Will a Larger Battery Than OEM Cause Undercharging in Opel Astra With Parking Heater?

Hello,
This year, for the first time in my life, I was forced to replace the battery in my Astra, which is important, equipped with a parking heater that consumes in the worst case for the battery about 12A for 30 minutes. And for the first time in one week of searching for the battery that interests me, I heard five times that "larger than in the catalog will be too big and will be undercharged". As an electrical engineer interested in the automotive industry, this information has amused me for a long time. But she stopped having fun when it turned out that most of the "experts" on the subject repeated the words of the sellers - "too big will be undercharged".
In this post, I wanted to explain a little more clearly why this is not entirely true. In many other posts, the topic was lame, but the same number of opinions was mostly for and against.

The myth about undercharging a large battery, once spread by mechanics, now by all "experts", was created in the times of the Fiat 126p, equipped with a generator and having a very low idle speed. In this vehicle, if you wanted to have the lights on, you had to drive at a speed above 40 km / h so that the battery was charged with even a trace current.

However, in today's cars, mostly injection cars, with automatic idle speed control (note - Skoda Felicja - the idle speed drops with age!), Equipped with an alternator of 70A efficiency and more, the concept of "battery capacity too large" in the context of undercharging is practically non-existent .

What determines the state of charge of a battery? First of all, as already mentioned in several posts, the energy balance, or simplifying the current. So whether the current consumed by all electrical receivers is smaller or greater than the current flowing from the alternator. In most cars, especially injection cars, with efficient alternators, the current of the receivers is practically always smaller and the balance is thus positive - so the battery is charged even in the worst conditions - idle speed and the vast majority of receivers are turned on.

What is the charging current of the battery in the vehicle? When it comes to charging with a rectifier, the recommendation is that it should be the so-called ten-hour current. However, there is no charge current stabilizer in the vehicle. There is voltage stabilization (14-14.5V) and the battery charging current is a result, i.e. it depends on the state of charge but rarely exceeds the five-hour current.

What does this tell us in terms of numbers? That for a capacity of 55Ah, the five-hour current (actually the maximum that the battery can "request" from the installation) is 11A. For a 44Ah battery it will be 8.8A. What is this increase in demand (after replacing the battery with a larger one) in a vehicle with a 90A alternator?

Summing up, it can be said that the capacity given in the catalog is the smallest capacity necessary for the proper functioning of the vehicle. Virtually any larger capacity (say less than ten times the capacity used at the factory) will only perform better electrically than the factory capacity. Of course, you need to be reasonable and remember about the greater mass of the greater capacity. After all, every kilogram is an enemy (Perhaps the only exception is the BMW battery under the rear seats).

Hello

Nice argument.
Do something for us. Buy a battery for your car but with a larger capacity, say 1.5 times larger, drive for 2 years without doing anything (additional charging) and then share with us whether your observations are correct.

greetings

PS
I did not want to offend anyone with this entry, especially the author of this post.

In each car I had a battery with a capacity of about 30% more than the recommended and I never had to recharge - the car is supposed to be self-sufficient Each battery lasted at least 5 years.
At the time of purchase, the Astra I mentioned had a battery with a capacity 35% greater than the recommended one - it lasted for 3 years, I'm not sure about the production date, but the service book shows that it was replaced in 2003.

Edit: In the second Astra (late 2005), the original battery just went out.

nikagda wrote:

it can be said that the capacity specified in the catalog is the smallest capacity necessary for the proper functioning of the vehicle.

Rather, it should be said that optimal . You have a parking heater and a larger battery is a good solution (increased demand for amps). Someone who made a disco out of a car usually also has to have a more powerful "power plant". For standard equipment, a standard battery is also sufficient. As for alternators, the factory usually produces many models of cars with different equipment and it would be illogical to install the same size of alternators, so for these smaller cars there is an excess alternator and for larger ones "butt joint".

The myth that a larger car battery will be undercharged is so often repeated on the Internet and by "specialists" that it is really hard to wonder for ordinary people that they believe in it.
Nikagda: You wanted it well, it was so average
It is enough to be aware of when the current is drawn from the battery:
only when starting - how the starter works.
Then, while driving, the battery is charged with constant voltage, about 14.3V.
Example:
when igniting, we turn the starter for 10 seconds, we assume that we take 10Ah from the battery (please do not argue about the units)
Then, while driving, we charge the 10Ah battery (I ignore the efficiency)
Please write to me - will there be a difference in this energy balance, whether the battery has 50Ah or 100Ah?

In my opinion, car manufacturers do not take into account the fact that the cars have LPG installations, navigation, CB radio, and other power-hungry elements, so the catalog cars are simply too small

Let us return to the short sections, where the alternator will not have time to charge the battery to the normal level after using the starter. Larger battery = more time to charge.

lukasz 530 - you write nonsense.

