This is the first part of a three part series on batteries. In this article we explain how to link batteries in a series circuit and a parallel circuit to obtain your required voltage and desired amp hours.
The first thing to remember when dealing with batteries and setting them up in different configurations, is that if you are unsure of what you are doing then take the job to an electrician! There are plenty of marine and auto electricians around, and they will be able to sort it all out in no time. Just ensure that they use tinned wire, switches, plugs, circuit breakers etc suitable for the marine environment.
This article will be of particular interest to anyone looking into buying or that owns an electric outboard motor. Electric motors come in many different sizes, the smaller ones are generally 12 volt while the bigger ones with more thrust are usually 24 volt, and then there are the really big ones which are usually 36 volt.
Now some of you may be thinking that you have never seen a 36 volt battery, and you would be quite right. If you require 36 volts, you will need to link three 12 volt batteries up in a series circuit to obtain the higher voltage.
So in a series circuit we can increase voltage by the number of batteries. 3 x 12 volt equals 36 volt, or 2 x 12 volt equals 24 volt.
When linking batteries in a series circuit you will only increase the voltage, not the amp hours available. For instance if the 12 volt batteries used were 100 amp hours, the total amp hours for a 36 volt circuit would still be 100 amp hours.
To link batteries in a series circuit, get your batteries and battery connectors and cables ready, and ensure that there are no appliances or anything else hooked up to the batteries. Take your battery connector cable and run it from the negative terminal on one battery to the positive terminal on the other battery.
To run your higher voltage appliance, attach the red or positive cable to the empty positive terminal on one of the batteries and that should leave you with an empty negative terminal on the other battery to which you will attach the black or negative cable.
Let’s say you had a 12 volt battery that ran the electric for one day, but you really wanted two days use out of it before needing to recharge the batteries again. If you had two 12 volt batteries at 100 amp hours and rigged them up in a parallel circuit you would get 12 volts and 200 amp hours. Three 12 volt batteries with 100 amp hours each in a parallel circuit would of course give us 12 volts and 300 amp hours.
To hook up a parallel circuit you will need to once again ensure nothing is hooked up to the batteries and that you have the connectors and cables on hand.
From here it is simply a matter of connecting the positive terminal on one battery to the positive terminal on the other battery and likewise with the negative terminal. When you attach your appliance you will simply attach the negative (black) cable to a negative terminal and the positive (red) wire to the positive terminal.