It can get well below freezing here. Does cold even bother these newer lithium batteries?
Not really. See table 2 here (a ways down the page)
Cold generally slows degradation.
But using them at cold temps is bad
IIRC heat is the bigger issue for lithium batteries.
They’re temporarily less effective in cold weather but excessive heat is the battery killer.
Heat is the killer for car batteries too; much to my surprise, I had to buy far more in south Texas than upstate New York. Cold makes batteries less capable, but heat accelerates degradation dramatically.
Check the data sheet or user manual for your equipment or battery, but generally batteries should be stored indoors at a human comfortable temp and humidity.
Here’s the manual for mine, but yours may differ:
Ryobi really needs a better URL for their manuals to be stored at. If the direct link to the file sketches you out, for the moment at least this, this link will lead to the same file:
Tldr:
Do not store or charge battery packs in locations where the temperature is less than 50°F or more than 100°F
But it also says
The lithium-ion battery pack can be used in temperatures down to –4°F. Put the battery pack on a tool and use the tool in a light duty application. After about a minute, the pack will warm up and begin operating normally.
And
A cold battery pack may be placed directly onto the charger port but charging will not begin until the battery temperature warms to within acceptable temperature range. When a cold battery pack is placed on the charger, the charger may indicate the pack is not ready to charge. Please refer to charger operator’s manual. When the battery pack warms to approximately room temperature the charger will automatically begin charging
I kept mine out in the cold and one of them died. These are ego batteries so replacing them is very expensive. I now store them inside in cold seasons.
Storing my batteries indoors was a requirement for having them replaced under my GreenWorks warranty. I recommend checking yours just in case.
Temp has an effect on all batteries. Wouldn’t hurt. And keeping it dry will keep metal parts from rusting as quickly
I hacked an e-bike battery into mine, so I just leave it in since removing it is a pain.
I figured if the lithium battery in my car can deal with it, the one in the mower should as well.