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Author Topic:   Battery and Wiring for 15-footer
69boo307 posted 07-09-2010 09:33 AM ET (US)   Profile for 69boo307   Send Email to 69boo307  
I'd like to solicit a little design help and feedback for improving the battery and wiring situation on my 15-foot Striper. Current situation: it has two batteries, one that is exclusively wired to the trolling motor, and then the engine battery to which everything else is wired. Each of these batteries has a cheap Shakespeare charger mounted to the battery case. The charger on the engine battery no longer works and I've disconnected it. The wiring under the console is a bit of a bird's nest and is old and has some corrosion. I'm planning on adding a VHF radio in the near future and hopefully re-doing the wiring at the same time.

What I'd like to be able to do:

--use the trolling motor battery as a backup for all systems including engine starting, in the event of a failure with the engine battery. I want to do this by means of some kind of battery switch setup. I don't want to have to manually swap wires on battery terminals while I'm out on the water.

--charge both batteries using a single on-board charger that can be connected to shore power or the 110AC in my garage, either charging both at once or only charging one or the other.

--have the engine charge both batteries while it is running. Is this possible without overloading something?. Could the proper on-board charger manage this as well as 'shore' charging?

--have some kind of terminal block in the console to provide power to all 12-Volt accessories such as the GPS receiver, fish finder, or the VHF, to avoid having individual power leads from each accessory running to the battery terminals directly.

Perhaps this is overkill on a 15-foot boat, but I like things to be tidy and reliable, and if I'm going to be hauling around two batteries I might as well be able to use one for a backup if I need to.

mrtoyz posted 07-09-2010 06:22 PM ET (US)     Profile for mrtoyz  Send Email to mrtoyz     
Hi boo,
I'm looking at doing the same for my Dauntless 15. Done a fair amount of research and here is what I'm planning on paper thus far.

Charging system:
The max pack comes with AC and DC chargers as well a very nice digital gauge. Kinda spendy ($515) but I've heard nothing but positive things. Can even add a towing charging harness that allows you charge while towing. There is also an EZ-start add that will allow you to combine batteries if your cranking battery runs too low.

Instead of using fuses for my house devices I'm planning to wire them to one of these circuit breaker/on/off panels. Keeps everything on top of the console, nice and neat, with individual on/off switches.

Hope this helps.


jimh posted 07-09-2010 09:10 PM ET (US)     Profile for jimh  Send Email to jimh     
See my article on small boat electrical distribution and wiring practices:

jimh posted 07-09-2010 11:20 PM ET (US)     Profile for jimh  Send Email to jimh     
Perhaps I have failed to appreciate the endurance of 69boo307 to pilot a 15-foot boat. Exactly how long are we planning to be at sea and and away from 120-VAC for re-charging the batteries or from charging current from the outboard motor?

Can you pull-start your outboard motor? This is a crucial factor in designing the electrical system.

An elaborate and expensive voltage convertor charging system such as the STEALTH1 device that has been recommended seems too much for a 15-foot boat to me.

My preference is for simple systems. They are easy to understand, easy to operate, easy to maintain, and easy to pay for.

The best way to simultaneously charge two batteries of different type is to have an outboard motor with a dual charging outlet. Actually, I just ordered that accessory for my motor, and I will be installing it next week. It will allow the motor to charge both batteries on my boat simultaneously and independently, that is, without paralleling the batteries.

Primary power distribution is easily handled by available battery selector switches. They come in many sizes and configurations. Look at the manufacturer literature, which will include application diagrams.

Secondary power distribution is easily handled by marine power distribution panels made precisely for that purpose. For a 15-foot boat a panel with six circuits ought to be plenty.

69boo307 posted 07-12-2010 12:50 PM ET (US)     Profile for 69boo307  Send Email to 69boo307     
I'm not planning on being 'at sea' for long periods of time, but it would not be unusual for me to have the boat in the water and away from 110AC for several days, such as on a vacation trip. I've also towed the boat to the lake before only to discover that the engine battery had a dead cell and could not even be jumped. That's when it would be nice to flip a switch and use the trolling motor battery. By the same token if the engine failed on the water it would be nice to have the option of drawing on both batteries for the trolling motor. I agree that I don't think I need a $500 charging device, that's beyond my budget.

I believe it may be possible to pull-start my engine (1990 Johnson 60), but if so I don't have a pull rope for it and I've never tried.

K Albus posted 07-12-2010 01:44 PM ET (US)     Profile for K Albus  Send Email to K Albus     
I'm essentially an electrical novice, but I recently added a second battery to my boat. When I asked for help here, I got a bunch of answers which were geared toward persons with much more electrical knowledge than I had. My main goal was to install a system with two batteries - one for starting the motor, and one for all of the electrical accessories on my boat such as the VHF radio, the stereo, and the GPS/fishfinder. I also wanted the motor to be able to charge both batteries anytime the motor was running, and I wanted the ability to "combine" the batteries if necessary for emergency starting.

I assume you are looking for essentially the same thing. The first question that needs to be answered is whether your trolling motor is a 12 volt motor? If so, there are two commonly used systems you look at first. One is the Blue Sea Systems Add-A-Battery kit which comes with an Automatic Charging Relay ("ACR"): . The other is the BEP Dual Battery Charging Cluster which comes with a Voltage Sensitive Relay ("VSR"): 716-sq-100avsr-dual-battery-charging-cluster . Either one of these systems will allow your motor to charge two different 12 volt batteries while your motor is running. I chose the Blue Sea Systems kit for my boat.

Whichever system you choose, you should wire your trolling motor and all other accessories to one battery, and wire your motor to the other battery.

Regarding a terminal block for your accessories, I believe that is a fairly simple deal. You just buy the terminal block with the appropriate number of posts on it, and mount it in a convenient place. You then connect the terminal block to the appropriate battery, and connect all of your accessories to the terminal block. Again, you can get terminal blocks from Blue Sea System or BEP or another manufacturer.

Regarding the on-board 110 volt AC battery charger, you'll have to get advice from others. With my current system I don't have a need to regularly charge my batteries during the season, but I do not have an electric trolling motor. I will say that it is my understanding that with my system, if I need to charge a battery, I can simply hook the charger directly up to one of the batteries and let it charge. If the other battery also needs charging, it is my understanding that I would have to charge it separately.

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