For years I've read articles, forums, newsgroups, etc about batteries and most people have no idea what they are talking about. :facepalm: Mind you, I said MOST...not ALL. There are a couple of people who understand the differences between batteries and they do their best to educate the rest of the battery using world, only to be followed by someone who spouts off with more mis-information. 
I've used all kinds of batteries in my line of work. This includes use in the solar industry all the way up to running high voltage DC pumps in a power plant. I've spec'd batteries and I've used batteries...all types and sizes!
Now I wasn't born with this great knowledge of batteries; I asked the experts...the people who actually BUILD them! I'm not going to get into chemistry...let's keep this simple! I hope you find this educational and fun!
BATTERIES 101:
There are basically three TYPES of batteries used in automotive/marine applications...
1. Starting
2. Marine (hybrid) (IT IS NOT A DEEP CYCLE BATTERY!!!)
3. Deep Cycle
1. A Starting battery has one job; to start an engine! In order to do this, it must provide a huge amount of current for a short period of time. Once the engine is running, the generator/alternator takes over the electrical demands of the vessel AND recharges the battery. Crank an engine more than 30-seconds and the starting battery will begin to die. They are usually rated in Cold Cranking Amps (CCA)
2. A Marine (hybrid) battery has TWO jobs! It needs to have enough current to start an engine, and enough CAPACITY to run lights when at anchor or tied to the dock. Have you ever noticed that boat engine crank SLOWER than car engines? Its not the starter....its the battery! Again, once the engine is running, the generator/alternator takes over the electrical demands of the vessel AND recharges the battery. But once the engine is off, the Marine battery needs to power the lights and electronics on board. These are listed with both a CCA and a Amp/Hr ratings.
3. A Deep Cycle battery provides a little amount of current for a LONG time! Deep Cycle batteries are not designed to start a vehicle and most CAN'T! They will power your lights, troll motor, radios, fish finders, and 12V blenders for a lot longer than a starting or marine battery will! These are rated in Amp/Hr. No need for CCA!
So what's the difference between the three?! It all comes down to the internal construction of the cells! Each cell think, compartment) on a battery is good for 2-volts. 12-volt batteries have six cells, and 6-volt batteries has three cells. You connect these cells in series and you increase your voltage by 2-volts each time. Inside these 2-volt cells you have PLATES! (Again, I'm not going to get technical on the chemistry!) You can have a lot of plates or just a few plates. These plates can be thick or thin. The THICKER the plates, the more CAPACITY they have, and the more room they take up! The thinner the plates, the less capacity they have, but you can stuff more in a single cell. Are you with me so far?!
Starting battery cells have a LOT of THIN plates in order to produce MORE CURRENT! But these thin plates run out of juice pretty fast!
Deep Cycle battery cells have only a few plates, but they are THICK and therefor takes a lot longer to discharge. Since you only have a few plates, you can't produce the high amount of current needed to start an engine.
Marine battery cells are thicker than starting batteries, but thinner than true deep cycle batteries; this is why they are called a HYBRID battery! They are just thin enough to squeeze enough in a cell to produce the needed CURRENT to start your engine...and just thick enough to give you some reserve capacity to run your lights etc.
That's all you need to know about the three different types of batteries! What is best for your application is up to you to decide. More on this in a minute! I want to talk about SIZE first!
SIZE MATTERS!
Actually, it doesn't...according to my wife! But I digress... Batteries are sized by GROUP. Again, I'm not going to go in to all kinds of details here. The BCI Group Number will give a physical size and type/placement of the battery post. The higher the Group # the larger the battery (basically). The larger the battery, the more juice you have...but it also weighs more too!
Quick story! A solar powered traffic control company sold trailers equipped with Group 4-D batteries! Whew those babies were big! They sure looked impressive! They are used in big rig trucks and farm equipment. You could even order 8-D batteries for "more power"! Bull! These big impressive batteries were designed to start diesel trucks and not power halogen or LED lights and be recharged by solar panels! Wrong battery for the wrong application!!! Needless to say, they didn't last long and had to be recharged by use of a battery charger OFTEN! FAIL! :facepalm:
Run the biggest battery you can fit, especially if using a Marine or Deep Cycle battery! Make sure they have the right posts for your application. If you have a group 24 and a Group 27 will fit, get the 27 (unless its just a starting battery)! If you can squeeze a Group 31 in there, go for the 31! That's enough about size!
