Wiring Batteries in series: Differences and Effects

While digging information on lithium batteries, the terms series and parallel are often encountered. If you find yourself asking the question about the differences between series and parallel in terms of batteries, here is a pretty simplified explanation on what it is and what happens with series and parallel connection. If you are new to the topic and you do not know absolutely anything about the battery connections, it may be confusing for you and you would benefit from the discussion here.

What is the difference between series and parallel connection of batteries?

Before knowing about the series and parallel connection of batteries, you may want to know about the battery tank. The battery tank is what results when you connect two or more batteries together for a single application. By connecting the batteries, the voltage or amp-hour capacity or both is increased and it results in more power and energy.

There are primarily two ways to connect two or more batteries: series connection and parallel connection. Series connection involves connecting two batteries together to increase the voltage of the battery system byt keeps the amp-hour rating the same. In series connection, each battery should have the same voltage and capacity rating. If it is not so, it may result in damaging the battery. Series connection is established by connecting the positive terminal of one battery with the negative terminal of another until you get the required voltage. The batteries should also be charged individually to avoid dissimilarities.

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For example, connecting two batteries with 12 V in series would give you a bank of 24 V system, however the total capacity would remain the same as 100Ah as it is for individual batteries. This is the case of batteries connected in series connection.

Parallel connection involves connecting two or more batteries together to mainly increase the amp-hour capacity of the battery tank. The voltage in parallel connection remains the same. In order to conncet batteries in parallel, the positive terminals of the batteries are connected together via a cable and the negative terminals are connected together until the desired cpapcity is reached. Paralle connections are useful for providing power to the equipment for a longer duration. It is not meant for increasing the voltage output. Batteries connected in parallel also require longer time for charging.

To better understand parallel connections, lets take an example. If you have two 12 V batteries with amp-hour capacity 100Ah and upon parallel connection, the voltage will remain the same of the battery bank, the amp-hour capacity will become 200Ah.

It is important to understand the differneces between series and parallel connection and what you want to achieve, increase in voltage or amp-hour capacity. Depending on series or parallel connection, the performance of the battery bank amy vary.

What happens when you connect batteries in series?

Connecting batteries in series helps in achieving higher voltage. The voltage of each cell is added to derive the total terminal voltage. While connecting batteries in series, it is recommended to use batteries of the same type and same capacity and not mix batteries. Series connection is common in portable equipment which require higher voltage for operation. Series connection is often used with car batteries to increase the voltage.

Does wiring batteries in series increase voltage?

Let's say you have a battery I?with a voltage?v0. Battery?I?is the only battery in a circuit with a resistor?R?also in the circuit. Resistor?R's?resistance is so high, that battery?I?is hardly able to generate a tiny current through the circuit.?v0?just isn't enough to produce a significant current through resistor?R.

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But now, let's say you add battery?II?and battery III?in series to battery?I, with resistor?R?still in the circuit, too. Batteries?II?and?III?also have voltages of?v0.

In each battery, within a closed circuit, an electron really wants to leave the anode while another electron from the wire enters the cathode. Battery?I?added to resistor?R, has a voltage?v0?which isn’t enough to make this happen. But now, with all 3 batteries in series, not only does battery?I's?voltage want to naturally push an electron away from it's anode, but battery?II's?cathode also is exerting a pull on an electron from battery?I's?anode, too! And with just a voltage of?v0, how is battery?II?able to give up an electron from its anode to so that it can receive one in its cathode from battery?I? Because it also feels a pull from battery?III's cathode, from battery?III's v0! Battery III finally feels the pull from Battery I’s cathode. This is how batteries in series increase voltage.

Excess electrons are unstable and loaded in the negative side of a battery and stored because the electrolyte will not allow them to the positive side where they can be accepted. There has to be a conductor between the negative and positive to allow them to flow or they will stay there, stored until they leak out slowly and there is no longer a potential (difference) between the two. When two batteries are added in series, the potentials (voltage) are added because since the same charge is moved twice each time through the same voltage (potential) the total work done is 2 * V but the current flow remains the same. With the added voltage of batteries in series, the final cumulative voltage is higher.

So, putting the batteries in series results in increased voltage and enhances the power of the device. Parallel connections increase the total amp-hour capacity and not the voltage. So, devices which require higher voltage specially portable devices like laptops, cars, scooters, vehicles mostly have some sort of series conncetion to charge up the equipment.

Connecting batteries in series results in increase in voltage and in parallel results in increase in amp-hour capacity.