Power

Power

All homes need power of some type and in an emergency you may lose gas and electricity and this means you lose most home appliances people take for granted, the most important power source needed is for lighting and various other gas and other fuelled lighting has been described in the previous chapter (fuel).
To get any form of light you need a source of power and most people assume this has to come from a battery and while this can be the case it can also come from kinetic energy or capacitor storage systems, these are fairly rare as these forms of power are in their infancy, but we also have to consider power usage and for lighting this has to be LED lighting due to its high light output with low energy consumption.

Kinetic energy torches are available and they will all be LED torches, but for an emergency you can get a wind up torch which uses capacitor storage to hold electrical energy and these discharge energy over a period of time and this depends upon the storage capacity of the capacitors and the energy consumption of the LED’s. Many will require winding up for 1 minute and will give around 1 hours worth of light, others will differ, but they require nothing but winding up and are a true stand alone unit. Variants of wind up torches are available and these are the wind up lanterns and radios and they are fairly cheap and readily accessible for most people. Variants of capacitor technologies exist which use the same kinetic energy to charge capacitors and instead of pure capacitor storage they add a small battery to the circuit and surplus capacitor power is discharged into the battery to charge it up, this gives instant light without winding it up before use and all they require is a wind up periodically to keep the batteries in a fully charged condition.

Ordinary disposable dry cell torches and lanterns are available but they rely upon a source of batteries to be held in stock and over time batteries deteriorate and this means you may end up with a situation where your torch/lantern works initially and when your batteries flatten you end up with them being replaced by flat or deteriorated batteries which give little or no life.

Rechargeable batteries are fine to a point but they suffer the same issues as ordinary disposable cells in that when they go flat you have no way of charging them unless you have an alternative source of power to charge them, but you may have alternatives as many modern digital chargers have a mains charger OR the capacity to be charged from a 12 volt supply such as a car battery which means you can plug them into a vehicle if you have one and the fuel available to run the engine; or a battery pack, or a green energy supply. Rechargeable devices may also have this capability if they have an internally rechargeable battery.

Building a simple battery pack

Building a simple battery pack is fairly easy if you have a car battery and a battery charger, you can buy a battery box to stand the battery in, or a make a battery box from basic materials such as plywood or similar and its objective is to hold the battery and a series of connectors which attach to the battery for using by plugging appliances into it, and one for charging the battery, having the battery in a box means it can be moved from a garage or workshop and into the home. Build a wooden carcass larger than the battery, ensure one end has room to attach your power plugs and room to cover them, an inverted L shaped end is preferable as you can have the terminals/sockets pointing downwards and covered from the rain and everything plugs in uphill. Use car bulkhead connectors as these screw to the wooden frame and they are cheap and plentiful and you can get the spare metal terminals if yours corrode, and these are all female, buy the male plugs and fit them to your appliances and they simply plug in. Inside the box you wire your battery to an inline fuse and directly to your electrical sockets for fused protection and everything unplugs when not in use and can sit inside your box ready for action, but keep spare fuses inside your battery box.
Ensure your charging plug/socket is different from your supply sockets and that your battery charger has the facility to have the plug fitted to it so you can plug your charger in, and that the wiring is capable of handling the load (charging current) supplied by your charger and do not fuse this circuit as a blown fuse will prevent the battery from charging.

You can fit more than one battery to your battery box but you have to consider the weight and the battery connections, you will have twice the battery capacity and twice the battery working life on a single charge, but it will also take twice as long to recharge. Connecting the batteries together is critical as you always connect them in parallel and this simply means you connect all the + or positive terminals together and all the – negative terminals together to maintain its 12 volt supply, if you connect the - negative pole of the first battery to the + positive of the second battery you will double your output voltage and this will give you 24 volts output at half the current supply and you cannot charge the batteries with a 12 volt battery charger. Consider your options and are you better with two batteries in a single battery box or are you better with two separate batteries in their own individual boxes? If you light your main living area every night then your main or larger battery will be used for this, but if you spend time in the kitchen cooking and eating your second battery can go in here and will last much longer, if you have a house then you may have one battery upstairs instead. Balancing your needs is crucial as you may find that a torch may suffice upstairs instead, or even a wind up lantern may be more appropriate, do your research and find your balance.

Upgrading batteries is easy and the cheapest upgrade is to replace the car batteries with a leisure battery/batteries as used in caravans and motorhomes, these are a slightly different construction to a car battery and can stand for long periods without internally discharging and will instantly charge when required, they can be more heavily discharged than a car battery without internal damage, and they are not much more expensive than a standard car battery.

UPS batteries are even more durable, these are often called different things such as commercial or industrial batteries or even semi traction batteries, and these are of an even heavier construction and can take much larger discharges without damage, but they are also more durable in the fact that they can stand for even longer periods of discharge without damage, and can be charged with higher currents from a lower state of charge but they are also considerably much more expensive.

