How to Connect 3 Batteries 12V to 36V (6 Step Guide)
Content
By the end of this guide, you will be able to connect three 12 volt batteries together to get 36 volts.
There are many occasions where connecting 3x12V batteries has really helped me, including on my boat and when starting my trolling motor. I think it's important to do it right so you don't fry the battery. Also, you can apply most of this logic to daisy chain more or fewer batteries.
Since 36V is the most common type of wiring, I will explain how to connect 3 12V batteries for 36V.
So to connect three 12V batteries to 36V batteries, follow these steps.
- Install or place all three batteries side by side.
- Connect the negative terminal of battery 1 to the positive terminal of battery 2.
- Connect the negative terminal of the 2nd battery to the positive terminal of the 3rd.
- Use a multimeter to check the battery voltage.
- Take the inverter/charger and connect its positive wire to the positive terminal of the 1st battery.
- Connect the negative cable of the inverter/charger to the negative terminal of the 3rd battery.
We will look at this in more detail below.
Difference between serial and parallel connection
A good knowledge of series and parallel connection will come in handy in many cases. For this demonstration, we are using a serial connection. However, additional knowledge will not hurt you. So here is a simple explanation of these two connections.
Series connection of the battery
Connecting two batteries using the positive terminal of the 1st battery and the negative terminal of the 2nd battery is called a series connection of batteries. For example, if you connect two 12V, 100Ah batteries in series, you will get 24V and 100Ah output.
Parallel connection of batteries
Parallel connection will connect the two positive terminals of the batteries. The negative battery terminals will also be connected. With this connection, you will get 12 V and 200 Ah at the output.
Easy 6 step guide to connect 3 12v to 36v batteries
Things You'll Need
- Three 12V batteries.
- Two connection cables
- Digital multimeter
- wrench
- fuse
Step 1 - Install Batteries
First of all, install/place the batteries side by side. Place the negative terminal of battery 1 next to the positive terminal of battery 2. Study the above image for proper understanding.
Step 2 - Connect the 1st and 2nd Batteries
Then connect the negative terminal of battery 1 to the positive terminal of battery 2. Use a connecting cable for this. Loosen the screws on the battery terminals and place the connection cable on them. Next, tighten the screws.
Step 3 - Connect the 2st and 3nd Batteries
This step is very similar to step 2. Connect the negative terminal of the 2nd battery to the positive terminal of the 3rd. Use a second connecting cable for this. Follow the same process as in step 2.
Step 4 - Check the voltage
Take your multimeter and set it to voltage measurement mode. Then install the red probe of the multimeter on the positive terminal of the 1st battery. Then install the black probe on the negative terminal of the 3rd battery. If you have followed the above process correctly, the multimeter should read above 36V.
Step 5 - Connect Inverter and First Battery
After that, connect the positive wire of the inverter to the positive terminal of the 1st battery.
Be sure to use the correct fuse for this connection. Using a fuse between the power supply and the inverter is ideal for safety. (1)
Step 6 - Connect inverter and 3rd battery
Now connect the negative wire of the inverter to the negative terminal of the 3rd battery.
A Few Things to Consider When Connecting Three 12V Batteries in Series
Even though the above process is simple, there are a few important facts to keep in mind when connecting three 12V batteries together.
Battery selection
Always select three identical batteries for this task. This means that you must buy three batteries that are made by the same company or in the same way. In addition, the capacities of these three batteries must be the same.
Don't confuse batteries
Never use a new battery with a used battery. Battery charge may vary. Thus, it is better to use three new batteries for your trolling motor.
Check batteries before starting work
Before making connections, check the voltage of the three batteries individually with a digital multimeter. The voltage must be above 12V. Do not use weak batteries for this process.
Keep in mind: One bad battery can ruin the whole experiment. So, make sure this doesn't happen.
Should I choose a 36V battery or three 12V batteries?
You might think that using one 36V battery is much better than using three 12V batteries. Well, I can't argue with that point. But I can give you some pros and cons of using three 12V batteries.
pros
- If one of the 12V batteries fails, you can easily replace them.
- The presence of three batteries helps to distribute the weight of the boat.
- For three 12V battery systems, you don't need a special charger. But for 36-volt batteries, you will need a special charger.
Cons
- Too many connection points in the three 12V battery connections.
Tip: Three 12V lithium batteries are the best option for a trolling motor.
F.A.Q.
How to calculate the power of three 12 V, 100 Ah batteries in series connection?
To calculate power, you need the total current and voltage.
According to Joule's law,
Thus, you will get 3600 watts from these three batteries.
Can I connect three 12V 100Ah batteries in parallel?
Yes, you can connect them. Connect the three positive ends together and do the same with the negative ends. When three 12 V and 100 Ah batteries are connected in parallel, you will get 12 V and 300 Ah at the output.
Can a lithium ion battery be connected to a lead acid battery?
Yes, you can link them together. But you may have some problems due to the voltage difference. The best option is to connect them separately.
How many batteries can be connected in series?
The maximum number of batteries depends on the battery type and manufacturer. For example, you can connect four Battle Born lithium batteries in series to get 48V.(2)
Summing up
Whether you need 24V, 36V or 48V output power, you now know how to connect batteries in series. But remember, always use a fuse between the power supply and the inverter/charger. This will keep your trolling motor safe. The fuse must be able to withstand the maximum current of the power supply.
Take a look at some of our articles below.
- Which wire to connect two 12V batteries in parallel?
- How to Use a Cen-Tech Digital Multimeter to Check Voltage
- white wire positive or negative
Recommendations
(1) power source - https://www.britannica.com/technology/power-source
(2) Lithium batteries - https://www.sciencedirect.com/topics/chemistry/
lithium ion battery
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