These headlights are ####!!!

[Loz]

Russell from Oz here. Just bought a T6 Transporter, and lights are indeed poor. If they are not getting full voltage as suggested above, fitting relays should solve the voltage issue for not a lot of cost. Thoughts? I'm off to measure my voltage on the weekend.

You would also need a voltage regulator as the bluemotion vans allow the alternator to idle so dc-dc stabiliser outputting 14v would improve them.

 

[Mooncat]

I have been trying to get Volkswagen to resolve the poor headlight problems on my T6 as well. I have since tested my and other T6 vehicles and found that the voltage at the H4 halogen light bulb is only 11.1 Volts. The South Africa and European standard is 13.2 Volts. It is estimated that at 11.1 Volts the H4 bulbs only emits 55% of the 100% emitted at 13.2 Volts.

I expect that Volkswagen will have to do an international recall to get the vehicles up to standard. I would suggest that everybody have their vehicle tested and take it up with Volkswagen in your region to get this issue resolved.

Sorry - a little bit late to the party but how are you measuring that voltage as it's miles off what I got when doing a test of 100W vs 55W at the weekend (only because my new headlights were supplied with both sets of bulbs). I was getting 12.9V feed to the headlight against 13.2V at the battery so a very acceptable 2.3% drop.

Edit - Note that the 55W bulb was operating whilst the feed at the bulb was 12.9V so it was a proper voltage drop test I was doing rather than replacing the bulb with a voltmeter.

 

[MatthewGreaves]

Thank goodness I found this thread - I was seriously wondering if I had a problem with my eyes; I’ve recently moved from a Disco with Bi-Xenons to the standard lights on my T6 and have to periodically check that they are actually on. They remind me of the ones on a 1991 Pug 405 I used own. They are truly terrible!

 

[Russell Arnold]

You would also need a voltage regulator as the bluemotion vans allow the alternator to idle so dc-dc stabiliser outputting 14v would improve them.

Could you not take the power from the battery? Although I am now worried about this canbus/bluemotion stuff which I don't understand, nor what error may happen when fiddling. I might wait till VW do first service and see what they say.

 

[Piet Roux]

VW measured 10.9 volts with the engine at 2500rpm and the aircon on on my T6. VW is trying to get away from this issue but I now have the Soutg African regulating Authority (NCRS) working with me on this.

According to the UNECE regulation no. 20 the voltage at the terminal must be adjusted the reach a specific light intensity. This is only for H4 bulbs.

I need T4, T5 and T6 owners to take their vehicles to VW to test the voltage at the terminal with the aircon on and file a complaint.

I believe this should trigger a recall. Please do this for the safety of all road users.

 

[Mooncat]

VW measured 10.9 volts with the engine at 2500rpm and the aircon on on my T6. VW is trying to get away from this issue but I now have the Soutg African regulating Authority (NCRS) working with me on this.

According to the UNECE regulation no. 20 the voltage at the terminal must be adjusted the reach a specific light intensity. This is only for H4 bulbs.

I need T4, T5 and T6 owners to take their vehicles to VW to test the voltage at the terminal with the aircon on and file a complaint.

I believe this should trigger a recall. Please do this for the safety of all road users.

I bet they measured across the bulb which is telling you the remaining voltage available after the bulb has put a load across it. You'll get about 11 volts doing that. They need to do a voltage drop test using feed and earth to get the proper measurement and on mine which came with H4 bulbs it's exactly what I'd expect. It's more to do with the design of the headlight rather than the voltage getting supplied.

 

[Dilbert]

@Mooncat I am struggling with your logic here! Surely you would measure across the bulb terminals to see what voltage is reaching the bulb?

After all, a well designed system would deliver at least 12V to the bulb itself and the wire gauge and control circuitry should be up to the job and rated to not introduce unnecessary voltage drop.

D.

 

[Piet Roux]

We don't need to get too technical. The fact is that the headlights are sub-standard and it could be a combination of the light design and the input voltage.

