[Energy] Standardizing pedal power for the occupiers

Amos Blanton amos.blanton at gmail.com
Tue Nov 8 14:06:03 EST 2011


Here are some thoughts on strategies for standardizing / improving our
pedal power infrastructure.

*TLDR; Use 12 volt cigarette lighter sockets / plugs as a standard
interface, focus engineering efforts on making a cheap open-source power
regulator that lots of different pedal generators can use.*


[image: PedalPowerstandards.png]



*This diagram breaks things down into two categories: supplies and loads*
Supplies are things you can plug stuff into to get power: generators (pedal
and wind), and power / battery packs. Loads are things that use the power
they supply.

*It would be useful to declare some standards - 12 volt being the first one*.
One could imagine a scenario where all the occupies agree on a standard and
an interface for things that create power and things that use it. If OWS
needs more power for an event, Boston can send them a few of their
generators for a couple days, and / or vice versa. You get all kinds of
emergence and unexpected benefits when you standardize the interface as a
constraint and then let people innovate what's behind it.

*If we're using 12 volts, then we might as well use the cigarette lighter
plug as the interface* because there are lots of things that work with them
out of the box. Aside from the many cell phone chargers, usb octopai, etc,
you can get for your car, there are also a lot of cool electrical things
made for RVs and boats, like coffee pots, slow cookers, refrigerators, and
what have you. And marine grade 12 V cigarette sockets / plugs will
actually lock in place.

This approach suggests we should focus our efforts in two places.

*1. Make universal power regulators that can be used with (almost) any
pedal generator*

It doesn't take a deep understanding of electrical engineering to make a
pedal generator: you just have to figure out how to turn a motor backwards.
The difficult part is what to do with the unregulated, dirty, DC
electricity that comes out of the generator wires in order to make it
consistent, safe, and usable, so it can interoperate with all the things we
might want to connect it to. Once a cheap power regulator is designed and
made available, lots of people can then make pedal generators. They can
order the assembled power regulator from sparkfun, or DIY it from plans
made available, and then they're golden: hook up the two wires from the
generator to the in, and then hook up the two wires for the out to a
cigarette lighter socket. It doesn't matter that their generator looks or
works differently than all the rest, as long as the output conforms to the
standards.

A thumbnail first draft of a spec for the power regulator:

   - Contains a bridge rectifier so you can't pedal backwards and generate
   negative voltage
   - Takes in power ranging from - 30V to +30V and consistently outputs
   clean 14.5 volts ( which most 12 volt things can accept, and the extra
   couple volts are useful if you are charging a battery pack)
   - Consider using a largish capacitor so one can slow down pedaling or
   even switch riders for a second and still put out consistent power.


*2.  Build Power packs with charge controllers*

12 volts won't travel far on a wire without losing its oomph, and we can't
put generators everywhere. So that means we need portable power packs to
distribute power to where its needed on site. Batteries need charge
controllers with simple interfaces to be usable by the masses. They should
prevent over charge or undercharge, and they should tell the user when they
are being charged or discharged, and approx. how much juice they have left.
And it should make difficult to lick the terminals or short the leads, or
otherwise do something dangerous.


*User Stories:*

Here are some user stories of how I could imagine this working as we scale
up:

   - The cook notices the light is getting dim, so the next morning someone
   takes the power pack to the pedal tent, where they charge it for an hour or
   so. They bring it back, plug it in, and the lights are good for another few
   days.


   - One of the people in the media tent needs to work on their laptop all
   night, so they go the pedal tent and "sign out" a power pack and and AC 120
   volt inverter (and possibly leave some kind of collateral). The next
   morning they return both to the pedal tent coordinator, who places the
   power pack in the "dead" queue. Legions of healthy young pedalers stop by
   throughout the day and charge it and the rest of packs back up, under the
   watchful eye of the coordinator / pedal power team.
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