NOOB electrical question

Ok, so I have a model year 1975 mercury 650. I'm looking to pick up a spare battery to keep in the boat with me "just in case". My question is this, on a motor this old isn't it accurate to stay away from a deep cycle marine battery. I've been told the deep cycle batteries will "fry" the electrical systems on those older motors. Also is there a difference between a marine battery and a deep cycle marine battery?

My apologies if this is a silly question.

Re: NOOB electrical question

Deep cycle batteries are made with thick plates as compared to normal engine starting batteries. Since the battery is the same size...24/27 and therefore is of fixed dimensions, obviously there will be fewer of them which means less surface area. Less surface area translates into lower peak current, like you would use to start your engine.

Whomever told you that BS about frying your electronics with a DS battery needs his mouth washed out with soap, no not just soap, but Lye soap. In reality, DS batteries usually are fully charged at about a half a volt lower than regular batteries.....like 12.25 vs 12.75V at STP.

As far as the rest of the BS about the fact that a DC is for trolling only and won't start an engine, I bought a 4020 (96 hp 400 cu in) John Deere DIESEL tractor once that had ONE deep cycle battery as it's starting battery and when I bought it I asked the owner when he installed it and he said that it was so long ago that he didn't even remember......I used it for a couple of years, year round and had zero problems (diesels are really cranky about starting in the winter) so, so much for that hoop lah.

So, what other questions do you have?

Mark

Re: NOOB electrical question

Car Battery versa Marine/Deep Cycle

Plate Size



Rechargeable lead acid batteries are classified in two categories. One type is starter batteries, used in automobiles, and the second type is deep cycle batteries, often used for recharging solar power systems. Car batteries or starter batteries have more lead plates than deep cycle types, but the plates are much thinner. Deep cycle batteries have fewer plates, but the plates are heavier and thicker. Marine batteries are hybrids and fall somewhere in between, similar to car batteries, but with slightly thicker plates.


Voltage



Similar to car batteries, the majority of marine batteries supply 12 volts DC. Car batteries are rated in cranking amps (CA) or cold cranking amps (CCA) while marine starter batteries may have a marine cranking amp (MCA) rating. Quality deep cycle marine batteries will have a reserve capacity (RC) rating that indicates how long the battery will operate before losing power. Marine batteries are also capable of more frequent and deeper discharges than car batteries.


Car Batteries



Car batteries have a greater number of thinner lead plates than the marine type, so they discharge a high initial current to spin the starter motor and crank the engine over. Once the engine is running, the alternator recharges the battery to run lights, ac/heater, radio, etc. When maintained, car batteries can last for years and be charged repeatedly. However, plate damage can occur if the battery is discharged more than 20 percent of full capacity for an extended period, or sits for weeks without being used.


Marine Batteries

Marine batteries operate devices such as trolling motors, navigation lights and fish finders.

Marine batteries are sturdier than car batteries to prevent damage from shaking and vibration caused when a boat rides on the water surface. Although sturdier, most marine batteries are not intended to be discharged more than 50 percent capacity, compared to deep cycle batteries, which can be discharged 80 percent continually, without plate damage. Good quality deep cycle marine batteries are recommended for boats equipped with trolling motors, radios, bilge pumps, navigation lights, GPS/fish finders and other electrical devices.

Re: NOOB electrical question

Thanks much Texasmark, I am new to owning a boat but have been turning wrenches on motorcycles and jets skis for years. Just not get intimidated by outboards. When i mentioned this to my uncle ( who has been boating and boating longer than i have been alive) he
had not heard this. I know on our fire dept. we take care of civil defense sirens and they have ALL deep cycle battteries, so I did kind of question his comment. Thanks again

Re: NOOB electrical question

It is amazing what nonsense myths some know-it-alls think up (or pass on) to make themselves appear knowledgable. :facepalm:

Deep cycle batteries harm older outboards?? Gimme a break.

Re: NOOB electrical question

Well if there is a problem with the advice,I would suggest to chime in with the correct advise instead of bashing the ones that take the time to at least try.

Re: NOOB electrical question

There is no problem with the advice Gomer. The problem is with people who don't read the cotton pickin' thread, then take insulting cheap shots.

The know-it-all I refer to is the jerk who told him that deep cycle batteries harm older outboards.

Re: NOOB electrical question

JB said:

It is amazing what nonsense myths some know-it-alls think up (or pass on) to make themselves appear knowledgable. :facepalm:

Deep cycle batteries harm older outboards?? Gimme a break.

Click to expand...

This is made me LOL. Thank JB, totally something I had never heard before nor had my Uncle, hence the reason I asked here to see if maybe we hd been living under a rock LOL

Re: NOOB electrical question

Boy do I owe an apology JB.I guees I didnt have enough coffee this morning before opening up my big mouth.Open mouth insert foot.Again I apologize for misunderstanding.

Re: NOOB electrical question

It was your turn to goof, Gomer. We all do it once in a while.

Peace.

Re: NOOB electrical question

ssmith your 1975 mercury 650 won't have a voltage regulator so you will need to get a battery with refillable cells if you want to leave it connected.

If you're only after some peace of mind then those jump start power pack things are a good alternative too.

Re: NOOB electrical question

Fed said:

ssmith your 1975 mercury 650 won't have a voltage regulator so you will need to get a battery with refillable cells if you want to leave it connected.

If you're only after some peace of mind then those jump start power pack things are a good alternative too.

Click to expand...

That's a big 10-4....definitely...... and carefully clean the landings off after pulling the caps and only use distilled water....no minerals to contaminate the plates. Also, adding water to an acid solution can pop (splash out)...ensure that your eyes are protected and only fill till the water makes a wet circle...about 3/8 to 1/2 inch below the top of the battery....the wet circle is deliberately formed to tell you that the battery is full of solution and allows room for expansion when charging....10 amp charger or less to prevent excessive venting (which boils solution out and onto your battery) and at that low charging rate you don't have to remove the caps while charging. Charging produces hydrogen gas so no lights/smoking etc, and unplug the charger from the wall before removing/connecting to any battery terminals..the spark could blow the place up.

Gotta share this. I used to work with a very intelligent guy who liked to tinker with things, and he decided to do something on the side; didn't do it for the money, just liked to tinker. He would go to used car lots and buy and sell batteries. He would take old batteries and recondition them then charge them and sell them. Charging consisted of series connecting a string of them and installing a diode rectifier in the line and then plugging it into the 115V wall outlet. Well that worked ok till one day he tripped over the cord and broke the connection after having a dozen (more or less) batteries charging in one room. You guessed it. The room blew up and the only thing that saved serious damage to his eyes were his glasses and he was a sight with burns on his face and hair/brows and all but these protected rings around his eyes.....he got out of the battery recycling business.

Mark

Re: NOOB electrical question

Lucky chap Texas, and yes I know about battery safety. Having spent 10 years working on motorcycles and jet skis. And we see numerous calls on the fire truck dealing with batteries. But thanks again, and THANKS to all for clearing up this up I do appreciate it.