People repeat the stupidity so many times that they will eventually believe it.
Larger battery = greater charging current


Just do not write that the alternator can not do - because today there are so strong alternators that in 10 minutes they are able to boil off any battery.

Larger than intended battery = good winter firing.

It largely depends on whether it will be recharged, on what routes we are driving, what long sections. I previously drove my wife's car every day 2x20 km (focus) poor charging 13.4 and did not require recharging. Since my wife drives 2x2 km I have to recharge it, which 2 weeks, despite the fact that I have repaired the charging 13.8 (burned voltage regulator contacts) 90A alternator. Now I drive on the same galaxy route, 2 batteries one 98 the second 62 and do not require recharging. That's why I think that a large battery is an advantage, especially in winter. Before that, I had doubts myself

My friend lukasz530 - quite the opposite and I wanted to emphasize this, because this is a false reasoning spread by ... almost everyone (my colleague, Dr. Eng. Also sold this wisdom to me, but withdrew after 30 seconds, as soon as I gave my arguments). Let's assume 10Ah used to start the engine. Immediately after start-up, the voltage of the installation rises to 14-14.5V, right? So what's the current going to the battery? As I wrote in the first post - it is a result - depends on the battery charge and its capacity, which translates into the internal resistance (inversely proportional). Thus, a larger battery, after an identical discharge, when we force it to the same voltage, will take more current and thus fill the loss faster than a smaller battery.
Buddy forestx - if the electricity was consumed only at startup, firstly I would not write this post, because I would not replace the battery Secondly, the focus would be on developing batteries with much smaller capacities and lower internal resistances. In practice, the alarm system costs quite a lot (I have often heard about an expensive car left in Okęcie by the airport for 2 weeks, which could not be opened after returning from the Canaries). In my case, parking heater. In many others (camping, etc.), a radio, etc.

Good loading is 14.4 if there is less, you need to fix it and not look for a hole in the whole.

I am not looking for a hole in the whole place. I was only outraged when they refused to sell me (sic!) The battery I wanted (they wouldn't give me a guarantee) and that's why I decided to spend some time today. Of course, I bought a bigger one myself, as I wanted, and it spins like crazy

They do not guarantee how poor charging is.
Let them measure.

romoo - you are right - it should be so. But I'm talking about how they treated me on two sites. Just as much as the factory and that's it ...

Then say that you have too small now and you read that it should be bigger.

Haha - it can't be done - they have their catalogs and that's it. You won't translate My opinion hardly mattered, so I bought it online and exchanged it. Philosophy too.

Unfortunately, most drivers will remember the verdict of "pseudofachwiec", uttered with full firmness that a too large battery will be undercharged than a lengthy lecture written on the Internet

I know that 13.8 is not much and how much it should be. I will not buy the second regulator because it is expensive, there is a specific regulator that gives the current depending on the temperature and an additional output. Current consumption the first 2 km is the starter, glow plugs, coolant heating plugs, windshield, blower blower. lights. Sometimes the driver's seat, but this is after turning off another receiver

A large battery is better (gives more confidence to start the car), but more expensive and heavier. In the future, cars will certainly use batteries with much larger capacity and higher voltage to reduce the currents. It is a matter of time and which manufacturer will first, then it's an avalanche.

nikagda wrote:

romoo - you are right - it should be so. But I'm talking about how they treated me on two sites. Just as much as the factory and that's it ...

Otherwise, they would have to think, and that probably hurts them.
Coming back to the matter, the battery capacity has such an impact on the state of charge in a car as does the phases of the moon on penguin's menstruation. I am the same industry as the author of this post and I confirm 122% (including VAT) of his words. The problem is always the condition of the installation in the car and the engine running time, not the battery capacity. Even a 45Ah battery will be undercharged if we only go to the kiosk around the corner to get cigarettes and the installation will be in a deplorable condition.

so far it is true that half of the altka's capacity is standard power consumption and the other half is spare
for "komuna" altek 45A could work with a maximum load of 24 hours and he was fine - today altek 120A can work for a maximum of 2 hours with full load and will burn
what the f .... you poverty is going on in this world? What does it mean that if my car is standing for 2 weeks with a 110 Ah battery, it will fire as much as possible, but the altek will fall after the first 10km because it will overheat?
gentlemen, linden and cost savings by car manufacturers and if there is something wrong during the warranty period, it is the customer's fault
I greet fans of new cars and wish them a lot of good luck and as few visits to the service as possible

Buddy hen, you are quite right - I gave up the idea of changing the car to a newer one this year after listening to the opinions of many car users after 2000. However, you have changed the subject a lot
Buddy artureklondek - you also changed the subject And you are also right. Probably the starter, and in particular the bendix, gets harder when powered from a decent battery. However, this is a topic for a completely different discussion. greetings

