Testing and Wiring Battery Systems. Alternative Energy Storage-Part Two:

July 12, 2009 - PRLog -- This is part 2 to our series about Energy storage systems for alternative energy sources, Some pretty significant advances have been made in battery technology that makes homemade solar systems and DIY wind generators more viable for homeowners. This series addresses some of the basic concepts for making your system perform to its maximum potential.

Checking your batteries’ condition
To be accurate, your batteries should be totally “at rest” for at least 3 hours before testing. This means that there have been no drain or charging on the battery for at least that length of time. The best time to check a battery is early morning or late afternoon. The reason is that the temperature is usually fairly stable at those times, which gives you a medium range of accuracy for your testing. Connect a voltmeter across the battery terminals to measure the voltage.
The following table will allow conversion of the voltage readings obtained to an estimate of state of charge. The table is good for batteries at 77·F that have been at rest for 3 hours or more. If the batteries are at a lower temperature you can expect lower voltage readings.
You can see that when your voltage reading is about equal to
the battery "nominal voltage" your battery is about 60% discharged.
Battery State of Charge Voltage Table
 
Percent of Full Charge   12 Volt DC System   24 Volt DC System   48 Volts DC System
100%   12.7   25.4   50.8
90%   12.6   25.2   50.4
80%   12.5   25   50
70%   12.3   24.6   49.2
60%   12.2   24.4   48.8
50%   12.1   24.2   48.4
40%   12.0   24   48
30%   11.8   23.6   47.2
Series Wiring to Accommodate Homemade Solar or
Wind Generator Electric Systems
Series wiring refers to connecting batteries to increase volts, but not amps. If you have two 6 volt batteries rated at 350 amp hours, for example, by connecting the positive terminal of one battery to the negative terminal of the other, then you have series wired the two together. In this case, you now have a 12 volt battery and the rated 350 amps does not change. If you were to series wire four 6 volt batteries in this manner, you'd have 24 volts at 350 amps, and so on.
(SEE PHOTO AT TOP OF ARTICLE)

Parallel Wiring
Parallel wiring refers to connecting batteries to increase amps, but not volts. If you have two 6 volt batteries rated at 350 amp hours, for example, by connecting the positive terminal of one battery to the positive terminal of the other, and the same with the negative terminal, then you have parallel wired the two together. In this case, you now have a 6 volt battery and the rated 350 amps increases to 700 amp hours. If you were to series wire four of these batteries as described above, you'd have 24 volts at 350 amps, and then parallel wire these four to the four other that are in series, then you'd have a 24 volt battery at 700 amps.  

Important Note:
Using these wiring examples it is possible to configure a complete battery bank with  any number of total batteries to achieve the required reserve capacity for a DIY Solar or Wind Generator alternative energy system.
Watch for our next article about the types of batteries to us for homemade solar systems and home alternative energy systems.
(Source) http://diyenergyusa.com

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