Batteries are usually made with an eye to working with a certain standardized load. So, there are batteries that ensure the functioning of microcontrollers - they have a voltage of 5 V. To work with engines, batteries are used that can provide 12 V or 24 V. And what if I need to get 60 V? Try to find a battery with such voltage. In this case, connecting the batteries in parallel can help us. What gives such a move? What is the scheme of such a connection? What are the special aspects of this move? How are batteries connected in parallel ? The diagram for this action looks like? We will consider all of these, as well as a number of other issues, within the framework of this article.
What gives parallel battery connection in practice?
So, for a start we will outline the general scheme. Connecting the batteries in parallel provides for such an approach that all positive terminals are connected to a specific point on the electrical circuit, which is called the plus. Similar needs to be done with negative conclusions. Only they are connected to the minus. Why do we need to do this? In the end result, we have the voltage that one battery has (the situation is considered that we have the same batteries). But here the capacity of the resulting design will be equal to the sum of this parameter of all
power sources that are in the circuit. Electric energy is equal to a unit value times the number of devices. This, however, does not depend on whether the connection is used - parallel or serial.
Why connect batteries to a battery?
The result of such actions we examined. And why do we need to connect the batteries in parallel? Any electrical system or device suffers ohmic losses when part of the energy is converted into heat and useful work does not occur. This is due to the impossibility of obtaining a 100% efficiency. At the same time, one can recall from the course of school physics that the higher the voltage, the less current at the same power and less significant ohmic losses. Thus, the higher-voltage batteries we use, the better the result. But even with this approach, the capacity of one battery may not always be enough. In this case, you can replace it with a high-capacity battery. But this is not always convenient, and sometimes it’s easier to just put another power source and use a parallel connection of the batteries so that they support some kind of system longer.
Is this option suitable for power supplies of various capacities?
The parallel connection of different batteries is not dangerous if we consider the problem from the point of view of voltage. Nothing terrible can happen to the
battery terminals . The discharge or charge of the power sources will occur synchronously due to the nature of the connection. But if you touch on the topic of currents, then here is a little more complicated. So, it is necessary to ensure that it does not exceed a certain value, which is indicated directly by the manufacturer.
The most common indicators are 100 A and 130 A. The reason for this limitation is that the terminals themselves will not be able to transmit such current (although theoretically the battery itself can do this). But this is the very top, which can only be a matter of seconds. Let's look at a more realistic use case.
Technical limitations
If you look at the technical specifications of the allowed current, then usually here you will not see large numbers. So, usually you should not allow batteries to be connected together, whose capacities vary from 5 to 25 times (this is usually the case). Moreover, this aspect must be carefully studied, since even a short circuit is possible. The risk of its occurrence is in the range of 15-70 capacities of the smallest battery (depends on the brand and technical implementation). Roughly speaking, the less time they function, the higher the current value you can work with. So, if the difference between them is 5 times, then this means that they will be able to function all the time (theoretically). But if we work with a 20-fold difference, then it is desirable that the score be for seconds. Many power supply manufacturers indicate current thresholds for their products. For example, 2.6 A.
Why are there limitations?
Let's further study the topic of parallel connection of batteries of different capacities. It was previously stated that manufacturers recommend restrictions in Ampere units, although in practice this limit can be exceeded many times. Why is that? To do this, consider the very structure of the battery as an example of a
lead-acid battery. This choice is made due to the prevalence of power supplies of this type.
So, for the successful course of the necessary electrochemical reaction, it is necessary to provide it with a high-quality electrolyte. It is also important to perform the process in the upper layers and the removal of products. The active mass of the battery plates helps a lot in this. Indeed, thanks to it, the substance participating in the reaction is easier to feed and discharge. But as the “resource materials” move down, things begin to happen more slowly. Actively affects the fact that sulfur appears in the electrolyte. Therefore, connecting the batteries in parallel is preferred only when the battery is charged. The lower the real voltage indicator, the more dangerous the operation of power supplies of different capacities. Therefore, it is desirable to ensure timely nutrition. It is best not to let the capacity fall below 1/3 of the nominal value.
Features of parallel charging
At the beginning of this process, it is preferable to transfer a fairly large charging current. After all, first the surface of the battery will be restored, and then its lower layers. At the same time, it is desirable to reduce the current, since the intensity of the electrochemical reaction decreases, as a result of which, due to the large amount of energy, the electrolyte can “boil” (its decomposition will occur).
If we consider one of the most popular types of batteries - lead-acid, then if you violate this requirement is unlikely to immediately fail. But his life is clearly significantly reduced. In general, if we talk about charging power supplies, then it is worth focusing on the fact that it is desirable to use factory equipment. If you exploit something else, then certain aspects may not be taken into account (or incorrectly taken into account), which will turn into problems in the future.
About batteries and capacity
Let's go deeper into the parallel connection of different batteries (as well as the same ones). It must be understood that if the total current does not exceed the established limits, then problems and dangers will not appear.
Let us consider the connection of two batteries in parallel at 2 A, when they are from the same batch and are charged with a current of 2 * 2 = 4 A. There are no dangers here, because thanks to the same design, the currents will be divided proportionally. And no boundaries will cross.
Now let's take power supplies where there is a significant difference. When the current exceeds the limits set by the manufacturer, it will flow through the battery, despite the fact that it is not designed for this. We think there is no need to talk about the result. This applies to everyone, not just lead-acid batteries. Even if you want to make a parallel connection of Li-Ion batteries, which are considered to have increased reliability, do not neglect safety measures.
We calculate the necessary indicators
So, we need to provide a significant amount of current using parallel-connected batteries. How to find out what we need? To do this, you can use the special formula, which now will be given:
T = RTOEP * CAPOT
And now the decoding of the formula:
T is the current that will turn out. It is necessary that it coincides with the desired result.
RTEEP - discharge current of a battery unit. That is how much one battery can give.
KEPOT - the number of batteries of one type.
In amateur radio practice, it can be difficult to obtain the necessary values. The same formula will make achieving the goal easier.
Looking for other ways to turn on batteries
We paid considerable attention to parallel battery connection. We hope that this will help to solve the tasks. But if during the review of the article you got the idea that the solutions described here are not suitable for any particular case, we suggest that you familiarize yourself with the following:
- Serial connection. Roughly speaking, we are increasing the voltage that uninterruptible power supplies will give us .
- Mixed compound. In this case, there is a simultaneous increase in both current and voltage. But this is a very complex scheme to build.
Conclusion
Finally, I want to give a few parting words. First of all, observe safety precautions. Also, before working with batteries, it will not be superfluous to familiarize yourself with the instructions and recommendations presented by their manufacturers. This will avoid situations that could adversely affect the life of the power sources. Also, be especially careful when working with batteries that provide significant performance. Indeed, in such cases, the risk of electrical injury becomes very likely. And with weak elements do not need to be treated lightly.