Temperature considerations

Hi,

I am designing my first Arduino project, a solar powered LED lantern in a jar. I would like to know in advance how well my circuit will perform in a jar in direct sunlight, in a 90 F summer. The greenhouse effect and all.

Here is my design in progress:

https://easyeda.com/andrew.pennebaker/project-firefly

Is this system safe to operate in a hot summer mason jar?

How concerned should I be about different batteries in this heat?

And what about summer rainfall? Does anyone sell rubber mason jar washers for extra water proofing the lid?

Check the datasheet for the battery.

what about summer rainfall? Does anyone sell rubber mason jar washers for extra water proofing the lid?

Just make your own from rubber sheeting.

For the rubber ring check caning supplies. Interesting project many pitfalls. Start by placing a thermometer in the jar and putting it in direct sunlight. Let it stabilizer for at least an hour and read the temperature, I think you may be surprised what you get. You will be powering an arduino and charging a battery, both of these operations generate heat. Your batteries are definitely a potential problem. We cannot do much until we know the real ambient temperature. Your LEDs will also generate heat. Post a schematic not a frizzy thing complete with links giving the technical information on all the hardware parts will be a big help. You should also calculate the current requirements of your circuit and photocell to be sure they will give you enough current to operate it for as long as wanted.

Good idea to test.

When I check some premade jar lanterns, they read about 90 F inside.

You need to measure the maximum temperature. AVR processors are generally rated for operation between -40 and 85 degrees C.

After measuring the temperature, check the battery data sheets for the manufacturer's recommendations.

What was the ambient and were they in the sun for an hour. Put some black paper inside to simulate the circuit board and batteries.

Sunlight will soon destroy the rubber. Look for silicon rubber sheet and make the seal out of that.
Paul