Electrical Setup Questions

[scott2000d]

First off I just wanted to say that I am new to this site and boating in general. I have just purchased a 14' Aluminum with a 1979 Johnson 25HP.

I am trying to figure out the best electrical setup for my purpose. My motor has electric start and I'm assuming will charge a battery (I haven't tested the output yet). I would like to be able to run a trolling motor, fish finder, cigarette lighter (to keep a cell phone charged as most fishing areas around here do not have digital service), some lights and possibly an arrator for a livewell in the future. First off is this possible/practical to do with the motor I have. And secondly what type of setup should I use. I already have one deep cycle battery (I think it was from an RV) that I think still works that I would be able to use. I keep seeing people talking about 2 bank battery charger/maintainers. Are these for charging from the motor or from a normal wall plug on shore? If it just for charges from the wall couldn't I just take the batteries out and charge once I get home? How should this all be hooked up for maximum efficiciency and to keep the battery charged. Any advice would be helpfull. Thanks in advance.

 

[Silvertip]

Re: Electrical Setup Questions

Let's take the trolling motor topic first. For that you need the largest capacity deep cycle battery you have room for and can afford. Forget trying to charge this battery with your engine. The engine simply does not have an alternator with enough output for this task. You would need to run wide open for days to fully charge that battery. An on-board charger is a sealed, "smart charger" that you plug into at the dock or you can use it at home if you don't have power at the dock. They having nothing to do with the engine charging system. "Smart" means these chargers can be left connected indefinitely with no damage to the battery. In fact it is good for them.

The starting battery for the engine can power everything else on the boat. Even if you run down that battery, you can still pull-start the engine. The charging system should be able to keep up with the demand on that battery.

 

[scott2000d]

Re: Electrical Setup Questions

So what your saying is to just keep the 2 batteries on completely different circiuts. Use the deep cycle for the trolling motor alone and don't even have it hookes up for charging in the boat. I can take it out when I get home and charge it there. As for the other electronics, I should be able to run them all day off the starting battery without a problem and it shouldn't kill the battery right?? I was thinking about this battery for the starting battery. What do you think?? http://www.canadiantire.ca/browse/product_detail.jsp?PRODUCT%3C%3Eprd_id=845524443248305&FOLDER%3C%3Efolder_id=1408474396672456&bmUID=1215393933183&deptid=1408474396672192&ctgrid=1408474396672206&subctgrid=1408474396672456

 

[Silvertip]

Re: Electrical Setup Questions

I repeat -- forget trying to charge the trolling motor battery with the engine. The alternator simply cannot do it -- it does not have enough output. The alternator is designed to only keep the starting battery charged. Trolling motors draw tremendous amounts of power (30 - 40 - 50 amps depending on size). Your alternator is probably about 6 amp maximum output. So if you ran the trolling motor for one hour at even 30 amps, you have to run the engine for five hours wide open to charge that battery. Even longer because it would also have to charge the starting battery. Two batteries connected in parallel behave like one giant battery. So the long and short of this you don't have a big enough alternator to charge both and even with larger engines, most people install on-board smart chargers.

 

[scott2000d]

Re: Electrical Setup Questions

Perfect. That's what I thought you meant. Would that Nautilus battery in the link I posted be good enough to be used for starting as well as power the cigarette lighter, fish finder, lights, and an arrator withough too much risk of draining the battery to the point that it can't start the battery, or is it not big enough to power that equipment?

 

[Silvertip]

Re: Electrical Setup Questions

That link goes only the Canadian Tire so I have no idea what battery you are talking about. Select a RV/Marine "dual purpose battery" for your starting battery. Select the highest capacity CCA or AH you have room for and have budget for. You cannot go too big -- just too small.

 

[scott2000d]

Re: Electrical Setup Questions

That's wierd that it doesn't go to the specific item. What is the difference between CCA and MCA? I'm assuming AH is Amp Hour. The one that i'm looking at is called "Motomaster Nautilus Starting & Deep Cycle Battery" and has 730 MCA and 160 minutes of reserve capacity, as well as either 70 or 93 AH capacity. Do you think this would be sufficient or should I look at bigger?

 

[Boatist]

Re: Electrical Setup Questions

I agree with silver on most of what he said.
For the trolling motor get a deep cycle group 27 or larger. For a 14 foot boat should have plenty of power.
Starting battery I would get a Plain auto starting battery group 24 or larger and hook your motor up to it.
I go to Walmart or Cosco and get a battery with 3 year free replacement and 100 month pro rated warranty.
How long your battery hold up depends more on how you charge it than Brand or type.

When battery is discharged it need to be fully recharged as soon as you can,
At least by the end of the day.
Discharging a starting battery more than 20 percent or a deep cycle more than 50 will shorten the batteries life.
The longer it is discharged the more it will shorten the battery life.
In summer charge both at least one time a month and in winter at least every 2 months.

The starting battery should be able to support the cell phone and a arrator pump with no problem if your motor is running.
When you say lights, if you mean navigation lights then no problem but if your talking
large spotlights or flood lights then your motor's charger will not be able to keep up.
Also if your talking Live well fill pump and recirculation pump you plan to run for
long times durning the day again your charger will not keep up.

I this case I would get a second deep cycle battery. It will have plenty of current to start a 25 HP motor.
Also the motor can be started with the roap.

Charging batteries at the end of the day a good smart charger or automatic charger at least 10 is a good choice.

A 2 bank on board charger cost more but an even better idea but again the output for the trolling battery
needs to be at least 10 amps.

While taking the batteries out to charge is ok I think putting batteries in a battery box and
charging onboard is a better way to go.
The reason I say that is the eaiser you make it to charge your batteries then the sooner you will do it
and the longer your batteries will last.

I use a auto starting battery and a group 24 deep cycle and have not had a battery last less than 6 years.
I do not have a electric trolling motor and charge both my batteries with a 64 amp alternator thru a battery isolator.

Still when I get home from a day or night of fishing after backing the boat in
the first thing I do is hook up my 10 amp Automatic battery charger.
I then unload the fish and the gear from the boat. Put the gear away and clean the fish then put the boat cover on.
Last I check the battery charger and if it below 1/2 amp I disconnect the battery charger and put away.

I maid my batteries very easy to charge by installing a plug on the bow of the boat where I can pulg
in my charger and charge both batteries at once thru a battery isolator.
This way I do not have to clime in the boat and hook up and charge one battery,
then clime in and switch to the other battery and clime in to disconnect.
The fact that it is so easy means I will do it one time a month in summer and every other month in winter.
That means the batteries will last a long time.
I can also charge form a 12 volt line from the truck to the trailer thru the same plug.
On board chargers cost a lot more but are easy to hook up and use.