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SwedeSpeed P1 (C30, S40, V50, C70) HID Retrofit Index
PLEASE do not revive this 2009 thread
This thread contains the original (c. 2009) investigation into the issues with P1 HID low-beam conversions. The Edited OP (c. 2011 - the real OOP was moved to post#2) was an older attempt to consolidate HID related info, and is included in the quote below only for posterity. If you are looking for the most accurate technical information on P1 HID retrofit issues, see the general HID discussion thread or https://www.skbowe.com/a/issues. Thanks!
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- SKBOWE Plug-and-Play harness for P1 HID conversion
- Background info, general questions, and share your HID setup
- KBOWE How-To (Original 2009 Version) build your own PWM filter
- Original 2009 investigation and technical discussion on S40 HID issues (you are here)
- ForceFed’s E46 D2S Bi-Xenon Projector Retrofit guide
- Rewire OEM Bi-Xenon headlights to work on the halogen harness
- DRL Disable Alone not enough for safe Aftermarket HID retrofits
- LizardOfBodom's EU/RHD Bosch ("E46") Bi-Xenon replica retrofitting writeup + angle eyes + running lights
PLEASE do not revive this 2009 thread
This thread contains the original (c. 2009) investigation into the issues with P1 HID low-beam conversions. The Edited OP (c. 2011 - the real OOP was moved to post#2) was an older attempt to consolidate HID related info, and is included in the quote below only for posterity. If you are looking for the most accurate technical information on P1 HID retrofit issues, see the general HID discussion thread or https://www.skbowe.com/a/issues. Thanks!
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theshadow27 said:This post has information accumulated from a variety of sources including the statistics thread (here and on C30 World), and a variety of HID related threads (1, 2, 3, 4, etc...).
Section 1 - Symptoms and Problem with P1 (S40 2004.5+, V50, C30, and C70 2007+) HID conversions
Some of the common problems that arise with an HID conversion include:
Any or all of these conditions can occur when attempting to install an HID kit in one of the applicable cars.
- Faliure to start - one or both bulbs
- Flickering during operation
- Dim output or excessive warmup time
- Bulb Out Warning (BOW) message on the dash board LCD screen (DIM)
- Windshield Wiper (WMM) failure
Section 2 - Cause of the Problems with HID retrofits
All of these problems come from one source. The computer module that controls the headlights, the Central Electronic Module (CEM) applies a pulse-width modulated (PWM) regulated voltage to the low beam halogen lamps to keep the voltage they see at 13.0V. It was designed to do this because halogen bulbs will last longer at 13V than the 13.5V or 14V at which the electrical system runs. Since the low beam bulbs are also the Daytime Running Lights (DRL) and are on all the time, Volvo wanted to maximize the life of the bulb. For halogen bulbs this is actually a good thing, and it does what it is supposed to.
The PWM works as follows: A halogen bulb is, in practice, a simple resistor. As such, the voltage across it is directly proportional to the current through it. By switching current on and off several times per second (about 80, actually), the CEM can control the average voltage across the bulb and thus keep it at 13.0V. The switching is not bad for the bulb, and the pulses are short enough (about 4/100th's of a second) that the human eye can't tell it's not a constant illumination.
We run into problems during an HID retrofit because of the HID ballast. What does the ballast do? An HID is an arc lamp which means there is no filament, but instead two contacts within a quartz envelope filled with xenon gas. Xenon is normally an insulator, meaning that it does not conduct electricity, but at a high enough voltage (between 800V and 2kV) the gas will ionize (just like a bolt of lightning), allowing electricity to flow between the contacts much more easily. We call this "lighting" or "igniting" the bulb. So the first job of the ballast is to ignite the arc.
If this high voltage was not removed, so much current would flow that the the contacts would melt and the capsule would shatter! So the second job of the ballast is to reduce the voltage to a more manageable level. HID bulbs are rated for a specific current (normally around 300mA) that they can operate at without damage. The ballast reduces the voltage to whatever level is required to keep this constant current flowing through the bulb.
When power is first applied to the ballast, it uses an inductor (in much the same way as the ignition coil sparks the spark plugs) to create the starting voltage across the bulb. Then, it gradually reduces the voltage until the constant current condition is met. To do this it uses a switch-mode power supply (SMPS) which is controlled by analog or digital feedback (this is where the "digital" in "digital ballast" comes from), that switches around 100KHz, or more. By measuring the current, it can switch on for longer or shorter to create the required average. This startup process takes about 3 seconds in most ballasts, although older ballasts can take much longer (30 seconds or more).
So there's a major problem when an HID ballast is hooked to the 80Hz PWM of the CEM. Every time the CEM switches the output on, the ballast begins it's startup procedure. When it shuts off, the ballast looses power.
Depending on the construction of the ballast and the duty cycle of the PWM (which depends on a number of factors, primarily battery voltage) the ballast might repeatedly try to start the bulb. Each time this happens, there is a large inductive flyback on the headlight ground - if you've ever touched the ground terminal on an old-fassion ignition coil while the car was running you know first hand - essentially a negative high voltage pulse. Normally this pulse would just go to ground, but it just so happens that the wiper motor (WMM) shares a ground wire with the headlights. Since there is an inherent resistance in the wire-chassies-battery connections, repetitive high voltage spikes can show up in the WWM and have caused many failures of a particularly sensitive component inside. This is the cause of symptom #4.
