Is it possible to install a larger battery? Is it possible to install a high-capacity battery in a car? One can imagine this analogy
When purchasing a battery, many people have natural questions about whether it is worth choosing a battery, for example, with a reserve, a larger capacity? Or with higher charging currents? Many people dream of getting rid of the numerous problems that battery maintenance or some problems with it promise them at once. At the same time, there are also specific fears that if you install a more capacious battery on a car than is required according to the instructions for the car, then it will not be charged from the generator, and if with a smaller capacity, then it will boil. Under any such circumstances, the battery will fail much faster and stop working adequately.
Experts point out that this style of thinking has a mythological nature. The voltage generator, which makes up the car’s power supply network, maintains a stable constant voltage in it, regardless of how much current this on-board network consumes. Accordingly, the voltage that is output to the battery always has constant characteristics. In fact, the current that goes to charge the battery from the on-board network is determined only by the battery itself, and not by the generator or the state of the network.
When the car engine starts, part of the energy from the battery goes to the needs of the starter, and the voltage at its terminals drops. The voltage difference between the network and the battery increases and the charging current becomes stronger, but only until the voltage equalizes. In the first seconds after the engine was started, the current in the battery rose by five to ten amperes, and after some time it dropped to a stable half-ampere. If the engine ran for an hour or two, then the battery supply current dropped to 0.3 - 0.1 amperes. Many believe that this is generally a type of leakage current due to the fact that the battery efficiency is far from 100%.
The generator indicates the maximum current it is capable of generating. However, he is not able to do this all the time. Moreover, the generator produces the current required by on-board consumers in the network, including the battery. Thus, any generator, no matter what power it develops, will give the battery exactly the amount of current that it “asks for”. A normal full charge will occur only to the amount for which the battery is designed, and no more. At the same time, you need to understand that the battery consumes a very small amount of current - it can be considered the smallest consumer of all.
Many motorists are of the opinion that the car battery must strictly comply with the stated standards - or problems will arise. Specifically: a battery with a lower capacity will boil during charging, a battery with a higher capacity will remain undercharged. The conclusion from this statement is that the battery life will be significantly reduced. Why is this statement false?
The principle of operation of the on-board power supply network
Each car has a power supply network, and it operates according to the following scheme: energy is supplied from the battery to the car generator, starter and on-board network (equipment).
To operate the starter, energy is consumed only during the time when the engine starts. However, it is worth considering that a small percentage of the battery’s energy is spent on one start. In absolute numbers, this is no more than 2 Amperes out of the available 40 or more. True, in the cold season this figure increases.
The generator's job is to replenish the energy lost when starting the engine, that is, to charge the battery. As for the voltage in the power supply network, it is maintained at a relatively stable level (about 14 volts).
The current that is involved in the network is the ratio of the voltage to the resistance value. The first indicator is the difference between two values, the voltage in the on-board network minus and the battery. And the battery resistance is at a constant level.
When the engine starts running, the battery loses a certain percentage of its charge and the voltage at its terminals drops. This leads to the voltage difference described above. Also, the charging current increases.
If you analyze these indicators, it becomes clear that immediately after the engine starts, the current level increases to 10 Amperes, but then decreases many times. When the engine operates for a long time (more than an hour), the charge current level is limited to one ampere, the average value corresponds to several amperes.
Key Takeaway: The capacity of the battery used may vary.
The process of bringing the engine into working condition requires energy, which is almost always the same, regardless of the capacity figure. That is, for the generator this figure is not of fundamental importance. The voltage in the on-board network is important. The battery uses a small percentage of the power available from the generator. That is, you can safely choose a battery that has a large capacity. It will just take longer to charge it. But in this case, the battery discharge time increases. The main thing is that the voltage of the battery and on-board network do not change.
Therefore, when choosing a battery, you must follow the following rules: the capacity can be any - the main thing is that it provides the starting current that is necessary.
What are the differences between batteries of different capacities? Let's show it with a practical example
The current indicators are equal - this is typical for modern machines. A battery with a smaller capacity will be recharged faster than a battery with a larger one - that’s the only difference.
Let's say the car has a 55 Ah battery. Let's take two batteries with different indicators. The first is less than the base one - for example, at 50Ah. The second - at 70 Ah. Let's imagine that they were completely discharged. After 55 hours of charging with a current of 1 Ampere, the first battery will be fully charged and will begin to boil, the second one at 70Ah will still need to be recharged. After 70 hours of charging, the second battery will also boil, and the first will be in a boiling state for already 15 hours. But you need to take into account the fact that the generator’s task is not to charge, but to recharge the battery to the required values. And the 1% of capacity consumed at startup is compensated in both cases in approximately the same time - no matter how different the capacity is.
