Liveaboard power consumption Chart on Zanshin

[Zanshin]

I have a Xantrex LinkPro battery monitor aboard Zanshin and it has a TTL-Level serial output port to which I attached an Arduino system (Atmel processor, DS1307 real-time clock, power supply and a micro SD card) and have been monitoring my power consumption 24x7 for the past two weeks.

I have a fridge and a freezer running in the subtropical waters here in the Caribbean and at night I have a Caframo fan turned to low in my cabin and have the anchor light on. During the night my power consumption averages around 2.67Amps@24V (5.34A@12V) so this is my baseline minimum power consumption of 64Ah per day. In reality I run the inverter to cook and use the computer quite a bit, plus the watermaker and washing machine occasionally as well.

I have a generator which powers a Victron inverter/charger that is currently set to limit charging amps to about 70, and the main engine alternator puts out about the same amount of current. I have 750 Watts of solar panels (6 panels, each with its own MPPT controller).

The battery bank is 4 220Ah Vetus AGM cells, giving me a 24V capacity of 440Ah.

I tend to sail every day, and use the engine to get out of one anchorage and into the next. I run the generator when I need a lot of power (heat up the oven to bake bread, run the dishwasher or washing machine or dive compressor). According to these numbers I have either the genset or the engine running 70 minutes per day on average; which is more than I thought but makes sense considering my daily sailing.


Click on the small image for the full-size chart

[Trevor]

Hi Zanshin,

This is a really good application of the data port on the battery monitor. I have the older square shaped Xantrex XBM model which has a serial comms port of some kind but maybe it is less functional than the later model. I note that Xantrex say it needs to have the "optional communications kit" to allow connection to a PC. I am guessing that is simply a TTL to RS232 convertor.

You certainly look after those batteries with your charging systems.

I have a few projects on the go at present but this certainly inspires me to think about the batteries a bit more and try to learn how I can graph my usage as well.

Many thanks for sharing that.

Trevor

[Zanshin]

Trevor,

the "optional communications kit" is nothing other than a TTL to Serial RS232 port. If you are interested you can build your own monitor with hardly any soldering with the following:

- Breadboard ($5)
- Arduino UNO ($20)
- SparkFun/Adafruit DS1307 Real-Time-Clock breakout ($15)
- AdaFruit/SparkFun Micro-SD breakout ($5)
- Micro-SD Memory card

And, of course, the program that I wrote. You only need to solder the headers onto the 2 breakout kits, the rest is done on the breadboard. My program uses another piece of kit, a Bluetooth breakout, so that I don't have to remove the SD card to read the data, I can connect from the free Arduino programmer and type in "DumpData 2016-04-07" and it dumps the readings in CSV form to the screen and I cut-and-paste it into my Excel spreadsheet.

For those who prefer it simpler and cheaper, one can solder together a Atmel ATMega328 ($3), Crystal ($0.10), 2 Caps ($0.05), Traco Power ($2) instead of a full-blown Arduino UNO!



Oh, here's the link to the Xantrex protocol: Xantrex Protocol Specifications

[dralyagmas]

Zandshin I am keen to know more about your set up and the program you have written.

I also have a Xantrex Link Pro battery monitor and I am using a Rasberry Pi 3 to run everything but have never considered the battery output as a data input source. I could easily get a TTL to USB cable and get that same information which I would be very interested in.

I see that the Xantrex does not talk in NMEA so I assume your program decodes the messages from the system and puts it into some kind of file readable by text or to be plotted? 

Any help in how to set this up for my boat would be greatly appreciated

[Zanshin]

If you've already got a Raspberry pi then you already have a lot more hardware and computing power than you need! The Xantrex LinkPro has a factory default setting of sending out the main attributes every second automatically, at 2400 Baud and no hardware handshake.
I believe the GPIO ports on the Raspberry pi are 3V TTL and the Xantrex output is 5V TTL, so all you need is a level shifter (e.g. SparkFun level Shifter) for $3 and you are good to hook up the signal. The back of the Xantrex has a 6-pin telephone RJxx plug which you'll have to find or make.

The data sentences sent are not complicated but are in binary, so a bit of programming is necessary to convert each sentence. The first byte contains the message type and then a variable number of bytes contain the payload. The coding is trivial, here's an excerpt of my code for the Arduino which will be pretty much the same for the Raspberry pi:


/************************************************************************************
** Method for optionally displaying the parsed values in a message and for storing **
** values for statistics                                                           **
************************************************************************************/
void ProcessSentence(const uint8_t sentence[XANTREX_MAXLEN], bool allMessages) {
  long TempLong = 0;
  switch (sentence[0]) {
     case 0x60:         // Main Battery Voltage
        TempLong = ((long)sentence[1]<<14) + ((long)sentence[2]<<7) + sentence[3];
        statistics.voltageCount++;
        statistics.voltageTotal += TempLong;
        if (allMessages) {
           Serial.print(F("Volts "));
           Serial.print(TempLong/100.0);
          Serial.println(F("V"));
        } // of if this message is to be shown
     break;
...


The messages are detailed in the document that I referenced at the end of my previous post

[Don Reaves]

I wish I could get my co-workers to write such neat code.

Don

[Zanshin]

I've got an updated and improved chart - now with 26 days of data.


Click on image to expand