Mareld Pro Lighting

Light curves and battery operating time

What is a light curve?

A light curve is a graph that shows the performance of a battery-powered lamp.

The horizontal X-axis shows the operating time and the Y-axis shows the amount of light in lumens. The curve shows how the lamp lights up over time.

The curve is an important aid when you want to compare the performance of different lamps and find the right balance between the battery's operating time and light output (lumen). For example, when you read about operating time at maximum power in a technical specification, it says very little about how long the lamp shines at full power. If the lamp starts at 1000 lumens, the operating time is measured until there is 10% (100 lumens) remaining.

Many lamps provide a maximum of 1000 lumens for a minute or so and then dim down to a lower level that they can maintain for a longer period of time.

There are two main reasons why a lamp cannot provide maximum power for a longer period of time:

1. The lamp gets too hot and have to be dimmed down to keep from overheating. A lamp with one diode cannot, in most cases, deliver more than 1000 lumens. Especially multi-lamps with their compact size have problems keeping the amount of light for a longer time before they get too hot.

2. The batteries cannot deliver the power the lamp needs. Alkaline batteries lose power over time, which causes the amount of light to continuously decrease during use of the lamp.

A multi-lamp can be good if you have the need for a lot of light for a slightly shorter time but where you can manage with less light for most of the time.

A lamp with alkaline batteries can be good when you don't need a lot of light and you prioritize the lowest possible weight.

If you have a dimmable lamp it is also possible to dim the lamp during use to extend the operating time and only use the maximum mode when really needed.

How many lumens do you need when using a headlamp?

  • 200-400 lumens: Lamps used indoors, lit roads or if you don't need much light
  • 500-1000 lumens: Sufficient light for most activists and available in a compact format.
  • 2500-5000 lumens: Provides a lot of light and is especially suitable for demanding outdoor activities