Isotherm fridge thermostat probs

[nigelmercier]

So, what's the most efficient way to run a fridge....?
I'm thinking pump on about 4 deg and off at 5, is that OK to keep food in?

From your graphs, that looks about right, but the graphs will change with the ambient temperature.

 

[GHA]

From your graphs, that looks about right, but the graphs will change with the ambient temperature.

Load of stuff on the web/instuctables.
Check this guys screen out, under 15 quid

http://arduinothermostat.blogspot.co.uk/
http://www.amazon.co.uk/TFT-LCD-Rea...4TQW/ref=sr_1_1?ie=UTF8&qid=1356951598&sr=8-1

Getting carried away now.....

With a decent sized screen it shouldn't be difficult to get ais & gps data displayed, maybe with an ais proximity alarm...

Hmm......

 

[GHA]

Still a mess of wires but the new arduino based thermostat seems to be solid.
So next thought, defrosting!

With a quick Google this seems to be done by heating the evaporator plate now and again, so why not implement that as well. Just a short length of some sort of 12v heating tape should do the trick.

Anyone else have an auto defrosting fridge on board? Any thoughts?

Ta

 

[charles_reed]

14 hours of fridge
Think the breadboard lead to the fridge from the transistor got pulled out for a while before 04:00.

Rats?

 

[GHA]

More fridge fun
With a cheap bluetooth adapter fitted it's now possible to view and change the fridge settings before getting out of bed using a bluetooth serial app on an android tablet

H

Help:
Press 'S' for settings
Press 'L' for live data
Press 'T' to display time 
Press 'V' to increase turn on temp 
Press 'C' to decrease turn on temp 
Press 'X' to increase turn off temp 
Press 'Z' to decrease turn on temp 
********************************
S

settings:
Turn on compressor when temperture reaches 5.00
Turn off compressor when temperture reaches 3.50
********************************
L

Compressor is not running
Sensor 01 temperature is:   Error getting temperature  
Sensor 02 temperature is:   C: 5.00
Sensor 03 temperature is:   C: 3.25
Sensor 04 temperature is:   Error getting temperature  
Sensor 05 temperature is:   Error getting temperature  
Sensor 06 temperature is:   Error getting temperature  
********************************
V

Turn on compressor when temperture reaches 5.10
Turn off compressor when temperture reaches 3.50
********************************
V

Turn on compressor when temperture reaches 5.20
Turn off compressor when temperture reaches 3.50
********************************
C

Turn on compressor when temperture reaches 5.10
Turn off compressor when temperture reaches 3.50
********************************
C

Turn on compressor when temperture reaches 5.00
Turn off compressor when temperture reaches 3.50
********************************
X

Turn on compressor when temperture reaches 5.00
Turn off compressor when temperture reaches 3.60
********************************
X

Turn on compressor when temperture reaches 5.00
Turn off compressor when temperture reaches 3.70
********************************
Z

Turn on compressor when temperture reaches 5.00
Turn off compressor when temperture reaches 3.60
Z

********************************
Z

Turn on compressor when temperture reaches 5.00
Turn off compressor when temperture reaches 3.50
********************************
L

Compressor is not running
Sensor 01 temperature is:   Error getting temperature  
Sensor 02 temperature is:   C: 5.00
Sensor 03 temperature is:   C: 3.25
Sensor 04 temperature is:   Error getting temperature  
Sensor 05 temperature is:   Error getting temperature  
Sensor 06 temperature is:   Error getting temperature  
********************************
S

settings:
Turn on compressor when temperture reaches 5.00
Turn off compressor when temperture reaches 3.50
********************************

 

[nigelmercier]

With a cheap bluetooth adapter fitted it's now possible to view and change the fridge settings before getting out of bed using a bluetooth serial app on an android tablet ...

You need to get out more

Seriously though, I'm impressed.

 

[GHA]

You need to get out more

Seriously though, I'm impressed.

Ta , there have been a one or two obsessive late nights
But very pleased it works, a few more programming tweaks, have a few "keep turned off for X minutes" available for receiving weatherfax. I've had a soggy fridge more than once forgetting to turn it on again . Get it to log voltage at the fridge, the analog in/outs only go up to 5v so a little voltage divider needed. A couple more temp sensors ambient and on the compressor and sort out the Sd card so it logs it all.
With an arduino uno r3 it pulls just 30mA, jumps between 30 & 50 with bluetooth on but not paired and 35mA paired. The ds18b20 temp sensors are great, very accurate, dead cheap and every one has it's own address so all the data comes back in down one wire.

So flushed with this success thoughts turn to more... What would be nice would be keeping an eye on the alternator, stuffing box and exhaust temperature, with an alarm. And why stop there, easy then to add hull temperature, amps in from solar and amps out to domestic. Maybe stick in an nmea feed from the gps and log position when it's turned on..or maybe to data coming down from the nasa metioman masthead, whatever format that's in... ....

What else would you like to have logged automatically onboard.....?