What factors need to be taken into account
1. The power characteristics that distinguish a particular generator are confused by many with the indicators necessary when choosing a battery. But the characteristics indicate something else: the maximum current at which the generator will operate. But practice shows: when recharging a battery, it uses a small part of this power (tens of times less).
2. How much electrical equipment is installed on a particular machine. If there are no additional options, a small amount of energy is used for the on-board network. With energy-intensive equipment, these figures will naturally increase.
3. You need to take into account the dimensions (dimensions) - otherwise the battery simply may not fit or may not be fixed in the place allocated for it.
4. Operating conditions. At low temperatures, it makes sense to choose a battery with a larger capacity.
So, in addition to a battery of the recommended capacity, your car will be perfectly suited to a battery with a slightly larger capacity, provided the other parameters are met. But you shouldn’t take a battery with a smaller capacity, as it will discharge faster in extreme conditions and may fail.
Very often I receive letters on my website about car batteries. Especially, one of the most popular - is it possible to install a battery on a car with a larger capacity? THAT is, the capacity of your battery is, for example, 55 Ah (Ampere * hour), and you want to install a battery with a capacity of 70 Ah! What will happen and can it be done? Let's talk about it...
I’ll say right away that there are a lot of myths about this issue. For example - The car is equipped with a 60 Ah battery (according to the instructions), if you put it at 50 Ah, it will boil, and if you put it at 70 Ah, it will not be charged!
This is wrong! You can install both batteries on your car, nothing bad will happen, the most important thing is that they fit in the regular place of your car. After all, more capacious batteries are larger.
And now in more detail
If we don’t go into deep technical details and speak in simple language (may the electrical gurus forgive me), the car network has a certain relationship: battery – generator – starter – vehicle’s on-board network. The vehicle's on-board network consumes little energy (ideally) if there is no additional energy-intensive equipment. What remains is the generator - battery - starter. The starter consumes energy only when starting the engine (it does not work further); it should be noted that during one start of a passenger car, on average, about 1 - 2 Amperes of energy from the battery are consumed (in cold weather it can be much more).
After, the generator must make up for the loss of battery current when starting the engine, that is, recharge the battery. Usually the voltage in the on-board network is about (13.8 - 14.2 Volts), it is almost constant, this is obtained from the voltage of the on-board network minus the voltage of the battery itself (which is almost constant).
The generator also has its own power characteristics - there are 40 A and 70 A and 80 A, etc., but this does not indicate what kind of battery this generator is designed for. This characteristic indicates the maximum current that the generator can produce per hour. But the current consumed by the battery (for recharging) is tens of times lower than what the generator produces.
What does this mean in practice?
If you install a battery with a larger capacity, but with the same voltage, it will simply take longer to charge, albeit not significantly, but longer! However, this means that it will take longer to discharge! This is especially true in cold weather; the current of the “larger” battery will be enough for a greater number of “cold” starts!
If at all on your fingers...
Imagine - there are two barrels of 55 liters and 70 liters (barrels are batteries). Both are equally filled with water with the same force (voltage in the car network), the barrels cannot be filled with water immediately (that is, supply 55 and 70 liters in one second, this is simply not realistic and can destroy the barrel, and this is not necessary), but need to be filled at a decent (uniform) water pressure so that the filling of the barrel is uniform (this uniform water pressure is uniform charging of the battery), then one barrel will fill faster than 55 liters, the other slower than 70 liters. But there will be more water in another barrel (70 liters) and it will last longer. What happens is that batteries are like barrels, only they are filled with energy, the capacity is measured in A/h, some have 55, some have 70, etc. With the same currents (and now almost all cars have the same current), one will fill with energy faster, and the other longer. THAT IS ALL THE DIFFERENCE!
In conclusion, I want to say that many people want to install a battery with a capacity that is not significantly larger, for example, a factory 55 Ah, but they want to install 60 or 63 Ah - guys, it’s okay, install it! This will not have any effect on the vehicle's on-board network, battery - generator or starter.
Now let's watch a short video.
That's all, read our AUTO SITE.