Quote:

Buddy hen, you are quite right - I gave up the idea of changing the car to a newer one this year after listening to the opinions of many car users after 2000. However, you have changed the subject a lot

I agree with you and I wrote earlier that offtopic but in the subject I will say this:
e.g. old car - average consumption standard 30A - altek 60A - battery 75Ah - engine operation after firing max 15 minutes and no problem
new car - average consumption standard 45A - altek 120A - battery 75Ah - engine operation after firing up to 15 minutes and there is a problem of undercharging
pay attention to the proportions and look for the cause
MY CONCLUSION FROM SUCH SITATIONS AND THE LIKE - "NEW" THIS IS G ... WHAT HAS NOT BEEN SO MORE, the same as the moss horse from the 90s is not equal to the KM from 2000

1. Someone who has a basic concept in the field of electrical / electronics and has a bit of knowledge and mid-range meters (oscilloscope, clamp meter, voltmeter, wattmeter, etc.) will tell you immediately that what is written on alternators and batteries is total advertising nonsense.
2.Larger than the factory recommended battery: Yes but with common sense, let's say a class stronger (from 55 to 60, from 80-90) of course with a complete efficient installation.
3. Complaints about the battery bordering on a miracle. On 10 you will be able to complain about 2 "after acquaintance".
4. Damage to alternators due to too large batteries: unfortunately yes, but only in cases where the battery is too discharged, a lot of additional "goodies" in the installation and, in addition, the alternator is not cooled sufficiently: literally killed with mud, or has blocked air supply pipes.
5.Any calculations based on the parameters written on the stickers (which are not true) must be wrong.
A simple example: The alternator windings are wound with a wire approx: 1-2 mm, usually 3 separate - let's say connected in parallel (which is not true - but I round off the calculation "in favor of the alternator). The maximum permissible current flowing through a wire with a diameter of 2 millimeters is only 8 amps (for a current density of 2.5 A per mm square, for highly cooled windings up to 5 A per mm square), i.e. with well-cooled windings, let's say 16 A.
And now: 3 windings times 16 amps it comes out less than 50 amps for an alternator that has, say, 110 amps of rated current written.
Rubbish or miscalculation ???
Neither one nor the other NO. Simply at frequencies of the kilohertz range, and alternators operate at such frequencies, there is the so-called skin effect of the current flowing in the wires, and you gentlemen use the CORRECT formulas, but for direct currents.
Unfortunately, the batteries are not charged with a perfect direct current, despite the diodes and regulators. You would need 100 formulas to calculate anything meaningful.
6 The first example of how easy it is to "fall for the patterns":
Two Identical Batteries: Same Capacity, Same Rated Current, Same Starting Current (Read: Same Labels).
One of them is larger in size and twice as heavy: let's say it has twice as much electrolyte and twice as much lead.
The formulas will surely be the same, or the same will come out in the practical use of the battery, I am convinced that it will not.
7: Someone mentioned that the technique will move forward and that someday the power supply will be 24 volts to reduce the currents, and thus the thickness of the wires, savings, etc .. My friend probably believes in miracles.
The Japanese invented and built a great system - a device mounted directly on the flywheel of passenger cars, working simultaneously as a starter-generator and the "kers" system (recently used in F1) - technically possible to do, moreover, there is no need to build separate starters and alternators .
So why not bring the "Japanese ideal invention" into mass production and why do batteries only last 3 years instead of 10 as it used to be?

Today all the cars started for me and it was -23 '
Everyone has an oversized battery.
Of course Pb.
They stand under the cloud because the garages are cluttered with shit.

Hello, my friend, the procedure is much larger than the recommended procedure, when you put on a smaller one, it will be loaded to the maximum, but during large frosts, it will turn out that there is no power at start-up (usually diesel)

PEOPLE - as if what would most often not go into the recess. And it will not be undercharged.

No exaggeration, but a slightly larger battery gives greater charge / discharge shock absorption, which increases the efficiency of the alternator / battery / installation system. Especially in winter, when the battery is exposed to self-discharge due to frost.

Hello, I will move away a bit from the topic, but not far.
Recently, I was dismantling an old rectifier, which had a transformer with many taps (each with a different voltage) and a standard Graetz bridge. Since the switch switching the desired voltage went out, I wanted to fix it by bridging the switch by permanently connecting one selected tap with the transformer to the Graetz bridge (I only need one range because I will only charge the batteries with a voltage of 12V). On each trailer I had a test voltage of 7V ... 12.5 13.5 14.5 15.5V (effective voltage). As the battery should be charged with a voltage of 14.5V (medium rectified voltage?) Which voltage should be selected at the output of the transformer?