On 11/02/2019 at 17:20, Halford said:

just changed my battery on the 1.2 TSi

 

Have you told the car it has a different battery? 

 

https://www.golfmk7.com/forums/showthread.php?t=7926

 

Thanks AG Falco

4 hours ago, piewacet23 said:

OK here is the latest....Battery at full charge 100% after slow charge using computerized slow smart charger  12.84v

20 hrs later..parked nothing touched doors not opened, not run now 12.14v  i.e. about 50% charge

I will leave it sit for about another 12 hrs touch nothing and check again.

I simply cannot accept that this is "normal" fact is in 3 days voltage will drop to the point where everything shuts down.

Remember if the battery is disconnected from the car it holds 12.57v for over 36 hrs, I have not run a load check on this battery I probably should do that.

Malfunctioning Bolero's are not exactly unheard of, some have been replaced under warranty.    

 

You will never ever charge a battery to 100% using a charger that only pushes out 12.84v. The minimum requirement for a flooded/EFB is a float voltage of 13.5v @ 20 deg C rising to 13.70v @ 10 deg C. And then it would take 3 - 7 days at that voltage to recharge a deeply discharged battery. Normally a multistage charger will use 14.5+ volts to do a bulk/absorption charge before switching to a float/maintenance voltage of 13.5 volts, reducing charge times to a more reasonable 12-24 hours. Having disconnected the battery from a real load, you will be merely monitoring a batteries "surface charge" where voltage is elevated with a phenomenon where an elevated voltage is exhibited from  the surface layers of the battery plates for 2-3 hours. Connecting a real load soon discharges this and reveals the real underlying charge and the correct lower terminal voltage.

 

So I think if your slow smart charger can only charge to 12.84v then you should bin it.

 

Your battery may now be knackered with persistent low charge levels (< 60% SOC) which always kill lead acid batteries through irreversible sulphation and vastly reduced capacity and increased internal resistance that goes with that damage.

 

Note that an AGM battery requires higher voltages than EFB.

 

Edited 12 February, 20197 yr by xman

20 minutes ago, xman said:

 

You will never ever charge a battery to 100% using a charger that only pushes out 12.84v. The minimum requirement for a flooded/EFB is a float voltage of 13.5v @ 20 deg C rising to 13.70v @ 10 deg C. And then it would take 3 - 7 days at that voltage to recharge a deeply discharged battery. Normally a multistage charger will use 14.5+ volts to do a bulk/absorption charge before switching to a float/maintenance voltage of 13.5 volts, reducing charge times to a more reasonable 12-24 hours. Having disconnected the battery from a real load, you will be merely monitoring a batteries "surface charge" where voltage is elevated with a phenomenon where an elevated voltage is exhibited from  the surface layers of the battery plates for 2-3 hours. Connecting a real load soon discharges this and reveals the real underlying charge and the correct lower terminal voltage.

 

So I think if your slow smart charger can only charge to 12.84v then you should bin it.

 

Your battery may now be knackered with persistent low charge levels (< 60% SOC) which always kill lead acid batteries through irreversible sulphation and vastly reduced capacity and increased internal resistance that goes with that damage.

 

Note that an AGM battery requires higher voltages than EFB.

 

Thank you I will pass your comments on to the manufactures of my smart charger, I trust you will support my request for a refund

From previous comments on here when a similar problem arose it was noted that the current draw through the radio system did not reduce immediately the radio was turned off, but was a gradual step down.  I don't know why that is, but modern cars have complicated systems, and do not the simple on/off of the past.

We also know from long experience that failing batteries throw up various "faults" and there does not appear to be any constitency in what those are.
We also know that the "brain" in the car switches off things like the radio and interior lights to preserve the battery and the lower the battery the quicker that switching off occurs.
If your battery has gone flat a few times then it is quite likely knackered, and therefore it will not be holding a charge for very long, if at all.
Therefore your first job is to fit a known, fully charged battery and see what happens.
After that, if it goes flat again your only option will be to get a qualified auto-electrician to look at it.

 

And can I suggest that making sarcastic comments to a member who has made a sensible and accurate posting is not the way to gain advice.

Edited 12 February, 20197 yr by Llanigraham

4 hours ago, AGFalco said:

 

Have you told the car it has a different battery? 

