Is the power supply sufficient?

Regarding my Sharan 7N, I'm wondering if the generator can produce enough electricity to keep the battery in a good state of charge. My commute to work is 21 km.

Special features that contribute to increased fuel consumption in a vehicle include: auxiliary heating, seat heaters, and the start-stop automatic system.

According to my battery tester, topping up the charge is necessary during the winter months. Could it be that with the engine running and all accessories (alternator, starter, lights) on, the onboard voltage is not sufficient to charge the battery, or is the charging regulation not optimally adjusted?

Hello!
In ADAC publications, on the internet, etc., it is usually stated that when all electrical consumers in the car are turned on, the alternator does not generate enough electricity, and the battery compensates for this. And that the battery can sometimes be drained as a result.

In my Golf (model 4), I usually drive twice a day for a distance of 5 km each way to work. In the winter, I also have to recharge the battery every 4-6 weeks.
I'm quite sensitive to it; I can hear it during the initial start-up when the starter motor slightly slows down the engine.

Here's what else I recall: In modern cars, the onboard electronics consume a significant amount of power. During a training session, an A6 model packed with control units was tested. After the car was turned off, it consumed around 10 amps for a few minutes.

Rear window defrosters and the interior fan are also among the energy consumers.
"The H4 headlights and all the other lights, of course. The Sharan probably also has a second heating element with a fan."

If you're unsure, it might be a good idea to monitor the onboard voltage.
There are these funny little Chinese voltage indicators for cigarette lighters; you can at least use them to get a rough idea of whether the alternator is delivering its full power under load.
If in doubt, you should use proper measuring instruments again. Or even better, connect with VCDS directly.
If the battery is working properly, there's not much else you can do except occasionally charge it or conserve power.

Possibly, incandescent light bulbs that are frequently or extensively used can be replaced with LED versions.

Best regards, Rainer.

Steffen G wrote:

If the battery is okay, but something else is wrong, you can't really do much except charge the battery occasionally or try to save power.

Currently, I don't suspect a faulty component. I'll connect my Fluke multimeter to the cigarette lighter socket after turning off the engine and see what readings I get. Probably nothing, because the cigarette lighter socket is de-energized immediately after the engine is turned off.

Hello!

There's no way the Lima can do that.

Seat heating: 5A / seat.
Base vehicle operation with ventilation: 30A.
Lights (conventional): 15A.

The auxiliary heater itself consumes very little power when operating. Only when the engine is off does it require electricity to start and for the fan. In return, when the engine is running, the afterglow period is correspondingly shorter, allowing the battery to be charged.

In total, that's a maximum of 50 amps. And it probably has a 140 amp alternator installed. And those can already deliver power at speeds below 20,001 RPM.

I have the same combination and have NEVER had any problems. Even the electric fan automatically turns on after starting the engine and goes up to level 2. The battery is from 2010.
If you suspect there are problems, check the alternator load using VCDS. I suspect either a faulty alternator or an aging battery that can no longer accept the charge as quickly.

Regards,
Pretzelman.

For models with a standing heater, it's often said that you should factor in driving time equivalent to the heating time. This is a general rule of thumb.
We have a Sharan 7M with two batteries (74AH and 60AH) and a 90A alternator. It also has a parking heater (this was factory-installed). The 60AH battery is solely responsible for the parking heater and the aftermarket seat heaters, and it's powered by the other battery. The car drives a daily distance of 2 x 31km, which works well in terms of charging. Despite the relatively small alternator. My wife also leaves the lights on constantly. They are Xenon D2S bulbs. I rarely top up the batteries. Previously, the car used to drive a much shorter distance each day, and the charger was regularly used then. For the car, I also bought an MXS10 CTEK charger because it has two batteries, which speeds up the charging process.
We also have a Passat with a currently installed 75 Ah EFB battery and a 140A alternator, plus all the other power-consuming features. It even has a heated windshield. The car travels 41 km twice daily and rarely needs to be recharged.
I usually preheat the car for about 20 minutes before starting my journey, and then let the heating continue running until the display shows 90 degrees Celsius. After that, I manually turn it off.

