![]() Types of Batteriesīatteries are divided in two ways, by application (what they are used for) and construction (how they are built). NiCads, Nickel-Iron, and other types are found in a few systems, but are not common due to their expense, environmental hazards, and/or poor efficiency. They all use the same chemistry, although the actual construction of the plates, etc varies. This includes the standard flooded batteries, gelled, and sealed AGM. In the past they were often used by railroads as backup power, but nearly all have now changed over to newer types.Īn important fact is that ALL of the batteries commonly used in deep cycle applications are Lead-Acid. It appears that the only current source for new cells seems to be from Hungary. Many inverters and charge controls have a hard time with them. Another problem is that they are very inefficient - you lose anywhere from 30 to 40% in heat just by charging and discharging them. One major disadvantage is that there is a large voltage difference between the fully charged and discharged state. We have had almost no direct experience with the NiFe (alkaline) batteries, but from what we have learned from others we do not not recommend them. They are expensive to buy and very expensive to dispose of due to the hazardous nature of Cadmium. ![]() A few systems use NiCad, but we do not recommend them except in cases where extremely cold temperatures (-50 F or less) are common. Even after over a century of use, they still offer the best price to power ratio. Practically all batteries used in PV and all but the smallest backup systems are Lead-Acid type batteries. ![]() True deep cycle AGM's (such as Concorde) can approach 98% under optimum conditions, but those conditions are seldom found so you should figure as a general rule about a 10% to 20% total power loss when sizing batteries and battery banks. Typical efficiency in a lead-acid battery is 85-95%, in alkaline and NiCad battery it is about 65%. Much of this loss of efficiency is due to higher internal resistance at higher amperage rates - internal resistance is not a constant - kind of like "the more you push, the more it pushes back". A battery rated at 180 amp-hours over 6 hours might be rated at 220 AH at the 20-hour rate, and 260 AH at the 48-hour rate. Slower charging and discharging rates are more efficient. There is a good explanation and demonstration of Internal Resistance here. The lower the internal resistance, the better. This is converted to heat, which is why batteries get warm when being charged up. Part - or most - of the loss in charging and discharging batteries is due to internal resistance. If you use 1000 watts from a battery, it might take 1050 or 1250 watts or more to fully recharge it. Batteries are not 100% efficient - some energy is lost as heat and chemical reactions when charging and discharging. In rechargeable batteries, this process can be repeated many times. As chemicals in the battery change, electrical energy is stored or released. Batteries do not make electricity, they store it, just as a water tank stores water for future use. What is a Battery?Ī battery is an electrical storage device. To see the full size picture, just click on the small one. The correct term is deep cycle.Ī 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. ![]() These are sometimes referred to as "deep discharge" or "deep cell" batteries. go to our Batteries for Deep Cycle Applications page. For a very brief discussion on the advantages and disadvantages of these and other types of batteries, such as NiCad, NiFe (Nickel-Iron), etc. These are nearly all various variations of Lead-Acid batteries. All we have room for here is a basic overview of batteries commonly used in photovoltaic power systems. The subject of batteries could take up many pages. Mini Factoids - Some small facts about batteries.Battery Charging (Here is where we get into the real meat).AGM Batteries (and why we do like them).Gel Cells (Gelled Electrolyte) (and why we don't like them).Industrial Deep Cycle Batteries (forklift type).Deep Cycle Battery as a Starting Battery?.Please do not use without prior permission. This entire page is copyright 1998-2014 by Northern Arizona Wind & Sun. The links below are on this page - you can also just scroll down if you want to read them all. Pump Installation Equipment & Accessories.Solar Pump Installation Equipment & Accessories.Solar Pump Controllers & Current Boosters.
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