 

https://www.golfmk7.com/forums/showthread.php?t=7926

 

Thanks AG Falco

no, and I didn't tell the wife either or she'll want something new.

 

I have seen posts elsewhere saying you need to tell the car it's got a new battery, but I think that's taking political correctness too far and if it does stop working I'll simply get a tree branch and give it a good thrashing

Has the battery been load tested at any point or are you assuming it's fine given it'll hold ~12.84v when disconnected?

 

It's not clear but I don't think you've followed the parasitic draw guide I linked.

 

The Bolero *could* be the cause but it may also be a symptom. Another control module might be causing the Bolero to stay awake rather than it being faulty. Feel free to replace the Bolero but I don't think there is sufficient data to confirm it's the only issue you're having.

Batteries lose capacity over time.

If you have a new 60Ah battery it will support a 1amp load for 60hours until the battery is flat.

The same battery after some 3 years of use may well only have a capacity of 20Ah so will only support a 1amp load for 20hours until its flat.

This battery whether new or used will show a fully charged no load voltage of 12.8v and will still have roughly the same voltage a week later.

So in conclusion it may be that the old battery just doesn't have the capacity to support the cars electronics for long enough.

 

 

15 hours ago, piewacet23 said:

OK here is the latest....Battery at full charge 100% after slow charge using computerized slow smart charger  12.84v

My interpretation of this line is that after having been fully charged the battery showed a resting voltage of 12.84V.

Not that it was being charged at 12.84V by the charger.

 

I'd be much more inclined to fix the problem with the Bolero rather than bin the battery, buy another one, then fix the cause of the charge loss.

33 minutes ago, Wino said:

My interpretation of this line is that after having been fully charged the battery showed a resting voltage of 12.84V.

Not that it was being charged at 12.84V by the charger.

 

I'd be much more inclined to fix the problem with the Bolero rather than bin the battery, buy another one, then fix the cause of the charge loss.

 

I wonder if he has tried simply physically switching the Bolero on/ off when parked, i.e. not relying on the ignition switch to turn it off.

 

Another thing to try could be a hard reset, not sure but usually this involves holding the power button down for about 10 secs.

 

 

11 hours ago, Llanigraham said:

From previous comments on here when a similar problem arose it was noted that the current draw through the radio system did not reduce immediately the radio was turned off, but was a gradual step down.  I don't know why that is, but modern cars have complicated systems, and do not the simple on/off of the past.

We also know from long experience that failing batteries throw up various "faults" and there does not appear to be any constitency in what those are.
We also know that the "brain" in the car switches off things like the radio and interior lights to preserve the battery and the lower the battery the quicker that switching off occurs.
If your battery has gone flat a few times then it is quite likely knackered, and therefore it will not be holding a charge for very long, if at all.
Therefore your first job is to fit a known, fully charged battery and see what happens.
After that, if it goes flat again your only option will be to get a qualified auto-electrician to look at it.

 

And can I suggest that making sarcastic comments to a member who has made a sensible and accurate posting is not the way to gain advice.

My sincere apologies...however you did suggest I know nothing about batteries, I was for many years a qualified aircraft engineer so I do have some background and qualifications.  There has been one event when the battery capacity fell to the point where everything shut down, repeated indications of the stop start not operating due to reduced battery voltage. The way forward now is to check the individual circuits at the fuse box as recommended  by VAG, simply checking for drain at the battery does not work. The family was in the motor trade for many years (main dealers) not directly related but interesting my contacts tell they believe they replace more AGM batteries than convention lead acid types, it could just be that there are now more of this type of battery in circulating. It may well be that the battery is duff but once disconnected from the cars systems it holds full charge for days on end !! 

At the risk of annoying you again, please Google "micro hybrid" and read to understand todays complex charging and energy recovery schemes used in virtually all of Skodas/VAG current cars.

 

Batteries are rarely fully charged on the car but work to a target state of charge, allowing enough capacity to always be available for energy recovery during braking. 

 

They use a complex algorithm and monitor state of charge using among other things, a current sensor built into the negative terminal connector which tracks how much charge is being put in or taken out.

