Battery

   #21  

Micky 32

Verified VCDS User
Verified
Joined
Feb 8, 2020
Messages
47
Reaction score
18
Location
Longford, Ireland
VCDS Serial number
C?ID=3392
How did the SOC and capacity compare on your 5 year old battery?
 
   #22  

technodevotee

Verified VCDS User
Verified
Joined
Apr 21, 2019
Messages
29
Reaction score
32
Location
Worcester, UK
VCDS Serial number
C?ID=339141
For comparison, the label on the battery in my Tiguan said VARTA 7P0915105 12V 68Ah 380A DIN 680A EN/SAE/GS

I've dug out all the information I have and it looks like I might have given you some duff info - sorry about that.

In March 2019 when the car was behaving it was giving me

Battery Aging (Charge) 84%, Battery Aging (Power) 77%, Voltage 12.224V, SOC 84%, Available Current 40Ah

In Sept 2019 when it wouldn't start it was giving me

Battery Aging (Charge) 71%, Battery Aging (Power) 66%, Voltage 10.6V SOC 12% Available Current 0Ah

After an overnight charge it was giving me

Battery Aging (Charge) 71%, Battery Aging (Power) 66%, Voltage 12.54V SOC 70% Available Current 29Ah

The thing is, a week or so later it was still fine and the dealer gave it a clean bill of health, which I think speaks volumes considering it wasn't covered by the warranty.
 
Last edited:
   #23  

Micky 32

Verified VCDS User
Verified
Joined
Feb 8, 2020
Messages
47
Reaction score
18
Location
Longford, Ireland
VCDS Serial number
C?ID=3392
Thanks for posting the info. Not sure if it shows on the logs i posted but i remember one stage It logged a very low SOC and capacity and went into phase 1 ( something to that effect) power management. Never failed to start though.
 
   #24  

technodevotee

Verified VCDS User
Verified
Joined
Apr 21, 2019
Messages
29
Reaction score
32
Location
Worcester, UK
VCDS Serial number
C?ID=339141
Should show up in the battery history as long as it wasn't too long ago.
 
   #25  

Micky 32

Verified VCDS User
Verified
Joined
Feb 8, 2020
Messages
47
Reaction score
18
Location
Longford, Ireland
VCDS Serial number
C?ID=3392
I just ordered one of those CTEK battery sense monitors. Should be interesting to log the SOC over the 7 days to see what % it maintains.
 
   #26  

Micky 32

Verified VCDS User
Verified
Joined
Feb 8, 2020
Messages
47
Reaction score
18
Location
Longford, Ireland
VCDS Serial number
C?ID=3392
I bought one of those bluetooth battery monitors that works with a phone app and it’s quite interesting how the charging system works on these cars. 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. That means the battery is working harder than on older cars where the alternator keeps batteries fully charging at all times. So it’s not surprising a battery after 3 years showing signs of wear.

The bluetooth monitor also logs cranking voltage. It recorded a low voltage warning crank of 8.9volts this morning on first crank of the day. Outside temp was a mild 16 degrees C. I’m guessing not a good sign for the AGM battery
 
  • Like
Reactions: Uwe
   #27  

Uwe

Benevolent Dictator
Administrator
Joined
Jan 29, 2014
Messages
48,902
Reaction score
33,621
Location
USA
VCDS Serial number
HC100001
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.
Right, when you are decelerating or braking, there is free energy available and they try to use this to keep the battery charged rather than using a tiny bit more fuel to do so the rest of the time.

That means the battery is working harder than on older cars where the alternator keeps batteries fully charging at all times. So it’s not surprising a battery after 3 years showing signs of wear.
Correct. They save a tiny bit of fuel with this nonsense, but at the cost of having to replace the battery more often. I wonder if anyone has analyzed how much energy is consumed in recycling the battery into a new one and how this compares with the energy/fuel savings? Car batteries generally are recycled, but melting and purifying the lead certainly isn't an energy- or pollution-free process.

It's a similar situation with more aggressive hybrids. There was recently a thread from a guy with a 8V A3 e-tron hybrid. He's got fault codes indicating an internal isolation failure in his battery at 127,000 miles. Now he needs a new hybrid battery that costs 8600 Euros. I wonder if he as saved 8600 in fuel by driving that car rather than a more conventional one?

One thing that might help battery life in a car like yours would be to put a trickle charger on the battery at night?

-Uwe-
 
   #28  

Micky 32

Verified VCDS User
Verified
Joined
Feb 8, 2020
Messages
47
Reaction score
18
Location
Longford, Ireland
VCDS Serial number
C?ID=3392
Just a bit more info to add, when driving along the voltage at the battery today was a constant 12.9 v ( i believe it’s closer to 14v on old non start stop cars) and then when you release accelerator it jumps to 14.3v. Interestingly when the car was locked up for a few hours the resting voltage reads a healthy 12.7v.
 
   #29  

PetrolDave

Verified VCDS User
Verified
Joined
Dec 16, 2014
Messages
7,882
Reaction score
7,758
Location
Westbury, UK
VCDS Serial number
C?ID=1423
Just a bit more info to add, when driving along the voltage at the battery today was a constant 12.9 v ( i believe it’s closer to 14v on old non start stop cars) and then when you release accelerator it jumps to 14.3v. Interestingly when the car was locked up for a few hours the resting voltage reads a healthy 12.7v.
I've been using a battery voltage monitor plugged into the accessory socket during lockdown. That shows pretty similar results to yours, except when the battery was really discharged when it showed 14.3V for most of a 10 mile drive but on the way back (when the battery was in better charge state) the voltage was 12.7V when on the throttle and 14.3V when off the throttle.

