Hello everyone I'm in need of some help .  I had some starting problems with my car and the battery was showing low voltage. 

I changed the battery and still have the same problem.  The car ran fine for about a month after fitting the new battery then one day I tried to start it and it was completely dead. Got a new alternator fitted and still have the feeling the car is gonna die in a few weeks.  At idle its still only reading 13 volts on my multimeter.  I have been told that it should show minimum of 14.2 volts.   

 

Any help would be great!  

 

Thanks

 

Had simular issue with a 1.9 tdi the battery at 13v is ok the problem starting was with the earth lead, I found that when I instaled a second earth from the stud on the wing down to the starter motor bolt the starting improved no end so your problem with the battery might be the earth lead from gearbox to the body not making good contact b y fitting an extra lead it could improve the condition of the battery

1 hour ago, levelken said:

 

Any help would be great

Does the battery light work correctly when the ignition is first switched on but the engine is not started?

Hi I will check that and get back to you tomorrow.   Thanks

Hi the battery light comes on them goes off when engine started.  Thanks

Please note - I am not a mechanic or expert in anything.

 

Where are you taking this 13v reading from and are you doing the test with a cheap digital multimeter as they can be inaccurate and unreliable.

 

Edited 22 November, 20223 yr by nta16

38 minutes ago, levelken said:

Hi the battery light comes on them goes off when engine started.  Thanks

Ok, it's not what I was thinking then. It'a a cheap and easy DIY test though.

I suspect something is draining the battery when not in use, and there may also be a bad connection somewhere in the charging circuit.

 

When the car is idling, and you're seeing only 13v or so across the battery, try measuring voltage between the body of the alternator (scratch through any oxide on the surface) and battery negative terminal. If there's any significant voltage there, it would tend to support the earlier comment about a poor earth connection. (By measuring the voltage drop between those points, you're indirectly measuring the resistance of the earth wiring and its connection points; a low voltage means low resistance connectivity, and vice versa).

 

If there's hardly any difference indicated by that measurement, try instead between alternator output post (where the thick wire attaches) and battery positive terminal, for the other half of the wiring.

 

Let us know those two numbers, as that will check both current paths (out and back to the alternator) and also, by adding all the numbers up, what the actual output voltage is at the alternator at idle.

 

 

 

 

 

 

 

 

Hi,

 

Apologies if I'm hijacking the thread.

 

I've come accross topic this whilst searching because I have a similar issue.

 

Only had the car since start of September last year, 64 plate Mk2 Monte Carlo 1.2TSi, Fitted a new battery at the end of September because battery seemed to be struggling with starting but by the end of December signs of dying battery.  With the engine running a voltmeter pluggged into the accessory socket measures anything between 13.5 and 14.2 and I get the same figures directly accross the battery terminals.  It seems to be an intermittant fault because for example today I drove approximately 11 miles, no accessories drawing power, no lights except drls, no aircon, no radio, etc and for the entire journey 14.2 on the voltmeter in the car.  Car parked for 10 miutes and then drove back home.  Nothing changed in car nothing drawing power that wasn't on for the first journey but the voltmeter now showing 13.7 the entire way.

 

This morning before leaving home I checked some earth points under the bonnet.  All of these measurements are from the negative battery terminal, to engine top 0 Ohms, to alternator casing 0 Ohms, and to where the terminal is connected to the bodywork 0 Ohms, regardless of whether the engine was running or not all three of these measured 0 Ohms.  Then when I got back home and the slightly lower voltage was showing I measured the resistances again.  With the engine running, battery to bodywork 0 Ohms, battery to engine 107 Ohms and staying stable at 107 and from battery to alternator casing I measured a resistance fluctuating wildly between 0 and 200 Ohms.  I then connected a cable between the battery negative terminal and the top of the engine the resistance dropped straight to 0 as I expected but the voltage measured only increased to 13.8V  I then switched off the car and removed the extra earthing cable all three resistances immediately dropped to 0 Ohms.

 

The car has been back where it was purchased from under warranty but their best advice was the battery is faulty and not charging properly.  Halfords who I bought the battery from have checked the battery and say there is nothing wrong with it, I have seen the screen on the battery tester that states "Good Battery".  Apparently the dealer can't do a thorough indepth check of the electronics as they are a Ford dealer and don't know the specifics of Skoda/VAG electronic diagnostics.  I am already unhappy with them as they have failed to repair 2 other issues and the last time I collected the car from them a third issue (non-electrical) had appeared meaning that the car became more broken whilst in their care instead of coming back fixed.  I suspect Ford/Skoda differences is just them trying to get out of doing the work but it could be that there are significant differences between Ford and VAG electronics, I don't know.

