The batteries should be wired in series. Electrically, it looks like this:
Positive lead to car (+ -) ----- (+ -) -----(+ -) Negative lead to car
Each set of parentheses represents a battery, the dotted lines are wires connecting the middle battery to the battery on each side. This will give you 36 volts at the positive and negative leads going to the car.
The other option is wiring in parallel, which gives you 12V, but triples the load capacity.
wire it in series
You do not need three 12 volt batteries to get 24 volts, all you need is two batteries. So I assume by using three batteries you want to increase the amperage. Wire two of the batteries in series and then wire the third battery to the second battery in parallel and you will have 24 bolts. Or you can just wire two 12 V batteries in series to get 24 V.
Connect three 12 volt batteries in series. You will triple the amperage but the volts will remain at 12. Click the link
The batteries need to be wired in a series configuration. Wire the negative of the first battery to the positive of the second battery, and the negative of the second to the positive to the third. If the batteries were placed in a straight line they will look like train cars, with all positive ends of the batteries pointing in the same direction. The batteries voltages are now added together for three 12 volt batteries making 36 volts.
Depends on the battery size. If your boat is a 12 volt system and you wire two 12 volt batteries in series you then have 24 volts. If the batteries are 6 volt batteries you will be fine. If you have a 12 volt system on your boat and want to use two batteries then wire two 12 volt batteries in parallel. You will still have 12 volts but will have double the amperage available and this will extend the running time of the batteries.
To get 24 volts from two 12 volt batteries, hook the positive post from one battery to the negative post of the other.
Connect three 12 volt batteries in series and you will have 36 volts but will only have the amperage of one of the batteries.
A cart that has batteries connected in series with one plus and one minus cables may have three 12V batteries connected with two jumpers, instead of twice as many 6V batteries with five jumpers.
You would wire them in "Parallel". That means positive post to positive post and negative to negative. Two 12 volt batteries wired this way doubles the capacity and amperage capability of the system. It does not cause any harm to the electrical system as the system sees them as one big battery.
Depends on if you want a series or parallel circuit. In a series circuit if you wire six 12 volt batteries together you will end up with 72 volts. Wire the same six 12 volt batteries together in parallel and you will still have 12 volts. In a parallel circuit you just wire all positive posts together and all negative posts together. In a series circuit you would wire positive to negative to increase the voltage with each battery added.
Connect the two batteries for the voltage needed. If they are 12 volt batteries and the lights are 12 volts, connect the batteries in parallel (negative to negative and positive to positive). If they are 12 volt batteries and the lights are 24 volts, connect the batteries in series (negative of one battery to positive of the other). Run a wire from batteries to first switch, then to two of the lights and the other switch (in parallel). From the second switch run a wire to the third light, then connect all three lights back to the battery.
You hook them in parallel pos to pos and neg to neg.