Suspected battery drain - desperate for help please

[LordRaiden84]

Hi all

 

Really, really need to get to the bottom of this it's stressing me out to the nines.

 

Basically, purchased a Varta battery to replace an old battery that had been in the car for a number of years.

 

The car will run completely flat after about 3 days which indicates battery drain.

 

Interestingly, a kind member on here swapped my Bolero for the Columbus like 4 years ago so if that was the issue surely I'd have ran into problems way back when.

 

Using a multimeter I get around 11.80V at battery doing nothing then (when it's been jumped by the better halfs car) on idle measures 14V.

 

It's getting to a stage now where jumping it, taking it for a run etc etc is obviously not the answer.

 

I know I need to diagnose the current draw or usage when the car is powered down but I have a problem.

 

Basically, I know I need the car to 'think' it's locked so have to manually open the boot but mine is modified due to being an aftermarket honeycomb grille.

 

The latching arm would not fit through the grille as there's no vertical gap like the OEM one so it's been bent to the side.

 

Am I right in saying I can pre-release the bonnet, then lock the car and immobiliser it, wait 30 mins or so for the car to go to sleep then just lift it by prising it up (I can fit my hand in the gap between under of bonnet and top of vent)?

 

Also, do I disconnect the neutral from the battery terminal and measure it across the fuses or do I need to do something else?

 

I really want to try to find out what's going on. I don't think it's a faulty battery as it's done this twice now and the previous one was thought to be faulty. Guess I was wrong.

 

Please help it's bothering me that much now I feel like getting shut of the car altogether.

 

It's a VRS CR170 MKII btw.

 

Thank you

Edited 29 February, 2020 by LordRaiden84

[mrgf]

Hi, I know not of this issue but I do know others have had a depleting battery, on the Fabia 2 forums. It sometimes seems to be due to water ingress at the fan, making the fan stay on or could be other issues. Might be worth a trawl around that forum or other battery related ones.

[Guest]

Bit of a coincidence, new battery and problems.

 

Can you return potentially faulty battery for a replacement?

[LordRaiden84]

This is a recurring issue so I'm more leaning towards it being something more sinister than the battery itself.

 

The initial new battery which is now in storage started going flat after a few weeks, thus swapped it for the Varta.

 

It is worth mentioning I use a works vehicle so don't have access to my car during the week. 

 

What is the normal expectancy for a derv to be left idle before turning it over.

 

Surely more than 3 days?

[J.R.]

Start off with a fully charged battery;

 

Open the bonnet and with a screwdriver or similar depress the latch part of the bonnet catch on the slam panel as if the bonnet was closed, this will close the microswitch & the car will believe the bonnet is closed, lock the car with the remote & return after 20 minutes.

 

This may take a bit of fiddling or require a second pair of hands, with your multimeter set to the 200ma range put the +ve probe to the +ve battery terminal ideally under the clamp so it can be removed, if not in the centre of the pole but the next stage will require steady hands, put the -ve probe to the +ve battery clamp and with both probes being held in constant contact remove the battery terminal.

 

at this point all the quiescent current will be running through the test meter and the dispaly should show less than 30 milliamps, any more than 40 is definitely a problem.

 

Dp you by any chance have a towbar with a bypass relay for the electrics? This was taking an additional 15ma IIRC from my battery all the time, if water has got to it then it could be taking more, earlier ones also took more current.

[J.R.]

After resolving my battery drain (the Canbus/head unit and trailer wiring relay) my new Varta battery was damaged and has lost 30% of its CCA, nonetheless it holds 12.5 - 12.7 volt for a few days dropping 0.1v every couple of days after that, if it gets to 11.8v with no other load I wont try to start it and put it on charge, it would start but the volt drop throws up fault codes & warning lights and it was through cranking with a low voltage that I damaged the battery.

 

I hope that your 11.8v on standby is because there is a very significant parasitic drain causing the volt drop, if not then I fear you may have damaged your new battery as I have done, I bought an electronic battery test meter from Ebay for £18 or you could get it checked by a garage.

 

I have solved my parasitic drian problems but it feels like the vehicle would be at less than 12v after a week at which point starting it would further damage my new battery.

[LordRaiden84]

That's a really well thought out reply. I appreciate the effort. I'll do this is in order so as in the hope it makes perfect sense to you and to help aid a methodical response.

 

Firstly, I can get hold of a neighbours charger and am prepared to leave it on overnight.

 

However, can I not just bung the leads on other halfs motor and jump it or could that damage the battery as well?

 

I will test the stand by voltage later and let you know what it is but last time it was deffo 11.8V

 

 

20 minutes ago, J.R. said:

put the +ve probe to the +ve battery terminal ideally under the clamp so it can be removed, if not in the centre of the pole but the next stage will require steady hands, put the -ve probe to the +ve battery clamp and with both probes being held in constant contact remove the battery terminal.