What is important is that we get as many as posible owner filing complaint regarding the same issue.

I am from South Africa and need people from all over the world filing complaints.

I will get VW to fix this one way or another but I need a larger voice so please help. It is for the benifit of all T6 owners and safety of all road users.

 

[Mooncat]

@Mooncat I am struggling with your logic here! Surely you would measure across the bulb terminals to see what voltage is reaching the bulb?

After all, a well designed system would deliver at least 12V to the bulb itself and the wire gauge and control circuitry should be up to the job and rated to not introduce unnecessary voltage drop.

D.

A voltmeter tells you the remaining available voltage. In the days when vehicles had voltmeters on the dashboard, you could see that every time a load was applied (heater motor, headlights, brake lights etc, the reading of the voltmeter would drop. This is telling you what the remaining voltage available is. When the engine is running and there is nothing of significance drawing a load, you see something in the region of 14.4V across the battery terminals. Turn on the headlights and that voltage then drops to 13.2V which means that you are still working within the capacity of the alternator as the remaining available voltage is still greater than a battery on it's own (12.4 - 12.8V). If you measure across the operating bulb, it is telling you the remaining available voltage in that circuit whilst it is supplying the bulb which is around 11V. Now if you had 1cm thick cables and industrial sized relays, you could get it closer to 13.2V at the bulb connections, however it doesn't need to be that thick to supply the required voltage to the bulb.

In the other thread I was testing 100W bulbs and also commenting about those running the 'additional harness' to supply high beam feed to both high beam and dipped for some aftermarket lights. In that case the standard electrical circuit 'probably' (choosing my words carefully) is not suitable.

If you don't believe what I'm saying about the stock wiring being adequate for stock bulbs, build a simple harness with 14 AWG wiring and good quality relays and connect that up to the headlights. If suddenly everything is much brighter and you can now drive in the dark, the stock wiring is unsuitable. If however your H4 powered headlights are still rubbish, you know it is the headlight units where the problem is.
Bearing in mind people are swapping out H4 units to VW H7 units and aftermarket units and can now see where they are going also demonstrates that the stock wiring is fine and it's the H4 headlights that are rubbish. Now twenty years down the line when the wiring gets older and the connections are not as good as they were, new wiring will make a difference.

 

[Dilbert]

@Mooncat I think you have just dismissed your own original arguments!

I don't disagree the original H4 lights are very poor but I still disagree that you think you should only get 11V on the bulbs.

Modern vehicles have excellent voltage regulation. If you only get 11V, something is wrong....

 

[Piet Roux]

Thanks Mooncat. I did the voltage drop test today and measured 2.2 volts drop from the battery to the light without the aircon running.

What is interesting is that VW uses a 1.5mm wire in the 55/60 Watt light that could cause a voltage drop.

My vehicle is going to VW tomorrow for tests. The NRCS requested that they do a complete electrical test to search for faults. They will have to have everything tested from the alternator to the light unit for light emitted so it seems that I am making headway here.

 

[Trevor]

Ordered upgrade on mine but out of stock for couple of months that in its self should say how poor the lights are on the T6

 

[mmi]

Thanks Mooncat. I did the voltage drop test today and measured 2.2 volts drop from the battery to the light without the aircon running.

What is interesting is that VW uses a 1.5mm wire in the 55/60 Watt light that could cause a voltage drop.

My vehicle is going to VW tomorrow for tests. The NRCS requested that they do a complete electrical test to search for faults. They will have to have everything tested from the alternator to the light unit for light emitted so it seems that I am making headway here.

Something is obviously wrong.

To get a 2,2 Volt voltage drop using 60W bulb (equals to 5 Amps at 12 Volts) and having 1.5mm2 wire (square mm’s - I think this is what you meant as it's a German car) would mean 38 meters of wire! For a load of 2x60 Watts would mean still 19 meters of wire.

