Re: [Legba2013] Power planning

[Jim F. <jim...@ra...>]

Combined response to a couple messages:

From Harvind:

> Absolutely agree on a discussion.  Power is life out there.

Indeed!

> We'll be bringing the power cart of course, and we'll be bringing many 200W solar panels.   And our wind turbine.
> 
> We still need to replace/fix the propane power generator.   I think our peak power demand is typically 1kW, which is mostly powering laptops.  We'll be using a fanless central server this year. 

The generator can probably be fixed.  I'd tackle that, except the cart is too big for my SUV...I would be interested in looking  at the charger inside and thinking about how the solar & wind inputs get combined.  I see from the wiki there's parallel chargers. Are either MPPT? That's best. Have the batteries been on float charge during their year of rest?  I'm told if not they will sulfate; ideally the charger should goose them every couple weeks or so with a short, big charge, which will cause bubbles to form, and thereby a little turbulence in the acid, reducing sulfating. If you want, send me all the manuals you have, or pictures of the stuff and I'll look into it.

From Pete:
> 
> I have a mess of generators with sound dampening sp they re super quiet .
> 
> More importantly , I have a line on 1 or 2. 1.5kw trailer mounted solar arrays that may be available for rent if you guys are interested 

Rough price on the panels?  Charger controller included?

> I also just spoke with another friend and we are beaming 30 meg of Internet fr reno direct to the playa with some commercial repeaters

Interesting!


From Diggz:

> David and I also discussed this in terms of running some lights for the camp to give it a little less, ahem, utilitarian look.   Obviously we'd be looking at low-power LED's that should be on a secondary system.  Just thought I'd add that in while we're discussion power requirements.  I was even considering having different power sources for utility lights (as in those required to not bump into things) and accent lights (those that make things look cool).

Sounds good to me too.  I would think with low-power LED's you can do a lot with 30-100 watts, no?

From Peter:

> Can we have separate power supply for infrastructure and for camp?
> 
> I am perfectly fine with abrupt power outages several times a day for
> laptops. Infrastructure, not so much.

I think that's a good idea.  It would imply however, a separate source (solar/wind), battery system, inverter).  I might want that for my electric cart, in which case it could conceivably do double duty, so let's see if that develops; if not we'll just monitor better, enforce charging discipline, and cut off that load as need be.  I just got a very nice AC/DC clamp meter so it will be easy to see what's happening.  We might do OK powering those loads about 1 hour out of 3 during the day, and not at all at night.

> As for camp - what is the efficiency of the inverter, and of laptop
> chargers, and how stationary are the laptop chargers?
> 
> If low efficiency or mostly stationary chargers, then having a laptop
> daycare center with the right connectors and voltages might make
> sense.

I think the efficiency of the chargers is decent, when they're actively charging (they're all switching power supplies these days), but when the laptops are charged the chargers still suck a moderate amount.  So our usage last year was probably inefficient.

The wiki has a decent section on power, but I will update with the notions of (hopefully) separate power for camp vs. infrastructure, decorative lights, etc.  It says the PV array is good for about 5.5kWh per day, and the the wind turbine about 1.2kWh.  5.5kWh + 1.2kWh is about 6kWh total available per day, this implies limited our average draw supported would be about 250 watts.   That's probably enough for the infrastructure, but not everything else.   See http://papalegba2013.wikispaces.com/Electrical+Power for the updated section, fix it as appropriate.

  -- Jim