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Electricity

Electricity

Electricity is not really something we can live without these days.

I am lucky that 12 volt electronics seems to come very naturally to me. I understand how direct current power works very well. I recall getting an A+ in the science subject at high school when I pointed out to a teacher that his answer to an exam question was wrong because his circuit diagram actually showed two separate circuits rather than one and that due to the positioning of the resistors and volt meter the answer to the question would not be what he said it was. I can still recall the look of comprehension on his face as he understood my point of view and realised he'd have to re-mark all of the exams again. Having said that, I'm not an electrical engineer, so be sure to check my advice before you go about following it.

If you are literally just doing really basic living in a car at the survival level you probably can make do with the car's interior lights and the power from the cigarette lighter. However, a car battery is not designed to be used in this manner. If you discharge your battery too often, it becomes less effective, and will loose its ability to hold charge. Replacing the battery will cost you more than it costs to set up some better alternative methods of using electricity.

Very cheap methods of power use.

If you are flat broke but need to use electricity in your car / van then I recommend at the minimum you buy a cut out switch. These cut off the power to loads (such as light, TV, whatever) when the battery reaches a specific low voltage. These can usually be brought on eBay and from automotive stores. Here in Australia, Super-Cheap Auto sell one for about $25-30. It plugs into a cigarette lighter and has a cigarette lighter plug that you can plug things into. It is not ideal, and will still damage you car battery in the long run, but it is a good starting point.

Battery starter pack. You can also buy these at automotive stores. They are usually a big yellow plastic box with big thick jumper leads attached. Most also have a light and cigarette lighter outlet installed. The better ones have a volt meter installed as well. You can plug these into your car cigarette lighter and they charge up while you drive. They are designed to jump start your car in an emergency. They can be used as a second battery to draw power from to your electrical appliances. The advantage of these are that they will not flatten your starter battery. However you can flatten the battery in these units. They typically use a car battery, so you have to treat them carefully. They need to be fully charged after use. They generally will not like it if you use them and then leave them discharged over night for example. They would be good though for using power say in the morning before you drive to work, then for a little power use at night, say for lights and radio only.

A typical upper range jump starter pack. This one has an air compressor too.

Dual battery set up.

This is your best option. Your car battery is pretty expensive. In Australia you are looking at about $113-$145 for a typical car battery at 2007 prices. That's not money that even people with a job can afford to fork out regularly. Flattening you battery will kill it. Leaving it flat for long periods of time will kill it even faster. You just can not afford to flatten your battery. You need it to keep your car going. Oh you could park on hills, roll start your car every time your battery goes flat and then fork out even more for a new clutch when that goes. It is far better to get a secondary battery. This and the porta loo are two of the most important buys if you are considering living in your car.

A typical arrangement with a dual battery system is that you have a main battery which is connected to a second battery via an automatic solenoid. The main battery is used for starting your car only. The second battery is used for your electrical appliances. Typically when your main battery reaches a specific charging level (normally 13.6 or 12.6 volts) indicating it is fully charged, the automatic solenoid trips, allowing the secondary battery to charge. When the main battery drops below a certain level (normally 12.6 or 11.8 volts) the solenoid trips again disconnecting the two to prevent the main battery from becoming flat. The two main cost elements for a system like this to be set up is the secondary battery and the charging solenoid.

I have a comprehensive guide on how to wire up a dual battery system here.

If you can't afford to buy a battery isolator you can get away with wiring in a manual cut off switch. Using thick cable and a heavy duty switch you can manually divert power to a secondary battery. You can then wire a cigarette style power outlet to your car battery. You have to remember to turn the switch on to charge the battery when you are driving, and off when your car's motor is not running. If you can keep on doing that you should be fine. But sooner or later you may forget.

Inverter.

An inverter is a device that allows you to produce mains voltage from 12 volts. I could go into the theory of how they work, but well it is complicated and truth is, you don't really need to know. Suffice to say, the thing produces 240 volts from 12 volts, or, if you buy one in America, it will produce 110 volts from 12 volts. There are some relevant points to buying an inverter:

Picture of the 240 volt TV plugged in to the inverter at top right Note the green light on the inverter

Charging electrical devices.

As fine as a dual battery system and inverter is, I realise it is beyond the reach of many people. You can charge your cell phone, laptop or other devices with batteries in them many locations. Libraries, bus terminals, airports, even some fast food restaurants will let you plug in your phone or lap top if you can look the part of a worker. If you pop in reasonably regularly to buy breakfast you can usually get away with charging up your lap top. This is particularly so of places that have Wifi, wireless Internet.

If you can locate an outside power point that is particularly useful as long as you don't get caught using it. I know of one guy who found one of all places on a billboard beside a highway. He used to regularly pull up behind that billboard, plug in and charge his batteries on all of his appliances. At least once a week he would do it, plugging in for about an hour and a half then unplugging the cord and camping a bit further up the road. Eventually he got a job servicing those bill boards and could plug into dozens around his town.

Solar power.

Solar power sounds great. Free power from the sun. Wonderful. Only, it's not quite free.

I have a great solar power set up on my camper van which produces enough power to power a 12 volt fridge, a small TV, laptop computer, my water pump and some lights. Only not all at once, and not all day. My system cost me around $3000 all up. The main components of that are:

Getting a professional in to wire such a system would have been a lot more expensive.

Solar panels on the roof of my campervan. Two Unisolars, a Suntech and at the left a small 15 watt panel.

I don't recommend you take the path I have unless you plan to live in a camper or a van for a long period of time. Most people won't notice a bunch of solar panels on the roof of any van that they can't see the roof of. So if you can't see the roof of your van while standing beside it on a side walk, then neither can most other people. A solar panel on a car just looks out of place though.