 

That is why the manual gives specific instructions about how to connect your charger using the tab mounted on the body and not the negative terminal of the battery.

 

Once you disconnect your battery and charge it off car, the vehicle loses track of state of charge and I'm not sure it's able to simply resync without resetting battery stats through diagnostics or perhaps recharging fully in situ. So basically the battery management will be all confused and not operate correctly, at least initially.

 

Having designed industrial electronics for decades, using batteries of all types I know a lot about them (batteries are an unpredictable pain in the neck as a designer unless you add complex monitoring).

 

However, the micro hybrid system our cars now use are more about scoring a couple of ECO points and complying with EU regulations and far less about reliability and long battery life which gets hit, especially if you are not using the car frequently enough which is an annoying compromise/feature for some of us 

 

Sorry again if you are offended or bored, but perhaps my rants can help others reading to appreciate that we have moved far on from the old days of the alternator just charging the battery at 14.3 volts to keep it topped up.

I have just found this on Amazon;

https://www.amazon.co.uk/s/ref=nb_sb_noss?url=search-alias%3Daps&amp;field-keywords=+Car+Automotive+Fuse+Current+Amp+Tester+%2F+Meter+~+Battery+Leakage+Detector+~+48V+20A+Standard+Blade+Type+with+LCD+Display+by+electrosmart&amp;rh=i%3Aaps%2Ck%3A+Car+Automotive+Fuse+Current+Amp+Tester+%2F+Meter+~+Battery+Leakage+Detector+~+48V+20A+Standard+Blade+Type+with+LCD+Display+by+electrosmart&amp;ajr=0

47 minutes ago, xman said:

At the risk of annoying you again, please Google "micro hybrid" and read to understand todays complex charging and energy recovery schemes used in virtually all of Skodas/VAG current cars.

 

Batteries are rarely fully charged on the car but work to a target state of charge, allowing enough capacity to always be available for energy recovery during braking. 

 

They use a complex algorithm and monitor state of charge using among other things, a current sensor built into the negative terminal connector which tracks how much charge is being put in or taken out.

 

That is why the manual gives specific instructions about how to connect your charger using the tab mounted on the body and not the negative terminal of the battery.

 

Once you disconnect your battery and charge it off car, the vehicle loses track of state of charge and I'm not sure it's able to simply resync without resetting battery stats through diagnostics or perhaps recharging fully in situ. So basically the battery management will be all confused and not operate correctly, at least initially.

 

Having designed industrial electronics for decades, using batteries of all types I know a lot about them (batteries are an unpredictable pain in the neck as a designer unless you add complex monitoring).

 

However, the micro hybrid system our cars now use are more about scoring a couple of ECO points and complying with EU regulations and far less about reliability and long battery life which gets hit, especially if you are not using the car frequently enough which is an annoying compromise/feature for some of us 

 

Sorry again if you are offended or bored, but perhaps my rants can help others reading to appreciate that we have moved far on from the old days of the alternator just charging the battery at 14.3 volts to keep it topped up.

Not at all thank you for the information, you are indeed very correct. An old collage chum of mine for many years had a business making batteries, now sold to Japanese. He tells me VAG have a very sophisticated device for checking battery health, which you set up with the individual SAE/DIN numbers from the battery. He also tells me to look for drain use VAGs method of voltage drop at the fuse box and convert to milliamps. Symptoms are one event of total shut down after standing for about 4 days, repeated shut down of the stop/start system quick check shows battery voltage down when this happens. In my case the battery has been charged on the car, using so called smart charger as per manual instructions, disconnecting a charged battery it will hold charge for 36 hrs constant at 12.6v. On the car voltage drop to about 12.0 will happen in 36 hours. That clearly says something is on the fritz. All I wish to do is to find the cause just changing a battery is an expensive option. Incidentally it would appear that battery drain in modern vehicles is a problem, some Fords have a system that shuts down the electrics if no activity has been detected for an extended period, you reset the system by a switch in the door pillar.  Someone has just sent  me a link to Amazon, there now a whole range of meters designed to measure amps at fuse locations, I don't see the point a multi meter is probably better but it shows how common these problems are.       

Edited 13 February, 20197 yr by piewacet23
More information

What have you changed to create this current draw?