Understanding Battery Basics

We will only concentrate on lead acid batteries as these are the cheapest and most readily available, they are the easiest to work with for the amateur and take the least understanding.
Batteries are generally rated under the 20 hour system generally, although some smaller batteries are rated under the 40 hour system so what does this mean in simple terms? If you have a battery rated at 100 amp/hour it means it will give 100 amps of output for one hour, in theory, yes, but draw 100 amps from that battery and you will only get the 100 amps for about 2 minutes in reality.
In practical terms you can only get the full 100 amps from the battery by using the duty cycle rating and to do this you use the batteries capacity of 100 amps and divide this by the duty rating of 20 hours, therefore 100  A/H ÷ 20 hour duty cycle = 5, therefore if you draw 5 amps or less from the battery you will get this for 20 hours or the full 100 amps from the battery if you draw less than 5 amps from the battery you will still get the full 100 amps, but for a longer working period. If you draw 3.5 amps from the battery your working life will be extended to 28.5 hours and if you only draw 2 amps from the battery then its working life will be extended to 50 hours.

Battery charging options

Batteries need charging and to do this you use a battery charger, the simplest type is the car battery charger which will self regulate until it is charging at its maximum capacity, when a battery is discharged it will only accept a small charge and this charge is relative to its remaining capacity or state of charge, in simple terms the more a battery is discharged the less charge it will accept. As the state of charge rises the more charge the battery will accept and if you ever charge a battery with a battery charger it will begin by accepting a small charge and this charging current rises as the battery is charged.
Intelligent or switch mode chargers work differently and this is by switching modes as they charge, they produce a small initial charge and they increase this charging current in line with the batteries requirements until they are at full charge and at that point they switch modes again and provide a maintenance charge or trickle charge. All batteries self discharge and as and when a battery self discharges to a point where it will accept more charging current the charger switches back to charging mode at a low level and recharges the battery before switching back to a maintenance charge. Intelligent chargers can be connected to a battery or battery pack and switched on and left on and they maintain a battery in peak charge condition.  

Generators are a viable alternative to provide electricity and to do this you need the fuel to do so and if it is a petrol generator you also need the petrol to run it and its life is determined by the quantity of fuel you have, noise is a factor and in any emergency scenario the noise of a running generator is enough to attract thieves who may steal it and anything else you have. Petrol generators are cheap as many domestic versions exist, but they use huge quantities of petrol for a given time or load and while diesel engined versions are available, they are considerably more expensive while being more economical and allowing the storage of larger quantities of fuel in relative safety without issues. Many generators have a battery charging facility and while in theory this is a useful feature, testing by myself and many others show this feature is useless as they massively over volt a battery and ruin it in a short period of time.

Green energy systems are the only real true stand alone system and these can be wind, solar, or water powered systems if you have the capabilities to afford and install one as they all have benefits and deficiencies as solar is ineffective in many applications, particularly winter, and wind is ineffective on a nice calm day and on days without sufficient wind speed to operate the turbine efficiently. Water power is the most consistent and efficient system as long as you have a water supply which remains constant and you have sufficient head (height) of water to make the system efficient in line with its turbine design, lose water in summer and you lose power.

Wind turbines are the most efficient alternative for actually producing power as we have wind speeds in the UK which regularly exceed the requirements for small wind turbines, but not larger wind turbines, and this could be the best option for most people, and the smallest wind turbines are also the cheapest, but you do need the appropriate ground conditions for them to work which means no obstructions such as tall buildings or trees which affect/impede the wind.
Solar power is less efficient than wind power but it makes up for the wind deficiencies in several areas, mainly that on a sunny day the wind drops to nothing and solar power is more efficient, however; solar is only really effective for a couple of hours a day when the solar panels are in the correct orientation for optimum efficiency to produce significantly useful power outputs.

Deficiencies within both systems have been partially remedied by incorporating both wind and solar power in one unit so you get the benefit of solar on a sunny, wind free day and wind turbine power on an overcast, windy day.

What power do you produce? This is an interesting question as for off grid/emergency scenario using 12 volts is a better option as most solar panels produce upwards of 20 volts and some produce much more, but the energy produced at AC mains voltages cannot be stored, by switching to a DC unit at low voltage you can quickly recharge batteries. Much of this is determined by the charge regulator and using a decent quality regulator is a necessity for many reasons, by using 12 volts you convert more of the available power into current which is actually what does the work and by charging batteries you can charge one while using another and this continuity gives consistent power for lighting at night.    

Water power is by far the most effective and efficient way of providing a constant source of power and as long as you have water running to your turbine you have power, in reality you can build a small water turbine and even if it produces 1 amp of power, it produces it for 24 hours a day and you produce a constant 24 amps of usable power and this can charge multiple batteries.

