TOPIC: What's the deal with "Marine" batteries?

How does a so-called Marine battery differ from your standard car battery? I'm currently using a car battery and my Dad used nothing but car batteries for many years with no apparent ill effect.

My local retailer sells two marine batteries, the Optima brand and Exide sold under their house name. The Exide is half the price and my retailer told me the only real difference from the Optima is sturdier construction allowing you to bounce it around more.

Just looking for your thoughts.

Edit: The Optima is a gel cell, the Exide is not.

Are these the "Gel Cell" batteries? If so they are going to be quite a bit more expensive. They prevent the spilling of acid if the battery tips or bounces too much. If the battery is in the back of the boat and strapped down in a case, that shouldn't be a problem. I have used a car battery for many years with no problems. The one difference between a car battery and a boat starting battery is the terminals on the battery. They hook up easier because of the wing nut connections. A deep cycle battery is for things like fish finders, trolling motors, radios, ect that have a small draw over a longer period of time. They will work in a pinch for starting but it won't take long for it to need to be charged because of the amps needed for a starter.
Bill

The main difference is in the construction.

Marine batteries are supposedly made tougher, thicker plates, etc so they can bounce around a bit more. Keep in mind how much more your boat moves than the average car- Pounding motions, especially. It's tough on equipment.

Car batteries DO work fine- And some people use them with no problems... But, I've always spent the couple of extra bucks on a 'boat' battery. I've heard the argument that you can just buy the cheaper car battery, and return it whenever it fails under warranty- But a failed battery on the water can REALLY ruin your day...

Also, keep in mind that some marine batteries, Deep cycle are designed differently, and if you are running heavy loads of equipment, you need one of these. Starting batteries are designed to provide a short 'burst' of power to crank an engine, where the deep cycles provide larger amounts of energy over time, and are usually more robust in construction. If you are running lots of electronics and/or trolling motors, you want a deep cycle.

Of course, there is a tradeoff- Deep cycle batteries usually don't produce the same cranking amps (a measure of the 'burst' power available to start an engine) as starting batteries. There is an 'in between', often called a dual purpose. It provides more capacity than a starting battery, with some added 'kick' that makes it preform better than a normal starting battery. They're great if you need one battery to both run loads and start a boat.

Comparing boat and car batteries side by side can be tough, since they are often rated differently. Car batteries are rated with Cranking Amps and/or cold cranking amps (CA & CCA), where marine are often rated in Marine Cranking Amps (MCA)... The numbers are fairly similar, but are a little different in how they are measured.

From what a battery guy told me, it relates to bounce. Car batteries internal plates are less secure than marine. They don't need to be as secure - cars have suspension. Marine batteries the plates are more secure because boats get bounced around a lot more.

Gel batteries are a completely different animal. Bounce does not relate. You can hang them upside down under your splash pan and they will be just fine.

Frank

Try this

www.westmarine.com/webapp/wcs/stores/servlet/WestAdvisorView?langId=-1&storeId=11151&catalogId=10001&page=Selecting-a-Marine-Storage-Battery

Please read: I must post this for fellow fiberglassics members before troubles arise. gel cells and optima batteries are only for use on voltage regulated systems. Please do not use them on 70s and 80s outboards with pulse packs. The reason is that the designers of these systems left the stators unregulated knowing that the lead acid battery would buffer the voltage spikes. The lead acid batteries act as capacitors, smoothing the unregulated charge. gel cells have very limited capacity and do not respond well to voltage spikes. what will happen is that the unregulated feed to the pulse packs (mercury calls them switch boxes) will eventually burn out one or more internal components. when that happens, the pulse packs must be replaced.
So, if you are running a 70s or 80s electronic ignition outboard, stick to lead acid type bateries. Starting batteries have more plate surface to maximize cranking amps, deep cycle have less plate surface but more lead. There is little difference between many automotive starting batteries and marine starting batteries. And starting batteries are best able to absorb the high voltage spikes generated to protect the pulse pack.
If you really want an optima or spiral cell type, then always make sure a lead acid battery is in parallel while the engine is being used.

I hope that this advice saves some people from unnecessary down time and expense. mercurys are particularly sensitive, especially those with dual switch boxes (the inline 6 and the black max series).
Happy boating!

72 was the last year for OMC outboards that ran with battery CDI ignition.

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All later OMC models run with magneto ignition systems, not directly energized / hooked up to a battery.

I used 4 very expensive, Optima deep cycle gel batteries in my 1984 32' Bayliner inboard. One failed after the first year (under warranty), two more failed the next year, on the third year i pulled them all and went back to lead acid deep cycle batteries. I am not sure what about the boat caused this, GM V6 engines, Delco 105 amp marine alternators, on a trickle charge year round at the marina when the boat is moored.

I expect to get 5 years out of my batteries, and the lead acids are performing. I use the deep cycle as 3 of the 4 batteries are on my house circuit, that powers my 4000W inverter and all my creature comforts and I need to be able to draw them long and hard when cruising.

Great info on the batteries guys, appreciate you sharing. (Especially the warnings on the gel type units!). I was always led to believe they (closed cell gel) were "top of the line", you probably saved some folks a bunch of cash, and aggravation.

Excellent forum.
Very informative.
Neil

Some good reading
Batteries, everything you need to know. newboatbuilders.com/docs/BatteriesEverything.pdf