Varta 3/V150H Ni-MH 3.6 V Rechargeable Backup Battery (150 mAh)

The Varta 3/V150H is a compact, 3-cell NiMH pack that delivers 3.6 V for memory retention and standby power in industrial and professional electronics. It is intended for circuits that provide a gentle recharge (trickle or managed charge) to keep backup power available for years of service.

Key specs

Nominal voltage	3.6 V (3 × 1.2 V NiMH in series)
Typical capacity	150 mAh
Chemistry	Nickel–metal hydride (rechargeable)
Intended use	Memory/RTC backup, PLCs, alarm/control panels, meters, instrumentation
Form factor	Stacked button cells; variants with solder tags or PCB pins (match your original)
Charging	Device-managed or trickle charge (see guidance below)

When to choose this pack

• Your device maintains the pack with a low current trickle charge.
• Backup currents are low and steady (typical tens of µA to a few mA).
• You want a rechargeable, serviceable solution rather than disposable primaries.

When to consider alternatives

• No charging circuit available or maintenance-free, multi‑year shelf life is required → use a primary lithium (e.g., 3.6 V Li‑SOCl2) solution.
• High pulse or sustained loads (tens of mA and up) → use a higher‑capacity pack or different chemistry.
• Ambient temperatures are consistently high (e.g., inside sealed enclosures near heat sources) → verify charge rate and derate expectations.

Runtime planning (rule of thumb)

Estimate theoretical hours by capacity/current, then apply 60–80% to account for cutoff voltage, aging, and temperature.

• 0.1 mA backup draw: ~1500 h (62 days) theoretical; expect ~900–1200 h.
• 1 mA draw: ~150 h (~6 days) theoretical; expect ~90–120 h.
• 5 mA draw: ~30 h theoretical; expect ~18–24 h.

Actual runtime depends on device cutoff voltage, charge maintenance, and cell condition.

Charging and maintenance

• Trickle charge: Many backup designs use 0.02–0.05C (about 3–8 mA) through a resistor—verify your device’s charge rate.
• Managed/fast charge: If supported, limit to low currents (around 0.1C ≈ 15 mA) with proper termination. Avoid constant-voltage “float” methods used for lead acid or lithium.
• Temperature: Charge at room temperature. Avoid charging in hot environments (>40–45°C).
• Avoid deep discharge: Prolonged discharge below ~1.0 V/cell can reduce life.
• Storage: Store partially charged in a cool, dry place; top up before installation.

Compatibility and fit

• Voltage and capacity: 3.6 V nominal, ~150 mAh. Matches many legacy NiCd/NiMH memory packs with similar specs.
• Mounting style: Order the same pin/tabs configuration as your original (PCB pins vs. solder tags). Do not solder directly to cells—use tagged versions.
• Charging circuit: If replacing a NiCd pack, confirm the trickle rate does not exceed ~0.05C for NiMH.

Environmental note

Rechargeable NiMH reduces battery waste over time. Recycle packs at end of life in accordance with local e‑waste programs.

FAQ

Is this a direct replacement for a 3.6 V memory backup pack?

Often yes—if your original was a 3.6 V NiCd or NiMH pack with similar capacity and the device provides a low trickle charge. Match voltage, pinout, and charging method before replacing.

How do I know my device can recharge it?

Check the service manual or board markings for a charge resistor to the battery, or documentation stating NiMH/NiCd backup. If unsure, measure charge current in-circuit or consult the manufacturer.

Can I use it without any charging circuit?

It will work initially, but self‑discharge will deplete it over time. For long, maintenance‑free backup in unpowered devices, use a primary lithium solution instead.

Can I solder wires directly to the cells?

Avoid direct soldering to cell cans. Use factory tabs or PCB‑pin versions to prevent heat damage and ensure reliable connections.

How often should it be replaced?

In well‑designed trickle‑charged applications, service life is typically several years. Replace when backup time noticeably shortens or during scheduled maintenance intervals.