Voltage Question,,,, thinking hats on please

[kjb1]

Ok, Angel eyes in pre Lci cars, with halogen H8 bulbs.  Question, does anybody know the Voltage when the dipped beam is switched on? the lights noticeably dim from their DRL setting when dipped beams come on.  What I am tryjng to find out is, what does the voltage drop to at this reduced light output.  Ie the input voltage to the bulb........answers required asap [emoji2]


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[kjb1]

Richard, surely you can answer this one??


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[X5Sport]

I'll try.

The normal method may not be to reduce the voltage but rather 'pulse' the voltage.  This is because unless a filament lamp is run at the correct voltage the filament burns out early.  The 'dim dip' system on car dip beam headlights uses this method.

By 'pulsing' the voltage the filament gets the right volts but not for enough time to fully light up.  Bulbs can be made that can be dimmed without premature failure.

If BMW do use a straight voltage reduction then you'll need to meter it on the back of the bulb.  At a guess it could be between 10-11V instead of the rated 13.2V for E approved lamps.  According to the BMW Uni docs, the maximum voltage is limited by the LCM to 12V to preserve bulb life.  It isn't clear whether a pulsed voltage or reduced voltage is applied to 'dim' the bulb.

Richard

[kenniff]

Phew. I'll sleep easier tonight knowing that.
:blink:

[kjb1]

Well, As one of my mtec £11 angel eye bulbs failed within only 9 months, I have bitten bullet today after lengthy talks with hids4u.co.uk today and think we have formulated a kit and harness which should have no issues running a 35w 8000k HID system in the Angel eyes of the e70.  Standby on Tuesday for pictures / reviews etc if you have the yellow halogen halos as this could be the one for you!! Ive spoken about group buy for the forum and seems its a go'er upon testing.  So will let you know how it goes.  I think hid is going to be the closest in terms of brightness that you can get to led newer angels on current bmws.  Fingers crossed [emoji16]


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[X5Sport]

Sounds like a project....

R

[pcdee]

Wow....sounds good

[Steamyrotter]

[quote="X5Sport"]
I'll try.

The normal method may not be to reduce the voltage but rather 'pulse' the voltage.  This is because unless a filament lamp is run at the correct voltage the filament burns out early.  The 'dim dip' system on car dip beam headlights uses this method.

By 'pulsing' the voltage the filament gets the right volts but not for enough time to fully light up.  Bulbs can be made that can be dimmed without premature failure.

If BMW do use a straight voltage reduction then you'll need to meter it on the back of the bulb.  At a guess it could be between 10-11V instead of the rated 13.2V for E approved lamps.  According to the BMW Uni docs, the maximum voltage is limited by the LCM to 12V to preserve bulb life.  It isn't clear whether a pulsed voltage or reduced voltage is applied to 'dim' the bulb.

Richard
[/quote]

BWM LCM modules incorporate PWM (Pulse Width Modulation) to dim certain lights.
The settings of which, in many cases, can be changed if you delve into the programming side.

Although it pulses the voltage, it is more of a current control thing than voltage control.
Current control gives you better control of the light output than voltage as it takes out volt drops from the equation and will retain the same levels regardless of connector resistances.

[X5Sport]

Makes sense.  I couldn't find if the sidelights at the front are on one of the PWM circuits though, any ideas?

[Steamyrotter]

They are on the E53 Pre facelift at least..
Easiest way to tell if it is enabled is to place the coil of a 12v relay across the supplies.
If the PWM is enabled it will chattter away nicely...
Ask me how i know............

[kjb1]

[quote="Steamyrotter"]
They are on the E53 Pre facelift at least..
Easiest way to tell if it is enabled is to place the coil of a 12v relay across the supplies.
If the PWM is enabled it will chattter away nicely...
Ask me how i know............
[/quote][emoji2][emoji106]


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[X5Sport]

[quote="Steamyrotter"]
Ask me how i know............
[/quote]

Shan't  :ras:

[Steamyrotter]

Oh you spoil sport...

>:D

[Riggie]

35w kit sounds interesting, I'd probably be up for that, but would need some fitting instructions!

[kjb1]

i will don installation guide for this thread with pics etc.


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