What happens when batteries are connected in parallel?

The fact

We received some confusing questions about the batteries connections in series, parallel, or series-parallel, and which one they should use?

Two methods of wiring batteries together are in series and parallel, these wiring configurations give us different voltages or amp-hour capacities. Connecting two or more batteries in series, parallel, or a combination of both parallel and series increases voltage, amp-hour capacity, or both. This article will discuss these battery connection configurations using schematics.

Before the formal introduction, you will first understand two basics.

• Battery terminals

In this picture, the terminal with the red backing and red protective cap is the positive terminal, and the terminal with the black backing and black protective cap is the negative terminal.

If you buy an enjoybot battery, the terminals come with M8 millimeter bolts, these are actually pretty good, you can definitely put a lot of ring terminals on here, they are long enough.

• Battery cable

In an independent power system, you would normally find an inverter and battery charger working together for the common goal of providing power. The cables connecting these devices provide the means for supplying or receiving power to or from batteries or DC distribution. Proper installation requires careful attention to the size of the cable, the proper use of terminals and overcurrent protection.

Cable sizing is calculated by determining the length of the cable and the amount of current that will flow through it. A label on the appliance, or the specifications sheet for that appliance, will provide you with this information. The longer the cable, or the higher the amperage, the larger the cable must be to avoid unacceptable voltage losses.

If you are purchasing an enjoybot battery, our recommended wire is 4AWG and we also recommend that you add a fuse to the positive side of the battery output to provide adequate overcurrent protection.

Connecting Batteries in parallel

Parallel is a mathematical term meaning side by side. When batteries are put in parallel, their positive terminals are joined together with a single wire to one part of the circuit, and their negative terminals are joined together with a single wire to another part of the circuit.

When batteries are wired in parallel, their amp hours add together but the voltage remains constant.

For example, two 12-volt 100 amp hour batteries wired in parallel are capable of providing 12 volts at 200 amp hours (100 amps x 2). Four 12-volt 100 amp hour batteries wired in parallel can provide 12 volts at 400 amp hours (100 amps x 4).

When are batteries connected in parallel?

When you need to double, triple or more the battery capacity while maintaining the same voltage level, you can connect batteries in parallel to achieve the desired capacity.

How are batteries connected in parallel?

If you are purchasing an enjoybot 12V 100AH battery, here are some parallel diagrams you can follow. This unit can connect multiple batteries, with a maximum of 10 batteries connected in parallel.

If you are purchasing an enjoybot 12V 200AH or 12V 300AH battery, here are some parallel diagrams you can follow. This unit can connect multiple batteries, with a maximum of 10 batteries connected in parallel.

Connecting Batteries in series

Connecting a group of batteries in series involves attaching one battery's negative terminal to another battery's positive terminal, then repeating the process until all batteries are connected. Lastly, attach a wire to the negative terminal of the first battery in your string and connect it to your application. Another wire would be connected to the positive terminal of the last battery in your string and connect to your application.

When batteries are wired in series, the battery systems overall voltage adds together but their amp hours (capacity) remain constant.

For example, two 12-volt 100 amp hour batteries wired in series are capable of providing 24 volts at 100 amp hours (12 volt x 2). Four 12-volt 100 amp hour batteries wired in series can provide 48 volts at 100 amp hours (12 volt x 4).

When are batteries connected in series?

When you need to double, triple, or more of the battery voltage while maintaining the same capacity or ampere hour (Ah) rating of batteries, you can connect batteries in series to achieve the desired voltage.

How are batteries connected in series?

If you are purchasing an enjoybot 12V 100AH battery, here are some series diagrams you can follow. You can refer to the wired connection to connect in series as 12V 100AH, 24V 100AH, 36V 100AH and 48V 100AH. We suggest that the max connection in series is: 4 pcs batteries to 48V.

If you are purchasing an enjoybot 12V 200AH or 12V 300AH battery, here are some series diagrams you can follow. We suggest that the max connection in series is: 4 pcs batteries to 48V.

Connecting Batteries in series-parallel

Series-parallel connection is a way to increase both the voltage and capacity of a battery system.

You can connect six 12 Volt 100 Ah batteries together to give you a 24 V 300 Ah battery, this is achieved by configuring three strings of two parallelled batteries. Alternatively, you can connect six 12 V 100 Ah batteries together to give you a 36 V 200 Ah battery, this is achieved by configuring two strings of three parallelled batteries. Both configurations have a total available energy of 7200 watt-hours (watt-hours = volts x amp-hours).

When are batteries connected in Series-Parallel?

When you need to increase the battery capacity or ampere hours (Ah) rating as well as battery voltages, you can connect in Series-Parallel.

How are batteries connected in Series-Parallel?

If you are purchasing an enjoybot 12V 100AH battery, here are some series-parallel diagrams you can follow. We suggest that the max connection in Series-Parallel is: 4S4P (four strings of four parallelled batteries).

If you are purchasing an enjoybot 12V 200AH or 12V 300AH battery, here are some series-parallel diagrams you can follow. We suggest that the max connection in Series-Parallel is: 4S4P (four strings of four parallelled batteries).

Batteries connection must be of the same voltage and amp hours

Batteries wired in series and parallel configurations must be of the same voltage and capacity rating(amp hours). For example, a 12-volt battery cannot be connected in series or parallel with a 24-volt battery, a 100 amp hour battery cannot be connected in series or parallel with a 200 amp hour battery. Mixing and matching voltages and capacities may cause problems that damage your batteries.

Mixing batteries from different brands can cause problems

Even if two batteries have the same voltage, capacity and chemistry, their voltage levels might be different due to slight variations in their manufacturing processes.

If batteries of different brands are connected in parallel or series, you are unlikely to see fireworks but may experience other issues, such as uneven or hazardous charging, ultimately shortened battery life. To avoid these problems, please use batteries of the same brand, voltage and capacity. If you do purchase another brand of battery, you can choose to component a new battery storage system, which is not a difficult task for most people.

Batteries connection safety tips

When working on circuits, The following tips can help you stay safe.

• When working with electrical circuits, do not touch the ends of wires that are not insulated, use rubber gloves if needed to insulate your hands from electricity and protect yourself.
• When connecting batteries, never connect the positive terminal of a battery with the negative terminal of another battery or you will create a short circuit that could lead to battery damage and fires.
• To avoid confusion and danger, make a diagram of your battery banks before attempting to construct them, always keep track of your connections, and always remember to be safe.
• To ensure that your batteries are charged properly and last as long as possible, always connect batteries of the same voltage level, same capacity and the same brand.

Conclusion

A battery's performance can be maximized by knowing the effects of both parallel and series configurations. Understanding how the results of your SERIES and PARALLEL connections vary and how to adjust the way you maintain your batteries will help you maximize their life span and performance.