Renata CR2477N Lithium Coin Cell (3 V): Practical Guide and Specs

At a Glance

• Type: CR2477N (primary lithium manganese dioxide, non‑rechargeable)
• Nominal voltage: 3.0 V
• Size: 24.5 mm diameter × 7.7 mm height
• Typical capacity: ~900–1050 mAh (depends on load, cutoff, and temperature)
• Operating temp (typical): −20 °C to +60 °C
• Traits: low self‑discharge, stable discharge curve, mercury‑free, leak‑resistant design
• Common uses: IoT sensors, beacons/trackers, smart buttons, meters, RTC/CMOS backup, medical peripherals (non‑implant)

When to Choose the CR2477N

• Need multi‑year runtime at low average current (tens to hundreds of µA).
• Device profile favors a flat cell over cylindrical batteries.
• Design requires predictable 3 V output and tight leakage control.
• Your holder or device explicitly specifies the “N” variant for reliable contact.

Avoid or Consider Alternatives If

• You need sustained high current (e.g., bright LEDs, motors) — consider CR123A, AA lithium primaries, or a rechargeable solution.
• You need frequent, heavy radio bursts without energy buffering — add bulk capacitance or use a higher‑drain battery format.
• Your device requires rechargeability — choose a rechargeable chemistry designed for that purpose and an appropriate charge IC.

Fit and the “N” Variant

CR2477 indicates the size family (24.5 × 7.7 mm). The Renata “N” suffix denotes a specific top/terminal style intended for certain holders. Some devices need this profile for proper mechanical pressure and electrical contact.

• Check your device BOM/label: If it calls for CR2477N, do not assume a flat‑top CR2477 will fit or contact correctly.
• Verify enclosure clearance: 7.7 mm is much thicker than a CR2032 (~3.2 mm).
• Polarity: the can is negative; the marked top is positive. Match device markings.

Performance Notes for Designers

Load & Pulse Current

• Best for low to moderate continuous current. For brief TX spikes, place a local storage capacitor (e.g., 47–220 µF low‑ESR) near the radio/rail.
• Reduce consecutive bursts and optimize sleep duty cycle to limit voltage dip.
• If average current routinely exceeds a few mA, consider a higher‑drain format.

Temperature

• Cold increases internal resistance and reduces usable capacity under load; test at your minimum temperature.
• Heat accelerates aging; avoid mounting near warm components or sun‑exposed surfaces.

Voltage Behavior

Expect a relatively flat discharge near 3 V at light loads, with a sharper drop near end‑of‑life. Use conservative brownout thresholds and, if possible, load‑based fuel gauging rather than open‑circuit voltage alone.

Runtime Planning (Simple Example)

Example device profile:

• Sleep current: 20 µA
• Radio burst: 10 mA for 50 ms every 60 s
• Burst average: 10 mA × 0.05 s / 60 s ≈ 8.3 µA
• Total average: 20 + 8.3 ≈ 28.3 µA (0.0283 mA)

Estimated life at room temperature with 950 mAh usable: 950 mAh / 0.0283 mA ≈ 33,600 h ≈ 3.8 years. Real‑world life will be lower at cold temperatures or with higher pulse rates; validate with your exact load and cutoff voltage.

Installation & Handling

• Power down device before replacement if possible to prevent data corruption.
• Use the holder’s release feature; do not pry on the cell body.
• Keep contacts clean; wipe with a lint‑free cloth if needed.
• Do not recharge (primary cell).
• Store cool, dry, and in original packaging; follow FIFO stock rotation.

Safety & Disposal

• Ingestion hazard: keep away from children; use devices with secure battery compartments.
• Do not short, crush, or incinerate.
• Recycle through approved collection points; follow local regulations.

Alternatives to Consider

• CR2032/CR2450: Thinner, lower capacity where space is tight and life requirements are modest.
• CR123A or AA lithium primary: For higher pulse and continuous currents.
• Rechargeable coin or Li‑ion pack: If you need recharging, but verify voltage, charging method, and safety requirements.

FAQ

Can I use a CR2477 instead of a CR2477N?

Only if your device or holder allows it. The “N” top style may be required for proper contact. Always follow the device specification.

How long will it last?

From months to several years, depending on average current, pulse profile, cutoff voltage, and temperature. Model with your exact load and validate at low temperature.

Is it rechargeable?

No. It is a primary Li‑MnO₂ cell. Never attempt to charge it.

My device resets during radio bursts—what helps?

Add a low‑ESR bulk capacitor near the radio/MCU, reduce burst frequency or duration, and ensure low‑resistance, secure contacts in the holder.

What do the numbers “2477” mean?

Approximate dimensions in tenths of a millimeter: 24.5 mm diameter, 7.7 mm height.

Specs (Typical)

Summary

The Renata CR2477N offers a compact, high‑capacity 3 V power source for low‑average‑current devices. Choose it when you need long life in a flat form factor, and verify the “N” top style matches your holder. Buffer high pulses with capacitance, validate at temperature, and follow safe handling and recycling practices.