 

Any help will be gratefully received.  Known component issues, anything at all.

 

Thanks.

I would suggest it's the alternator rather than the battery which is suspect.

@TheBlackDog

If I were you I would take off each end of the chassis to engine earth cable, and clean thoroughly with very fine wet-and-dry lubed with WD40 or similar, or a fine wire brush. Cleaning without removing will do almost nothing. 

 

Alternator voltage regulators have a pronounced temperature dependence, which may account for some of the variance in readings that you are seeing.

Approx  -0.005V/°C from memory, so somewhere approaching half a volt higher when stone cold in winter compared to fully warmed up/heatsoaked alternator isn't unexpected. 

Edited 14 January, 20233 yr by Breezy_Pete

Please note - I am not a mechanic or expert in anything.

 

Your main problem seems to be the people you bought the car from, very rare to get a faulty battery, yes it can be made bad by poor storage and garage/driver's use, abuse and neglect - or a faulty charging system.

 

If it's an intermittent fault they're more difficult to track down but you've already done some spade work for them and battery charging systems and their faults are not new to cars and generally not marque and model specific.

 

You've had two good suggestions already, I'd add test perhaps doing volts tests as well as or instead of resistance but 200 is clearly enough to show up at the start.  You want all electrical connections to be clean, secure and protected (I use Contralube 770 for inside the connections, others are available). 

 

I would recommend even though the battery is quite new that you check its resting state of charge at the terminals a couple of hours after the car has been parked up and consider fully recharging it with an appropriate battery charger and maintainer as a low battery on a 2014 VW, even if the car starts and the lights seem bright enough, can cause all sorts of unexpected problems which you won't want adding to or mixing in with your current (no pun intended) issues.

 

Thanks for the suggestions.  Something to do Saturday.

 

Something a colleague suggested today is to check for any AC voltage appearing accross the battery terminals as this could show a problem with the voltage regulator/rectifier.

27 minutes ago, TheBlackDog said:

Thanks for the suggestions.  Something to do Saturday.

 

Something a colleague suggested today is to check for any AC voltage appearing accross the battery terminals as this could show a problem with the voltage regulator/rectifier.

 

That's true, although your problem is more likely the voltage regulator than the rectumfrier.

Please note - I am not a mechanic or expert in anything.

 

I suggest that you fully recharge your battery with an appropriate charger and maintainer, even though it's not 4 months old, as this is not the time of year to beak down as many others are with flat batteries and charging system problems, usually alternator. 

 

Whether you put the charger on tonight or over the weekend, if you know the battery is fully charged then you have a good point of reference to start from for your diagnostics and perhaps when dealing with the people where you bought your car from.

 

Machines for testing batteries and alternators are not rare exotic items freely available in a wide range of sorts to garages and DIY, whether they are always used appropriately and properly is a different matter, unfortunately not all the people in the motor trade are as honourable as they could be, your lot might not be trustworthy enough to sort an alternator problem - but I'm being biased as I don't know of course, they might be as pure as the driven snow and perhaps your alternator is fine and you have a rare faulty battery that won't accept charge.

 

What Halford battery did you buy?

 

On 14/01/2023 at 17:36, TheBlackDog said:

With the engine running a voltmeter pluggged into the accessory socket measures anything between 13.5 and 14.2 and I get the same figures directly accross the battery terminals.  It seems to be an intermittant fault because for example today I drove approximately 11 miles, no accessories drawing power, no lights except drls, no aircon, no radio, etc and for the entire journey 14.2 on the voltmeter in the car.  Car parked for 10 miutes and then drove back home.  Nothing changed in car nothing drawing power that wasn't on for the first journey but the voltmeter now showing 13.7 the entire way.

 

Perfectly normal behaviour dependant on the battery SOC, the current being drawn by the electrical system, the ambient temperature and the engine revs.

 

You have nothing to be concerned about with the voltages you have quoted.

 

I had a digital LED voltmeter and would see those variations and more all the time, the PCB got broken by the insertion of USB plugs so I replaced it, the new one has a bar graph changing colour LED cascade, the printed voltages are too small to see without a magnifying glass and bright light, driving stop start in crawling for over an hour on the Paris périphérique I noticed that at idling sometimes one green bar was showing, sometimes orange and once or twice hovering on the red, I was a little concerned until I was able to read the actual voltage figures.

 

The difference in the 14.2 and 13.7v you mention above, which by the way is two tenths of four fifths of eff all, is explained by the post cold start charging and the much easier warm restart with a hotter battery.

 

There is a reason that manufacturers don't like us to see readings like battery voltage, water/oil temperature or will fiddle the readings to give a consistent acceptable figure except when outside of limits.