There is a constant opinion that if a 63A / h battery is put on the car according to the manual, then if you put 55A * h, then it will boil, and if 90A / h, then it will not be charged. In both cases, it is assumed that it will fail in a short time. To our delight, this is not the case. Let's think.
The vehicle's on-board power supply network with the engine running is a device referred to in radio electronics as a "voltage generator" (with some stretch it is). 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 pass it at school), the current in the circuit is determined by the ratio of the voltage to the resistance of the circuit.
The voltage in our case is the difference (on-board network voltage minus battery voltage). Battery resistance is an almost constant value, i.e. The charge 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 in is determined by the state of it itself, and not the car's onboard network.
A little about the values of currents. Once I measured the charge current on the 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 a value of 0.5 amperes. On an engine that has 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 tells about the maximum current that they can give, but this does not mean that they always give it. They always give the current that consumers require.
AND NOW CONCLUSIONS: In the case when the battery “requests” 1-2 Amperes from the generator, they will be equally well given by a 35A generator and a 200A generator. Therefore, if you want, put any battery on any car. Everything will be charged. The main thing is that the voltage of the battery and the onboard network would be the same.
Although in fairness I’ll say that you can pick up such a pair of auto-batteries, in which the battery will not be charged. This is such 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. So the battery will be undercharged only on a car whose generator will not pull even one headlight. Or in another way, a battery is such a small consumer in an automotive electrician, probably only a clock in a “tidy” is smaller.
And now for the ridiculous unscientific evidence. Suppose that the fact of overcharging-undercharging takes place. Then:
1. Imagine a fence in a field. On one side of the fence are a huge ZIL (truck) and a small OKA. Two pairs of holes were drilled into the fence and two pairs of wires were inserted into them. One pair comes from the truck's onboard network, the second from the OKI's onboard network. The engines of both cars are running and turning their generators. Being on the other side of the fence, we do not see where which pair comes from, but with a tester we see 13.8 volts on each pair. We connect to each pair of the same battery, designed for OKU. Now, if we say that the one connected to the truck will be recharged, then how will this battery “determine” that it is connected 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 is 1,000 GW. In one city, Masha plugs an iron into the socket at home, and in another, Kolya turns on his iron. Question: which of them will burn the iron immediately? Probably Kolya, because he has a power plant 1000 times more powerful! Did you get even funnier?
Thus, we have proved that the consumer current is determined by the consumer itself with a constant supply voltage and does not depend on the generator.
So when choosing a battery, there is a simple rule - the capacity of the battery 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 will not fit into the trunk. By the way, where it's cold, it makes sense to put the battery just more powerful, because It is known that with decreasing temperature, the actual capacity of the battery decreases.
More about the balance of battery capacity / generator current.
Question: “I put a 120 Ah battery on the Zhiguli instead of 55 and it will recharge up to its 120? It's a recharge, not a recharge. This is the current limit.
Since the question is asked quite often, I found it necessary to put THIS in the title of this conference. So, the answer is: This is the most typical misconception this season (like the letters ZZZ - galvanized body on 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-hours (less realistic). The starter is “absolutely not aware” 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, 3 meters deep or 3 kilometers - sinking the same way."
The engine started, the generator started. So, for the generator, it’s also deep purple, how many ampere-hours there are in the battery - it is “interested” only in the VOLTAGE in the on-board network. And the downward deviation of the battery voltage relative to the “accustomed to the generator”. And the battery starts to "eat" energy. And he eats not incomprehensibly how much, but exactly as much (the efficiency of the battery is almost 100%), how much he lost when starting the engine. Those. the same 0.5 ampere-hours. And he eats at such a pace as the power balance of the income / consumption of electricity allows.
One can imagine such an analogy.
There are 2 buckets of water - 10 liters and 5 liters.
The hostess sometimes needs a liter - then she tops up. So what's the difference - how much water is in the bucket?
The hostess is interested in the LEVEL of water? (battery voltage) Then the water level at the ebb of one liter will decrease not depending on the amount of it, 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 (a large discharge current with a small capacity), or you can have a narrow and high one (the capacity is large, and the current is small - these are 60Ah 180A batteries, by the way). And a large capacity of real batteries (an order of magnitude more than required) is needed mainly in order to have a larger starting current. A bucket can be made of any shape, but the battery cannot be made “wide and shallow” - these characteristics are really strongly connected and you can achieve “width” only by making “depth”.
Yes, there are still people who believe that if you put a barrel under a water tap instead of a bucket, then the tap will not withstand such a capacity and will break ...
Bottom line - you can put at least a 500A / h battery - a 55-ampere generator can handle it too. Just a question - do you need so much?
