The links below are on this page - you can also just scroll down if you want to read them all.

This entire page is copyright 1998-2014 by Northern Arizona Wind & Sun. Please do not use without prior permission.

• What is a Battery?
• Types of Batteries
• Battery Lifespan
• Starting, Marine, or Deep Cycle?
• Deep Cycle Battery as a Starting Battery?
• What Batteries are made of
• Industrial Deep Cycle Batteries (fork lift type)
• Sealed Batteries
• Battery Size Codes
• Gel Cells (Gelled Electrolyte) (and why we don't like them)
• AGM Batteries (and why we do like them)
• Temperature Effects
• Cycles vs Lifespan
• Amp-Hours - what are they?
• Battery Voltages
• Battery Charging (Here is where we get into the real meat)
• Charge Controllers (for wind/solar)
• Mini Factoids - Some small facts about batteries

The subject of batteries could take up many pages. All we have room for here is a basic overview of batteries commonly used with photovoltaic power systems. These are nearly all various variations of Lead-Acid batteries. For a very brief discussion on the advantages and disadvantages of these and other types of batteries, such as NiCad, NiFe (Nickel-Iron), etc. go to our Batteries for Deep Cycle Applications page. These are sometimes referred to as "deep discharge" or "deep cell" batteries. The correct term is deep cycle.

A printable version of this page will be available in Adobe PDF format when we finish updating this page for downloading and printing: Most of the charts have small images for faster downloading. To see the full size picture, just click on the small one.

Battery History

Although Alessandro Volta in Italy is usually credited with being the inventor of the modern battery (Silver-Zinc), ancient cells have been discovered in Sumerian ruins, origin around 250 BC.

The first evidence of batteries comes from archaeological digs in Baghdad, Iraq. This first "battery" was dated to around 250 B.C. and may have been used in simple operations to electroplate objects with a thin layer of metal, much like the process used now to plate inexpensive gold and silver jewelry. Possibly one of the first uses for batteries, although there is some dispute among scholars. Wikipedia entry for Baghdad Battery.

Batteries were re-discovered much later by Alessandro Volta after which the unit of electrical potential was named, the volt. The jar was found in Khujut Rabu just outside Baghdad and is composed of a clay jar with a stopper made of asphalt. Sticking through the asphalt is an iron rod surrounded by a copper cylinder. When filled with vinegar - or any other electrolytic solution - the jar produces about 1.1 volts.

What is a Battery?

A battery, in concept, can be any device that stores energy for later use. A rock, pushed to the top of a hill, can be considered a kind of battery, since the energy used to push it up the hill (chemical energy, from muscles or combustion engines) is converted and stored as potential kinetic energy at the top of the hill. Later, that energy is released as kinetic and thermal energy when the rock rolls down the hill. Not real practical for everyday use though.

Common use of the word, "battery" in electrical terms, is limited to an electrochemical device that converts chemical energy into electricity, by a galvanic cell. A galvanic cell is a fairly simple device consisting of two electrodes of different metals or metal compounds (an anode and a cathode) and an electrolyte (usually acid, but some are alkaline) solution. A "Battery" is two or more of those cells in series, although many types of single cells are usually referred to as batteries - such as flashlight batteries.

As noted above, a battery is an electrical storage device. Batteries do not make electricity, they store it, just as a water tank stores water for future use. As chemicals in the battery change, electrical energy is stored or released. In rechargeable batteries this process can be repeated many times. Batteries are not 100% efficient - some energy is lost as heat and chemical reactions when charging and discharging. If you use 1000 watts from a battery, it might take 1050 or 1250 watts or more to fully recharge it.