|
T his is my particular set-up utilising a
240VAC > 22V 12A DC power supply to simulate a solar panel.
My own power supply is one I built with components from my "scrap
box" comprising a 200VA transformer, bridge rectifier, filter capacitors and
regulator squeezed into an old computer power supply case complete with
cooling fan. This power supply has two DC outputs, an
unregulated output (22V no load, 16V @ 12A) for battery
charging and a regulated 12V @ 1.5A for the cooling fan and an external relay.
I have set the solar regulator
(Plasmatronics PL20) to limit charge current to 10A.
The
transformer needs to have an output of 16VAC @10A for an input of
230VAC. Transformers with primary and/or secondary taps are a definite
advantage.
Please do not attempt to
build your own power supply or do any work involving 240VAC without the necessary skills and knowledge.
Anything over 50V can be fatal.
There is an off-the-shelf switchmode power supply available that fills
the bill, a Mean Well S-150-15, rated at 15VDC @ 10A and adjustable from 13.5
to 16.5V for $47 from Computronics Corporation Ltd, Phone 08 9470 1177 and
Jaycar Electronics for $109 (or $95 from them if branded Soanar) and yes,
that is their advertised prices.
(It is also possible to modify the circuitry of an old XT computer power
supply. I have modified a couple of these but while they can make a
good power supply, this could and should only be undertaken by a suitably
qualified and experienced person.)
I use an external 12V 30A
changeover relay driven from the power supply 12V output. The
changeover switch in the diagram above is the relay contacts.
When the relay is not operated (240V off), the solar panel neg is
connected to the PL20, when the relay is operated (240V on), the solar panel
neg is disconnected and the power supply neg is connected.
However, it is often not
necessary to do this.
If the solar panel has a
blocking diode fitted, it may not need the solar panel to be disconnected
while the battery charger is on. However, in case of a
fault, I like only one source supplying the regulator, also when I run the
Honda generator, this is the point where I can connect the nominal 12VDC from the
generator although usually, now that I have recently fitted a Shore
Power/Generator changeover switch, I power the battery charger directly from
the generator 240V output.
A cheap 5 Amp
(or higher) battery charger
may be a suitable power supply also and may be the best and cheapest solution
for those not willing or able to build their own.
Please note that a solar
regulator usually operates with a ripple free DC supply (a solar panel)
whereas a linear AC>DC supply will often have a high ripple content.
My own supply has a very high ripple content at maximum output but this has
not been detrimental to the regulator nor did I expect it to be.
The previously mentioned Mean Well S-150-15, typical of switchmode supplies,
in this case has low ripple of 100mV p-p at 10A o/p for 230VAC i/p.
A switch mode supply may be advisable for gel and AGM batteries however, since
there is some evidence from one particular USA battery manufacturer that high levels of ripple at frequencies below 250 Hz
where a battery is continuously cycling (charging and discharging) may
have a adverse affect on VRLA battery life. (Switch mode supplies have very
low ripple and at frequencies around 25 Khz whereas linear supplies have comparatively
higher levels and at 100 Hz because it is much more difficult to filter out at
the lower frequency.)
This setup has been in service
since 2000 and with the same battery - a Trojan flooded (wet) battery and performance and
reliability is excellent.
It has completely solved the problem of how to fully
and quickly charge the house battery while on the move as well as
correctly maintaining the battery the rest of the year while the caravan is
not in use.
See a
recently added diagram on the Battery & 3-Way Fridge Problems
page for an explanation of my overall set up and how I charge the caravan battery
while mobile. This shows a simple arrangement and easily implemented,
unlike the somewhat more complicated setup shown below.
In response to numerous emails over the last couple of years, I have finally
decided to include this block diagram below of my system.
This is a block diagram intended to give an overview only, it is not a wiring
diagram nor does it show all components such as fuses and circuit breakers
etc.
This
diagram has been on this page for a couple of years now and I have
received many emails, mostly ones asking for more details, some for a
wiring diagram and some pointing out "errors".
The most common "error" is, I have missed out a wire between
"X" and "Y". I can only repeat myself,
this is a block diagram NOT a wiring diagram, there are hundreds of
wires missing if it were a wiring diagram.
Another that has cropped up a couple of times is,
"You are using the battery to drive the
inverter to run the fridge, why would you want to do that ?"
The answer is I wouldn't and I don't. When I am stopped I
may select the inverter to run off of the battery to operate whatever in
the caravan that needs 240V but as soon as I stop I will have switched
the fridge to gas.
It's a bit like asking a car manufacturer,
"look, you can run the headlights with the
engine switched off, why would you want to do that ?"
Another frequent one queried the vehicle supply.
This diagram is intended to show the general arrangement only,
certainly not every nut, bolt and wire.
In this case it does not show any detail of the vehicle wiring which is
not simply a direct connection to the battery. That is a
subject in itself that I may cover soon.
I am happy to answer questions seeking general information but please
don't email me with requests to provide detailed wiring
diagrams. I have included this diagram for the sole
purpose of describing my particular system and a full wiring diagram
is not needed to achieve that.
I don't want to offend anyone but if you want a similar system and
need that sort of info, you should contract the services of someone
qualified and experienced in this field to do that work for
you.
If
you are contemplating anything similar, this
is not a project for the novice, it must only be undertaken by
a suitably qualified person.
All I am doing here is showing my electrical system, I am not
trying influence you to do the same, if you do, you do so
completely at you own risk and accept all consequences. |
All parts of the
circuit carrying 240VAC, switching components (must be double pole),
inlet socket, cabling, every component associated with 240VAC must be
certified and labeled for 240VAC operation and of suitable current
rating.
* See a simple arrangement on my Battery & 3-Way Fridge Problems
page *
|
|
