Battery or alternator issue?

[Ozsko]

Have you noticed that in all cases the problem has arisen since colder weather has arrived and mine is no different. Batteries deliver less in colder weather.

[Micky 32]

My Feb 2017 Passat has an AGM battery. I noticed last winter i began to see “power consumption too high” intermittently especially in low ambient temperatures but for most part start stop worked ok. It never happened the previous winters. I was also getting a glitch where on the first start of the day the heated steering wheel would switch itself on after it cranked. I presume it’s a weakening battery but since the summer has started it’s being behaving fine.

[Micky 32]

I asked them to check the battery as these VWAG start-stop batteries r notorious to start failing after 2.5 to 3 yrs.

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I bought one of those bluetooth battery monitors and it’s quite interesting how the charging system works on these cars, not surprising your above comment. The car seems to depend more on the battery than the alternator. It only seems to charge the battery when it needs it. The alternator mostly puts full output out when de accelerating/braking. The logged charging graph on the bluetooth monitor goes up and down during the drive especially on country roads where you accelerate and brake for corners. That means the battery is working harder than older cars where the alternator keeps batteries fully charged at all times.

The bluetooth monitor also records cranking voltage. It recorded a low voltage crank of 8.9volts this morning on first crank of the day. Outside temp was a mild 16 degrees C.

[zzc2010]

I bought one of those bluetooth battery monitors and it’s quite interesting how the charging system works on these cars, not surprising your above comment. The car seems to depend more on the battery than the alternator. It only seems to charge the battery when it needs it. The alternator mostly puts full output out when de accelerating/braking. The logged charging graph on the bluetooth monitor goes up and down during the drive especially on country roads where you accelerate and brake for corners. That means the battery is working harder than older cars where the alternator keeps batteries fully charged at all times.

The bluetooth monitor also records cranking voltage. It recorded a low voltage crank of 8.9volts this morning on first crank of the day. Outside temp was a mild 16 degrees C.

That’s the blue technology. Energy regenerating. Pleasure to see the technology working well, however, the batteries were gone faster than usual. Prefer the old fashions.


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[Micky 32]

Got one of those Topdon battery conductance testers.

My AGM battery is 3 1/2 years old (160,000km).

For comparison i tested my battery against my friends new car battery.

My battery Varta AGM 680 A en , 68 ah:

State of health : 54%

Measured amps : 500A ( rated 680A)

Interestingly the report is “Good Battery”

Friends battery Varta EFB+ 700A en, 70ah

State of health : 100 %

Measured amps : 815A ( rated 700A).

It seems these battery don’t last long , probably due to stop/start and the car keeping the battery at 80% charge.

[Hillbilly]

My B7 was the same lasted 4 1/2 years and only 35,000km as didnt use car often. Both heat and cold will kill them and if S/S is not going is sure sign battery is on way out. I used a Ctek for a few months but got sick of it and put a new battery in and al troubles were gone