Attaching a generator to the output of a Lifter is probably the most anticipated method to use the energy stored in a raised Carriage. As I attempted to get the most from this out door Lifter I tried a couple of different setups. The first one shows the generator providing enough output to charge a 1000 mA battery pack and a 4 watt 8 LED USB light bulb. The rpm of the generator has been set by using 3 of the 4 pulley stages, the final stage of the pulley system was matched to the generator pulley, and reducing the Carriage weight to around 400 lbs. This allowed the Carriage to drop a little more than 1.5 feet per minute. With no load, other than the rectifier and volt/current display it provides around 12 volts. Once the battery pack and the light are connected, the DC-DC regulator drops the output to 5 volts. As you can see in the video it is very marginal. More weight would have provided greater RPM at the generator and produce more voltage. ( One of the DC-DC regulator boards is not working and the input is shorted to the next regulator. Note: Don't spin the generator in reverse with leads attached unless you have a blocking diode in place. )
Weight was added to the Carriage, bringing it up just over 500 lbs, and a larger 6 in. pulley was placed on the final stage of the pulley system. I also took out two of the DC-DC regulators. This setup provided a drop time of about one foot per minute and delivered enough torque on the generator to keep it at an RPM high enough to power the LED light. A greater than one foot per minute drop time is something to shoot for, because one would like to keep the drop time longer than the time it takes to tilt the Carriage up. Of course, if you have a twenty or thirty foot vertical support, then a one to two minute per foot drop would certainly make a Lifter with 500 lbs. in its Carriage, much more usable.
Generator Output - Fast
Generator Output - Slow
If you are using some other source of energy like maybe solar energy, to tilt your Carriage up, you would want to match the number of tilts to the time of optimal solar energy production and the height of your Lifter.
A generator this size would be a good starting point for a larger Lifter. I am still looking for something smaller, requiring less torque.
For a DIY example of a light powered by gravity see this example at rimstar.org, DIY Gravity Powered Light. The steps needed to calculate the generator rpm, gear ratios, weight and drop time are reviewed much better than I could explain it.