Skoda superb elegance 2.0 TDi DSG

 

My battery went flat around 12 months ago, it was old so I got a new one, before i did i checked what the alternator was producing and it was very low, but once revved over 1500rpm it kicked into full charge. If i remember correctly, it only had to go above 1500 once and the alternator kicked in and continued to even when idling at 900.

 

I told a garage about this in an MOT and they still left lights on and flattened my new battery. I managed to get a new one under warranty but it's gone flat with the cold and not using it often enough. I was in it 7 days ago for a long run out but it's dead now and on charge with an optimate.

I once seen on here about a gearbox overrun cable that can cause this but no more info?

What year is your car? Does it have start/stop? If so, was the battery coded to the vehicle after replacement?

 

To be honest, going flat after sitting for a week doesn't sound too far off in a Superb. There's a lot going on electrically, even when the vehicle is off.

What year is your car? Sounds like the alternator excitation wire may be busted. 

Year and ideally engine code and I can look up the details in wiring diagrams.

On 08/01/2021 at 20:06, Wino said:

What year is your car? Sounds like the alternator excitation wire may be busted. 

Year and ideally engine code and I can look up the details in wiring diagrams.

You know your stuff 

On 08/01/2021 at 20:06, Wino said:

What year is your car? Sounds like the alternator excitation wire may be busted. 

Year and ideally engine code and I can look up the details in wiring diagrams.

Hi, It's a 2010, Whereabouts do i find the engine code, If i'm looking at the correct part the code is CFG, is that correct?

Engine code can be found on a sticker on the cambelt cover usually, and on the build sticker in the boot.  CFGB is a 2.0 diesel used in Superbs at the time yours was made, so that's probably it.

 

The wire in question on your car goes to pin 1 of the two way connector that goes into the alternator and is black/blue at that point. It changes into a yellow white wire on pin 2 of a 4-way connector at 'front left side of the engine bay'. That's left as you sit in the car looking forwards so right as you look into the engine bay from in front of the car.

From there it goes to both engine ECU pin 70 and pin 32 of a brown 52 way connector at the BCM in the cabin.

 

Look for unpluggedness of the alternator connector to start with, then if that was plugged in OK, trace that wire as best you can to each destination.

 

 

 

Thanks very much, I will get a look at this next week hopefully. I have checked again at the battery and when started with everything off it only puts out 11.8V, then once it's revved over 1500rpm once the alternator kicks in properly at 14.5V and remains at this.

Please let us know how you get on.

 

I will update here once I get some spare time soon. Hopefully the next week 

If you have a multimeter you can probably establish the wire's intactness or otherwise by measuring voltage at pin 1 of the alternator loom connector with it unplugged. Ignition would need to be on at the time, and I'd expect to find around 12V or a little less if the wire is OK.

Not sure how accessible the connector is on your car/engine though, may not be straightforward to reach.  The 4-way connector where the wire changes colour may be a better bet access-wise, but I don't know exactly where that is.

Edited 18 January, 20215 yr by Wino

this sounds like the problem i have  having to blip the throttle to over a 1000rpm to get it to charge then its ok puts out 14.2v all the time never drops  my car having regen braking it should vary my car is a 2015 Skoda Superb estate 2.0tdi 140 engine code CFFB its fitted with a 180 amp alternator i will prob this plug as soon as i can i don't think it drains the battery VCDS says the battery is at 84% being charged at 1.5amp after a short drive putting a fluk meter on the battery next morning reads 12.5v 

So an update, luckily it ended up being a loose plug on the alternator preventing the alternator kicking in until the engine reached 1500rpm. I don't know how this has came loose or if someone in a garage might have done it in the past. 

 

After finding the charging problem last week, my battery is still draining slowly, it's been used for 3 shorts runs over the last 6 days since i fixed it. Yesterday i went to start it and it felt lazy, today it almost never started. I have disconnected the earth lead from the battery and checked for earth leakage between the negative lead and terminal and it's drawing  .3 mili amps so thats ok, I've checked it 4 times over 2 days. The battery is around 18 months old from memory. could there be something else or is it purely the cold killing the battery and minimal use?

 

I'm going to disconnect it and give it a full charge with an optimate 4, what baffles me is that 6 weeks ago i took it out for a 70 miles round trip and the next day it got sluggish to start.

0.3mA is not a plausible reading, do you mean 0.3A?  Or 30mA? 

