Low Power Pi Openplotter setup - screen

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roblpm

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Im just musing about a low power nav system for my boat. I have a laptop with opencpn but not a great solution either running off laptop battery or invertor.

I have a shipmodul multiplexor so the instrument/data side is fine.

What I suppose I am really wondering is what screen people are using to keep the power down for longer (imaginary!) trips.

I will end up with a plotter as well in the long run but I am imagining turning most stuff off and running the pi to save amps.

So dedicated 12v screen of some sort? Tablet?

Anyone done the sums on the lowest power draw?
 
I've been using a Pi onboard with Openplotter for a while now, really powerful system!

It's mounted below the chart table with a samsung 19" 12v monitor running straight off the boat batteries.
Underway , I have a sony xperia tablet on a bracket in the cockpit under the sprayhood - bright enough even in sunshine. The tablet runs Opencpn android with AIS,GPS being fed over wifi from the Pi along with a host of other voltage/temperature data. The monitor down below rarely gets used, mostly just to update the excellent logbook konni plugin.

With the monitor off the Pi pulls about 0.3A.

Passage planning often will be done on a laptop the the navobj.xml files copied across to the Pi & tablet, you need to be a little careful to keep everything in sync or you can lose tracks or other data but otherwise it works well with bookmarks in the Filezilla program to connect to the Pi or tablet (need to run a wifi file transfer app to get the address to log on to)

These days I just leave the Pi on all the time as it logs various stuff to a database, battery voltage & engine temperature, SOG, COG etc.

Works great! The opencpn AIS display must be as good as there is & having engine temperature displayed as well is really useful though I had to do a little trick to turn engine temp into water temp NMEA message so the opencpn dashboard can display it all on one screen.
 
This is my nav station display which is a 17" 12Vdc powered LED/LCD TV than can display from VGA, Video, S-video or UHF Tv input. This is driven by a 12v PC but not a PI.

jD8Nltu.jpg


This is my cockpit display which is a 7 " Car DVD headrest display with Video input driven by a VGA to Video converter from E-Bay

P91H5uX.jpg
 
roblpm said:
Im just musing about a low power nav system for my boat. I have a laptop with opencpn but not a great solution either running off laptop battery or invertor.

I have a shipmodul multiplexor so the instrument/data side is fine.

What I suppose I am really wondering is what screen people are using to keep the power down for longer (imaginary!) trips.

I will end up with a plotter as well in the long run but I am imagining turning most stuff off and running the pi to save amps.

So dedicated 12v screen of some sort? Tablet?

Anyone done the sums on the lowest power draw?
Click to expand...

A £80 Lenovo tablet will take the data off of wifi and run OpenCPN, the battery lasts ages.
 
GHA said:
I've been using a Pi onboard with Openplotter for a while now, really powerful system!

It's mounted below the chart table with a samsung 19" 12v monitor running straight off the boat batteries.
Underway , I have a sony xperia tablet on a bracket in the cockpit under the sprayhood - bright enough even in sunshine. The tablet runs Opencpn android with AIS,GPS being fed over wifi from the Pi along with a host of other voltage/temperature data. The monitor down below rarely gets used, mostly just to update the excellent logbook konni plugin.

With the monitor off the Pi pulls about 0.3A.

Passage planning often will be done on a laptop the the navobj.xml files copied across to the Pi & tablet, you need to be a little careful to keep everything in sync or you can lose tracks or other data but otherwise it works well with bookmarks in the Filezilla program to connect to the Pi or tablet (need to run a wifi file transfer app to get the address to log on to)

These days I just leave the Pi on all the time as it logs various stuff to a database, battery voltage & engine temperature, SOG, COG etc.

Works great! The opencpn AIS display must be as good as there is & having engine temperature displayed as well is really useful though I had to do a little trick to turn engine temp into water temp NMEA message so the opencpn dashboard can display it all on one screen.
Click to expand...

Is that just a standard monitor that happens to run off 12v normally through an ac/dc power supply? And works fine straight from the batteries?
 
roblpm said:
Is that just a standard monitor that happens to run off 12v normally through an ac/dc power supply? And works fine straight from the batteries?
Click to expand...

One of these - http://www.nivo.co.za/buy~samsung.ls19a100n.18.5.led.monitor~p37407

And yes, straight off the batteries , regularly to up near 15v, seems to be OK so far..
Draws a fraction under an amp.

Just been playing around with an ammeter - cheap dc buck converter with everything running (not inc monitor, just the 5v stuff) it was pulling around 0.6A on 13.7v input. A better buck/boost converter with just the Pi it was about 0.32A, keyboard, extra wifi dongle & dual FTDI usb/serial around 0.48A then just hitting 0.5A with the monitor turned on. The monitor is VGA so there's a HDMI/VGA converter which might pull a little.

When you're doing the wiring it's worth considering getting a good dc converter set a little high, mine is about 5.15v, then butchering a mini usb cable so you have a fatter wire supplying the Pi with power, it can be very picky with even just a little voltage drop during the peaks.
 
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For the very lowest consumption, an e-ink display would seem the way to go - they only use power when changing the display. however, their ability to display colour is limited (there are colour displays, but they don't seem to be available in the amateur market).
 
AntarcticPilot said:
For the very lowest consumption, an e-ink display would seem the way to go - they only use power when changing the display. however, their ability to display colour is limited (there are colour displays, but they don't seem to be available in the amateur market).
Click to expand...

