GravityLight – Light from the Lift of a Weight


This smells like some attempt at getting money out of bloated aid agencies.

A car battery and an el-cheapo solar panel can be had for the same price (or less - used batteries that may not hold enough charge might still be suitable to power some lights can be obtained for free) and has the advantage of being a simple system, understandable by everyone, repairable in the field with easy to obtain parts and way more rugged & reliable than what seems like a plastic, proprietary contraption with intricate moving parts and electronics.


I’m not an expert but I believe the recommendation is to use deep discharge marine (i.e. boat) batteries instead of car batteries.


If you have the resources to get those, sure. But even a standard car battery will do, at least for some time, and if you can get more use per dollar out of those (and I assume end-of-life car batteries can be obtained very cheaply as they are essentially waste and no longer usable for their intended purpose) it will still work out better than paying extra for the "proper" battery.


12V car batteries are recycled. You actually get money back when you return one to a store.


It also produces a tiny amount of light they say 15lm on the page - by comparison my cheapo IKEA ceiling light does 1800lm at 45W. I can't imagine this being an optimal lighting or power solution for anyone.


It's supposed to compete with kerosene lamps. It's an enormous improvement.


Given the price point these are selling at, the target market of “people without reliable electricity” seems a bit off. Shouldn’t this the MSRP be $10-20? It seems more like it’s marketed as a novelty to rich westerners…


Probably, rich westerners pay the US/etc website's premium retail price and get a novelty that subsidizes sales elsewhere.

The light is marketed for a different subsidized price on local website versions in the Global South, or through other channels.

Kinda like pharmaceuticals.


Kind of. They have a donate page


Probably aimed at aid agencies, that may buy these and distribute them as they see fit.


No, they're a good value proposition compared with Kerosene, which you have to keep buying forever.

The issue isn't that people can't afford it, if they could afford kerosene then they can afford this, but access to credit or savings to allow them to make use of these cheaper technologies that have an up front cost.


Probably worth adding that you can already buy essentially the same thing, except powered by a hand crank, for $15-20 on Amazon.


In general, I find those terrible.

As a human I have large muscles and limbs capable of creating quite a bit of force. A 3.5 inch crank held between my thumb and forefinger doesn’t seem like a great way to generate electricity. I would much rather lift 50lbs a few feet every half hour than spin a tiny crank.


Even better: use a rope and pulley to let gravity help you.


Or go one expensive step further and buy a battery backup like the Jackery (I own one for camping and power blackouts).


I really like an idea of gravity-based light, reminds me of a weight-driven wall clock we had as a kid. So it was somewhat sad to read that GravityLight has been discontinued.

This page has a nice, technical explanation: In short, the cellphones got popular, but the gravity mechanism was only producing ~0.1 watt of electricity, which is not nearly enough to charge them.


This is a good idea, but has been overtaken by solar and batteries precipitous price declines.

Kerosene lighting is both expensive and unhealthy and inflexible compared with solar/battery/LED.

One of the few things it wins on (for now at least) is up front cost, but there's various finance models that enable the future savings to be used to advance the upfront costs.


The other thing about kerosene is that it works for decades if not more with only occasional user serviceable maintenence. It can be dropped in mud, banged up, etc, and still be repaired most of the time without lots of expertise or tools. Will something like this have even a percent of the longevity and resilience?


yes. it will last for more than one month.


> In 2019 we stopped manufacturing GravityLight to focus on a new product called nowlight.


Seems like these designs serve different purposes - gravity light would be better for stationary lights while the now light would be more useful for portable lights. Unless there’s way to attach a weight to the now light as well?


I'm curious why the pivot? What were the challenges with gravity?




Considering the incredible low cost of LEDs, would it not make better sense to have solar / wind installation, at a village level, to distribute energy for local needs?

This seems a lot of waste (both in effort and in materials)/


I would still think that something much simpler (and "bycicle based") together with a battery could be much more useful in places where there is no mains and for emergencies.

Something loosely like :

It seems like 60-80 W are sustainable for a longish period of time, so say half an hour that should be doable could be 40 Wh, something like 4 hours 10 W or 8 hour for a 5W led lamp.

I always thought that (for people sitting on a couch watching TV and not moving/walking/biking enough) connecting a small TV to the generator (with a minimal cache battery) could be a good product (though I doubt anyone would ever actually buy it).


Low tech magazine did an in-depth look at this a while ago:


Reminds me of this, can an olympic cycler toast a slice of bread?


It'd be really cool if instead of having to pull the cord for a long time you could just detach a heavy weight from the bottom and reattach it on the top of the loop.


I'm sure I've seen a video of that. I assume it's an older prototype. As I remember, you got any 10 minutes of light from lifting a really quite heavy weight, which looked kind it would quickly get annoying.

I feel the pulley system is a direct response to that. One minute of pulling sounds like a decent amount of work for a light, but having two hours before you have to do it again should sweeten the deal


Pulley is safer for kids to operate and not drop on their leg


The weight would be high and lifting up, may not be feasible to all, especially young children.

In contrast, having a rope that can be tugged, is a more practical solution.

Also, I wonder if such devices can be installed on village well walls, so that the time of the lamp is higher.


Destin from Smarter Every Day made a video on this product in 2015:


This is their current product:



I always get a lump in my throat when I read articles like these. For these hilariously misanthropic concepts to get approved and funded ("The best way to solve water shortage is trick the kids into doing child labour by painting the pump handles all sorts of fun colors"), indicates to me that these bleeding-heart humanitarians don't think of Africans as fully human.


> indicates to me that these bleeding-heart humanitarians don't think of Africans as fully human.

That's an interesting take but I think that's been the case for a few hundred years now. It won't miraculously go away, even though these attempts are well intentioned if somewhat misguided.