Saft Batteries: How to Choose the Right Industrial Battery for Critical Applications

Saft builds industrial batteries for environments where downtime is not an option. This guide explains Saft’s main chemistries, when to use each, how to size a battery, and key safety and compliance points so you can select with confidence.

What Saft Offers

Saft’s portfolio focuses on three core chemistries, available as cells, modules, and engineered packs for aerospace, defense, rail, energy, metering, and industrial IoT:

Chemistry	Rechargeable	Best For	Key Advantages	Watch-outs
Lithium-ion (Li-ion)	Yes	High energy/power, frequent cycling, ESS, aviation/defense systems	High energy density, fast charge, long cycle life with BMS	Requires certified BMS, controlled charge (CC/CV), thermal management
Nickel-Cadmium (Ni-Cd)	Yes	Backup/starting, rail and aviation, wide temperature extremes	Very robust, tolerant of abuse and temperature swings	Contains cadmium—must be recycled; heavier and lower energy density than Li-ion
Lithium-Thionyl Chloride (Li‑SOCl₂)	No (primary)	Ultra-long life, low to moderate drain, meters, sensors, asset tracking	Very low self-discharge, long shelf/service life	Not rechargeable; verify pulse capability or add hybrid layer capacitor

How to Choose

1. Define load profile: continuous current, peak pulses, duty cycle, and target runtime or cycle life.
2. Match chemistry to use case:
   • Choose Li-ion for daily cycling, high power, or weight/volume limits.
   • Choose Ni-Cd for emergency/backup and harsh temperature or charge conditions.
   • Choose Li‑SOCl₂ for multi‑year, low-drain devices with minimal maintenance.
3. Confirm environment: operating/storage temperature, altitude/pressure, vibration/shock, humidity.
4. Plan integration: charging method, BMS, protection, connectors, mechanical envelope, and certification.
5. Verify compliance: UN 38.3 transport, IEC/UL cell and pack standards, and recycling obligations (especially for Ni‑Cd).

Scenario-Based Recommendations

• Remote water meter or parking sensor (10–200 µA average, occasional pulse): Use Li‑SOCl₂ primary cells for 5–15+ years service. If pulses exceed cell capability, add a pulse buffer (HLC or supercap).
• Aviation or rail backup for emergency lighting and control: Ni‑Cd packs tolerate repeated charge/standby and wide temperatures. Choose vented or sealed formats based on maintenance policy.
• Energy storage or high-cycling industrial system: Li‑ion modules with certified BMS; pick chemistry variant tuned for energy vs. power, and confirm thermal management and safety cases.
• Defense and aerospace payloads: Consult Saft datasheets for radiation tolerance, vibration profiles, and redundancy requirements; prioritize proven, qualified series.

Quick Sizing Examples

Primary (Li‑SOCl₂) runtime estimate

Example: Average load 100 µA, monthly 1-second 100 mA pulse, target 8 years.

• Base consumption: 0.1 mA × 24 h × 365 d × 8 y ≈ 7,008 mAh.
• Pulses add a small increment; add 10–15% margin for self‑discharge and temperature.
• Select a cell or combination ≥ 8,200–9,000 mAh effective at the coldest operating temperature and with pulse buffering if required.

Rechargeable (Li‑ion) cycle life planning

Target: 4,000 cycles to 80% capacity. Reduce depth of discharge (DoD) and moderate temperature to extend life. For example, operating between 20–80% state of charge and keeping cell temperatures within manufacturer limits can markedly increase cycle count. Always size capacity with end‑of‑life (EoL) energy in mind.

Operating Conditions

• Temperature: Saft offers lines for extreme environments; verify the specific series rating (some ranges operate from approximately −50°C to elevated temperatures). Capacity and pulse current drop at low temperatures.
• Storage: Store Li‑ion around 30–50% state of charge in a cool, dry place. Primary cells store best cool and dry in original packaging.
• Charging:
  • Li‑ion: CC/CV with pack-level protection and cell balancing.
  • Ni‑Cd: Constant current with temperature sensing; periodic maintenance/conditioning per datasheet.
  • Do not attempt to recharge Li‑SOCl₂.

Safety and Compliance

• Use certified cells/packs and a BMS for Li‑ion; include over‑current, over/under‑voltage, and thermal protections.
• Transport only after UN 38.3 testing; follow IATA/IMDG packaging and state of charge rules.
• Follow applicable standards (e.g., IEC 62133/UL 62133 for rechargeable portable cells/packs, UL 1642 for cells) where relevant to the application.
• Recycle per local law; Ni‑Cd contains cadmium and must not enter general waste streams.

Common Pitfalls to Avoid

• Selecting a primary Li‑SOCl₂ cell for loads with frequent high pulses without a buffer capacitor.
• Using a charger not matched to chemistry (e.g., applying CC/CV to Ni‑Cd or trickle‑charging Li‑ion indefinitely).
• Ignoring low‑temperature derating; capacity and pulse current can drop significantly below 0°C.
• Overlooking regulatory testing for custom packs (transport and safety standards).

FAQ

Can I replace a Ni‑Cd pack with Li‑ion?

Often yes, but not drop‑in. You’ll need a compatible charger/BMS, mechanical fit, and validation for temperature range, fault tolerance, and safety standards.

How long do Li‑SOCl₂ cells last in the field?

Many designs achieve 5–20 years depending on average current, pulse profile, and temperature. Plan with margin for self‑discharge and cold‑temperature effects.

What’s the operating temperature range?

Ranges vary by series. Saft offers products engineered for extreme cold and heat; always confirm the exact datasheet rating for your model and duty cycle.

Do I need a BMS with Saft Li‑ion packs?

Yes. A properly designed BMS is required for protection, balancing, and state‑of‑charge estimation, and is essential for safety and longevity.

Are Saft batteries recyclable?

Yes. Follow local regulations. Ni‑Cd requires specialized recycling due to cadmium content; Li‑ion and primary lithium cells also have defined recycling streams.

Next Steps

Gather your load profile, temperature range, mechanical constraints, and compliance requirements, then select a Saft series whose datasheet meets those needs. For custom packs, engage early to align on certification, BMS features, and thermal design.