Electrical DIY
March 2008
I have a Dell laptop with a Centrino CPU.
I just close the lid when done using it and it goes into standby mode. I rarely ever turn it off. I do go offline first.
It is running off my 70Ah house battery along with the TV etc.
Laptop is powered through a 150 watt MSW inverter to the laptop power supply. I have a dc laptop power supply but have yet to get around to putting the special Dell plug on it.
Consumption is so reasonable I may not bother.
Watching the ammeter when I am on line, consumption is right on 2 amps. Rarely jumps up to 2.5 amps, mostly when doing the morning virus scan. In standby it is less than a quarter of an amp and that is probably mostly consumed by the inverter.
So, if the computer was in use for 5 hours a day my daily consumption would be about 10 Ah plus about 4 Ah through not bothering to turn off the inverter.
This procedure keeps the laptop battery always fully charged.
If I discharge the laptop battery then the ammeter jumps up to about 7 amps while recharging it, but I rarely do this.
Just a bit more:
TV draws an amp and LEDs bugger all. With no solar I have to put it back. If I drive a bit, no problems, the inverter and charger and alternator handle my consumption just fine. If I am bush camping and my fridge is past the four days of cold storage, the hour a day on the genny keeps me going, charging the fridge and the house battery. I can easily get 20 Ah back in the house battery during this hour. This is a bit more complicated as the genny runs two chargers, one for the house and one for the starters at 24 volts. I have a 24 volt 350 watt MSW inverter off the starters to the house charger, but the charging figure is correct.
I would do better if I can stop falling asleep with the TV on.
More detail below:
240 Volts the Simple Way
There are heaps of regulations, so they might best be avoided along with any permanent 240 volt wiring.
That being said, I have all the 240 volt supply I need, whether connected to mains or to my generator.
My fridge is 240 volts, same with 24 volt and 12 volt battery chargers and I use a 24 volt 350 watt MSW inverter.
Inverter charges the house battery through the 12 volt charger when driving.
It charges from mains or generator in the usual way when stationary.
I use 240 volts for my laptop and modem from this inverter as well.
Wiring is dead simple. Just like plugging in, in the house.
$19 for a 25 meter extension cord from Bunnings goes to a power bar with an RCD plug inside the bus.
From this power bar I plug in the fridge and chargers and another power bar for the laptop feeds off this first one.
My TV system is 12 volts but it can also run on mains power bricks.
Move plugs around to suit the use at the moment.
Complicated switching is not needed.
I also use a shorter extension cord in place of the long one for the generator. I like to keep it close to the side of the bus.
A little planning keeps the extension cord and power bars neat and as out of the way as permanent wiring.
Flipping a switch is more convenient than moving a plug or socket, but it does get complicated in the various modes one uses.
Switching from shore power to generator is as simple as putting the extension cord plug either in the CP GPO or the generator. Same as for permanent wiring. Socket end goes to RCD in the bus, in either case. The plug switching is needed when neither is being used and the inverter is.
Legal inbuilt switches already exist on the chargers, inverter and other appliances. The absence of individual switches for each socket of a power bar is just like those absent in North American house sockets.
If that were an issue, maybe power boards with individual switched sockets are available. Bound to be single pole though, rather than the double pole kind mandated for permanent wiring.
Doing it the hard way with permanent wiring is not only a cost issue. It also involves finding a qualified installer one can trust to know what he is about. No easy matter at times. There is also the continuing problem on 10 amps and 15 amps and cheater cords and the absence of a suitable solution to that 15 amp input socket on the outside wall of the motorhome.
CAUTION
Take due care where the extension cord enters your motorhome. Any possibilitly of contact with the active wire and the metal shell of the motorhome could be lethal. The RCD inside the motorhome will not provide protection in this case.
There are pictures of my choice in chargers at the bottom of this page.
I continue to recommend a cheaper modified sine wave inverter as completely suitable for most applications. I got mine on eBay for forty bucks. Make sure to wire the dc side in well with a suitable fuse close to your battery bank.
One of the ways I have joined wires for years is as follows.
Strip the insulation for about one inch from each piece.
Cross the two pieces at about the centre of the bared wire.
Twist the right end around away from you while twisting the left hand end toward you.
This produces a large area of contact and pulling the wires only tightens the join.
Wrap the join tightly with PVC tape.
For thicker wire make strip sections longer.
I still like wire nuts, but they do not seem to have caught on in Australia yet.
Neither have Robertson screwdrivers.
I imagine that heat shrink tubing would work well with the above join method for a good waterproof join.
I manage to collect a bunch of wire ends with factory crimped eyes and other terminals on them. Using these to join to other wire in place, using the above join method, can produce a quick reliable electrical connection.
As always, looking to adopt the KISS principle and save a buck.
TV ANTENNAS
The Oatley in vertical and horizontal mode. The antenna in the middle is a bin find with the seven buck Oatley amplifier.
