Bob B- what is "cycled" monthly? Charged monthly? Thanks. Let me reach way back to school..... ------ Wet cell batteries (car batteries and the like) turn two dis-similar metals submerged in acid into electrical energy by a chemical reaction. There are two different types of plates in each cell. They are made up of (1) lead peroxide and (2) sponge lead, which is porous. Each cell creates 1.5 volts and 8 are connected in series to create a total of 12 volts. ------------------ The grids of each of the places is made from cast lead then covered with a paste (like peanut butter) that hardens. One plate is covered with (1) above and alternates with (2) and so on. There are two things that batteries do not like. One is heat, the other is vibration (or pounding). Marine batteries have changed the chemical composition of the elecrolyte (sulfuric acid) to make it thicker. When the "peanut butter" (dried and hardned) flakes off of the grids and wedges between two of the plates, that particular cell has been shorted. This will drain your battery when it sits around (it is a current draw just like leaving the lights on). Those flakes are usually small and each one cannot carry much current- sometimes they do. Too many of those and your battery needs replacement. Pounding around in a boat can cause this. --------------------- Some batteries are designed to be charged up, then used before being recharged (deep cycle). Some batteries cannot stand that sort of treatment. When a battery discharges, it takes electrons from the lead peroxide plate and deposits in onto the sponge lead plate. This causes a chemical change in the lead peroxide, called sulfate. Lead Sulfate is a hard, non-porous material that is non reversible. You may have heard the term "Sulfated battery." Therefore, a automotive battery that is used as a "deep cycle" (boat) battery will become sulfated over time. What that causes is a battery that is 90% or its original storage capacity, or 60% or 20% etc. ----------------- Cranking amps is a measure of how much current (not voltage) your battery is able to supply at one time. This used to be rated in amp/hours. Now they just say cold cranking amps. Actually, A typical car battery can supply, say 300 amps for 20 seconds. By then your car should have started. Most cars start after 2 to 3 seconds of cranking. After too much of that amperage traveling around, the wires heat up, the battery heats up, the plates inside of the cells become depleted. After all of that is over, the sulfuric acid works on the plates to reverse the electron flow you just made. The electrolyte depletes rapidly and needs more help (you will notice that if you wait a few minutes, you can get some more "cranking" out of your "dead" battery. This is because of the chemical reaction-- which takes time). When the engine starts, the alternator recharges your battery by a reverse flow of electrons at about 14.6 volts, thus re-charging your battery. By the way, most outboard motors only charge at about 10 amps. They are not designed to charge your battery. AS stupid as that sounds, they were designed to keep your battery charged. There is a subtle difference there. If you come out to your boat and it is dead, take the battery out and charge it up properly. Unless you are making a 5 hour run, your battery will not be "full." ---------------------- Lets talk "deep cycle batteries." Deep cycle batteries were not made to be completely discharged, like the name implies. "Deep Cycle" was a trade name used by Delco (I think) to sell marine batteries when they first came out. Deep cycle batteries can take more of a drain than an automotive battery can, but not that much. Deep cycle bateries, automotive, and gel cell batteries require different types of chargers to work at peek effeciency. Some chargers are what we used to call trickle chargers, some need rapid charging at firs, then taper down to a trickle, some need to maintain a particular VOLTAGE in order to regulate the AMPERAGE on the charge. Those two terms are many times interchanged by people who are not into electricity, I have found. A cycle is simply going full circle from the charger, through a load (lights on for however long) then back to the charger. ---------------------- Your battery will drain by itself if given enough time. That is why cousin Billy's car in the back yard needs a jump every spring. By the way, jumping a battery only gives it a surface charge (energized plates) but the electrolyte is still neutral. They used to tell us that it takes approx 100 hours (4 days or so)to fully charge a completely dead battery at one amp. When a battery is receiving a charge, it creats heat. Heat is resistance to current flow. This is called internal resistance. Internal resistance is a force acting against the battery charger. The heat will boil the electrolyte, but not FULLY charge the plates. That is why it needs to be done slowly. Rapid, or jump chargers will never FULLY charge a battery, but they will get you up to about 80%. One other thing that comes to mind: A fully charged battery will have strong electrolyte (acid). As the battery discharges, the electrolyte becomes more water, less acid. A discharged battery can actually freeze in cold weather. --------------------------- Anything that limits current flow (voltage drop) will cause your battery to be less than fully charged. Clean battery terminals are part of this. Putting grease on them doesn't help. Grease is a non-conductor. Grease will keep the green crap from growing on the terminal, but it doesn't help the battery. Maintenance helps the battery. "Splash" from a boiling battery that lands on top of the battery can conduct current flow, leading to a discharged (or partially discharged) battery. Pouring water/baking soda on the top, then rinsing with clear water will remove this. ----------------------- So, to make a long story longer.... You can use any battery you want, so long as it meets your requirements, is serviced and stored properly. Some will last longer than others. If you are in a duck boat going 3 miles an hour for 1/2 mile twice a week, I think you can do nicely with any automitive battery, or even a lawn mower battery provided you know your limitiations. I personally would get a gel cell and keep it for years. Others perfer to get a new, cheaper one every year. Its all good. You STILL have a pull-rope, right? ---------------------- I fear I have bored everyone, but that is about all I know about batteries. It's a throw back to my last lifetime. (Master mechanic for General Motors- 14 years). Dave ------------------ For some reason, I can't get spaces between paragraphs (sorry).
