intelligent battery monitor
One of the things that annoyed me about depending upon
battery power while camping was never really knowing how much power
I had left in the batteries. You can apply a voltmeter to the
terminals, but this is a wildly inaccurate way of gauging the state
of charge. The reading can suggest your battery is fully charged
when it is actually less than half charged thanks to surface charge.
I think I have now solved the problem.
installed a Victron BMV-600S to my camper. This is an intelligent
battery monitor which keeps track of all the current flowing into
and out of the batteries and even calculates the Charge Efficiency
Factor as it goes and uses Puekert’s Exponent (Google it if you want
to know...) to be as accurate as possible.
To set it up
you connect the supplied 500 Amp shunt to the battery negative
terminal and then connect all the negative wires to the “load” end
of the shunt. This allows the monitor to keep track of all current
movements. The shunt needs a light wire (supplied) connected to the
positive post to do its magic. You then connect the Monitor to the
shunt with the supplied network type cable which is 10 metres long,
certainly long enough for any camper trailer use!
You mount the
gauge in a suitable spot, feed it the setup data like battery type
(AGM, GEL, WET, etc.), total capacity, etc. – up to 28 different
parameters if you want to - and then zero everything with the
batteries fully charged.
now keeps track of all the current flows and does the math. The LCD
readout on the monitor can be scrolled through displays of
Battery Voltage (V)
Current (I), either positive
or negative, depending upon what is going on
Consumed Amp hours (CE),
since the battery was last fully charged
State of Charge (SOC) as a
percentage, to one decimal place
Time To Go (TTG) which gives
you a rough estimate of how long before you really need to
recharge the batteries - 50% SOC by default- based on the
current flows over a user selectable time, up to 12 minutes.
There is also
another connector on the rear of the Monitor which can be used to
turn on a generator automatically once a user set State of Charge
threshold is reached. The State of Charge display is about as
accurate a measure of your batteries’ current energy capacity as you
will get. The more I use it, the more impressed I am.
state of charge