BMS in operation...
 
  • Like
Reactions: Uwe
   #30  

Uwe

Benevolent Dictator
Administrator
Joined
Jan 29, 2014
Messages
48,902
Reaction score
33,621
Location
USA
VCDS Serial number
HC100001
Just a bit more info to add, when driving along the voltage at the battery today was a constant 12.9 v ( i believe it’s closer to 14v on old non start stop cars) and then when you release accelerator it jumps to 14.3v. Interestingly when the car was locked up for a few hours the resting voltage reads a healthy 12.7v.
12.9V is not horrible. It's enough to keep the battery from discharging, but it sure isn't going to put a full charge into it either.

-Uwe-
 
   #31  

PetrolDave

Verified VCDS User
Verified
Joined
Dec 16, 2014
Messages
7,882
Reaction score
7,758
Location
Westbury, UK
VCDS Serial number
C?ID=1423
12.9V is not horrible. It's enough to keep the battery from discharging, but it sure isn't going to put a full charge into it either.
I seem to remember reading that the BMS tries to keep the battery no more than 80% charged - to allow room for the "regenerative charging" when off the gas?
 
   #32  

Jack@European_Parts

Gone But Not Forgotten
Professional VCDS User
Joined
Jan 29, 2014
Messages
21,923
Reaction score
9,308
Location
Montgomery, NY, USA
VCDS Serial number
C?ID=57337
I seem to remember reading that the BMS tries to keep the battery no more than 80% charged - to allow room for the "regenerative charging" when off the gas?


I really like this post for compare and contrasts of industry futures quatrains to come........ :rolleyes:

One day there was a fire and off gasses killed everyone in the car before it even started?
 
   #33  

Micky 32

Verified VCDS User
Verified
Joined
Feb 8, 2020
Messages
47
Reaction score
18
Location
Longford, Ireland
VCDS Serial number
C?ID=3392
I seem to remember reading that the BMS tries to keep the battery no more than 80% charged - to allow room for the "regenerative charging" when off the gas?

With the car locked up for the last few hours the voltage according to the Bluetooth monitor is reading 12.65v. For an AGM that’s approx 80% sounds about right. It varies though, last night it was 12.54( probably 70% ish)which resulted in a crank voltage 8.5v this morning and glitching the heated steering wheel to come on by itself after the cranking.

Today the car was charging the battery at full 14.3v in all conditions, foot to the floor and braking ( start stop working ok) but yesterday it was mostly charging when deaccerating and braking. A very strange charging system.
 
   #34  

PetrolDave

Verified VCDS User
Verified
Joined
Dec 16, 2014
Messages
7,882
Reaction score
7,758
Location
Westbury, UK
VCDS Serial number
C?ID=1423
yesterday it was mostly charging when deaccerating and braking. A very strange charging system.
All because the manufacturers need to meet lower emissions targets :banghead:
 
   #35  

Uwe

Benevolent Dictator
Administrator
Joined
Jan 29, 2014
Messages
48,902
Reaction score
33,621
Location
USA
VCDS Serial number
HC100001
All because the manufacturers need to meet lower emissions targets :banghead:
Yep, CO2 emissions targets in the EU and Fuel Economy targets (which are essentially the same thing) in the US.

Yet some people here complain that the current US administration wants to put a brake on those ever tightening targets.

-Uwe-
 
   #36  

Micky 32

Verified VCDS User
Verified
Joined
Feb 8, 2020
Messages
47
Reaction score
18
Location
Longford, Ireland
VCDS Serial number
C?ID=3392
I tried one of those Conductance battery testers today, supposed to be a good one, results i got were:

SOC : 73% ( i wouldn’t expect full charge due to energy recoup.)

Cranking amps ( EN) rated 680A, actual 515A

SOH : 57%

Int R : 4.40 mega ohm

Result : “Good Battery”, hmmm i would have thought 57% state of health not exactly good.
 
   #39  

Jack@European_Parts

Gone But Not Forgotten
Professional VCDS User
Joined
Jan 29, 2014
Messages
21,923
Reaction score
9,308
Location
Montgomery, NY, USA
VCDS Serial number
C?ID=57337
Yet some people here complain that the current US administration wants to put a brake on those ever tightening targets.

-Uwe-

Totally possible and it clearly doesn't have to make the car too expensive either. Why not make cars with less shit in them and so people can buy a stripped base, even rubber floors vs carpets & manual locks & hand cranked windows, no radio, etc.?
 
   #40  

Micky 32

Verified VCDS User
Verified
Joined
Feb 8, 2020
Messages
47
Reaction score
18
Location
Longford, Ireland
VCDS Serial number
C?ID=3392
Thought i’d update this thread. Nearly 3 years later. I’m still on the original battery lol. Coming up on 6 years 160,000 miles. It’s done approx 45,000 starts (according to vcds) . It’s one tough AGM battery hanging in there.

 
Back
Top