Internal back-up battery	Battery voltage (V)	Nominal capacity (mAh)	Power (Wh)	Operating temperature range (°C)
Extremely low self-discharge Li-SOCl2 battery	3.6	2700	19.44	-55 to +85

Li-SOCl2 Batteries and passivation effects

1. Introduction to Li-SOCl2 Batteries

Lithium-Thionyl Chloride (Li-SOCl2) batteries are widely used in IoT applications due to their high energy density, long shelf life, and ability to operate in extreme temperatures. Their stable output voltage makes them ideal for long-term deployments in remote or low-maintenance devices like smart meters, industrial sensors, and tracking systems.

2. Understanding Passivation: Pros & Cons

One characteristic of Li-SOCl2 batteries is passivation, where a thin lithium chloride (LiCl) layer forms on the lithium anode.

Benefits of Passivation:

Reduces self-discharge, ensuring long-term energy retention.
Extends shelf life, making these batteries reliable for long storage periods.

Drawbacks of Passivation:

Can cause voltage delay when the battery is first used after storage.
High initial resistance may result in a temporary voltage drop, especially in high-drain applications.

3. Issues After Long Storage & Voltage Drop

If a Li-SOCl2 battery has been stored for an extended period, the passivation layer can become thicker, leading to:

Lower initial output voltage when first used.
A brief period where the device may not receive full power.

In IoT applications, this means sensors or communication modules might experience startup issues after long inactivity.

4. What to Do After Long Storage

For devices using these batteries, if a low voltage is detected after a long storage period, a simple solution is to send a record to the server. This brief activity will help break down the passivation layer, and the battery output voltage will automatically rise back to normal within approximately 24 hours.

This approach ensures reliable operation without manual intervention, making Li-SOCl₂ batteries a practical choice for IoT and long-life industrial applications.

	CAUTION: RISK OF EXPLOSION IF BATTERY IS REPLACED BY AN INCORRECT TYPE. DISPOSE OF USED BATTERIES ACCORDING TO THE INSTRUCTIONS.
	Battery should not be disposed of into general household waste. Bring damaged or worn-out batteries to your local recycling center or dispose them into a battery recycle bin commonly found in supermarkets.