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When the mains drops in a Norwegian building at −25 °C, the emergency lights must stay on for the full backup time the code requires. Lead-acid batteries fade in the cold. Sodium-ion batteries do not. Here is what changed, and what a real Nordic project teaches us about emergency lighting backup in extreme cold.
When the mains fails in a cold building, the backup battery has to deliver its full rated time at the coldest ambient the site ever sees — not at 25 °C in a lab. Lead-acid batteries are the default in many buildings, but they have three cold-weather weaknesses that show up every winter:
For integrators and building operators in Nordic and other cold-climate sites, the everyday reality is this: the backup battery that should keep people safe is the weakest link in the cold.
A sodium-ion cell moves sodium ions between a hard-carbon anode and a layered cathode in a non-aqueous electrolyte. The detail matters less than two practical differences from lead-acid:
In Veken’s internal testing, sodium-ion cells discharge at −30 °C with a stable voltage curve, and they pass nail-penetration and over-charge tests without catching fire or exploding. Both points matter in a building asset.
An emergency lighting integrator in Norway retrofitted several commercial buildings, with stairwells and parking decks at −20 °C to −30 °C and strict fire-safety rules for equipment above escape routes.
Three pain points drove the battery choice:
The team chose Veken sodium-ion cells:
| Pain point | Solution | Tech support |
|---|---|---|
| Cold capacity fade | Stable discharge to −30 °C, no heater | Wide-temp electrolyte |
| Frequent replacement | Long cycle life lowers total cost | ≥8,000 cycles (internal test) |
| Fire-safety rules | No thermal runaway, no fire, no explosion | Passes nail-penetration test |
Results from the project:
For emergency lighting backup in cold climates, the two chemistries compare as follows. Sodium-ion data is from Veken’s internal testing; lead-acid figures are typical.
| Feature | Sodium-ion | Lead-acid |
|---|---|---|
| Low-temp discharge | Stable to −30 °C | Capacity drops below 0 °C |
| Cycle life | 8,000+ (internal test) | 300–500 (typical) |
| Fire risk | Low (no thermal runaway) | Higher (hydrogen, acid) |
| Maintenance | Low | Water top-up, venting |
| Cold-climate cost | Lower over life | Lower up front only |
| Best fit | Cold sites, fire-rated rooms | Mild climates, budget |
Checklist for sourcing cells in a cold-climate emergency lighting project:
For a sodium battery OEM partner with its own factory, stable large-scale order capacity, and an experienced engineering team, Veken is one option. See the sodium battery page and the battery product line.
Yes, for most cold-climate retrofits and new builds. Verify the cold discharge curve and the safety test reports at your site.
Veken’s sodium-ion cells are designed to discharge stably at −30 °C in internal testing. Lead-acid loses useful capacity well before 0 °C.
In internal testing, cells reach 8,000+ cycles, which translates to years of service before replacement in a real building.
In Veken’s lab, cells pass nail-penetration and over-charge tests without fire or explosion, and they do not vent hydrogen like lead-acid.
Data note: Cycle life, cold-temperature discharge, and cost figures come from Veken’s internal testing and the Norway project record. They are conservative estimates for engineering comparison, not contractual warranties. Last updated: 18 August 2026.
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