Old Scirocco - battery drain
Discussion
1985 Scirocco. Owned 20 years. Trouble free diesel conversion 9 years ago.
The past few years, I’ve been suffering flat batteries. Car only just ‘catches’ after a week. Much longer and it’s dead.
Battery is Yuasa 096 80Ah 760A. Engine 1.6 diesel from a similar era to the car. More than capable for the task at hand. Been drop tested and is fine.
14.05v at idle from the alternator.
I looked at some YouTube guides on how to measure battery drain. Disconnected the battery negative and put multimeter terminals between the negative lead and terminal. I’m getting a reading between 23.5 and 25.0. The reading doesn’t fluctuate that much when being checked. But it does give a slightly different reading each time if that makes sense.
YouTube guide said to remove fuses one by one. Started with fuse 3 - Radio, clock, interior lamp, cigar lighter.
Reading then drops to virtually zero.
I pulled the radio out. Semi modern Alpine. There’s two options to wire it in. Cars like this with just a permanent live and for cars with a permanent live plus a switched live.
Some of the VW forums say modern Bluetooth radios can cause bother on just a permanent live. Changed over to permanent plus switched from the fuse box.
Didn’t make any difference. I’ve also removed the cigar lighter and the one bulb from the interior lamp.
Still getting a reading around 23-25 on the multimeter.
I can’t see there being any draw from the LCD clock in the internment cluster?
At a bit of a loss of where to turn next!
Help, please!
The past few years, I’ve been suffering flat batteries. Car only just ‘catches’ after a week. Much longer and it’s dead.
Battery is Yuasa 096 80Ah 760A. Engine 1.6 diesel from a similar era to the car. More than capable for the task at hand. Been drop tested and is fine.
14.05v at idle from the alternator.
I looked at some YouTube guides on how to measure battery drain. Disconnected the battery negative and put multimeter terminals between the negative lead and terminal. I’m getting a reading between 23.5 and 25.0. The reading doesn’t fluctuate that much when being checked. But it does give a slightly different reading each time if that makes sense.
YouTube guide said to remove fuses one by one. Started with fuse 3 - Radio, clock, interior lamp, cigar lighter.
Reading then drops to virtually zero.
I pulled the radio out. Semi modern Alpine. There’s two options to wire it in. Cars like this with just a permanent live and for cars with a permanent live plus a switched live.
Some of the VW forums say modern Bluetooth radios can cause bother on just a permanent live. Changed over to permanent plus switched from the fuse box.
Didn’t make any difference. I’ve also removed the cigar lighter and the one bulb from the interior lamp.
Still getting a reading around 23-25 on the multimeter.
I can’t see there being any draw from the LCD clock in the internment cluster?
At a bit of a loss of where to turn next!
Help, please!
23-25 milliamps (23-25 1000th of an amp per hour) is nothing in the grand scheme of things and would not drain a car battery in a week.
I’m assuming your not getting 23-25amps as that would be some mega current drain and flatten the battery pretty dam sharpish, hours not days.
Are we certain the alternator is charging (although at 14v at idle the alternator must be charging).
How old is the battery. Could it just be knackered and not holding a charge so draining over the course of a week as it’s not holding the charge.
I’m assuming your not getting 23-25amps as that would be some mega current drain and flatten the battery pretty dam sharpish, hours not days.
Are we certain the alternator is charging (although at 14v at idle the alternator must be charging).
How old is the battery. Could it just be knackered and not holding a charge so draining over the course of a week as it’s not holding the charge.
MJK 24 said:
Before we go further, I’m not 100% sure I’m correct in interpreting the figure I’m giving you from the multimeter!
A picture paints a thousand words....
Isn't that multimeter set to AC Volts?A picture paints a thousand words....
If you are measuring current it should DC Amps. I would say you want to turn it 3 clicks clockwise to 200mA setting.
Unless I’m mistaken you have the meter set to Volts AC. Your need to measure in amps.
In laymen’s terms (very simplistic), volts is the amount of force behind the electricity amps is the amount of electricity flowing.
To see if you have a drain you need to measure amps first. If you get no reading then switch to a smaller scale milliamps.
I’m not sure on your meter as I’m viewing it on a small phone screen but you probably need to move the leads around as well. Do you have the multi meter model and I will see if I can look up the setup for you.
Edited to add. Looking at the image zoomed in I you need 1 lead in com (where the red one currently is, the other needs to be in 10A DC.
I would rotate it 4 clicks to the right(clockwise) 10A, if you get nothing or a very low number, rotate it 1 click back anti-clockwise.
Also to ensure you don’t damage the meter don’t rotate the selector or move the leads while the probes are on the battery terminals.
The meter will have an internal fuse so if you f
k it up and the meter stops working you will have blown the fuse.
In laymen’s terms (very simplistic), volts is the amount of force behind the electricity amps is the amount of electricity flowing.
To see if you have a drain you need to measure amps first. If you get no reading then switch to a smaller scale milliamps.
I’m not sure on your meter as I’m viewing it on a small phone screen but you probably need to move the leads around as well. Do you have the multi meter model and I will see if I can look up the setup for you.
Edited to add. Looking at the image zoomed in I you need 1 lead in com (where the red one currently is, the other needs to be in 10A DC.
