Battery charging

I have a Mercury 80 outobard motor on my 16ft boat. I plan to run my fish finder, and my stereo, and maybe my navigations lights if needed.

My question is this.

Does the battery ever get charge from the engine once it is started? Because if I am out fishing, and I start the boat to move to a different spot 10-15 times through out a full day of fishing, will this not kill the battery if it gets no charge with the mix of my fish finder and sometimes a stereo usage?

Is there a setup I can use to charge the batter when the engine is running?

The battery that came with the boat (just bought it from a guy) is a brand new car battery, not a marine battery since there are not many electronics on this, he told me that a car battery was fine for starting the motor and for little electronics use.

But where I live, I have a LARGE lake 5 miles from my house. So having a dead battery on a lake this size, could be a very big problem.

Thanks all.

Re: Battery charging

That motor should have a charging system. You can verify that it is working by checking the voltage at the battery with the motor off then check it again with the motor running. You should see an increase in voltage and as RPMs increase it should go up to around 14 volts.

Re: Battery charging

The stereo will pull alot more current then the fish finder and nav lights, you should consider putting it on a separate battery, I did.

Re: Battery charging

Two batteries is the way to go. It gives you a spare for starting, and if the motor dies it gives you twice the battery capacity for the trolling motor.

Re: Battery charging

A stator under the flywheel recharges the battery when it is running. You are charging when you're running, and drawing amps when shut off. A difference I saw looking at car and marine batteries is that the marine battery has a second set of terminals that are designed for the accessories. I like that because it is easy to pull off the accessories while I'm charging or working on the engine. I don't want to risk ruining any accessory. There are also two types of batteries. A cranking battery has a high cranking amps rating and is good for strong starting but draws down faster when using the accessories while stopped. A deep cycle battery has lower cranking amps but will last longer for things like trolling motors. They are also used for accessories on RVs. If you do decide to get a second battery, consider a deep cycle battery. You must however charge them longer at lower rates. Larger motors that put out higher amps from the stator can damage a deep cycle battery (charges too quickly), therefore they are not best used hooked to the engine. You can however get away with it with the small outboards. My mechanic told me my 60hp merc would be OK hooked to one so I've used a deep cycle battery by itself and have not had any problems. If you do two batteries, put the cranking battery on the motor and the deep cycle on the accessories, separate. You'll have the best of both worlds. The boat will keep the cranking battery charged if you run it enough, but of course you will need to charge the deep cycle battery manually. Deep cycle batteries handle being exposed to the cold better and surviving being run down to dead with less permanent damage also. Hope that helps. Charles