Hello!
I just remembered something else.
You can also measure the quiescent current consumption.

Hello everyone!

Steffen W wrote:

For models with a standing heater, it is often said that you should plan for as much driving time as the (previous) heating time.

As a general rule of thumb...
...at least .
And that's precisely the crux of the matter here.

An auxiliary heater consumes electricity, depending on its age and size, roughly between 5 and 12 amperes (up to 30A during startup), but please also remember to factor in the vehicle's fan, which uses approximately 10-15 amperes.

It is also important to know that the electrical energy extracted from a lead-acid battery cannot be recharged} in the same amount of time, but depending on the age and wear of the battery, it takes at least 20-50% longer.

So, if you preheat it for 30 minutes, it already consumes about 10 amp-hours of electricity, which are not fully replenished in the battery until after approximately 45 minutes of driving – and even then, not at 100%.
The latter ultimately leads to a lead-acid battery that becomes increasingly difficult to fully charge due to sulfation and further loss of capacity, until eventually, even with a "full charge," the engine will no longer start, especially in cold temperatures.
The less frequently the vehicle is driven or loaded after being heated, the faster the wear and tear described above will progress.

Especially with regular use of the auxiliary heater and (frequent) short trips, I would strongly recommend charging the battery overnight (or longer) once a week using a good quality charger. Otherwise, a lead-acid battery won't last very long. I, like Steffen_W, have been using the CTEK MXS10 with great satisfaction for many years.

Regarding the generator/alternator, this component delivers approximately 50% of its rated power even at idle speed. This is still sufficient to power lights, ventilation, etc. And if it's not enough, the load management system will automatically disable features like the rear window heater, deactivate the start-stop system, and/or increase the idle speed to provide more generator output.
As Brezl mentioned, you can use VCDS to access the Motor Vehicle Information System (MStG), which contains data about the generator load.

Best regards from Passau!

Here's the translation:

"To complete the information:"

The battery is the AGM variant.
I charge with a CTEK 5.0.
The integrated alternator has a capacity of 180A.
I had to replace the battery 1.5 years ago because the original ones were already dead after only 5 years.

I'll check the generator load using VCDS.

Hi!
Okay, that combination should definitely not cause any problems with your driving profile. I think it's also true that for an AGM battery, the charging time is no longer directly proportional to the usage time.

Are the battery terminals properly tightened? Otherwise, Steffen's suggestion about checking for quiescent current is definitely worth investigating.

I measured the quiescent current and made some interesting observations. It takes approximately 5 minutes for the quiescent current to decrease from ~3A to 0.095A. Another 5 minutes are needed for the quiescent current to finally drop to 0.015A. This was observed with the doors locked and the alarm system active.

In that regard, there's nothing unusual. It's likely that the electricity demand is so high that daily distances of approximately 50 km are not enough to maintain the battery charge, especially in winter. Although I make sure that the vehicle isn't left idling for too long, and also that the sliding doors and tailgate (both electric) aren't used excessively when the car is stationary.

Hello!

I read your last post this morning at work. By chance, a colleague of mine was also sitting at the table. He has an A6, about 6-8 years old, and I remembered that he's been complaining about his Audi lately too.
Battery management system issues, problems in winter, auxiliary heating malfunctions, etc., everything is bad, this stupid car, the battery always dies, etc.

I immediately asked him about it because he also has a commute of only about 10 kilometers each way.

He told me:
He would have then acquired a "tool" that allows him to read the battery charge level of the car, or to display it on the car's screen. (I didn't even ask what kind of tool or how it works).
He would have had an initial battery charge of 80%, and after 10 minutes with the heater running, the charge level dropped to 30%.
(Whatever those percentages are.)

He's a mechatronics technician himself, and he already realized that this isn't possible.
He told me a few weeks ago that he had already installed a new battery.

Now he said it wouldn't be a problem to use the auxiliary heater for 20 km per day. He also didn't install the battery just last week; it's been in there for quite some time.


"And, I'd say that Volkswagen wouldn't build cars where you can't use the heated seats for everyday driving of 50 kilometers and normal use of comfort features. 50 kilometers is already quite above average for ordinary people."