I would rotate it 4 clicks to the right(clockwise) 10A, if you get nothing or a very low number, rotate it 1 click back anti-clockwise.
Also to ensure you don’t damage the meter don’t rotate the selector or move the leads while the probes are on the battery terminals.
The meter will have an internal fuse so if you f
k it up and the meter stops working you will have blown the fuse. Edited by MB140 on Saturday 14th September 19:11
MJK 24 said:
Thanks for the help.
Red lead now: 10A DC
Black lead now: COM
Reading 0 in both 200m and 10A
Put the red lead into the other socket and set it to 200mA. If you don't get a readin. go to 20mA setting. Leave the black lead in COM. Red lead now: 10A DC
Black lead now: COM
Reading 0 in both 200m and 10A
Just double checking you have meter wired in series? One lead tobthe battery twrminal and the other to the disconnected battery lead.
Edited by cuprabob on Saturday 14th September 19:30
Edited by cuprabob on Saturday 14th September 19:33
MJK 24 said:
cuprabob said:
MJK 24 said:
Thanks for the help.
Red lead now: 10A DC
Black lead now: COM
Reading 0 in both 200m and 10A
Put the red lead into the other socket and set it to 200mA.Red lead now: 10A DC
Black lead now: COM
Reading 0 in both 200m and 10A
To be honest, if you are getting a reading below 20mA, that will not discharge a battery in a week.
cuprabob said:
MJK 24 said:
cuprabob said:
MJK 24 said:
Thanks for the help.
Red lead now: 10A DC
Black lead now: COM
Reading 0 in both 200m and 10A
Put the red lead into the other socket and set it to 200mA.Red lead now: 10A DC
Black lead now: COM
Reading 0 in both 200m and 10A
To be honest, if you are getting a reading below 20mA, that will not discharge a battery in a week.
I’ve just had a thought. The +ve terminal is still connected isn’t it or you will only ever get 0 amps as you have no complete circuit.
Edited by MB140 on Saturday 14th September 19:52
MJK 24 said:
Yes, positive terminal still connected.
Should that be disconnected?
No it needs to be connect to complete the circuit to allow the current to flow.Should that be disconnected?
I was just trying to make sure we weren’t going down a rabbit hole of constantly getting 0 amps as the +ve battery terminal was disconnected.
If the +ve is disconnected you will only ever get 0 amps.
How old is the battery? I'm not ever so convinced by these modern battery testers, I've had problems on and off over a few years with the battery on my Vito van. The battery will test fine but in reality struggles to hold enough charge to start the van after 24hrs. We've done all of the voltage drain checks too and nothing is drawing any real current when everything is off. But put a brand new battery on it and it's back to being 100% fine.
Just to note to anyone is wondering why I suffer with reoccurring battery failure - I drive less than two miles to work, the van can sit at work all day with the doors being opened, left open for a while and this has the effect of powering up the lights and waking the ECU up etc. The battery is therefore being deep cycled and come winter time I dare say that with the lights, heater and wipers on, I'm using more power to start the van than it can recharge in those two miles.
The moral of the tale, if in doubt about the battery, try a new one before you look for a more complex issue.
Just to note to anyone is wondering why I suffer with reoccurring battery failure - I drive less than two miles to work, the van can sit at work all day with the doors being opened, left open for a while and this has the effect of powering up the lights and waking the ECU up etc. The battery is therefore being deep cycled and come winter time I dare say that with the lights, heater and wipers on, I'm using more power to start the van than it can recharge in those two miles.
The moral of the tale, if in doubt about the battery, try a new one before you look for a more complex issue.
MJK 24 said:
Before we go further, I’m not 100% sure I’m correct in interpreting the figure I’m giving you from the multimeter!
A picture paints a thousand words....
Going back to this image, when I removed fuse 3 for radio, clock etc, thus reading went down to virtually zero.A picture paints a thousand words....
Does that explain anything? Or is it irrelevant with the way I had the multimeter set up?
MJK 24 said:
MJK 24 said:
Before we go further, I’m not 100% sure I’m correct in interpreting the figure I’m giving you from the multimeter!
A picture paints a thousand words....
Going back to this image, when I removed fuse 3 for radio, clock etc, thus reading went down to virtually zero.A picture paints a thousand words....
Does that explain anything? Or is it irrelevant with the way I had the multimeter set up?
To measure voltage you measure in parallel with the circuit. To measure current you measure in series.
Sorry I’m trying not to go to deep as it may just end up confusing you. A bit like when my wife’s accountant tried explaining corporation tax and vat rates and s
t. I just sat there looking like an idiot. We each have our forte in life. As Matt said. I would be looking at a new battery if you can’t find a current drain. It might be the quickest thing to eliminate. Even if you could identify the circuit by pulling fuses I don’t want this to sound rude or putting you down but you don’t seem to have the skill set required to find the short and then replace the wire/ loom (apologies if I’m wrong about this). So replacing a battery is going to be cheaper than paying a skilled auto electrician his hourly rate.
I’ve not bought a battery in a long time but I can’t see it being anything highly sophisticated or expensive on that age of car. So about £40 from ECP I would imagine. Not like an AGM battery in modem stop starts that can be £100-£200.
Sorry OP the wife has finished getting ready so we’re ff out for dinner but I will have a check back in tomorrow to see how your getting on.
Edited by MB140 on Saturday 14th September 20:23
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