Distribution Panel
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© 2015 by Roadtrek, Inc.
Battery Voltage Display
Voltage display
In the upper left corner of the distribution panel there is a
battery voltage display. This display shows the voltage across
the battery terminals in a twelve volt configuration (two six volt
batteries in series), NOT the actual state of charge of the
batteries. Fully charged batteries at rest have approximately
12.85 volts; fully discharged batteries have approximately 12.0
volts. HOWEVER, to precisely determine the true charge you
must disconnect all loads and wait a considerable period, a task
more suited to engineering students than to someone camped in
a beautiful spot and enjoying the outdoors. Real-life display
voltages can be anywhere in this range, or above or below it,
depending on load outputs and charging inputs. Gain familiarity
with your system by operating it under various conditions before
attempting to determine battery state of charge by looking at
this meter reading.
Most people run the engine generator until the battery voltage
display is up to a certain voltage, somewhere around 14.0 volts,
because you reach the point of diminishing returns where further
engine generator operation provides little additional charging. Your batteries aren't 100% charged, but it's not worth the
extra fuel to put the last little bit in. Likewise, you will see voltages near or even below 12.0 when running high-amperage
loads such as the air conditioner or microwave with the inverter. As soon as you turn these off, the voltage will rebound to a
reading closer to the true battery voltage. The inverter has a low voltage cutoff with an audible alarm to protect the batteries;
you don't have to monitor voltage constantly, because the system does that for you. If you hear the alarm, start your engine
generator or plug in; otherwise, just use the system as you wish. It will take care of itself.
When your solar panel or the charging portion of the inverter has fully charged the battery bank, it goes from a higher
voltage down to approximately 13.5 volts (up to 14.0 volts at lower battery temperatures) which is the "float" voltage - the
sensors in these components have determined that the batteries are at full charge, and the float voltage is all the power
needed to maintain them at that level. If you stay plugged into shore power, after a few hours your voltage display will show
this float voltage.