DEEP CYCLE BATTERIES:
A TRUE DEEP CYCLE BATTERY is usually 6-volts! Yes, they make 12V deep cycle batteries, but they still don't have the capacity of a 6-volt battery! I know, you need 12-volts...so buy TWO 6-volt batteries and hook them up in series! The RV industry has been doing this for YEARS! They'll sell you a new RV with a single 12V to keep the price down. But you learn quick that it doesn't last very long. They are more than happy to sell you two 6V batteries! Again, don't buy two 12V batteries and hook them up in parallel...buy two 6V and hook them up in series! Trust me on this!
Not everyone needs deep cycle batteries on their boat! If you have a house boat...then YES! If you troll...YES! If you have a competition ski boat and the engine is always running, then a starting battery is fine! If you like to float around and listen to tunes for a little bit, then a Marine battery is your flavor. If you are going to run two batteries, get one for starting and one for your electronics, BUT RUN A BATTERY ISOLATOR A battery isolator charges both batteries when the engine is running, but isolates them from eachother when the engine is off. This is different from your 1/2/BOTH switches! Running a starting and marine battery in parallel is not a good idea; you can damage your batteries. Choose the right battery for your application!
WET ACID/AGM/GEL CELL BATTERIES:
Wet (flooded) acid are still the BEST batteries you can get! Sorry, but its true. Yes you have to maintain them, but you get the most amount of power and life out of a wet acid battery. AGM (absorbed glass mat) batteries are also acid type batteries and they have their advantages! They don't vent fumes and they don't leak...usually. I use one in my Jeep! They also cost more and don't last as long as a PROPERLY MAINTAINED flooded wet cell. GEL CELL batteries belong in ALARM CABINETS! Gel cells have their advantages, but you CAN'T quick charge them! If you do the gel heats up and moves away from the plates. Then an oxide forms and the battery is destroyed. AGM YES...Gel Cell NO!!! They are different!
STAY AWAY FROM OPTIMA BATTERIES!!! They used to be great, then they sold the company and they are now being made in Mexico. Google is your friend...look up OPTIMA BATTERY FAIL!
The best AGM battery made today is the Odyssey. The Sears Platinum battery is made by Odyssey and $100.00 cheaper. Autozone has a Platinum battery too but it's made by Deka (not Johnson Controls). Its another $100.00 cheaper but not as good as the Odyssey. If you must have the best AGM, Odyssey is the way to go!
Any questions?!
Dino - KX6D
I've used all kinds of batteries in my line of work. This includes use in the solar industry all the way up to running high voltage DC pumps in a power plant. I've spec'd batteries and I've used batteries...all types and sizes!
Now I wasn't born with this great knowledge of batteries; I asked the experts...the people who actually BUILD them! I'm not going to get into chemistry...let's keep this simple! I hope you find this educational and fun!
BATTERIES 101:
There are basically three TYPES of batteries used in automotive/marine applications...
1. Starting
2. Marine (hybrid) (IT IS NOT A DEEP CYCLE BATTERY!!!)
3. Deep Cycle
1. A Starting battery has one job; to start an engine! In order to do this, it must provide a huge amount of current for a short period of time. Once the engine is running, the generator/alternator takes over the electrical demands of the vessel AND recharges the battery. Crank an engine more than 30-seconds and the starting battery will begin to die. They are usually rated in Cold Cranking Amps (CCA)
2. A Marine (hybrid) battery has TWO jobs! It needs to have enough current to start an engine, and enough CAPACITY to run lights when at anchor or tied to the dock. Have you ever noticed that boat engine crank SLOWER than car engines? Its not the starter....its the battery! Again, once the engine is running, the generator/alternator takes over the electrical demands of the vessel AND recharges the battery. But once the engine is off, the Marine battery needs to power the lights and electronics on board. These are listed with both a CCA and a Amp/Hr ratings.
3. A Deep Cycle battery provides a little amount of current for a LONG time! Deep Cycle batteries are not designed to start a vehicle and most CAN'T! They will power your lights, troll motor, radios, fish finders, and 12V blenders for a lot longer than a starting or marine battery will! These are rated in Amp/Hr. No need for CCA!
So what's the difference between the three?! It all comes down to the internal construction of the cells! Each cell think, compartment) on a battery is good for 2-volts. 12-volt batteries have six cells, and 6-volt batteries has three cells. You connect these cells in series and you increase your voltage by 2-volts each time. Inside these 2-volt cells you have PLATES! (Again, I'm not going to get technical on the chemistry!) You can have a lot of plates or just a few plates. These plates can be thick or thin. The THICKER the plates, the more CAPACITY they have, and the more room they take up! The thinner the plates, the less capacity they have, but you can stuff more in a single cell. Are you with me so far?!
