Guys anyone faced battery draining overnight issue in skoda fabia? 

My skoda fabia 1.2HTP (Petrol 2010 mk2) randomly drains battery overnight even sometimes while driving. 

The problem which I faced was drained battery overnight 2 times and while driving the car the the battery drained to the level that the car stalled.

Finally last time the charging light came on and off then when i parked the car it didn’t crank( Due to drained battery) 

.

Again after the same night after 5 mins I tried to crank and it stared with struggle( due to the low battery)t then I have disconnected the alternator wire(B+)  from the bteery fuse and checked the voltage with digital meter it was 4.2V then I checked the AC voltage it was 15+Volt (As much as I remember) then i stopped the car and check the resistance from B+ and car body it shows some resistance on both way (connecting red to postive and to the body) so i suspect the alternator is the culprit which is draining the battery but when i checked the current draw using multimeter in serial connectin with battery + and alternator output it doesn’t show any value(maybe overdrawing amps than my multimeter range ie.a?) then i tried conmecting the alternator wire back to the battery fuse i saw a small spark like (2amps which is my intuition) but not sure what is the problem.

Then Ive checked the most common problem which is discussed here ie the alternator sensor/load wire. Those wires already snapped and fixed when i checked the voltage with ignition on one was goving 5+volts amd other wire giving 9+ volt( Both without engine running cause I can’t statrt the car ) and the battery voltage was 11.4V.

Additional thoughts: The service center telling me the alternator is fine and something else is drawing the power but if the alternator is fine then how the car stalled while driving since the ?

My veridct: I think the alternator is the culprit and the rectifier kust be gone should i change/repair the rectifier or change the alternator? Or this could be any other problem??

Thanks advance for all the help.

Sounds stupid but have you actually checked the battery? Dasia's do like a good battery so a half worn one will start to cause trouble and your car is noe 8 years old. I am on my third battery on an 09 model. One replaced as knackered, the second just recently, under warranty from the last one, that had a 5 year warranty with about a year left. It seems around 5 years is a battery life on these, perhaps longer if looked after. I do a lot of stop/start and low speed driving as I am an instructor. You may get longer but it will almost certainly be getting weak.

1 hour ago, mrgf said:

Sounds stupid but have you actually checked the battery? Dasia's do like a good battery so a half worn one will start to cause trouble and your car is noe 8 years old. I am on my third battery on an 09 model. One replaced as knackered, the second just recently, under warranty from the last one, that had a 5 year warranty with about a year left. It seems around 5 years is a battery life on these, perhaps longer if looked after. I do a lot of stop/start and low speed driving as I am an instructor. You may get longer but it will almost certainly be getting weak.

Forgot to mention that I’ve changed (upsized 65ah from stock 45ah) the battery recently (3months before) and in the service center they’ve tried with their own battery and that too drained overnight. 

Ok. I have also seen it mentioned that the battery earth cables can work loose at the chassis so make sure that is nice and tight and clean. VW also specify NO petroleum jelly or other grease/lubricant to be applied to the battery terminal posts. That are very specific about that!

4 minutes ago, mrgf said:

Ok. I have also seen it mentioned that the battery earth cables can work loose at the chassis so make sure that is nice and tight and clean. VW also specify NO petroleum jelly or other grease/lubricant to be applied to the battery terminal posts. That are very specific about that!

Does loosened earth can cause overnight dead battery?

If thats the case then it should not crank on full battery right?

Ive seen the earth cable its tiny but still looks solid and properly connected to the body.

PS: Another problem i used to have is that the interior bulbs both(led/halogen) used to flicker slightly(Which again makes me suspect the alternator AC ripple) when the car is in idle. But after changing the battery I’ve forgot to notice that. 

Charge the battery up fully, then disconnect the alternator connection from its fuse. Leave overnight and see if the terminal voltage of the battery still drops. If it hasn't changed you can probably say the alternator is the problem. If it has still dropped, do the same with the cabin fuse instead (next one along, probably).

 

Edited 8 October, 20187 yr by Wino

17 minutes ago, Wino said:

Charge the battery up fully, then disconnect the alternator connection from its fuse. Leave overnight and see if the terminal voltage of the battery still drops. If it hasn't changed you can probably say the alternator is the problem. If it has still dropped, do the same with the cabin fuse instead (next one along, probably).

 

Thanks wino, That is what I’ve planned to do but since I have to make a lomg drive to pick up my uncle this friday i want to make sure can i depend on this car to make a long drive I’ve got no other option. If i come up with a determined solution ill swap the part or fix the issue before that long drive. 

One more question, Is it normal to see a spark while connecting the alternator cable to the batter while the car is not running?

Yes, spark is no problem, just capacitors in the power supply parts of all the electronic modules charging up rapidly.

 

Wait, no, for battery cable connection normal, for alternator cable probably not.

Edited 8 October, 20187 yr by Wino

1 minute ago, Wino said:

Yes, spark is no problem, just capacitors in the power supply parts of all the electronic modules charging up rapidly.

No wino, ive disconnected only the alternator wire not the whole connector when i reconnect the (only) the alternator Seen some spark, I think there must be no spark if the alternator resistor/rectifier is working properly which prevents the alternator from drawing the power from battery.

