UNDERSTANDING DC BATTERY CONNECTION CIRCUITS
When building a battery bank or any other configuration that requires many batteries, it is imperative to comprehend the distinctions between connecting batteries in series and parallel.
The batteries must be linked according to their intended application to sustain the specific load combinations. So which approach is suitable for a given configuration?
It’s an easy task if the load or equipment is simple and only needs one battery. However, one of the two setups can be necessary if the application needs more power than a single battery can provide.
The total number of watt-hours available is increased by both parallel and series connections, although in different ways.
The primary distinction between the two is that, although connecting batteries in parallel maintains voltage while increasing capacity, connecting batteries in series increases the output voltage.
A battery’s capacity, measured in ampere-hours (Ah), is the maximum amperage it can deliver in an hour, or the amount of energy charge necessary to allow 1 amp of current to flow for an hour.
But the overall energy available — measured in watt-hours — remains the same in both forms. To put it simply, two 12-volt batteries with 100 Ah capacities connected in series will provide 24 volts and 100 Ah of output, while the same two batteries connected in parallel will produce 12 volts and twice the capacity, i.e., 200 Ah of power. By multiplying volts by amp-hours, 2400 watt-hours of total energy are available for both setups.
i.e. · 12 volts times 200 amp hours equals 2400 watt hours (Parallel) 24 volts times 100 AH equals 2400 watt hours (Series)
PARALLEL CONNECTION CIRCUIT
The capacity of batteries increases while the voltage stays constant when they are connected in parallel. Two 12-volt, 100 Ah batteries, for example, will still produce 12 volts but have a doubled capacity of 200 Ah.
Any connected battery’s positive or negative terminal can be used to measure the voltage in parallel.
To reduce the possibility of causing damage to the batteries, every battery connected in parallel should have the same voltage and capacity rating, just like in series connections.
In theory, there is no limit to how many batteries can be connected in parallel. The drawback is that when the duration is increased, the current is also raised. As a result, stronger, more resilient cables and fuses are required; otherwise, there is a significant risk of fire without them.
Furthermore, the battery bank takes longer to charge the more batteries you add to it.
How batteries are connected in a parallel circuit
The first battery’s positive (+) terminal is linked to the next battery down the line’s positive (+) terminal.
In a similar manner, the first battery’s negative (-) terminal is linked to the following battery’s negative (-) terminal along the line.
Finally, the first battery’s positive and negative terminals — or the last battery’s — are linked to the load’s positive and negative inputs, respectively.
Benefits of Using a Parallel Configuration
Because of the higher capacity of a parallel battery bank, the primary benefit of this configuration is an improvement in the runtime of appliances or systems linked to it.
By using two batteries of the same type, an application that could operate for an hour on a 12v 100Ah battery will now run for two hours, and with three batteries, it will run for three hours, and so on.
Furthermore, unlike a series setup, in a parallel connection, if one battery fails, the other batteries will still power the application.
The Drawbacks of Parallel Configurations
Because voltage and current are inversely correlated, lower voltage results in increased current draw, which would increase voltage drop and necessitate the use of more expensive, thicker cables.
Moreover, parallel battery connections require more time to charge.
SERIES CONNECTION CIRCUIT
Series battery connections result in a doubling of voltage but a fixed ampere capacity. For example, two 12-volt, 100 AH batteries will simultaneously produce 24 volts of output voltage and 100 AH of amp hours.
Batteries should all have the same voltage and capacity rating before being connected in series; otherwise, there is a chance that the batteries could be destroyed.
How batteries are connected in a series circuit
This process is repeated down the line of batteries in the series by connecting the positive (+) terminal of the first battery to the negative (-) terminal of the following battery in the line.
Next, the load or application’s negative input is connected to the first battery’s free negative (-) terminal, and the load or application’s positive input is connected to the last battery’s free positive (+) terminal.
The total voltage from the connected batteries is now sent to the load or application.
Benefits of a Series Battery Bank Setup
Because voltage and current have an inverse relationship, wiring batteries in series lowers system current as voltage increases. Because there will be less current, thinner cables can be used, and the layout will have less voltage drop.
A system or appliance’s power consumption can be computed by multiplying its operating voltage by the current it consumes.
For example, an application requiring 240 watts at 12 volts will consume 20 amps (240 w/12 v = 20 a, or 12 v x 20 a = 240 w). Only 10 amps will be drawn by the same application if it’s a 24-volt appliance, i.e. (240 watts / 24 volts = 10a or 24 volts x 10 a = 240 watts).
A 24-volt application will draw less current since the higher the amps, the higher the current drawn. For larger battery power banks that need greater voltages, this can be helpful.
The Series Configuration’s Drawbacks
Because a series configuration raises battery voltages, lower-voltage devices, and applications cannot be connected to the battery bank without the addition of a converter to convert or step down the power. The majority of DC products and gadgets in homes and workplaces run on 12 volts (or less), so adding a converter or power step-down device may cost more.
The maximum quantity of batteries that can be connected in series is determined by the charge controller or inverter’s capacity. Additionally, it may depend on the battery manufacturer, who may advise against going over a specific limit when connecting in series.
SERIES-PARALLEL CONNECTION CIRCUIT
A series-parallel arrangement is the third alternative, which doubles both voltage and runtime. In order to accomplish this, multiple batteries are wired in series, and a parallel connection is made to another series battery bank.
In short, it’s a parallel connection between two independent series-battery banks. Since this is not as simple and a mistake could have disastrous consequences, it is best left to the expertise of a trained professional.
The scenario involves connecting two 12V 100Ah batteries in series to produce 24V 100Ah. Another bank of 24 volts and 100 AH batteries is made. One 24-volt 200 AH bank is created by wiring the two 24-volt 100 AH banks in parallel.
Which configuration should be adopted?
It entirely depends on the purpose for which the battery bank is meant to be used to determine which arrangement is preferable.
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