 

Ok, same neighbour can assist me here if I do get paranoid about jazz hands during this process.

 

Just to clarify (apologies if I sound thick), am I right in saying your instructing me to put the + probe of the test meter under the clamp so it can be uncoupled then lifted off?

 

Also, I'm gathering from the above the - probe of the meter goes on the clamp whilst the clamp is still housed on the positive terminal of the battery?

 

Would that not cause a short?

[J.R.]

first starting with the 11.8 volts, its too low but is it just a discharged battery or volt drop due to a discharge or maybe both?

 

So charge the battery then after its rested unconnected check the cell voltage, you want 12.7v, if you have less it wont prevent you doing the standby current test.

 

My long explanation was to make sure that the car has gone into rest mode after 20 minutes and that the voltage is not removed from the electronics during the test if you disconnected the battery then reconnected it through the meter on the 200ma range it would come out of sleep mode, draw more than 200ma and possibly blow the fuse, I wanted you to effectively "shunt" the connection between the battery clamp and the terminal that way when the terminal is removed the standby current will flow through the meter without the circuit being broken and the electronics woken up.

 

The other way is to just try connecting the meter and coming back in 20 minutes to see what the reading is and hope that the initial current does not blow the internal meter fuse, its by far the simpler way and easier to describe.

[Daniel_Bos]

48 minutes ago, LordRaiden84 said:

 

 

Just to clarify (apologies if I sound thick), am I right in saying your instructing me to put the + probe of the test meter under the clamp so it can be uncoupled then lifted off?

 

Also, I'm gathering from the above the - probe of the meter goes on the clamp whilst the clamp is still housed on the positive terminal of the battery?

 

Would that not cause a short?

What you essentially need to do, is make the meter part of the circuit, so the current flows through the meter.

So, for the meter to measure all the current flowing out of your battery, you need to put it in between the battery terminal and the battery clamp.

To not interrupt the "sleep status" of the car by disconnecting and then reconnecting the battery, you'll have to connect the leads to pole and clamp respectively, then remove the clamp from the pole without breaking the contact between the meter probes and the pole on one probe and the clamp on the other.

If you do that, all the current flowing out of your battery now has to flow through the meter, allowing the meter to measure just how much current that is.

 

An alternative way to do the above is as follows:

Take off the battery clamp.

Tightly wrap a length of bared wire around the very base of the terminal and twist it so it'll stay put, leave a short length of wire sticking out with the insulation still on.

Stab one of the probes of the meter firmly into the end of this bit of wire so it is making good contact and won't come out.

Put the clamp back on but don't tighten it.

Attach the other probe to the clamp, you can tape it on or use a large peg etc. Anything that'll hold it in place securely.

 

Then put the key in ignition, leave it for a minute for the car to "reset" after having it's power supply interrupted.

 

Then (with the bonnet close sensor clamped/disabled) lock the car, leave for 30 mins before removing the clamp from the battery.

Having the probes pre-attached means you can use your hands to shine a torch, or pull fuses to see which circuit makes the power drawn significantly less and thus try to identify what's causing your car to wake up tired from it's slumber.

[J.R.]

Thanks for the much better and concise explanation than mine Daniel!

[bigjohn]

Disconnecting one fuse at a time can give strange results with modern can bus car electronics. There has been an interesting post on this in the past by @Wino where you keep fuses in and measure voltage drop across fuses and reference on a large lookup table:-

 

 

Edited 29 February, 2020 by bigjohn

[langers2k]

58 minutes ago, bigjohn said:

Disconnecting one fuse at a time can give strange results with modern can bus car electronics. There has been an interesting post on this in the past by @Wino where you keep fuses in and measure voltage drop across fuses and reference on a large lookup table:-

 

 

 

Exactly this. Follow the attached guide as it's the correct way to trace any parasitic draw 👍

[J.R.]

I identified the problem before getting to that stage but presumably you have to do the same thing to the door closed sensor as the bonnet catch in order to get to the fusebox, how is that done?

 

I think I may have found how to do it in the past for something else but cant recall.

[LordRaiden84]

Thanks for the very informative response chaps. Going to see neighbour later today hopefully when they get back from their travels and loan their battery charger.

 

I will obviously shop around and invest in one of course. It seems silly keep asking to borrow it although they don't really mind we get on very well.

 

If it gets charged tonight then tomorrow after work I will check the battery voltage first and foremost to see it is actually taking a charge then proceed with the steps advised.

 

I had a brainwave earlier and realised a while back the rear wiper would sometimes not fire the fluid but you'd hear the motor.

 

Quite sporadic it's behaviour tbh. Not sure if it's grit in the nozzle but will poke it with a needle or something of that ilk.

