Generating low voltage

Generating low voltage

is one component of a possible alternate energy system. the use of a low voltage charger is economical. the system will be cheaper than pv (solar cell), and wind power, including the price of fuel and maintenance over a ten year period.

car alternators are a good source for cheap low voltage d.c. power. they are available in outputs up to around 200 amperes. the alternator rotor, usually turned by the engine can also be operated by a gas, diesel or propane motor. ratings between 3.5 horse power to 8 horse power will operate an alternator to its full rated output.

lawn mowers and other similar motors are good sources. the motor must be sized to the alternator that you wish to us. a 3.5 horse power motor goes well with a 35 ampere alternator. a 5 horse power engine matches well with alternators rated at between 50-75 amperes and an 8 horse power engine should be used with alternators rated over 125 amperes.

prices vary depending on the rating, and where you purchase it. rebuilt units cost much less and one in good condition and a reasonable ampere output can be had for around $100.00. an alternator is defined as a mechanically powered current amplifier. it produces 3 phase a.c. power internally when turned between 3,000-6,000 r.p.m.s. the diodes, usually mounted in the case, convert the a.c. current to d.c.

the unit also has to be sized to the batteries that you intend to use . it must be able to deliver a sufficient rate of current to ensure proper charging. the output must be regulated to prevent overcharging and possible damage.

note: you need to add a switch between the negative battery terminal and the alternator, if you don't the motor will have problems starting. only use a high ampere swich such as those from cars or trucks. just make sure that the switch can handle the current draw of your application.

automobile regulators will not work properly in this application and should not be considered. next time we will provide you with schematics for protecting your batteries.

the low voltage output of the alternator can be used to power 12 vdc appliances, lighting and d.c. power equipment. if you add an inverter to the system you will be able to power some 120 vac appliances and you will have basically made a generator for a fraction of the price of a factory unit.

make sure to take all 12 vdc. power through the inverter rather than directly from the batteries as this will result in differences between cells and will greatly reduce the life of your batteries.

all components of any alternate energy system must be sized to function efficiently. in future articles we will cover all the different factors necessary to put together power systems that you can be proud off.