Yeah, see my edit to previous post.

I guess the voltage regulator module in the alternator will have some power supply capacitance of its own, but I doubt large enough to cause an observable spark when reconnecting. Can try on my own car at lunchtime if you like, for comparison.

Edited 8 October, 20187 yr by Wino

Start the car and check the battery voltage with the engine running and headlights on. Should be around 14.3 volts. Anything below about 13 volts and either the alternator or wiring is at fault.

(With alternator usually the built in voltage regulator brushes have worn out, can be changed on many alternators)

Edited 8 October, 20187 yr by xman

1 minute ago, Wino said:

Yeah, see my edit to previous post.

I guess the voltage regulator module in the alternator will have some power supply capacitance of its own, but I doubt large enough to cause an observable spark when reconnecting. Can try on my own car at lunchtime if you like, for comparison.

 Thank you so much bro, Ive seen you helping most people here. If you really don’t mind you can check and tell me bro.

@xman; if the battery is in a very low state of charge, one might see the charging voltage pulled down, particularly at idle revs, and particularly when measured at the battery end of the cables, no?

 

@Vigneshwaran, no problem, I'll try it in the next hour or so.

Then try it at 1500+rpm, the alternator will pump 60+ amps if the voltage is below 14 volts and all batteries, regardless of SOC will rise to 14 volts within seconds when faced with that. Charging current then drops off because of the way Lead acid handles charging (slowly) with 14+ volts at the terminals.

 

For information, this is valid for Fabia ii, which doesnt have start/stop or smart charging which is altogether more complex scenario (for visitors with other later models such as Fabia iii)

Edited 8 October, 20187 yr by xman

No spark after 30 minutes disconnected.

Not sure whether this suggests that your alternator could have a diode failure rather than voltage regulator or brush fault?

1 minute ago, Wino said:

No spark after 30 minutes disconnected.

Not sure whether this suggests that your alternator could have a diode failure rather than voltage regulator or brush fault?

Thanks wino, Are you sure that not even a little spark? I’ve seen a very little spark every time i touched the cable to the battery fuse . But the thing is if i connect a multimeter in serial to the cable to check the draw it show 0A/ 0.00 (no reading) .ok ill go to the service station and check with them. 

Nothing at all that I could see.

Maybe check that the fuse hasn't blown inside your multimeter?

Small sparks are to be expected sometimes connecting live cables, don't attach significance to them, they are caused by transient currents/voltages and how you connect/disconnect cables.

 

Connecting/disconnecting cables to the alternator when battery is still connected can damage the alternator and other vehicle electronics by generating voltage spikes (which cause sparks!), so don't do it!

 

Do the test I described earlier and establish if your alternator is charging correctly or not.

2 minutes ago, xman said:

Connecting/disconnecting cables to the alternator when battery is still connected can damage the alternator and other vehicle electronics by generating voltage spikes (which cause sparks!), so don't do it!

Even with engine not running, ignition off? How?

Op is talking about removing various alternator wires and reconnecting when the battery is still connected, the alternator connects directly to the battery not via the ignition.

 

First thing any workshop manual will tell you is to disconnect the battery if any work is to be carried out on the electrics, for safety reasons and eliminate possibility of collateral damage to electronics.

 

The alternator is a big inductor, when current is instantly interrupted ....(think ignition coil)

 

Edited 8 October, 20187 yr by xman

I think me and the OP are talking about the ignition off/engine stationary case, which I can't see being a problem. There won't be any current flowing in the alternator, if the diodes are all intact, will there?

11 minutes ago, xman said:

Op is talking about removing various alternator wires and reconnecting when the battery is still connected, the alternator connects directly to the battery not via the ignition.

 

First thing any workshop manual will tell you is to disconnect the battery if any work is to be carried out on the electrics, for safety reasons and eliminate possibility of collateral damage to electronics.

 

The alternator is a big inductor, when current is instantly interrupted ....(think ignition coil)

 

@xman If i remove (only) the alternator wire wouldn’t the battery will work like a capacitor to prevent the voltage hike? Most people say disconnecting the battery while the car is running will damage. I am just saying not sure. 

I certainly wouldn't suggest disconnecting the alternator while the engine is running, but I didn't think that was happening? Was it?

Please yourself, but one careless move,  a touch to ground could prove expensive.

 

@xman @Wino Just got the car from the service center they were still unsure about what is causing the drain they’ve told me that last night with a fully Charged battery it lasted whole night and didn’t drain. They given alternator to to the repair guy he said that the alternator is good i am not sure how did theyve tested it. Does that always provide 14ish voltage without the DFM cables being connected?  Since they were unsure about it i got the car back and going  to test the alternator by myself. A little help needed from you guys.

 My questions are:

1- I am going to test the ac ripple test if there is too much AC voltage the should I consider the alternator is the cause of drain?

2- How to check the DFM pins in the alternator there is 2 pins . Does DF gets 12V only while cranked? How about M wire does that have any specific voltage to be tested?

(I can check in the cut where the DFM socket was removed and wires connected directly)