and in sun.

I was kind of stunned to see how hot the roof got.
You can’t fry an egg, but you can sure as heck cook one on the roof or the pavement.
I would bet batteries in remotes would last longer if not kept in a roof compartment.
For those who are Celsius thinkers:
126.3F = 52.4C
146.6F = 63.7C
138.5F = 59.2C
170F = 76.7C
192F = 88.9C

You can see how quickly the car cools off when I head home with the AC running full blast.

I’ll post the answer in a few days after a few guesses have been made.
All the Best,

RESULTS - Coolest place in the car post #27


Guess Again

Below is another temp log. This time looking at the worst places to store a light in a car.
The test subject is the same as the above.
It’s parked in the same spot in the parking lot.
The high for the day was 96F. That’s 17F less than the first run.

Guess which is:
Front Seat Area – cabin temp if you will
Center Console
Roof Console

And I’m withholding any temps taken while the car was running.
That should make the guessing game a bit tougher.
Later I’ll post a version that shows more data.
And yes, jon probably got this one right also…
All the Best,

Heat rises. There are other variables in a car such as whether or not sunlight can get at various places and other heat sources such as engine, exhaust, so forth. So the best is going to be under the drivers seat in most cars.the glove box may be influenced by engine heat and or the heater core and or direct sunlight. So the center console is probably the second best choice. Edit I try not to park where the sun will be coming in the windshield if I can help it in the summer. In the winter it’s just the opposite.

Center console is my bet. Would liked to have seen a control reading based on cabin air temperature. But still good data.

My guess:

Blue: Below Driver's Seat
Yellow: Center Console
Red: Glove Box

I also think, from coolest to hottest:

  1. Under the driver’s seat
  2. Center console
  3. Glovebox

Center console Blue
under driver seat red
glovebox yellow

Center console Blue
Under driver seat yellow
Glovebox red

I will go with Calvin on this one.

Under seat coolest, glove box 2nd coolest, middle console worst.

I second that one. The hottest items are exposed to the sun.

This is my guess too. Speculating that the closed compartments benefit from not being directly exposed to the hot cabin air, while under the seat would be.

Let me go all wrong here :stuck_out_tongue:

Blue=Glove Box


like @4492011 said

Yellow=Glove Box

does it matter?
they are all too hot to charge the battery (all are over 113F), so dont leave a liIon on charge in the vehicle, on a hot day

the hottest spot is also above the max operating temp for a LiIon (140F), so dont try to use that light until it cools doewn, or it may have “venting with fire”

otoh, if you neither charge, nor use the lights, at the temperatures stored in a car

it makes no difference where in the car the light is…

I hate guessing, so, when youre ready, just tell me Im right… cause I already know where the hottest spot is, and I aint tellin… lol

I’m going to say under the seat is the hottest due to the heat coming off the asphalt. My initial thought was that the glovebox would be the hottest place since the sun would be beating down on the dash but I’ve never noticed my glovebox being hot when I reach in it.

1. Glove box the coolest
2. Under the seat
3. Center console the hottest

Of course the coolest spot in my Blazer is in the rear in the ice chest. Also another major variable is if your windows are tinted and how dark they are. Even with my fishbowl the rear being tinted 20% you can tell it’s cooler than the front seats with 35% on the doors. I use a windshield shade if I have to park long term in the sun. My interior is saddle (tan) so it will be cooler than a grey or black most modern cars come with.

Anybody who’s ever worked on a sunroof is familiar with how hot the roof of a vehicle can get. A few square feet of sheet metal acts as a nice collector and heat sink in direct sunlight.

It’s tough on thin layer of foam between the headliner fabric and the backing board, and the adhesives that hold the sandwich together. Drooping headliners are not uncommon, even though they’re serve no duty other than as decoration, and receive no direct contact or wear. Refinishing them requires an adhesive that is both strong and heat resistant.

Modern vehicle designs with steeply raked windshields result in more dashboard surface area, and more exposure to sunlight, and a dark-colored dash, as they often are, adds to that. So the glovebox, sitting below that nice heat collector, is my guess as the hottest of the candidates.

Between the center console, and under the driver’s seat, the latter sees the least exposure, and is unenclosed, so it will be the cooler of the two. The floor contains most of the sound insulation material in a car, and between it and the carpeting, is well insulated from ground heat, as well as that generated by components like the catalytic converter and the exhaust system.

under driver seat is the coolest.

You and me got this!

^ this

I’m going to go the opposite of the majority and say that:

Column E = Glove Box
Column D = Under the driver seat
Column C = Center console