There is always an opinion that if a car is equipped with a 63A/h battery according to the manual, then if you put 55Ah, it will boil, and if it is 90A/h, it will not be charged enough. In both cases it is assumed that it will fail in a short time. To our joy this is not the case. Let's think about it.
The vehicle's on-board power supply network, when the engine is running, is a device referred to in radio electronics as a “voltage generator” (with some stretch this is true). Those. Regardless of the current consumed by the equipment, it maintains a stable voltage in the network. Then we claim that the voltage supplied to the battery is always constant (like 13.8-14.2 volts). And according to Ohm's law (some people learn it at school), the current in a circuit is determined by the ratio of voltage to circuit resistance.
The voltage in our case is the difference (on-board voltage minus battery voltage). The battery resistance is almost constant, i.e. The charging current is determined by the battery's own voltage.
Now we finally start the engine. When starting, the battery loses a certain amount of energy and the voltage at its terminals decreases. The above voltage difference increases and the charging current increases. But you need to understand that the current that the battery takes into itself is determined by the state of the battery itself, and not the car’s electrical system.
A little about the current values. Once upon a time I measured the charge current on a VAZ-2106. So, in the first 0-15 seconds after starting, the current in the battery rose to 5-10 amperes, then within a couple of minutes it dropped to 0.5 amperes. On an engine that had been running for an hour or two, this current was 0.1-0.4 Amperes. Apparently this is a certain leakage current during charging, which, by the way, indicates that the battery is not 100% efficient. Although that battery was about 3 years old, plus it was domestic. But the main thing here is to understand that the average charge current does not go beyond 1-2 amperes.
Now about generators. The current value on them only indicates the maximum current that they can provide, but this does not mean that they always provide it. They always provide the current that consumers require.
AND NOW CONCLUSIONS: In the case when the battery “requests” 1-2 Amperes from the generator, both a 35A generator and a 200A generator will provide them equally well. Therefore, if you want, install any battery on any car. Everything will be charged. The main thing is that the voltage of the battery and the on-board network is the same.
Although in fairness I will say that you can choose a pair of car batteries in which the battery will not be fully charged. This is a pair in which the average charging current of the battery will be greater than the maximum current of the generator. But this does not apply to us, because... I showed you that the average battery charge current is several times less than the current of even one low-beam headlight lamp. So the battery will only be undercharged in a car whose generator cannot run even one headlight. Or in other words, the battery is such a small consumer in automotive electrical systems, probably smaller only than the clock in the dashboard.
And now for the funny unscientific evidence. Let us assume that the fact of overcharging and undercharging takes place. Then:
1. Imagine a fence in a field. On one side of the fence there is a huge ZIL (truck) and a small OKA. 2 pairs of holes were drilled into the fence and two pairs of wires were inserted into them. One pair comes from the truck's on-board network, the second from the OKI on-board network. The engines of both cars are running and spinning their generators. Being on the other side of the fence, we do not see which pair comes from, but with the tester we see 13.8 volts on each pair. We connect to each pair an identical battery designed for OCU. Now, if we claim that the one connected to the truck will be recharged, then how will this battery “determine” that it is connected specifically to the truck? After all, in both cases there will be the same voltage and the same charge current. Funny, isn't it?
2. Let's develop the situation to the point of absurdity. We have two cities. One is powered by a 1 GW power plant and the other by 1000 GW. In one city, Masha plugs her iron into the socket at home, and in another, Kolya turns on his iron. Question: which of them will burn out the iron right away? Probably Kolya, because his power plant is 1000 times more powerful! Does it make you even funnier?
Thus, we have proven that the consumer current is determined by the consumer itself at a constant supply voltage and does not depend on the generator.
So when choosing a battery, there is a simple rule - the battery capacity can be any, provided that it provides the necessary starting current to the starter. But no less. More? Yes, please, just stop on time, otherwise the battery won’t fit in the trunk. By the way, where it’s cold, it makes sense to install a more powerful battery, because It is known that as the temperature decreases, the actual capacity of the battery decreases.
More about the balance of battery capacity/generator current.
Question: “I put a 120 Ah battery on a Zhiguli instead of 55 and will it be recharged to its 120? This is recharging, not charging. This is the current limit."
Since the question is asked quite often, I considered it necessary to put THIS in the title of this conf. So, the answer: This is the most typical misconception this season (like the letters ZZZ - galvanizing the body on a VW).
The fact is that there is a misunderstanding of the processes of discharging/charging batteries. In order.
When starting the engine, some energy is wasted. Almost the same, regardless of battery capacity.