If the answer is nothing then what has changed?

A disconnected battery will hold 12.8v  for weeks  no matter if its full capacity or reduced capacity so Voltage will indicate state of charge but is not a test as to whether a battery has the capacity to maintain the electronics.

 

Easy test for the battery.

With the battery out of the car and assuming its a 71Ah lead acid  battery voltages are different for agm.

1, fully charge the battery

2, leave for a couple of hours then measure voltage, should be 12.8v

3, connect a 12v 10watt normal lamp across the battery this will discharge the battery at about 1 amp

4, after 24hrs disconnect the lamp this will have taken approx 24Ah or 1/3 of the capacity of a healthy battery 

5, wait an hour or so then measure the voltage it should be 12.3 or 65% capacity

If the voltage is much lower than that then the battery has lost capacity and needs replacing.

 

ETA

12.6v is not a fully charged battery it should be nearer 12.8 even after a week or so.

Edited 13 February, 20197 yr by idleness

2 hours ago, piewacet23 said:

Not at all thank you for the information, you are indeed very correct. An old collage chum of mine for many years had a business making batteries, now sold to Japanese. He tells me VAG have a very sophisticated device for checking battery health, which you set up with the individual SAE/DIN numbers from the battery. He also tells me to look for drain use VAGs method of voltage drop at the fuse box and convert to milliamps. Symptoms are one event of total shut down after standing for about 4 days, repeated shut down of the stop/start system quick check shows battery voltage down when this happens. In my case the battery has been charged on the car, using so called smart charger as per manual instructions, disconnecting a charged battery it will hold charge for 36 hrs constant at 12.6v. On the car voltage drop to about 12.0 will happen in 36 hours. That clearly says something is on the fritz. All I wish to do is to find the cause just changing a battery is an expensive option. Incidentally it would appear that battery drain in modern vehicles is a problem, some Fords have a system that shuts down the electrics if no activity has been detected for an extended period, you reset the system by a switch in the door pillar.  Someone has just sent  me a link to Amazon, there now a whole range of meters designed to measure amps at fuse locations, I don't see the point a multi meter is probably better but it shows how common these problems are.       

Think I have got it yes its the battery : Just done the Voltage drop checks as per VAG document - i.e. across the fuses of all of them, only two show any drop at all F9 instrument cluster, OK expected clock and all the other stuff in there and F4 interior lights,Voltage control unit OK to get at the fuses door has to be open and voltage control unit is active.

Would it be plausible to assume that the battery will hold charge when not connected to the car when connected it struggles with even these relatively low demands ?  

3 hours ago, xman said:

 They use a complex algorithm and monitor state of charge using among other things, a current sensor built into the negative terminal connector which tracks how much charge is being put in or taken out.

 

That is why the manual gives specific instructions about how to connect your charger using the tab mounted on the body and not the negative terminal of the battery.

 

Thank you @xman.  Always wondered the precise reason for this.

1 hour ago, idleness said:

What have you changed to create this current draw?

If the answer is nothing then what has changed?

A disconnected battery will hold 12.8v  for weeks  no matter if its full capacity or reduced capacity so Voltage will indicate state of charge but is not a test as to whether a battery has the capacity to maintain the electronics.

 

Easy test for the battery.

With the battery out of the car and assuming its a 71Ah lead acid  battery voltages are different for agm.

1, fully charge the battery

2, leave for a couple of hours then measure voltage, should be 12.8v

3, connect a 12v 10watt normal lamp across the battery this will discharge the battery at about 1 amp

4, after 24hrs disconnect the lamp this will have taken approx 24Ah or 1/3 of the capacity of a healthy battery 

5, wait an hour or so then measure the voltage it should be 12.3 or 65% capacity

If the voltage is much lower than that then the battery has lost capacity and needs replacing.

 

ETA

12.6v is not a fully charged battery it should be nearer 12.8 even after a week or so.