Having 2,6 meters long 1,5 mm2 wire the voltage drop would be about 0,3 Volts when having 2x60 Watt load. Even a relay or two in-line won’t change the situation significantly. I think this goes with what @Mooncat observed earlier.

As you obviously measured and observed a significant voltage drop from battery “+” to the bulb “+”. Loose connection? Pinched wire?

If you are measuring voltage drops, to get full picture where the loss is you need to measure one also from battery “-“ to the bulb “-“. And to verify the measurements, one more across the bulb. The three values summed together equals battery voltage.

 

[Piet Roux]

The battery voltage was at 13.8volt. The drop measured 2.2volt and across the bulb 11.4volt. It will be worse if I have the aircon running.

I was thinking that they might limit the voltage with a regulator to 12 volt then the drop will be 0.6 volt that, according to previous posts, makes sense.

I will be asking for an official voltage drop test tomorrow.

 

[Mooncat]

@Mooncat I think you have just dismissed your own original arguments!

I don't disagree the original H4 lights are very poor but I still disagree that you think you should only get 11V on the bulbs.

Modern vehicles have excellent voltage regulation. If you only get 11V, something is wrong....

Not at all - you're not supposed to measure across the bulb. You're actually getting somewhere nearer 12.9V if you do the correct voltage drop test (measure drop on feed to the bulb and then on the earth wire from the bulb), but not across the bulb. Voltmeters only tell you the remaining available voltage between the probes which is why you have to do it that way.

 

[Mooncat]

Something is obviously wrong.

To get a 2,2 Volt voltage drop using 60W bulb (equals to 5 Amps at 12 Volts) and having 1.5mm2 wire (square mm’s - I think this is what you meant as it's a German car) would mean 38 meters of wire! For a load of 2x60 Watts would mean still 19 meters of wire.

Having 2,6 meters long 1,5 mm2 wire the voltage drop would be about 0,3 Volts when having 2x60 Watt load. Even a relay or two in-line won’t change the situation significantly. I think this goes with what @Mooncat observed earlier.

As you obviously measured and observed a significant voltage drop from battery “+” to the bulb “+”. Loose connection? Pinched wire?

If you are measuring voltage drops, to get full picture where the loss is you need to measure one also from battery “-“ to the bulb “-“. And to verify the measurements, one more across the bulb. The three values summed together equals battery voltage.

Exactly!! I'm measuring a 0.3 volt drop which is exactly what you state for 1.5mm2 wire.

For your last paragraph, again exactly right, that test will show that it is the bulb consuming the voltage and that the circuit to and from the bulb is ok. If either the feed to the bulb or the earth wire show a loss of over 3% with a 55w bulb, that part of the circuit needs to be investigated for a fault. The tests I've done show those are where they should be so it's not a generic design issue.

 

[Stigofthedub]

Voltage positive source to bulb + voltage across bulb+ voltage bulb to negative source = voltage across source.
Measure any 2 and you can reduce the third.
Just be careful when looking at decimal places on your average meter unless it's calibrated.

 

[Dilbert]

Voltmeters only tell you the remaining available voltage between the probes which is why you have to do it that way.

But surely that is what the bulb sees? In a simple circuit, battery voltage minus the drop on the + and - wires = the voltage across the bulb. Measuring the voltage drop across the 2 wires and subtracting from the battery voltage gives you the same result.

I am very confused by your logic!

D.

 

[Mooncat]

But surely that is what the bulb sees? In a simple circuit, battery voltage minus the drop on the + and - wires = the voltage across the bulb. Measuring the voltage drop across the 2 wires and subtracting from the battery voltage gives you the same result.

I am very confused by your logic!

D.

It's not logic, it's physics! The volt meter can't measure what is already being used by the bulb.

 

[Dilbert]

What the bulb is using causes the voltage drop across the resistance of the wires. Its ohms law......

Unless the laws have been rewritten. I will leave it there as it appears my last 40 years in the electrical and electronic industry have obviously misled me somewhere...