Underground car parks: IP65 is the starting point, not the whole answer
A car park is a hostile environment for a luminaire: it gets hosed down, it gets hit, and in winter it gets cold enough that the battery stops behaving like the datasheet says.
The four failure modes that actually happen
- Water ingress, in car parks that are periodically washed down with a hose. This is why IP65 rather than IP44 is the usual specification.
- Impact damage from vehicles, which is a mechanical failure and is not addressed by any IP rating — it needs an IK rating.
- Condensation during temperature swings, particularly where warm air meets a cold soffit.
- Battery capacity loss at low temperature, which first shows up as a short discharge test rather than an obvious fault.
Configuration that addresses them
- IP65 fittings throughout the parking decks and ramps, including the exit signs.
- An IK rating that reflects vehicle proximity, checked separately for columns and low-level fittings.
- Battery packs specified for the actual winter temperature on site, not for 25°C.
- Self-testing units where the ceiling height makes manual testing impractical, so a failing battery is reported instead of discovered.
About duration and cold
The duration figure on a datasheet is measured at a rated ambient temperature. Usable battery capacity falls as temperature drops, so a 3-hour rating verified at 25°C will not automatically hold at -10°C. If the site sees freezing conditions, ask for discharge data at the low temperature you will actually experience, and consider whether the pack can be positioned outside the coldest zone.
This is also where chemistry choice matters: LiFePO4 generally holds up better than ternary lithium at low temperature and gives roughly twice the cycle life, at some cost in energy density.
Before you order
- Winter and summer extremes on site, in degrees, not "cold".
- Whether the decks are washed down, and with what.
- The required duration, from the local authority, not from the supplier.
- The IP and IK ratings for the specific model, with the test reports behind them.
Anshine supplies IP-rated emergency luminaires, exit signs and LiFePO4 packs from 3W to 300W, with batteries warranted for 3 years and other parts for 5 years.