Home' Afloat : AFLOAT February 2014 Contents 48 AFLOAT.com.au February 2014
cool or warm white
• G4 back or sidepin:
8 SMD $15.00
10 SMD $20.00
15 SMD $25.00
• Festoon 37mm or 42mm
6 SMD $15.00
MR11- 6 SMD $15.00
MR16-15 SMD $25.00
• BAY15D Tower
18 SMD $35.00
For full details see our website
11 Babbage Rd, E-Roseville NSW 2069
Tel: 02 9417 8455
Fax 02 9417 8423
by Kurt Küpper*
*Kurt Küpper is director of Aquavolt Electric Boat
Parts. Tel: 02 9417 8455 www.aquavolt.com.au
Oncea decision to fit solar panels
has been taken and the size of the
panels determined, consideration
must be given to regulation of the charge
from the panel(s).
Solar regulators are relatively small
solid state devices that control the amount
of energy that feeds the battery from the
solar panel, by sensing the battery status.
Most now are microprocessor controlled so
that they can monitor system parameters
and give an accurate picture of battery
condition and charging requirements.
They are connected between the solar
panel and batteries.
Solar panels typically produce charge
at about 17V. This is too high for battery
charging and can damage the batteries,
so the regulator (also called a controller)
must reduce the charging voltage. Once
the battery is fully charged, continued
charging at this level would also cause
damage, so the regulator must also
sense when this has occurred and stop
feeding further charge to the batteries.
Overcharging will lead to battery gassing,
loss of electrolyte and overheating.
To determine the required rating of
the regulator, divide the total rating of the
panels (in Watts) by 17V. This will yield the
current (Ampere) rating of the regulator.
The regulator must be oversized by at least
a third, but if more panels may be added
at a later stage, doubling the required
capacity is recommended.
If the panels are small relative to the
battery size, it is possible to do without
a regulator. As a rule of thumb, if the
charging current is less than 1% of the Ah
rating of the batteries, a regulator is not
essential. However, regulators are cheap
compared to the cost of batteries, so it is
recommended to always fit a regulator.
Most regulators incorporate diodes that
prevent a reverse flow of charge to the
panels at night.
The better regulators allow selection
of the charging voltage appropriate to
the battery technology being used, i.e.
flooded, AGM, Gel etc.
Some regulators have a load circuit
onto which the loads can be connected.
Often this circuit will have a protection
circuit which shuts down the loads when
battery voltage falls below a set minimum.
On some regulators this circuit is one that
only turns on when there is no current
being fed in from the panels, i.e. it is
effectively a photo sensitive switch that
can be used to turn on lights at night. It
must be noted that the total output of this
circuit is limited to the rated output of the
regulator, which makes it quite unsuitable
for most boat applications.
Under no circumstances can starter,
inverter, winch or thruster circuits be
connected to load terminals. It is not
recommended to use the load circuit on
Most regulators have at least LED
indicators that give an indication of the
current state of charge of the battery. More
sophisticated models have LCD displays
that will indicate battery voltage, Ah
collected/day and Ah used/day.
Some will let you know whether the
charge cycle is in bulk, absorption or float
status, and can store historical data to
enable you to log system performance.
It must be noted that the battery Ah
monitoring function will only be accurate if
all loads are connected to the load circuit
of the regulator. As this is impractical for
most boats, a stand-alone battery monitor
is required for proper battery monitoring. If
that has been fitted, a controller with just
LED indicator lights is adequate.
Some controllers are supplied with
an external battery temperature sensor,
allowing the controller to adjust the
charging voltage to suit thermal conditions
to achieve optimal charging.
A more recent development is the
Maximum Power Point Tracking controller.
This has the ability to vary the charging
voltage. When the battery voltage is very
low, a lower charging voltage will suffice
for the batteries to accept charge.
This means that the available power
can be more efficiently employed, i.e. the
charging current will be higher than with
a fixed voltage controller. As the battery
comes close to being charged, the charging
voltage is increased to force the last charge
into the battery, albeit at a lower current.
An MPPT controller can typically increase
charging from the same solar panel by
about 15% .
A few regulators have a feature
where two batteries can be controlled
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