Any of the three mount choices shown takes half a minute to put up. The antenna is rotated from inside the bus with hand out window while watching the TV.
Detail of the easy mount switch from horizontal to vertical and flat antenna for storage. The bus in travelling mode with antennas removed and little stub in place to keep the cable connector dry and protected
Click here
for the complete $19 amplified Oatley antenna.
Click here
for the $7 antenna amplifier module from Oatley to be placed on your own antenna.
You also do not need to spend the extra four dollars for the AC plugpack as the stuff runs from 12 volts. Handy if you want the antennas for your house though. I originally tried the Oatley inside in a back bedroom and it worked great clamped to the door.
The two antennas pictured above are set up in exactly the same place. Both are producing perfect pictures in my driveway so comparison is difficult. Both have digital signal strength and quality on all channels in the 80 and 90% range. Full blanking signals on analog as well.
I would prefer to keep my Oatley antenna kit out of the rain, so I bought the $7 module as well. I connected this to an old UHF antenna and sprayed the board with a waterproofer for sticking outside.
I am not about to fork out the bucks for a Wineguard. A comparison here would prove little at this location as the Wineguard would produce a perfect picture as well.
I have tried my Oatley in a range of locations and results are variable as one would expect. It has always been just clipped inside the bus looking out a window, so far.
One test was at the Toowoomba Show Grounds, renowned for it's poor to zero reception.
I was side by side with LaWrie with his Wyneguard on the roof. My Oatley was inside the bus again.
We both watched TV.
LaWrie was getting a better picture than I was.
It would only be fair to compare both in exactly the same place at the same height.
Now that I have constructed the outside rotating mount in the pictures above, we are ready, willing and able for another Wynguard showdown test.
Both of my antennas above are easily rotated for vertical signal and my Oatley worked very well at the St Helens Rally in Tasmania where the signal is vertical. Some others reported getting no reception.
I did recent tests using the strength and quality meter in the bus STB.
The Oatley antenna does better in the fringe areas than the bin find with the Oatley amplifier board.
Signal strength is considerably improved with antenna coax running as straight as possible without tight radius bends. Coax was also bought from Oatley.
Latest TV above and DVD player and STB. The white box is for switching signals from the STB and DVD to the LCD TV. It will have additional switches and sockets for other toys as acquired.
My reversing-rear view and GPS navigation in dash monitor. The monitor, wireless camera system totalled about $140 all up from eBay. The monitor retracts in to the slot above the radio when not required. The shiny box to the left is the radio receiver for the camera in the rear window. Behind the dash is a Redarc 24volt to 12 volt reducer to run this stuff and the MP3 music system. The 10 amp Redarc was $41 on eBay. It will also power a laptop directly on the 12 volts DC for the navigation and mapping software.
My Battery chargers:
Are the two larger ones on the right below. One each for 12V and 24 V with 12A and 6A outputs.
SWITCHMODE DUAL STAGE LEAD ACID BATTERY FLOAT CHARGERS - $99.95 each
The smaller output one on the left is only twenty bucks less so why bother with it?
Hard to find in the Jaycar catalogue so enter 2 stage charger in the search function.
Mine have been running for a year and permanently connected to house and starting batteries. Sometimes switched on for weeks at a time to float the batteries.
I like them and the price is right. I have measured full output close to 12 amps into my house AGM and drop in current is modest until battery is nearly full.
While I was in the Jaycar store buying some of those small DC plugs and sockets to replace the cigarette lighter plugs, I noticed some 2 and 4 gauge battery cable in the cheap bin.
Just the thing I needed for wiring up my house and starting batteries to inverters and chargers.
Now for the eye terminals! Theirs had eyes too small for my needs and at $4.50 a piece I thought a better solution was called for.
Much has been discussed on this forum about the relative advantages of bolt down, crimp and solder terminals for battery cables.
I had some 9.1mm soft copper gas tubing left over from my gas installation. I cut some two inch sections, split these with tin snips and splayed them a bit. One end I flattened for a tab and inserted a little over an inch of either 2 gauge or 4 gauge wire in to the splayed end. Both sizes fit nicely. I squeezed the copper tubing snugly around the copper wire.
Now, I placed the flattened tab on the element of an electric stove to heat up. Resin core wire solder was slowly fed in to the tab end of the copper tube until a solid solder job was achieved for about two thirds of the inserted wire length. I stopped before the solder wicked to the end of the fitting so that the wire would remain flexible at the terminal junction.
The job was neatly finished with the appropriate colour of PVC tape.
Now I can drill the needed size eye in to the tab.
The same procedure should work for the larger 0 and 00 gauge cable with the regular soft half inch copper pipe.
I noticed that the low melt temperature resin core solder was easier to use than other kinds.
The two major objections to soldered terminals on battery cables should have been eliminated. No acidic flux was used to cause corrosion and the wire at the terminal junction remains flexible and solder free. The soft copper from these pipes should not harden and crack.
END
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