Author Topic: RPi off grid  (Read 4372 times)

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DamonHD

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RPi off grid
« on: July 05, 2014, 10:53:26 AM »
Hi,

I currently run all my main Internet-facing services from home (DNS primary, mail, Web, NTP, etc) on a SheevaPlug drawing 4W--8W from a solar-powered off-grid system with a fair chunk of battery storage (lead-acid gel and LiPO4).

I'm now trying to move all those services to a Raspberry Pi Model B which with just software tweaks, and already running probably the most heavyweight of my apps, the RPi draws about 1.75W, even with a *big* SD card to hold all of my current files/repositories with some to spare (meaning no external Flash thumbdrive is needed either on the RPi).

http://www.earth.org.uk/note-on-Raspberry-Pi-setup.html

I have added an RTC card.

I will shortly add some ADCs for monitoring battery voltage, and have started using the GPIO already: this will mean that I don't have to run a k8055 USB I/O card which will save another 300mW over the SheevaPlug system.

http://www.earth.org.uk/note-on-Raspberry-Pi-setup.html#GPIO1

So after some fiddling around today making myself an ad-hoc RPi 'shield' I have a software-controlled solar desk light!

In any case, I really hope that the RPi solution will come in at well under 2W* all-in, which makes the ADSL modem at 7.7W look greedy for example!

Rgds

Damon

*Possibly under 1.5W when I replace the crappy on-board 3V3 linear regulator with a switcher...
« Last Edit: July 05, 2014, 11:48:08 AM by DamonHD »

DamonHD

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Re: RPi off grid
« Reply #1 on: July 14, 2014, 10:01:16 AM »
Hi,

I got my batter voltage monitoring working AND a bonus high-side live power monitor that I've not had before.

http://www.earth.org.uk/off-grid-stats.html

It's based on the INA219 and is I2C-based so plugs right onto the RPi bus, though would also work nicely with an Arduino, which makes me want to populate all my solar PV and turbine with these to monitor power flows over wireless!

Another day though, as I'm trying to move all the remaining services off the SheevaPlug (which is the item who's power is being monitored).

Rgds

Damon

PS. I may be able to replace my RPi Model B with a B+ to take advantage improved power and USB, in particular I won't need to do any surgery to replace the linear regs with efficient switchers...

stephendv1

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Re: RPi off grid
« Reply #2 on: July 17, 2014, 10:06:41 AM »
Hi,

I'm using the rPi to manage a midnite classic charger, Sunny Island inverter and manage house loads through mango automation software.  But running mysql + tomcat is straining the wee beasty and it's definitely far from snappy to use.  Been considering upgrading to one of these quad core arm boards with 2Gb of ram: http://www.hardkernel.com/main/products/prdt_info.php?g_code=G138745696275


DamonHD

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Re: RPi off grid
« Reply #3 on: July 17, 2014, 02:01:46 PM »
My RPi has now taken over from the SheevaPlug and everything seems to be working; yes a bit slower but definitely a bit lower power (~2.3W* most of the time) and a lot physically smaller without the k8055 board, etc!

If only I had waited a few weeks: I now have a B+ waiting here to use instead and save possibly an extra 0.5W...  %-P

But in any case I'm happy with the result though will be happy to trade up speed and memory in a few years' time if the power consumption is low and the system is very widely used.

Rgds

Damon

*A fair chunk of the 'extra' consumption seems to be dealing with the ~30 malicious 'attack' packets per second of various types.

DamonHD

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Re: RPi off grid
« Reply #4 on: July 19, 2014, 11:11:39 AM »
Hurrah! Upgrade to B+ done and server is now using 1.7W, so a 0.6W/~30% saving.

Rgds

Damon

stofanel

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Re: RPi off grid
« Reply #5 on: March 12, 2015, 10:40:37 AM »
Just jumped on the Rpi bandwagon myself. Got myself a Maximum #400 anemometer, hooked it up to the GPIO via a common emitter amplifier and wrote some Python code that sends wind speed data via TCP. I hope the site has enough wind to justify a large (18ft dia) homebrew windmill.

DamonHD

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Re: RPi off grid
« Reply #6 on: June 10, 2016, 02:28:02 PM »
I accidentally killed my RPi B+ while rearranging the system (simplifying it, taking out the LiFePO4 battery, preparing to add about 500Wp+ of cheap second-hand panels) but had a RPi2 to hand that I'd been sent by a supplier for free to help along my projects:

http://www.earth.org.uk/note-on-Raspberry-Pi-2-setup.html

And amazingly just moving over the micro SD card and plugged-in devices (eg A-to-D, clock, GPIO control) just worked, with a much faster CPU system!  Good enough that I've been able to kill off a virtual server on the other side of the planet and bring its work home to the kitchen cupboard!

I'm also pretty happy with my detection of battery SoC and handling the optional/'dump' load (moving up to about 300Wh/day off-grid), for example accounting for sag from discharge and lift during charging, so I've taken a snapshot:

http://www.earth.org.uk/RPi201406/code/snapshots/20160610/powermng.cpp

I use the grid-tie output meter as one whopping great photocell, deciding when the battery should be being charged or not, and when I want to take the optional load off-grid to reduce night-time 'vampire' load (by a whole 13--14W)!

Rgds

Damon

PS. Gratuitous battery voltage pic!

« Last Edit: June 10, 2016, 03:10:27 PM by DamonHD »