It was extremely encouraging that so many people said they would use a GravityLight instead of a kerosene lamp. What was even more useful was finding out why some people would not:
A significant objective in our global trials was to discover what needed improving: What didn't work and why? What would make that last 10% switch their kerosene lamp for a cleaner, safer GravityLight?
Maximising GravityLight's brightness:
GravityLight doesn't need the sun or batteries but it does need 10-12kg of weight, such as rocks or sand.
Not only did we design GravityLight's bag to be robust enough to hold this weight, we also shaped it to maximise its 'drop time' or light duration. It was tall and narrow, which meant that when the base touched the ground it had 20 seconds of dimming light as a 'warning' that the bag needed lifting again.
As the weight of different rocks and soil varied, in some cases we needed a bigger bag!
It also meant that where the bag had been filled but weighed under 12kg, trialists didn't benefit from the maximum brightness that GravityLight could deliver.
We've taken this into account in our new bag design for the next generation GravityLight - GL02 - which is:
- UV resilient
- can be locally sourced
Making GravityLight easier for all to use:
Another challenge we found was that some people struggled to lift GravityLight's weight to it's full height. This meant that people experienced a shorter drop time and light duration.
We want GravityLight to be accessible as possible to all members of the family. Given GravityLight can be used as a clean, safe light for children to study by, it is especially important to us that children are able to lift the weight too.
Jim's sons have been great mini trialists of thenew winch system in GL02. With this, a 12kg weight now feels like 3kg. It also enables people of any height (and different sized biceps!) to use GravityLight and benefit from the maximum light duration.