You have probably seen the terms series and parallel. We are frequently asked the question “what is the difference between batteries in series and parallel”, “Can batteries be connected in series?” and similar questions. It can be confusing if you’re new to solar lithium batteries or batteries in general, but we hope we can help you simplify this.
1. Basic principles
Let’s start at the beginning. The battery bank is the result of connecting two or more batteries together for a single application (ie a sailboat).
What is obtained when joining the batteries?
By connecting batteries in series and parallel, you increase either the voltage or the amp-hour capacity, and sometimes both, ultimately allowing for more power and/or energy.
1) The first thing you need to know is that there are two main ways to successfully connect two or more batteries: the first is called a series connection and the second is called a parallel connection.
2) Series connections involve connecting 2 or more batteries together to increase the battery system voltage, but maintain the same amp-hour rating.
Where to find reliable lithium batteries for sale? It is recommended that you can choose some stores with a large number of evaluations in the Amazon store, and most of them are well-received stores to buy the lithium battery you want. Secondly, it is also a great choice to choose to buy on the official websites of some big brands in the solar field. Because these companies have been in the field of lithium batteries for many years and have rich experience in research and development, their products are often more guaranteed. For example Renogy.
Battery connection in series
Keep in mind that in series connections each battery must have the same rated voltage and capacity, or you may end up damaging the battery.
1) To connect batteries in series, connect the positive terminal of one battery to the negative of another until the desired voltage is reached.
2) When charging batteries in series, you must use a charger that matches the system voltage.
3) We recommend that you charge each battery individually, with a multi-bank charger, to avoid imbalance between batteries.
In the image below, there are two 12 volt lithium battery connected in series making this battery bank a 24V system. You can also see that the bank still has a total capacity of 100 Ah.
Battery connection in parallel
Parallel connections involve connecting 2 or more batteries together to increase the amp-hour capacity of the lithium ion solar battery bank, but their voltage remains the same.
1) To connect the batteries in parallel, the positive terminals are connected to each other by one cable and the negative terminals are connected to each other by another cable until it reaches the desired capacity.
2) A parallel connection is not designed to allow your batteries to power anything above their standard voltage output, rather they increase the duration for which they could power equipment.
3) It is important to note that when charging batteries connected in parallel, the higher amp-hour capacity may require a longer charge time.
In the example below, we have two 12V batteries, but you can see the amp hours increase to 200 Ah.
Can batteries be connected in series and parallel?
Standard product line: Standard lithium batteries can be wired in series or parallel depending on what you are trying to accomplish in your specific application. The series and parallel battery data sheets indicate the number of batteries that can be connected together, by model. We generally recommend a maximum of 4 batteries in parallel for standards, however there may be exceptions that allow more depending on your application.
High Performance Series: The HP Battery Series can only be connected in parallel and allows up to 10 batteries in parallel. It is important to understand the difference between series and parallel batteries, and the effects they have on the performance of your battery bank.
Whether you’re looking for an increase in voltage or amp-hour capacity, knowing these two settings is very important to maximizing lithium battery life and overall performance.
2. What is the difference between series and parallel battery connections?
In SERIES CONNECTION, batteries of similar voltage and amp-hour capacity are connected to increase the voltage of the battery bank. The positive terminal of the first battery is connected to the negative terminal of the second battery, and so on, until the desired voltage is reached.
Final Voltage is the sum of all battery voltages added together, while Final Amp-Hr, Cranking Performance, and Reserve Capacity remain unchanged.
In PARALLEL CONNECTION, batteries of similar voltages and capacities are connected to increase the capacity of the battery bank. The positive terminals of all the batteries are connected to each other, or to a common conductor, and all the negative terminals are connected in the same way.
The final voltage remains unchanged, while the bank capacity is the sum of the capacities of the individual batteries in this connection. Amp-hours, cranking performance, and reserve capacity increase while voltage does not.
3. Series vs parallel battery definitions
In this section we will show you the definitions of batteries in series and parallel:
COLD CRANKING AMPS (CCA): The maximum amps that can be continuously drawn from a battery for 30 seconds at zero degrees F before the voltage drops too low to use (7.2 volts). This term is used only for engine starting batteries and has little to do with amp hour capacity or deep cycle batteries. This rating will also appear on many deep cycle marine batteries.
Damping Amplification (CA)
A fairly optimistic market-driven rating, especially for “economy” or “value priced” batteries. The same CCA, but a temperature of 32 degrees F (0 C).
The Battery Council International standard rating is CCA, at 0 degrees F (approximately -18 C). The AMC, or Marine Cranking Amplifiers is basically the same thing in AC. CCA is about 20% less than CA or MCA.
Reserve Capacity (RC)
Reserve capacity is sometimes used to evaluate deep cycle batteries ( For example rv batteries and marine batteries are frequently used on daily life). It is the number of minutes a battery can maintain a useful voltage at a constant discharge rate of 25 amps at 80 degrees running heavy loads, although most batteries also have charts showing AH capacity at different discharge rates. AH is approximately equal to RC X 0.60)
4. Differences between batteries in series and parallel
There are 2 different ways to connect the batteries to form a larger bank.
1) Parallel Connections: These connections are used when you want to increase the amperage of the battery bank. Most often, parallel-only connections are found on 12-volt systems. The connections on this type of battery bank go positive to positive and negative to negative, when you connect this way you double your amps.
2) Series Connections: This type of connection is used when you need to increase the voltage of the battery bank. You’ll find these types of battery connections on all types of battery banks, including 12-volt, 24-volt, and 48-volt systems. The connections on this type of battery bank are different than parallel. Your batteries will connect from positive to negative, linking the batteries together to increase the voltage of your battery bank.
In some cases when you have a larger battery bank you will commonly have both series and parallel connections on your battery bank.