Now we need to look at power requirements, if you have lighting switched on in one room and this draws 2 amps and you have this switched on from 7 pm to 11 pm you consume 2amps x 4hours or 8 amps of power per night and if you have a kitchen light switched on for 2 hours per night and this draws 1.5 amps of power or 1.5 X 2 it consumes another 3 amps of power giving us a daily power consumption of 11 amps per day, with a 100 amp battery it gives us approximately 9 days of evening lighting. In these 9 days you can reasonably recharge at least one other battery with wind or solar, or combined wind and solar charging and potentially more than one other battery which can be used for charging other items such as cordless drill batteries using the 12 volt charging option, you may have a battery charger for rechargeable batteries which can run from a 12 volt supply, or even lanterns with an internal rechargeable battery with a 12 volt recharging facility.

Basic Mistakes

Many people make some very basic mistakes and while some are obvious to some of us, they are not obvious to everyone, so here goes.

1) If you connect a generator to your fuse box/consumer unit, have you switched it off? If not you will be sending power back into the same supply which is damaged and powering all your neighbours homes and overloading your generator, or totally destroying it.
2) Have you switched off all your domestic appliances? Fridges, freezers, heating systems, televisions, alarm systems, and any other item which is constantly switched on will consume power and you don’t even realise it; switch everything off and unplug it as even a TV or satellite dish consumes power and this increases your generator fuel usage, take nothing for granted.
3) Switch off all unused circuits in your consumer unit and only keep those switched on which are necessary, with no power other than a generator, you only need downstairs lighting and switching off every other circuit means something you have forgotten to switch off will not be consuming power which saves generator fuel.
4) Many people keep a supply of rechargeable batteries and never charge them up, the cost of a digital or intelligent charger is peanuts and get into a routine of charging up all your rechargeable batteries and don’t forget to remove and charge batteries from appliances such as torches or radios as an intelligent charger will top their charge up in very little time so make time and do it regularly.
5) Standardise on batteries as much as possible and keep the same size batteries in as many appliances as possible, AA are the most popular size followed by AAA and most intelligent chargers will charge both types, so keeping them charged and in a convenient location which is easily accessible in light or dark conditions is crucial.
6) Keep a supply of torches in your home and in the event of an emergency everyone can have a torch and teach children only to use them when necessary, it may sound silly but having a couple of wind up lanterns can allow any sheds, workshops or garages to be lit while you work in them after dark, and the cheapest torches are sufficient for most things.

Portable solar power is currently big business and you can get the fixed smaller solar panels designed (allegedly) to charge car batteries by plugging them into the cigarette lighter and placing the solar panel into the dashboard in front of the windscreen, so do they work? In a word no. Most car batteries are 40 A/h upwards and the minimal output from such chargers will do nothing to maintain them due to serious basic errors. Solar panels need standing outside and facing the sun with no shade on any part of the solar panel and simply standing them inside a car is the first problem as most car windscreens are coated to prevent many elements of the sun passing through them and this includes many required to efficiently convert the suns energy to electricity. Most modern house windows also have similar coatings and block the suns output in the same way.
In reality these types of chargers may have some uses and with such low outputs they wouldn’t really touch a car battery; but if you have a rechargeable lantern with a much smaller 2.5 – 4 A/h internal battery then it could actually charge it and become useful.

Study is the key to success here and looking at the internet provides many good ideas, one of the best I have seen recently is a system made from bicycle wheels which are large and using small pieces of drainpipe to collect the wind and turn the bike wheels, this is connected to a small model motor rated at 15 volts. If you connect a small pulley of 1.2” (12mm) diameter to the motor and drive it from an 18” bike wheel; for every full turn of the wheel it will turn the motor shaft at 36 RPM and of the wheel is turning at 50 RPM it will turn the motor at 1800 RPM and this is a useful speed to produce power from very little wind and this is usable power. If you have a simple test or multi meter you can establish the positive and negative terminals at the motor and you can connect this to a simple charging circuit by buying a simple battery charge control circuit for around £2-5 and as long as you can solder wires to your motor and your charge controller you have a battery charger for peanuts and a good project for you to work on with children with visible results. These simple integrated charging circuits may need a heatsink for the charge control chip and many can take 7-30 volts input and convert this to 13.7 – 14.4 volts to charge a battery.

Another simple idea was to use basic plastic water pipe and connect this together and run it downhill with a head or drop of 1 metre, this ran into a simple joint box which was circular and a basic and very simple turbine was made, this was installed into the circular box and fed an outlet pipe and ran into water barrels for water collection. One end of the turbine shaft was connected to a 6 volt electric motor which was bonded to the top of the circular turbine housing and connected to it with a rubber band and drove it, this was connected to a simple LED chip which worked on a DC input of 3.5 – 10 volts and this provided a light for his home, the LED chip cost £1.25p.

Modules and basic battery charging kits are available for charging a range of different battery types including Lead acid (SLA), Ni cad, NiMh, Lithium and Lithium Polymer (LiPo) and a range of other batteries and many come with a range of variable voltage inputs from solar or wind sources, this means one source of power can charge many batteries.

There are many usable ideas out there for producing small quantities of electrical power for lighting or charging 12 volt lead acid batteries and a little basic research can yield some surprising results for simple off grid power.

very useful.
I understand now that there have been major advances in capacitor technology and Tesla cars are now being made with reliance on capacitors instead of batteries.