 

Anyways what I'm getting at is I recall someone saying on the Octavia the rubber hosing to the rear washer can become loose at a joint or something so the fluid just goes straight down the back inside the panelling and possibly onto the electrics.

 

Might be a bit out there but does this sound familiar to anyone?

 

Also, although I'm 99.9% certain the columbus can't be the culprit as it was installed ages ago, do hear a whirring like fan sound coming from the double air con vents above when car has been shut down and locked (I stay very still in car so as not to trigger alarm).

 

Does this suggest something not shutting down or is this normal?

[Carlston]

It would be useful if you could provide some data. You will need a volt meter.

 

Fully charge the battery. In the first two hours or so after you disconnect the battery charger, the battery voltage may go down quickly to about 12.8V with a good battery. After that a normal situation is for the battery to take 2 or 3 months before it gets down to 12V if the car isn't being used.

 

So after a couple of hours, measure the voltage. Then after about 24 hours measure again. Then after 48 hours measure again.

 

So let's say after two hours the voltage was 12.8V, after 24 hours 12.6V, and after 48 hours 12.4V.

 

This would indicate a problem. as after 72 hours you could predict that you would be down to 12.2V and after 96 hours you would be down to 12V at which stage your battery may be too low for your engine to start. Also, it is not a good idea to keep starting your engine from such low voltage as this can significantly reduce the life of your battery.

 

When you are taking voltage measurements from your battery, don't have any electrical equipment turned on that draws a heavy current such as headlights or heated rear window. In fact, try to have all electrical equipment turned off. This is because having electrical equipment turned on reduces the voltage that you will measure across the battery terminals.

 

You can check your battery by disconnecting the terminals and doing as above. ie. fully charging it and measuring it after 2 hours and 24 hours. That should be enough. If the battery is bad it will already have fallen to 12.6V or lower. Maybe do this first before checking it connected to the terminals. You can then begin your checks knowing that the battery is good. In fact, you might want to go straight to looking for the electrical leak. Maybe with an amp meter connected in series and removing the fuses one by one, but putting each fuse back before removing another one. If after removing a fuse the current draw suddenly drops a lot, that could be where the problem is. You would of course have to find out what that particular fuse did.

 

What Ah battery are you using? If you had a 40Ah battery, changing to a 60Ah battery would allow you 50% more time before your car wouldn't start. 

Edited 2 March, 2020 by Carlston

[langers2k]

8 hours ago, Carlston said:

When you are taking voltage measurements from your battery, don't have any electrical equipment turned on that draws a heavy current such as headlights or heated rear window. In fact, try to have all electrical equipment turned off. This is because having electrical equipment turned on reduces the voltage that you will measure across the battery terminals.

 

Just unlocking the car, opening the door and bonnet will cause lots of systems to come online and consume power.

 

The correct method for diagnosing parasitic drain on modern CAN-bus based cars was reposted by bigjohn earlier.

[J.R.]

I should add that that procedure does not mention how you can have the door open to access the fusebox to carry out the checks without waking up the canbus, you ca switch off the interior light but I think the canbus will remain active all the time that the car sees the door open.

12 hours ago, Carlston said:

 

 

Fully charge the battery. In the first two hours or so after you disconnect the battery charger, the battery voltage may go down quickly to about 12.8V with a good battery. After that a normal situation is for the battery to take 2 or 3 months before it gets down to 12V if the car isn't being used.

 

So after a couple of hours, measure the voltage. Then after about 24 hours measure again. Then after 48 hours measure again.

 

So let's say after two hours the voltage was 12.8V, after 24 hours 12.6V, and after 48 hours 12.4V.

 

 

You can check your battery by disconnecting the terminals and doing as above. ie. fully charging it and measuring it after 2 hours and 24 hours. That should be enough. If the battery is bad it will already have fallen to 12.6V or lower. Maybe do this first before checking it connected to the terminals. You can then begin your checks knowing that the battery is good.

 

 

My battery isn't good despite being new after having overdischarged it during the current drain problem, in fact even from new it dropped immediately to 12.5v after a charge whereas the much older one which I am no using again holds 12.7v even a year later.

 

So I dont have a good battery but I do watch the standby voltage like a hawk & have fitted a voltmeter I can see through the car window, I have just done a long run & fully charged the battery, the older one that does hold a good voltage after a charge and shows 70% life on an electronic tester. Its been standing and hour and showing 12.7 volts, it will be down to 12.5 later on and will be at 12.3v tomorrow morning however it will only drop another 0.1v max after a week, the longest that it has been left, it always starts well and I think it would last a month but not 2-3 months, its a larger 096 battery bigger than standard.

 

My point is that certainly with a less than perfect battery the voltage drop vs time is not linear in the first few days so cannot reasonably be used to predict the autonomy over a few months.

