Friday, 31 May 2013

Victron BMV600–First Thoughts


We’re moored just above Hillmorton Top lock with the off-side hatch open enjoying the ambiance. Every so often a boat passes at a speed much greater than ‘tick-over’ bouncing Waiouru around in its wake.  Jan has taken to calling out in a loud and friendly voice “Thank You!” Somehow I think the sarcasm is lost on the recipients.

There must be a rabbit burrow on the opposite bank as there are at least six young ones playing in the grass.  Mrs Duck is also being a good mother as she still has 12 ducklings.

Through the porthole glass

All this cooing and sighing……. All I can think of is duck a l’orange and rabbit pie!

Problem?    Then why the long face!

For the second consecutive day I walked back into Rugby.  Yesterday was only a dress rehearsal for today’s doctor’s appointment.  It went well and I now have a six month supply of my heart medication.  The only problem is they now want a sample of my blood.  Jan said ”That’s impossible… you haven’t got any!”  No doubt our children would say it was cold.  Of course I know it’s warm and blue!

The BMV600 Battery Monitor has now been working for almost 20 hours.  Once the alternator negative lead was connected to the shunt (duh… can’t believe I left it off) and the engine started and the Smartgauge reported the SOC as 55% and the BMV showed 168A flowing into the battery.  The theoretical combined output from the two engine alternators is 220A but nothing is 100% efficient.  After a short time the BMV reported a steady decline in the amps going into the battery bank.  When the Smartgauge reported the SOC as 85% the BMV was reporting the amps as 10-16A. 

Interestingly, the BMV reported the battery bank SOC as 100% much earlier than the Smartgauge.  But the BMV may still be calibrating itself.  It was also interesting to watch the BMV reporting the amount of solar power going into the batteries.  It was the same figure as the amps shown on the Tracer Solar Controller remote display.  A positive sign for the Tracer.

My concern about the Smartgauge has always been it reports the battery SOC as a percentage.  But a percentage of what?  Having the BMV will now enable us to see exactly how much energy is going in and out of the batteries to reach 100% SOC.

The other advantage of having the BMV is it is possible to identify the critical point where running the boat engine should cease and the charging be completed using the generator.  There seems to be little point in running the boat engine to produce a theoretical 220 amps when the batteries can only accept 10 amps!

We tried this out today and at 80% SOC (accordingly to the Smartgauge) the batteries were only accepting 16 amps of charge (according to the BMV).  So the engine was stopped and the generator started with the remainder of the charge being completed via the shoreline and the Victron inverter/charger.  The generator happily ran on ‘tick-over’ for a couple of hours getting the batteries to the final ‘Float’ stage.  They are now being maintained there by the output from solar panels.  I suspect on a sunny day we will be able to rely on the solar panels rather than have to run the generator.

Finally, the BMV is allowing us to see what the energy consumption is for each ‘consumer’.  We now know the freezer draws 3.4 amps when it is running.  By isolating each piece of 12 volt equipment we should be able to produce a reasonably accurate energy audit and modify our behaviour accordingly.

Later….. The BMV is now calibrated and reporting the SOC as 99.4%.  The Smartgauge is reporting 100% and doesn’t display decimal places.  The BMV is reporting at our present usage rate the battery bank will last 73 hours.  All appears to be going well.


Davidss said...

Several times, in different posts, you report the boat is being moved excessively by moving boats 'going to fast'. Sometimes you have fitted spring ropes to counteract this. Based on previous pictures you have published I'd like to suggest you modify your basic mooring techniques.
Aim to put your mooring pins further away from the bow / stern (that is, further along the bank, not closer to the towpath). My rule of thumb is 1/3 to 1/2 of boat length, so for a 60ft boat that's 20 to 30 feet from the bow / stern. The change in angle between the rope and the boat means that the boat snuggles up to the bank sooner as the boat moves away from the oncoming craft. Thus your boat moves much less.

HTH David.

Tom and Jan said...

Always willing to give most suggestions a try David!