Lead-acid batteries are the most common in PV systems because their initial cost is lower and because they are readily available nearly everywhere in the world. There are many different sizes and designs of lead-acid batteries, but the most important designation is whether they are deep cycle batteries or shallow cycle batteries.
Shallow cycle batteries, like the type used as starting batteries in automobiles, are designed to supply a large amount of current for a short time and stand mild overcharge without losing electrolyte. Unfortunately, they cannot tolerate being deeply discharged. If they are repeatedly discharged more than 20 percent, their life will be very short. These batteries are not a good choice for a PV system.
Deep cycle batteries are designed to be repeatedly discharged by as much as 80 percent of their capacity so they are a good choice for power systems. Even though they are designed to withstand deep cycling, these batteries will have a longer life if the cycles are shallower. All lead-acid batteries will fail prematurely if they are not recharged completely after each cycle. Letting a lead-acid battery stay in a discharged condition for many days at a time will cause sulfation of the positive plate and a permanent loss of capacity.
Sealed deep-cycle lead-acid batteries are maintenance free. They never need watering or an equalization charge. They cannot freeze or spill, so they can be mounted in any position. We especially recommend sealed batteries for remote, unattended power systems, but also for any client who wants the maintenance free feature and doesn't mind the extra cost associated with these batteries. The Concorde PVX series (Sun-Xtender) is an excellent choice.
Sealed Gel Cell (gelled-electrolyte) batteries are relatively maintenance free, however unlike a high quality sealed lead-acid battery like the Concorde PVX extra care must be taken to insure a Gel Cell battery is not charged above 14.1 volts for a 12 volt battery, for example. Over charging a Gel Cell even once for a sustained period can really shorten it's life and even ruin it. Any charge source or charge regulator used must have user adjustable settings for sealed Gel Cell batteries to insure charge voltage does not exceed a safe limit. If your application dictates a sealed, gelled battery the Deka-East Penn MK series is an excellent choice.
ko ne zna engleski .... najbolji su DEEP CYCLE (otvoreni ili zatvoreni) OLOVNI AKUMULATORI