Yet to have a play , but seems there are thousands of e-ink displays available, probably a great many boats have one onboard already... ;)

Though for chart plotting type stuff, I don't think it's much of an option yet.

Roll on signalk!

https://digitalyacht.net/read-anything-good-lately/

kindle-with-hand.png
 
HighlandDave said:
This thread has encouraged me to ask Santa for a Pi this christmas. Its been in my "save until later" box for a while.
Is there any problems getting charts? Im not overly tech savvy nowadays so may be asking a lot of questions later.
TIA
Click to expand...

If you are wanting vector charts then this year OpenCPN Vector Charts became available on OpenCPN for the first time in the UK this year for less than a weekend in a marina.

If you want Raster - things get trickier for legal solutions.
 
I generalised the bigger the screen, the bigger the power consumption.

Since my 10 inch laptop screen was reasonably usable at the chart table, I went for a 10.1 inch 1280x800 led screen from Tomtop.

It works direct from the 12v battery.

I do however have it hdmi connected to an Intel NUC running Windows 10 (which also runs direct from the 12v battery). I have not measured current consumption but will do if anyone is interested.

https://m.tomtop.com/p-s981eu.html?currency=GBP&Warehouse=CN&aid=gplaukyly&gclid=EAIaIQobChMIu4KT-dqC2AIV0MmyCh0PQgUoEAQYASABEgKYffD_BwE
 
GHA said:
Yet to have a play , but seems there are thousands of e-ink displays available, probably a great many boats have one onboard already... ;)

Though for chart plotting type stuff, I don't think it's much of an option yet.

Roll on signalk!

https://digitalyacht.net/read-anything-good-lately/

kindle-with-hand.png
Click to expand...

Martin_J said:
I generalised the bigger the screen, the bigger the power consumption.

Since my 10 inch laptop screen was reasonably usable at the chart table, I went for a 10.1 inch 1280x800 led screen from Tomtop.

It works direct from the 12v battery.

I do however have it hdmi connected to an Intel NUC running Windows 10 (which also runs direct from the 12v battery). I have not measured current consumption but will do if anyone is interested.

https://m.tomtop.com/p-s981eu.html?currency=GBP&Warehouse=CN&aid=gplaukyly&gclid=EAIaIQobChMIu4KT-dqC2AIV0MmyCh0PQgUoEAQYASABEgKYffD_BwE
Click to expand...

Sounds great but expensive!

I am thinking pi, and a £30 second hand monitor off ebay!

I wonder what the difference in power between a pi and a 12v pc. Anyone?
 
I use the NUC5PPYH on board. The specification states 6W under moderate stress... And 12-19v supply


I guess I'll have to measure whilst running OpenCpn..
 
roblpm said:
Sounds great but expensive!

I am thinking pi, and a £30 second hand monitor off ebay!

I wonder what the difference in power between a pi and a 12v pc. Anyone?
Click to expand...

Think it depends on the PC, this lot claim some of their "PCs" take between 5 and 10W which is about the same ball park as a Pi. Most are 10s of watts though.
EDIT to add the link: https://www.tinygreenpc.com/fitlet-rm-x.html
 
Last edited:
Martin_J said:
I use the NUC5PPYH on board. The specification states 6W under moderate stress... And 12-19v supply


I guess I'll have to measure whilst running OpenCpn..
Click to expand...

That does look a neat little machine. Power jumps to more like 30W under load though from what I have read.
 
I built a low power windows system years ago (before that raspberry thing was released)

Managed to make a 12v PC that would only take 400ma running transas navigator or opencpn. That includes the power for the USB GPS too.

Anyway, pleased with that, I spent ages trying to source a suitable low power screen to go with it. Ended up buying several cheap 12v screens off eBay. Most that I bought were 12" screens sort of industrial quality sold under the category of shop equipment on eBay. They were meant for tills and the like. Found a huge variance in available brightness and current consumptions from brand to brand. In the end one from a make called 'digipos'
(Pos being an abbreviation for point of sale I.e. tills) was the best.

That screen would draw as low as 500ma on an indoor brightness, it would also go up quite bright (almost good enough for sunlight) although the current went up to 1.2a.

Might be worth a look on eBay?

However, when I changed boats I took the PC and left the monitor. On the new boat I went for a Hewlett Packard 18" monitor for the chart table. Again happened to be 12v with a mains adapter, again happy running directly off the 12-14.5v boat batteries.

That one takes 1.5a, but I learned with the first system.. The monitor current doesn't really matter. Even old windows xp can switch it to standby after some minutes of inactivity. So the ampere hours with maybe an hour of cumulative use per 24 is negligible.

The computer itself of course on all the time on a long passage gnaws away at the batteries all the time so getting the current down as you are makes perfect sense
 
In case anyone is interested..
Measuring total consumption just now on a NUC5PPYH with 10.1" 1280x800 12v screen
950mA running OpenCPN with wireless keyboard/mouse and screen active
460mA running OpenCPN with wireless keyboard/mouse connected but screen sleeping
320mA running OpenCPN with wireless keyboard/mouse connected but screen powered off


So
It looks like my little screen uses about 490mA when on at standard brightness
but still uses 140mA when sleeping and just powering the front LED.

I have not changed any Windows settings to reduce power consumption. I think powering off the monitor will make more of a difference for now.

Wind, depth, ais and navigation data are all obtained via ethernet so I've not included USB<-> Serial adapter consumption.
 
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