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 actually not charging the battery, but recharging - returning the “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%, so they will be charged back by the generator at the same time. But "on loan" eighty will still give more.
There is a constant opinion that if a 63A / h battery is put on the car according to the manual, then if you put 55A * h, then it will boil, and if 90A / h, then it will not be charged. In both cases, it is assumed that it will fail in a short time. To our delight, this is not the case. Let's think. The vehicle's on-board power supply network with the engine running is a device referred to in radio electronics as a "voltage generator" (with some stretch it is). 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 pass it at school), the current in the circuit is determined by the ratio of the voltage to the resistance of the circuit.
The voltage in our case is the difference (on-board network voltage minus battery voltage). Battery resistance is an almost constant value, i.e. the charge 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 in is determined by the state of it itself, and not the car's onboard network.
A little about the values of currents.
Once I measured the charge current on the 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 a value of 0.5 amperes. On an engine that has 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 tells about the maximum current that they can give, but this does not mean that they always give it. They always give the current that consumers require.
AND NOW CONCLUSIONS: In the case when the battery "requests" 1-2 Amperes from the generator, they will be equally well given by a 35A generator and a 200A generator. Therefore, if you want, put any battery on any car. Everything will be charged. The main thing is that the voltage of the battery and the onboard network would be the same.
Although in fairness I’ll say that you can pick up such a pair of auto-batteries, in which the battery will not be charged. This is such 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 dipped headlight lamp. So the battery will be undercharged only on a car whose generator will not pull even one headlight. Or in another way, a battery is such a small consumer in a car electrician, probably only a clock in a “tidy” is smaller.
And now for the ridiculous unscientific evidence. Suppose that the fact of overcharging-undercharging takes place. Then:
1. Imagine a fence in a field. On one side of the fence are a huge ZIL (truck) and a small OKA. Two pairs of holes were drilled into the fence and two pairs of wires were inserted into them. One pair comes from the truck's onboard network, the second from the OKI's onboard network. The engines of both cars are running and turning their generators. Being on the other side of the fence, we do not see where which pair comes from, but with a tester we see 13.8 volts on each pair. We connect to each pair of the same battery, designed for OKU. Now, if we say that the one connected to the truck will be recharged, then how will this battery “determine” that it is connected 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 is 1,000 GW. In one city, Masha plugs an iron into the socket at home, and in another, Kolya turns on his iron. Question: which of them will burn the iron immediately? Probably Kolya, because he has a power plant 1000 times more powerful! Did you get even funnier?
Thus, we have proved that the consumer current is determined by the consumer itself with a constant supply voltage and does not depend on the generator.
So when choosing a battery, there is a simple rule - the capacity of the battery 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 will not fit into the trunk.
By the way, where it's cold, it makes sense to put the battery just more powerful, since it is known that with decreasing temperature, the actual capacity of the battery decreases.
More about the balance of battery capacity / generator current.
Question: “I put a 120 Ah battery on the Zhiguli instead of 55 and it will recharge up to its 120? It's a recharge, not a recharge. This is the current limit.
Since the question is asked quite often, I found it necessary to put THIS in the title of this conference. So, the answer is: This is the most typical misconception this season (like the letters ZZZ - galvanized body on 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-hours (less realistic). The starter is “absolutely not aware” 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, 3 meters deep or 3 kilometers - sinking the same way."
The engine started, the generator started. So, for the generator, it’s also deep purple, how many ampere-hours there are in the battery - it is “interested” only in the VOLTAGE in the on-board network. And the downward deviation of the battery voltage relative to the “accustomed to the generator”. And the battery starts to "eat" energy. And he eats not incomprehensibly how much, but exactly as much (battery efficiency is almost 100%), how much he lost when starting the engine. Those. the same 0.5 ampere-hours. And he eats at such a pace as the power balance of the income / consumption of electricity allows.
One can imagine such an analogy.
There are 2 buckets of water - 10 liters and 5 liters.
The hostess sometimes needs a liter - then she tops up. So what's the difference - how much water is in the bucket?
The hostess is interested in the LEVEL of water? (battery voltage) Then the water level at the ebb of one liter will decrease not depending on the amount of it, 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 (a large discharge current with a small capacity), or you can have a narrow and high one (the capacity is large, and the current is small - these are 60Ah 180A batteries, by the way). And a large capacity of real batteries (an order of magnitude more than required) is needed mainly in order to have a larger starting current. A bucket can be made of any shape, but the battery cannot be made “wide and shallow” - these characteristics are really strongly connected and you can achieve “width” only by making “depth”.
Yes, there are still people who believe that if you put a barrel under a water tap instead of a bucket, then the tap will not withstand such a capacity and will break ...
Bottom line - you can put at least a 500A / h battery - a 55-ampere generator can handle it too. Just a question - do you need so much?