[langers2k]

1 hour ago, J.R. said:

I should add that that procedure does not mention how you can have the door open to access the fusebox to carry out the checks without waking up the canbus, you ca switch off the interior light but I think the canbus will remain active all the time that the car sees the door open.

 

 

It's a generic procudeure for all VAG cars. Just like the bonnet, there will be a switch somewhere on the door/door frame or built into the lock mechanism. You'll need to find it and trick it into thinking the door is shut.

 

[J.R.]

Worh pointing out nonetheless.

 

On my Octavias there was a sort of metallic acorn stud on the bottom of the door which engages into a female plastic socket on the door cill but if there was a sensor behind it I never managed to get it to switch, it might just have been something to locate the door & stop it bursting the lock in a crash.

 

Certainly the lock catch will need closing like the bonnet, will have a try one day.

[LordRaiden84]

Can I just confirm then and get everyone to agree as per Carlston's earlier post that I firstly need to diagnose the battery itself prior to using the guide, which btw is really appreciated.

 

I will disconnect it completely and charge it indoors overnight and then test it over say a 48 hour period to see if there's any discernable volt drop.

 

If it does drop significantly, then it would suggest a faulty battery contrary to what I first thought.

 

I think this should be the first step. Am I correct?

[Daniel_Bos]

1 hour ago, LordRaiden84 said:

Can I just confirm then and get everyone to agree as per Carlston's earlier post that I firstly need to diagnose the battery itself prior to using the guide, which btw is really appreciated.

 

I will disconnect it completely and charge it indoors overnight and then test it over say a 48 hour period to see if there's any discernable volt drop.

 

If it does drop significantly, then it would suggest a faulty battery contrary to what I first thought.

 

I think this should be the first step. Am I correct?

I would take a simpler first step:

Next time you park it up (for a few days) just disconnect the battery negative.

If it starts fine next time you come to use it, it's not your battery or alternator. Not really any need for charging and measuring etc.

Measuring the voltage of a battery doesn't tell you everything...

[Carlston]

1 hour ago, LordRaiden84 said:

Can I just confirm then and get everyone to agree as per Carlston's earlier post that I firstly need to diagnose the battery itself prior to using the guide, which btw is really appreciated.

 

I will disconnect it completely and charge it indoors overnight and then test it over say a 48 hour period to see if there's any discernable volt drop.

 

If it does drop significantly, then it would suggest a faulty battery contrary to what I first thought.

 

I think this should be the first step. Am I correct?

 

It's up to you if you want to remove the battery from the car. But at the very least you will need to disconnect the negative cable from the battery. Disconnecting just the negative cable is as good as disconnecting both the positive and the negative cable, as just disconnecting the negative cable prevents any electricity being drawn from the battery.

 

If the battery isn't holding a full charge ie. 12.7V to 12.8V after just 24 hours, then at least one of the cells has gone bad. A 12V car battery is made up of six 2V cells. The six 2V cells are connected in series thus giving the full 12V. When a battery first goes bad, it's usually just one of the 2V cells that has gone bad. To have a good battery you need six good cells, not five good cells and one bad cell. 

 

Even just a 24 hour test might be enough to detect a 2V cell that has gone bad.

[Carlston]

10 minutes ago, Daniel_Bos said:

Measuring the voltage of a battery doesn't tell you everything...

 

Measuring the voltage of a 12V battery is the easiest and best way to check a battery. Even a bad battery might take a few days after being fully charged to not start the car, as the voltage would have to drop to about 11.8V to 12V for it not to be able to start the car. By using a voltage meter, you only have to wait 24 hours to check whether the battery has gone bad, as the voltage will drop quickly over these 24 hours probably to less than 12.6V.

Edited 3 March, 2020 by Carlston

[Daniel_Bos]

But a "good" voltage reading doesn't necessarily mean you have a good battery...

I've had batteries at 12.3v after a week fail to start a car, and ones at 11.6 start that same engine just fine...

You can have very low voltage drop with the battery disconnected, yet lose all of that voltage as soon as a high load is put on. Hence my suggestion to just try to start it, it'll test the battery under load.

[Breezy_Pete]

The resting voltage for a given state of charge is also rather temperature dependent, and slightly affected by the battery technology involved (Conventional/EFB/AGM).

If you google it, the good results will give a 2-dimensional table of voltages with temperature as one of the variables.

 

The charging voltages of alternators is similarly (by design) temperature dependent, being higher at low temperatures and lower at higher temperatures (because this is what batteries can cope with).   Obviously from a cold start to a hot engine/bay condition this can be quite a range.

 

Flatly stating this or that should be this or that voltage without specifying the  temperature conditions of measurement isn't brilliantly useful.