When operating a battery driven lamp at lower temperatures there are some aspects that are important to be aware of to get the best performance out of the lamp.
At low temperatures most materials change characteristics.
Mechanical parts move differently due to harder rubber or lubrications losing viscosity
Thermoplastic materials can become more fragile and easier to be damaged or break
Electronics parts and components mostly keep performance and behaviour
LED performance remains only little changed as they heat up fast
Most battery types, including rechargeable Lithium-Ion batteries heavily change
performance and behaviour at temperatures below 0°C.
Lithium-Ion batteries – charging
WARNING: Low temperatures seriously affect the charging of a battery.
Do not charge a lithium battery at temperatures below 0°C or above +45°C!
Charging at lower temperature will permanent damage the battery and can cause safety risk.
For best charging time and lifetime it is recommended to charge the battery between 10°C to 30°C only.
Lithium-Ion batteries – discharging
The performance and capacity of a Li-Ion battery drops fast at lower temperatures!
Switching on a lamp with high discharge at 25°C creates a voltage drop from 4,2V to 3,9V.
Switching on a lamp with high discharge at 0° C creates a voltage drop from 4,2V to 3,5V.
A Li-Ion battery at 25°C is capable of providing 3.0C (9A from a 3000 mAh battery = 33W)
A Li-Ion battery at 0°C is only capable of providing 1.0C (3A from a 3000 mAh battery = 11W)
A Li-Ion battery at -20°C is only capable of providing 0.2C (0.6A from a 3000 mAh battery = 2.2W)
The overall capacity of a battery is also reduced due to the lower efficiency in the chemistry of the cell.
The capacity of a cell is rated as 100% based on temperature of 25°C.
The capacity of a cell is reduced to 50-70% at a temperature of -20°C.
Lamp operation at low temperature
Obviously, low temperatures reduce the performance of a Li-Ion battery and this has a direct visual effect on the performance of the Li-Ion battery powered lamp – and cell phone or Electrical Vehicle for that matter.
This reduction will be experienced as lower light output intensity and less total light output.
It is not due to a defect to the lamp and/or the battery that the output and runtime from a lamp is reduced at low temperatures – it is the law of nature.
Recommendations for low temperature operation
To get the best possible experience with a lamp at low temperature a few simple things that can be followed:
Store in a warm pocket when not used
It is recommended to store a lamp in your pocket so it can be warmed by the body temperature. Remember to set it in Transport Lock, if available.
Turn on at low output mode
If turning a lamp on at low temperatures, it is recommended to turn it on with a low light output. The battery will gain inner temperature, and this will allow it to operate at higher output after a short time. Starting at too high output can cause the lamp to turn off.
Insulate the battery
To keep the battery warm to gain performance it can be insulated. Wrap a clothing or gloves around the tube where the battery is positioned.
Take care not to block the light beam as that can cause overheating.
Keep battery charged
Keep the battery at a high charging stage, to keep the voltage as high as possible
We must note that all Product Specifications and Performance data are based on a surrounding temperature of 25°C.
Low, and High temperature operation can, dependent on the product, effect these specification and performance data.
It cannot only affect data as described above, but also change mechanical aspects i.e. IP classification and drop resistance.