Starting battery cells have a LOT of THIN plates in order to produce MORE CURRENT! But these thin plates run out of juice pretty fast!
Deep Cycle battery cells have only a few plates, but they are THICK and therefor takes a lot longer to discharge. Since you only have a few plates, you can't produce the high amount of current needed to start an engine.
Marine battery cells are thicker than starting batteries, but thinner than true deep cycle batteries; this is why they are called a HYBRID battery! They are just thin enough to squeeze enough in a cell to produce the needed CURRENT to start your engine...and just thick enough to give you some reserve capacity to run your lights etc.
That's all you need to know about the three different types of batteries! What is best for your application is up to you to decide. More on this in a minute! I want to talk about SIZE first!
SIZE MATTERS!
Actually, it doesn't...according to my wife! But I digress... Batteries are sized by GROUP. Again, I'm not going to go in to all kinds of details here. The BCI Group Number will give a physical size and type/placement of the battery post. The higher the Group # the larger the battery (basically). The larger the battery, the more juice you have...but it also weighs more too!
Quick story! A solar powered traffic control company sold trailers equipped with Group 4-D batteries! Whew those babies were big! They sure looked impressive! They are used in big rig trucks and farm equipment. You could even order 8-D batteries for "more power"! Bull! These big impressive batteries were designed to start diesel trucks and not power halogen or LED lights and be recharged by solar panels! Wrong battery for the wrong application!!! Needless to say, they didn't last long and had to be recharged by use of a battery charger OFTEN! FAIL! :facepalm:
Run the biggest battery you can fit, especially if using a Marine or Deep Cycle battery! Make sure they have the right posts for your application. If you have a group 24 and a Group 27 will fit, get the 27 (unless its just a starting battery)! If you can squeeze a Group 31 in there, go for the 31! That's enough about size!
DEEP CYCLE BATTERIES:
A TRUE DEEP CYCLE BATTERY is usually 6-volts! Yes, they make 12V deep cycle batteries, but they still don't have the capacity of a 6-volt battery! I know, you need 12-volts...so buy TWO 6-volt batteries and hook them up in series! The RV industry has been doing this for YEARS! They'll sell you a new RV with a single 12V to keep the price down. But you learn quick that it doesn't last very long. They are more than happy to sell you two 6V batteries! Again, don't buy two 12V batteries and hook them up in parallel...buy two 6V and hook them up in series! Trust me on this!
Not everyone needs deep cycle batteries on their boat! If you have a house boat...then YES! If you troll...YES! If you have a competition ski boat and the engine is always running, then a starting battery is fine! If you like to float around and listen to tunes for a little bit, then a Marine battery is your flavor. If you are going to run two batteries, get one for starting and one for your electronics, BUT RUN A BATTERY ISOLATOR A battery isolator charges both batteries when the engine is running, but isolates them from eachother when the engine is off. This is different from your 1/2/BOTH switches! Running a starting and marine battery in parallel is not a good idea; you can damage your batteries. Choose the right battery for your application!
WET ACID/AGM/GEL CELL BATTERIES:
Wet (flooded) acid are still the BEST batteries you can get! Sorry, but its true. Yes you have to maintain them, but you get the most amount of power and life out of a wet acid battery. AGM (absorbed glass mat) batteries are also acid type batteries and they have their advantages! They don't vent fumes and they don't leak...usually. I use one in my Jeep! They also cost more and don't last as long as a PROPERLY MAINTAINED flooded wet cell. GEL CELL batteries belong in ALARM CABINETS! Gel cells have their advantages, but you CAN'T quick charge them! If you do the gel heats up and moves away from the plates. Then an oxide forms and the battery is destroyed. AGM YES...Gel Cell NO!!! They are different!
STAY AWAY FROM OPTIMA BATTERIES!!! They used to be great, then they sold the company and they are now being made in Mexico. Google is your friend...look up OPTIMA BATTERY FAIL!
The best AGM battery made today is the Odyssey. The Sears Platinum battery is made by Odyssey and $100.00 cheaper. Autozone has a Platinum battery too but it's made by Deka (not Johnson Controls). Its another $100.00 cheaper but not as good as the Odyssey. If you must have the best AGM, Odyssey is the way to go!
Any questions?!
Dino - KX6D
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