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 actually not charging the battery, but recharging - returning the “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%, so they will be charged back by the generator at the same time. But "on loan" eighty will still give more.
During the purchase of a battery, many people have natural questions about whether it is worth choosing a battery, for example, with a margin, a larger capacity? Or with stronger charging currents? Many people dream at once to get rid of those numerous problems that battery maintenance or some problems with it promises them. At the same time, there are also specific fears that if you put a more capacious battery on the car than it should 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 any adequately.
Experts point out that this style of thinking has a mythological nature. The voltage generator, which is the car's power supply network, regardless of what current this same on-board network consumes, maintains a stable constant voltage in it. 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, the voltage at its terminals drops. The voltage difference in the network and in the battery increases and the charging current becomes stronger, but only until the voltage equalizes. In the first seconds after the engine is started, the current in the battery rises by five to ten amperes, and after some time drops to a stable half-ampere. If the engine worked from one to two hours, then the battery supply current dropped already to values of 0.3 - 0.1 amperes. Many believe that this is generally a kind of leakage currents associated with the fact that the battery efficiency is far from 100%.
The generator is marked with the maximum current it can generate. However, he is unable to do this all the time. Moreover, the generator produces such a current, which will be required by on-board consumers in the network, among which is the battery. Thus, any generator, no matter what power it develops, will give the battery exactly the amount of current that it “asks”. There will be a normal full charge 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.
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Is it possible to put a larger capacity battery on the car?
Motorists often wonder what will happen if a battery with more power is put on the car than the manufacturer provided for?
The editors of the portal site respond if the terminals are suitable and the battery has the same dimensions, then you can use it, even if its power exceeds the power of the battery supplied from the factory.
Why then is there so much controversy?
There are two myths:
- If you put a battery of a smaller capacity, it will boil.
- If you put a battery with a larger capacity, it will not fully charge and may burn the starter.
To dispel these misconceptions, imagine 2 barrels of water of different volumes. One barrel contains 100 liters of water, the other 200 liters. Connect a source of water to them, which will fill each barrel at the same rate. Naturally, the first barrel will fill up 2 times faster.
Now we will drain from each barrel 20 liters of water. In the first barrel we will have 80 liters, in the second - 180 liters. Let's connect our source again and add 20 liters of water to each barrel. Now every barrel is filled again.
How does it work in a car?
Now imagine that the generator is our source of water. It charges accumulators (barrels) at a constant rate for as long as needed. The alternator cannot give the battery more power than it can take. More precisely, the generator produces energy when there is a consumer for it. The battery takes it when it is needed and as much as needed (full barrel).
Now the starter (hose). It takes energy from the battery. Let's say for 1 start of the engine, the starter takes 20 Ah. No matter how powerful the battery is, it will still take its 20 Ah. When the engine is started, the generator comes into operation. He must make up for the loss. And he makes up for - the same 20 Ah. Regardless of the capacity of the battery installed in the car.
In addition to the starter, on-board vehicle systems can also consume battery power if they operate with the engine off. Often, motorists find themselves in unpleasant situations when they fail to start the car using the starter, the battery is dead. This happens because the driver forgot to turn off the lights or the audio system.
We see that the capacity of the battery does not affect the operation of the car. Whatever battery is in the car, the generator will charge it exactly as much as the consumers have planted.
Then what are the myths based on? It's about changing concepts. There is a fundamental difference between the concepts "battery is charging" and "battery is being recharged." It's like in our example above, if we apply a constant current of 1 A to each battery of 100 Ah, it will boil after 100 hours, and the second, at 200 Ah, will not be recharged yet. After 200 hours, the second battery will boil, while the first one will boil for 100 hours. Of course, the numbers are given conditionally, only to explain the process itself. Not a single battery will boil for 100 hours.
The above process is called battery charging, but this is not the case in question.
When we talk about the operation of a battery in a car, we mean the process of recharging, and not charging from scratch. Consumers took some, not all. This number is the same for both batteries. So it doesn't matter which one takes longer to charge.
If the battery is completely dead, we will not be able to start the starter from it. Then the battery will have to transfer the power needed for the starter from an external device (“light it up”). Again, once the starter has started the engine and the alternator is running, the fact that one battery takes longer to charge than the other won't make any practical difference to us. While driving, the generator is responsible for the energy supply, and not the battery at all. If we turn off the engine, for example, after 5 minutes, both batteries will be charged by the same amount. During the next engine start, the battery charging will continue evenly.
To understand the reason for the emergence of these myths, it is worth going back to the 70s of the last century. It's all about broken roads. When drivers got stuck somewhere, they got out "on the starter". Naturally, he burned out. Therefore, the manufacturers took this step, limiting the power.
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