Operating Temperature Versus Storage Temperature

Spec sheets often list more than one temperature range because a battery faces different jobs. Powering a load, charging and sitting on a shelf are three different jobs, and each can have its own limits.

The three ranges you'll meet

Operating (or discharging) range. This covers the time the battery is giving out power. One maker's example lists discharging from -4°F to 104°F (-20°C to 40°C) for one portable power station.¹

Charging range. This is narrower. The same example lists charging from 32°F to 104°F (0°C to 40°C).¹ That's a different range from the discharging one on the same unit, so you can't read just one line.

Storage range. This is for when the battery sits unused. Maker guidance says the charging table is for charging, not storage, and that you should follow the guidance for your exact model for storage.¹

Which one applies to you

It depends on what the battery is doing right now, not on where you live.

If the battery is in a garage and feeds the fridge in an outage, the operating range matters. If you plug it in after a cold night, check the charging range first. If it sits in a cupboard all summer, the storage range applies.

The same maker warns that you shouldn't treat a charging limit as a full storage limit. It also says not to use one model's temperature table for another model.¹

Storage advice varies

Different makers say different things. A trade article on solar battery banks also covers storage, and it says to refer to the battery manual for specifics.²

Use the storage charge level and temperature range in your own maker's manual. This page doesn't give figures for either.

Heat during storage matters too. Battery University treats a battery dwelling above 30°C (86°F) as being at elevated temperature.³ Elevated temperature, it says, hastens permanent capacity loss.³

So a hot shed in July is a poor place to leave a battery, even if it's switched off. The exact number your own maker gives is the one to follow.

A quick routine

• Find all three ranges in your manual. If one is missing, ask the maker.
• Write the three ranges down next to where the battery lives.
• Check the room your battery lives in, at its hottest and coldest times of year.

There's a walk-through of where these lines hide in how to read your manual's temperature section. And if you want the reason a cold battery refuses a charge, that story is here.