I wouldn't just accept that; I would investigate further.

Monitor the battery voltage while driving; with the current temperatures, it should be around 14.4V, even with consumers running.

2. Somehow figure out if the battery is actually completely discharged.
"If a company has 100 people working in the office, they are generally always fully occupied with work, regardless of how much work there is. A charger probably works similarly, meaning it will always recharge the battery."

I check if it's possible to also measure the acid density of the batteries. Sometimes, batteries have exactly the same screw caps as in the past. However, these are usually covered with a sticker.

I suspect it's Lima.
It is well known that it is a three-phase alternator.
Most commonly, a power diode fails, and then you only have 2/3 of the rated power output. In the summer, you don't notice this at all.
These are typically the cases/customers who buy a new battery in November and then complain about it after 4 weeks. (New battery is broken ).
Then there will be trouble and pointless arguments.
until someone actually checks the LIM and realizes it.

There are testing rigs for alternators, but you can also test them directly in the car.
Simply increase the speed to around 3000 RPM and observe the voltage.
Then, one by one, connect the consumers to ensure that the alternator can provide sufficient power. It needs to be able to deliver at least 50-60% of its rated output, and ideally achieve a voltage of around or above 14V.
I realized that it's important to charge the battery beforehand. A fully functional but empty battery can be difficult to assess; it might draw a significant amount of power to recharge.

Based on my experience, with a partially failed alternator, you can typically measure around 13.3 to 13.8 volts.
It becomes critical to assess this at 13.8V, especially when measuring circuits with high current draw and potential contact resistances.

It's best to measure it directly at the battery or use VCDS.

Steffen G wrote:

that he has also been complaining about his Audi lately. Battery management system issues, problems in winter, auxiliary heating malfunctions, etc., everything is bad, this stupid car, the battery always dies, etc.

I don't recall complaining or saying anything negative about it.

To the best of my knowledge, my battery tester is the same one used by ADAC.

Here are the values I recorded this afternoon. The first measurement was taken with the engine idling, with the headlights (xenon) on, and the radio and ventilation set to automatic.

Address 61: Battery Management (7N0 907 534)

13:25:03
13.50 V - Generator nominal voltage.
2.000 A - Excitation current.
13.376 V Battery voltage.
0.3 A Battery current.
95.0% Battery Charge Level
95.0% Battery aging based on charge cycles.
78.0% Battery aging related to performance.
5.2 mΩ Internal resistance of the battery.
34.0 A Generator current.
164.8 A Generator power reserve.


2. Measurement taken with the engine idling, headlights (Xenon) on, radio playing, ventilation on automatic, both seat heaters set to the highest level, steering wheel heating and air conditioning activated.

Address 61: Battery Management (7N0 907 534)

13:26:05
15.00 V - Generator nominal voltage.
2.250 A Excitation current
14.720 V Battery voltage.
-0.4 A Battery current.
95.0% Battery Charge Level
95.0% Battery aging based on charge cycles.
78.0% Battery aging related to performance.
5.4 mΩ Internal resistance of the battery.
50.8 A Generator current.
131.2 A Generator Power Reserve.

Just a reminder: The battery is an AGM type, which means it's maintenance-free (I know that doesn't really exist).

Hello,

Im zweiten Datenblock sieht man eine minimale Entladung, die mich eigentlich wundert. Im Stand sollte die Lima deutlich mehr als 50A bringen. Interessant wäre hier noch der Messwert der Lima Auslastung in %. Ich weiss leider nicht, was der max. Current flow is.

Greetings, brezelmann01.

Hi there,
I have questions about the measurements.
- What is the generator's target voltage? (In my opinion, this is a setpoint value; is there an actual or measured value?)
- Is there a measurement value for the output voltage of the regulator?
- How should the polarity of the battery current be interpreted (charging or discharging)?
hg
Herbert.

Hello!

I'm still puzzling over some of the individual terms.

But especially the second measurement, with all those loads connected, clearly shows that...
that the Lima is intact.
A battery voltage of 14.72 is perfect for an AGM battery.