It must be 0.3A, I did get someone else to double check it and said it's fine being below 0.5a. The battery is now back on charge as it's too flat to start the car. I bought it in mid October 2018 when i found the receipt. So its 2 yrs and 4 months old. I'm sure the warranty is 3 to 5. It's not like it's sitting for weeks on end without being started.

 

I have disconnected the car terminals from it and charging it up fully again. I will then try checking the battery on volts as someone turns the engine over to see if the starter motor is excessively pulling from it as someone local suggested it might be on it's way out. If this is worth it, what figures would i be looking at?

 

Other than a weak battery and not enough use I don't know what it can be now. I don't want to buy another incase it does it again. I may have to buy a solar charger that plugs into the 12V lighter socket to top it up if it's the lack of use or shorter runs.

Quote

 

 

0.3A is around ten times what is OK if the car is fully 'asleep', so you'll need to check that again.

 

 

1 hour ago, ddan1275 said:

I may have to buy a solar charger that plugs into the 12V lighter socket to top it up if it's the lack of use or shorter runs.

 

 

A solar charger will not 'top it up', rather it may (if it's output is high enough) replace what the car is drawing whilst it is stood. For this purpose I use a 4 watt one, but I also use a normal charger occasionally if I know it is going to be freezing outside..

 

If you have done a 70 mile trip, and the car struggled to start the following morning then either a battery or charging or drain issue.

The battery can be tested with a digital machine, however it has to be in a good state of charge for a garage to be able to test this way.

 

A diesel does take a good amount of power to start up. What battery do you have, what CCA is it?

it s an Oldham advanced and says 74Ah 12V 670CCA 

I did take it to a garage to get it double checked to make sure my multimeter was reading it correct. I only have one setting for amps, it says mA A and has direct and alternating pattern on the same dial where as volts has separate settings for direct and alternating ac/dc. 

 

When it's set at rest the display shows 00.00, once it's connected it shows - 289.6 m A

Either you and the garage aren't measuring it right, or something is staying on when it shouldn't.  

 

This may help, depending on the style of fuse you have fitted. Skip straight to the end for a download link for the document. https://www.briskoda.net/forums/topic/377587-technical-bulletin-about-parasitic-current-draw-measurement/

 

 

Thanks ill have a read of the link you sent. This is what i get on my multimeter.

I presume you're measuring that between battery negative post and the clamp, disconnected from it?

 

You need to let the car shut down completely first, and then do the measurement without waking it up again. Any interruption of the connection will wake things up, so you have to be a bit stealthy.  Try this:

 

Open the bonnet

Loosen but don't remove the battery negative clamp, make sure you can wiggle it free/off with minimal effort

Flick the bonnet latch over so that the car thinks the bonnet is shut, even though it isn't, giving you access to measure current use directly at battery negative.

Lock the car, all doors. Making sure the key is outside the car.

Wait 30 minutes.

With multimeter on 200mA DC Current range (or similar) and probes in the appropriate meter sockets, put the negative/black meter probe onto the battery's negative post, straight downward. Hold the positive/red meter probe against the battery clamp in such a way that you can keep it on there (and the other one still on the battery post) while you gently jiggle the negative clamp up off the post around your black meter probe so that you now have everything connected through the meter (and the power to the car was never interrupted). This operation is probably much easier with an assistant, but quite doable solo.

 

Read the true quiescent current now.

 

Slip the negative battery clamp back down/on, remove meter probes, tighten clamp. Open up car and operate the bonnet release to reset the catch.

 

 

I tried this yesterday, same setting and method as I was doing which you mention above but this time i tried with the the bonnet open and the catch down with car locked up for 1 hour simulating it being locked. My multimeter was just jumping all over the place so I need to take it to another garage or someone with a decent meter with more amp settings. It was impossible to take a reading with the numbers jumping about. I couldn't even get the same reading as i had previously shown above.

I tried a second time, and later tried doing it then turning the meter off and back on to see if that gave a steady reading but the car alarm started going off so i'm guessing the connection must of slipped to cause that.

Hmm, sorry that didn't work out for you.

If you fancy one more go, try it without locking the car, but otherwise everything the same.  The reading jumping about may have been a flashing LED in the driver's door lock button (signalling "alarm set") if there is such an LED on your car? Was it jumping between two numbers about 5-10mA apart?

I'll give it a try with 4 hands and get back to you asap, thanks for the help & patience 

Edited 26 February, 20215 yr by ddan1275