That is not to say they don't have their place. You can buy small solar panels that are intended to trickle charge your car battery. I have one for a car I own but rarely drive. These cost about $22-30 in Australia. They won't charge your battery in a few hours though. For that you need a larger solar panel, such as a 15 watt one. This can generally be plugged straight into your battery using the supplied clamps. If you are not using much or any power from your car though these should be unplugged as they will over charge your car battery and cause damage to it.

A 15 watt solar panel can produce enough power to allow you to run a single light, a radio / Mp3 player and a small 12 volt LCD TV for a few hours each day. The TV would use the most power. If you use the TV less the lights and radio will last a lot longer. If you are in a sunny area you could probably run an incandescent car interior light all night from the charge provided by the 15 watt panel. It should be noted that a LCD television uses a lot less power than a conventional television so don't expect to be running a conventional television for hours on end off of one of these small panels.

These cost about $140 to $180 depending on where you buy it from. You can buy these on eBay but having checked eBay around January to March 2007 I can see that the sellers are charging about $45 for postage on these. If you run your car for about half an hour each day your alternator will produce a lot more power than one of these solar panels can. The advantage of a solar panel though is that it will produce electricity silently, at a reasonably steady rate, and that once you have paid for the solar panel, the electricity is free.

One negative about using solar panels is that you have to park your car in the sun for them to work. You can mount the panel on a removable rack if you like but moving it each time you come and go is a pain. Also solar panels are expensive, so people have been known to steal unattended ones. If you live rurally then a removable solar panel is a good option.

Generator.

A generator is the only guaranteed way of producing electricity. Shade and gloomy weather can reduce the output of solar panels. No wind can stop the output from a wind turbine. A small petrol generator will produce power when you want it provided it is well maintained. There are all sorts of quiet ones available now. I have found though that the quieter they are, the more you can expect to pay for them. A basic little 750 to 850 watt generator can be purchased for about $125-$135 at places like hard ware stores. It will be made in China or some other country but most have a 1 year guarantee. For $200 you get the generator and probably more than enough fuel to run it for as much as you will need to run it in a year.

The trick with generators is not to run them all the time. Run them when you need the power and store power in deep cycle batteries. Run things like your TV, fridge when the generator is running, then when you have run it for a couple of hours shut it and the fridge down and use power from your batteries.

One important note. You pretty much can not run many appliances. With high power demand from a generator. Forget running a washing machine, microwave oven and most heaters from a generator. My former next door neighbors went camping and for some reason they took their microwave oven and a generator with them. They fired up the generator, plugged in the microwave, switched on the power to the microwave oven and watched both the oven and the generator blow up. The microwave truly blew up in a shower of sparks while the generator fizzled a bit, blew a fuse and had to be switched off and the fuse replaced. The microwave was useless after that.

12 volt appliances.

There are all sorts of 12 volt appliances. One thing to keep in mind though is that anything that is designed to produce heat, to make things cool or to run a motor will use a lot of power. You can pretty much forget about running a microwave oven or electric hot plate from a car or van's electrical system. Microwave ovens chew power at a phenomenal rate. Even if I did fork out the massive cost of a high wattage inverter to convert my 12 volt to 240 volt, a microwave oven would drain my batteries in a matter of minutes. And these are not standard car batteries, they are heavy duty deep cycle batteries. Similarly a fan heater would require an expensive inverter and would drain my batteries as well.

Good things to use off of a 12 volt battery are:

In a forum I use, one person posted the following. It was an intelligent question to ask, and a common one from many people:

Can anyone tell me how I can figure out what size panels I will need to keep my system up and running without needing to connect to any outside power source? I am thinking of:

Clearly they not be able to achieve what they want to do in a van. I estimate that their power needs will require about 2400 watts of power to run your needs, provided they did not run the air con continually. Even a large bus would have problems mounting 2400 watts of solar panels on it's roof. Even if you use 120 watt modules, that's still 20 panels.

But there are many things you can do to reduce your electrical needs. First, everything that cools or heats uses lots of power. Heating and cooking should be done using gas. LPG if you can. Your stove is much better off being a small gas powered stove, professionally installed of course with the gas bottle outside of the van, or in an internal compartment vented to the outside of the van. Your hot water service should also be gas.

Those on demand hot water services flash boil water (or use a similar process) that will use almost as much power as a microwave oven. Microwave ovens use a huge amount of power. I have 200 amp hours of power storage in good quality deep cycle batteries. That’s enough to run my 12 volt fridge for about 10-12 hours before cutting off. But it would not run a microwave oven for more than 10 minutes, even small runs would only run for about 7 minutes. So use gas for heating.

For cooling, park in the shade, open windows, use a small 12 volt truckies fan. Or, use a lot of cool water. Or, visit places that have air con, like libraries. Cooling is a pain in vehicles. If you get desperate, buy ice or pull into a caravan park and plug in a caravan aircon unit that you can roof mount.

Car stereo and radio will be fine. Typically they are not large consumers of power. They will happily run all day on less power than your headlights use.

Fluorescent lights also don’t use a huge amount of power except when starting. LED lights use heaps less and have finally started to come down in price to where it does make sense to buy them.

A laptop will use about 20-30 watts of power per hour although high end ones may use up to 50 watts an hour.

I estimate that a system that will run a typical laptop for 4 hours a day, a radio and LED or fluro lights for 4 hours a day and a small 34 cm/13 inch TV for 1 hour a day via a 500 watt inverter will require between 80 and 120 watts of solar panels and only 120 amp hours storage battery. I have done a lot of work sizing small solar power systems, so his is about it. This of course is for a sunny area like most of Australia, and southern USA. LED lights will allow you to run them longer. An LCD TV will use less power than a cathode ray tube TV (and is healthier for you) Also, a dual battery system will allow you to argument your power by running the vehicle engine.