pcloward wrote:Is there any reason not to move the two batteries to a more protected location?
Boston Whaler designed the boat to have the batteries located in the engine splash well, and provided reinforcement material below the laminate of the deck to support the weight of the batteries. Boston Whaler sold many thousands and thousands of boats like yours with the batteries located in the engine splash well.
The idea that you will be
making an improvement in the boat by moving the batteries out of the engine splash well and placing them inside the center console is not particularly a sure bet. There are many problems in your plan. I will mention just a few of them.
First, and perhaps foremost, increasing the distance between the engine starting battery and the engine starting motor on the engine that the battery is supposed to crank over is a terrible idea on the electrical perspective. Anyone who understands electrical current flow and the effect of resistance in the wires in the circuit will immediately see the problem. If you need a more thorough explanation of the electrical problem that will be created if you add 10 or 15 feet to the length of the cables, let me know, and I will give you a more detailed explanation. But the simple answer: making the wires longer is a very, very bad idea.
Second, the transom location will generally give the batteries the most comfortable ride, as compared to other locations, there will be less pounding and slamming of the hull in waves at the very stern than anywhere else on the boat. This will give the batteries a longer service life.
Third, the center console was never designed to support the weight of one battery, let alone support the weight of three batteries. Nor was the deck below the center console designed for such a concentration of weight to placed there. Nor will there be room for three large batteries in the center console. Nor will it be easy to service or inspect or remove the batteries from the center console. And the weight off all those batteries when the hull is slamming into waves will be a huge and unanticipated load on the deck at that location.
As long as the batteries are in proper battery boxes, and the battery boxes are secured to the deck with proper straps, and the straps are secured to the deck with proper Footman's Loop fittings, there is really little concern about the location being in the engine splash well.
Even if the boat were to be overtaken at the transom by a huge following sea, the conductivity of freshwater is very small, and the conductivity of saltwater, while much higher than fresh water, should not immediate cause a short circuit at the battery terminals. To prevent any short circuit, you can spray the connection between the cables and the battery terminals with a coating of insulating wax, such as BOESHIELD T9.
More information about use of BOESHIELD T9 in marine applications can be found at
https://boeshield.com/marine/This will effectively insulate the batteries from any water, and also significantly reduce any corrosion that would otherwise occur in normal use.
WHY THREE BATTERIES
Also, I do not understand your motivation for adding a third battery to carry the house loads. To me this is complete madness. You have only a single engine. Your boat electrical system can be handled by just two batteries. One battery is dedicated to engine starting, and a second battery is dedicated to house loads. In the event of a problem you can parallel the two batteries to get the engine started.
Most outboard engines come with only one battery charging output. Exactly how you will plan to maintain the charge in THREE batteries from one engine charging output is unknown to me--and perhaps unknown to you as you may not have even considered this problem.
If you need more advice on how to configure a modern outboard boat and its batteries, read my article on my own boat's electrical system. See
Auxiliary Battery Charging Kit for E-TEChttps://continuouswave.com/ubb/Forum6/HTML/002758.htmlI wrote that article and made those changes 14-years ago, and the system has been working exactly as planned for 14-years.
For advice on what type of battery to use, see my article
Battery Recommendationshttps://continuouswave.com/forum/viewto ... f=9&t=4648Be prepared for the price of these premium batteries to have increased significantly due to the crazy inflation created in our economy by the government printing money in the post-pandemic era.
I am getting about ten years of service life on these batteries. Typically I replace the engine cranking battery with a new battery, and move the previous engine cranking battery over to be the house battery. I use the older house battery as the trade-in on the new battery.
If you re-power the boat, look for the option of adding a second charging output to the standard engine configuration. Having a second charging output from your outboard engine will made maintaining two batteries at full charge much simpler.
If you re-power with an engine that does not offer the option of a second battery charging output, you will have to get an automatic combiner relay. If that happens, you can start a new thread on the topic of the proper method to install an automatic charging relay and solicit advice.