Thanks for your response but I think I have found the problem...Battery is agm and will charge using smart charger to about 12.84V. I have been suspicious of a parasitic drain this morning I checked for voltage drop at the fuse box as per VAG procedure. Voltage drop on two fuses only, F9 Instrument cluster OK clock and stuff feed from here and F4 voltage control and interior lights OK door open to access fuse box. Looks like the battery capacity is poor. (alternator output on full load has been checked and is good) Nothing has been changed on this car, had it from new all standard no additional stuff added. Your post makes sense if the battery has a capacity problem then a 1amp drain would run it down fairly quickly it takes longer because we have a smaller drain from the cars systems.   

30 minutes ago, piewacet23 said:

Thanks for your response but I think I have found the problem...Battery is agm and will charge using smart charger to about 12.84V. I have been suspicious of a parasitic drain this morning I checked for voltage drop at the fuse box as per VAG procedure. Voltage drop on two fuses only, F9 Instrument cluster OK clock and stuff feed from here and F4 voltage control and interior lights OK door open to access fuse box. Looks like the battery capacity is poor. (alternator output on full load has been checked and is good) Nothing has been changed on this car, had it from new all standard no additional stuff added. Your post makes sense if the battery has a capacity problem then a 1amp drain would run it down fairly quickly it takes longer because we have a smaller drain from the cars systems.   

Ok

I had assumed the 12.84v was after you had disconnected the charger. Needs to be way higher than that to get a decent charge into the  battery. 

The principle of the test is the same for AGM just different voltages.

30 minutes ago, idleness said:

Ok

I had assumed the 12.84v was after you had disconnected the charger. Needs to be way higher than that to get a decent charge into the  battery. 

The principle of the test is the same for AGM just different voltages.

Likewise; @piewacet23 I'd expect a charger to be delivering more like 14.4v.

18 hours ago, Halford said:

I have seen posts elsewhere saying you need to tell the car it's got a new battery

 

I think the car will only charge the new battery to the old batteries capacity.

It is a bit like putting a bigger fuel tank in a car and the car wont fill it up above the old limit.

So you won't benefit from the bigger battery at all.

 

Thanks AG Falco

8 minutes ago, AGFalco said:

 

I think the car will only charge the new battery to the old batteries capacity.

It is a bit like putting a bigger fuel tank in a car and the car wont fill it up above the old limit.

So you won't benefit from the bigger battery at all.

 

Thanks AG Falco

 

Using the correct diagnostic, when you replace the battery, you can recode several things inc battery manufacturer,specific type/technology, Ah capacity and serial number among other things.

8 hours ago, AGFalco said:

 

I think the car will only charge the new battery to the old batteries capacity.

It is a bit like putting a bigger fuel tank in a car and the car wont fill it up above the old limit.

So you won't benefit from the bigger battery at all.

 

Thanks AG Falco

 

7 hours ago, xman said:

 

Using the correct diagnostic, when you replace the battery, you can recode several things inc battery manufacturer,specific type/technology, Ah capacity and serial number among other things.

thanks for the heads-up guys I hadn't even considered that (doh!),

a voltmeter check showed the alternator was putting out 14.4+ volts, but I hadn't considered the ECU would switch it on and off.

 

just found an old post pointing to the VCDS guide

will see if my local garage (who have the bluetooth VCDs whatsit) will change the settings for me

 

 

update: .........

 

my local garage didn't have VCDS they have a "snap-on" tablet which was far simpler as it features a "Battery Reset" button option, the only drawback was whilst featuring Varta battery presets, it doesn't recognise Bosch, so we had to manually input the 70Ah setting and enter the serial code (which was 9 digits and not the snap-on requested 10 digits - that stumped us for a few mins). A re-check showed the new settings had taken.

 

Will stick a voltmeter on the battery in a month or so and make sure it is actually charging fully.

thanks again

 

On 12/02/2019 at 22:38, AGFalco said:

Have you told the car it has a different battery? 

 

 

15 hours ago, Halford said:

just found an old post pointing to the VCDS guide

 

The link I provided last time had this information in it for you.

 

Thanks AG Falco

 

Edited 14 February, 20197 yr by AGFalco

3 hours ago, AGFalco said:

 

 

 

The link I provided last time had this information in it for you.

 

Thanks AG Falco

 

Yes I saw that, useful information, my problem is that it is the original battery from new just over three years old...it is not AGM it is the EFB type which is cheaper than AGM, It has been suggested that Skoda fitted lower capacity batteries to some models to keep costs down