See full version: How to Hook Up Boat Batteries
Install a second "house" battery in a parallel union by attaching the first battery's neutral (black) port to the second battery's neutral (black) port and the first battery's positive (red) port to the second battery's positive (red) port. This will give you longer battery life, but not more power than the original battery.
Strap the battery in tight with a heavy-duty battery strap so boat movement does not toss it around in the engine compartment. more
Attach the existing house battery to the new addition by connecting neutral (black) port to positive (red) port. This creates a series to provide additional power. A series does not give longer battery life, but lets you plug in more appliances and other electrical equipment.
Boat owners can save themselves a lot of money if they do much of the yearly maintenance on their crafts themselves. One routine job is removing the boat's batteries for the winter and re-installing them in the spring. Hooking up a boat battery is not a whole lot different than hooking up a car battery. Car owners rarely deal with such issues because auto mechanics are in abundance and not as expensive as marine mechanics. Boat owners also usually want more than one battery. Installing several batteries is easy, however, once you understand the principles behind how the batteries work.
Set an additional battery in position next to the existing "house" battery that runs everything but your engine. Attach it to the battery compartment with a heavy-duty battery strap.
Hook the neutral (black) wire to the neutral (black) port first. This prevents a spark when you hook up the positive wire that could cause an explosion.
For instance, if you parallel wire your two starting batteries and add a third deep cycle for running accessories with the engine off you can run into problems when you switch to both for charging purposes. To rectify this you can purchase a battery isolator that will correct voltage/current for the different battery types and allow them to charge evenly and correctly. [links]
The isolators come with concise wiring diagrams and are very easy to install. Done right it can be a vacation saver for sure. [links]
Sorry guys I forgot to add a little more info for you. I have a 2 way switch and want to add the extra battery for safety but also want to keep it charged up with the alt. it will primarily be used as a back up in case of failure of either one or both of the other ones. I don't have a lot of electronics on board just a FF and VHF the radio is crap so I don't use it. I just don't want to get out in Lake Erie with no comunications or engine not starting. As I have identical twin grandsons that want to go fishing with Papa and sure don't want us stranded for any reason what so ever as that might tramatize them for going out again. I love the outdoors and fishing as do my own 2 sons, I want that trend to go on down the line with them! thanks.
Re: How do I conect 3 batteries? more
LippCJ7 gave you the right advice. Please take note his mention of batteries of the same age. I will further that with the fact that they should be identical in manufacturer, size and ratings. [links]
Isolators are old-school. ACR's are far more effective devices. There is also no need to have parallel wired batteries from the same manufacturer or for that matter, don't have to be the same capacity. the charging system monitors "system" voltage and cannot distinguish between batteries. It is certainly best to not mix battery technology and it is recommended that the batteries be roughly the same age and capacity but that is not an absolute. Fact is, you can have two identical batteries and they will not have the same identical capacity as indicated on the label. So the weaker of the two will always draw down the stronger until the two equalize.
What size wire is needed for a 36 volt trolling motor?
Q: What size wires do I need for my 12v or 24v trolling motors?
Many accessories on a boat are powered by a battery, but they don’t operate on a 12-volt power source alone. For instance, larger trolling motors require either 24 or 36 volts. However, batteries with these voltages are difficult to procure. As a result, one has to connect multiple batteries in series to increase voltage where the amp hours remain the same.
To engage in such processes, you need to procure identical batteries. Avoid using old batteries with new batteries while connecting in parallel or series.
manufactures information in our articles for [links]
Before moving further, you should have an idea about a battery bank. When two or more batteries are joined together for a single application such as for an electric trolling motor, the integrated solution is known as a battery bank. The purpose of this connection is to increase voltage or amperage or both.
If you still wish to have two starting batteries wired in parallel just hook it up pos - pos, neg - neg and wire as if it were one large battery.
Re: Can 3 batteries be charged with one alternator here
Hi, I have a 75 or 85 amp alternator and 2 starting batteries.
I would like to install a thrid deep cycle battery for all my excesories. more
I have 2 starting batteries(identical) that I want to use and hook up in parallel and one deep cycle battery that I want to hook up to all my accessories.
Can I hook up three batteries on a single alternator?