For example, 0.5 ampere-hour (less realistic). The starter is “absolutely unaware” of how many ampere-hours there are in the battery - he is “interested” only in what he needs. Well, it’s like “it doesn’t matter whether the depth is 3 meters or 3 kilometers - you sink the same way.”
The engine started and the generator started working. So, for the generator it is also deep purple how many ampere-hours there are in the battery - it is only “interested” in the VOLTAGE in the on-board network. And the downward deviation of the battery voltage relative to the “usual generator”. And the battery begins to “eat” energy. And he eats not incomprehensibly how much, but exactly as much (battery efficiency is almost 100%) as he lost when starting the engine. Those. the same 0.5 ampere-hour. And he eats at such a pace as the balance of power inflow/output of electricity allows.
One can imagine such an analogy.
There are 2 buckets of water - 10 liters and 5 liters.
The housewife sometimes needs a liter - then she tops it up. So what difference does it make - how much water is in the bucket?
Is the owner interested in the water level? (battery voltage) Then the water level at low tide of one liter will decrease not depending on its quantity, but on the DIAMETER OF THE BUCKET (starting current of the battery)! But it can be made different! You can have a wide, shallow bucket (high discharge current with low capacity), or you can have a narrow and high one (large capacity, but low current - these are 60Ah 180A batteries, by the way). And the large capacity of real batteries (an order of magnitude more than required) is needed mainly so that the starting current is higher. A bucket can be made of any shape, but a battery cannot be made “wide and shallow” - these characteristics are really strongly connected and you can achieve “width” only by making it “depth”.
Yes, there are still people who believe that if you put a barrel under a water tap instead of a bucket, the tap will not withstand such a container and will break...
Bottom line - you can install at least a 500A/h battery - a 55-amp generator will cope with it. Just a question - is that much necessary?
When charging a completely empty battery with the same current, for example 1A, after 50 hours the 50th will already boil and the 80th will still remain undercharged. And after 80 hours, the 80th will also boil, and the 50th will boil for 30 hours. And when charged with a different current of 10% of the capacity of each, they will boil simultaneously after 10 hours. Therefore, when charging, the current is selected not in amperes, but as a percentage of the capacity. And the purpose of the generator is not actually charging the battery, but recharging - returning what was “borrowed”, for example, to start the engine or after landing with music or headlights. And the car should initially have a fully charged battery of any capacity. That is, if, when starting the engine, the 50th battery uses up 1% of its capacity, the 80th only 0.625%, therefore they will be recharged back at the same time by the generator. But a “loan” of eighty will still give more.
If you put a battery in your car that is larger than what is stated in the “book” included with your car, it will always be “undercharged,” and if it is too low-power, it will definitely boil. In both cases, you won’t live long - in approximately this spirit, garage and Internet “experts” usually intimidate inexperienced car owners who are faced with the need to replace a failed battery for the first time. Who first released this strange “horror story” to the masses will never be known. But we can say with certainty that this man not only had no idea how the main electrical units in the car work, but he was also not friendly with common sense.
So that the darkness of technical superstitions no longer obscures the crystal purity of relationships with yours, you should remember the following. Any car generator does not care at all how many ampere-hours there actually are in the battery with which it is paired. The generator is designed in such a way that it “reacts” only to the current amount of electricity consumption from the vehicle’s electrical network. If consumption is low (for example, only for the needs of the ignition system and engine control), then it produces one amount of energy. When the electricity consumption is higher, for example, during charging, the generator supplies the on-board network with more energy.
But it (the amount of energy produced by the gene) is always equal to the level of consumption, no more and no less. Returning to our “rams”, that is, let’s give a couple of examples demonstrating the harmlessness of installing a battery of a larger or smaller capacity on your car than recommended in the owner’s manual for your car. It is known that over time, during operation, any battery loses its original capacity. In this case, it turns out that the car actually has the “wrong” battery. And it doesn't boil when charging. Although, according to, I simply must!
The opposite example is police patrol cars. They are required to be equipped with an additional battery to power flashing lights, radios and other service equipment. And none of the police officers have yet complained about the rapid failure of these batteries due to chronic undercharging! The conclusion from all of the above is the following: a less capacious one (compared to the standard one) will be charged by your car’s generator faster than the one installed at the factory. If you install a more capacious battery, it will reach its maximum charge a little later than the standard battery. That's all: there can be no catastrophes under the hood due to batteries of abnormal capacity!