Other ballasts have a "warm start" condition in which they can tolerate short breaks in input power and continue operating so long as the gas remains ionized (about a second or so). These ballasts may work intermittently, again depending on the duty cycle of the PWM. This may seem OK, except that there is a filter circuit inside of the ballast required for proper operation of the SMPS. This circuit consists of an inductor and a capacitor, set up to "cover" the high-current spikes produced by switching, and allowing the ballast to draw a relatively steady current once running (see graphs). The filter is designed to deal with the operating frequency of the ballast, which is 10,000 times faster (or more) than the the PWM frequency of the CEM. In effect, subjecting it to low frequency modulation causes a large AC current to flow through the capacitor in the filter, several times more than it was designed for. This causes excessive heating and premature failure. The various stages of this degradation will cause the other symptoms listed above.
In all cases, when the ballast is no longer able to maintain the arc within the HID capsule, the capsule acts as an insulator, preventing current from flowing. This reduces the current that the ballast draws, which trips the BOW warning in the car.
Section 3 - How to fix the problem
There are three ways to get around these problems:
- <b>DRL disable does NOT disable PWM (just the DRL 1/2 brightness)</b><s>Disable the PWM modulation. This can be done by having a dealership flash the car to disable DRLs. This is the best option if DRLs are not a legal requirement where you live, and you don't mind the $80 for the dealer to do the flash. </s>
- Bypass the CEM all together by using a battery harness with a relay. This gives the HID ballasts a constant DC voltage, since the relay stays switched on regardless of PWM modulation. The downside to this is that the relay does not draw as much current as the halogen bulb did, and the "bulb out warning" message will continue to be displayed.
- Smooth the PWM modulation to approximate a DC voltage at the ballast. This is the cheapest solution that doesn't cause an error message, but because of the low frequency (80Hz) and large current (3A+), an extremely large (22,000uF or more) capacitor must be used. See here.
The third option is what developed from this thread (and the others). Essentially we designed a "bulb out warning eliminator" (BOWE) of which the first was built for SwedeSpeed member Kyle (ForceFed Motorsports), which for lack of better nomenclature became known a "KBOWE". The KBOWE consists of a large bypass capacitor and a diode, situated between the CEM and the HID ballast.
The capacitor serves to smooth the PWM voltage by shunting the AC components to ground. It's specification isn't supercritical, but it must have a ripple rating of at least 5A, which generally precludes sizes smaller than 22,000uF, and a voltage rating of at least 16V, but 25V or even 35V provide a better safety factor. Several smaller capacitors can be used in parallel if a larger unit is not available, provided they are all rated at least 16V.
The diode is situated to prevent current from flowing back to the CEM from the capacitor when the PWM switch is "off". While the exact mechanism is not known, empirical data suggests much better performance with the diode than without, and in some cases omitting the diode prevented the circuit from working at all. This is probably due to the current measurement mechanism within the CEM. The diode specification, again, is not critical, but it must be rated to at least 5A (10A or 15A provides a better MOS) and 16V or higher reverse voltage. A low forward voltage is also desirable, so most KBOWEs have employed Shottkey rectifying diodes.
The ground terminal of the headlight, CEM, and capacitor are all tied together and then directly to the chassis at the location of the KBOWE. Both the capacitor (which can absorb negative transients) and the grounding combine to eliminate the possibility of damage to the WMM.
One of these diode-capacitor assemblies is required per ballast. The most straightforward approach is to combine two assemblies in one box and tap it into the wires where they come out of the connector. This allows both capacitors to share a ground connection. Such an assembly is described in detail in this tutorial. Another approach with a slightly higher cost would be to create two identical units, hooking up between the vehicle wiring and the ballast at the headlight assembly, and grounding each independently.
The KBOWE has been extensively tested with over ten vehicle-years of operation since 2009 (as of 2011). The KBOWE is designed specifically for the challenges inherent to the P1 cars and, at the time this article was written, the only "adapter" type design that provides both HID functionality and WMM protection.
Section 4 - How not to fix the problem
A number of "solutions" have been proposed to allow retrofits to function normally. The majority users end up purchasing what have been called "BOW eliminators", "error cancelers", "harnesses", ect... They typically consist of a small box with two connectors, one male which plugs into the HID ballast, and one female which plugs into the power supply wires. For the sake of notation, we will call this class of solution the BOW-3, which is the model number of the product produced by DDM tuning.
The BOW-3 is essentially a beefed-up version of the filter inside of the HID. It contains another inductor and capacitor, to reduce the small 100KHz ripple imposed on a DC supply voltage. It works well with cars that (1) supply a DC voltage, and (2) are confused by this ripple.
The capacitor in the BOW-3 filter is about four times bigger than the capacitor in the ballast, and it has a correspondingly greater ripple (AC) current rating. However it's nowhere near big enough to deal with 80Hz PWM - and even if using a BOW-3 initially allowed an HID retrofit to work acceptably, most fail within a year or two because of this ripple current. About 75% of BOW-3 units work the first time, of those 65% fail within one year (sample size = 18 installs) and 20% take the WMM out when they fail. If you have a BOW-3 and it is still working, consider yourself on borrowed time.
Section 5 - Random Comments
Some users (6 of 44 recorded) have reported kits to function "perfectly" without any adapter, relay harness, or software flash. The majority of these users have "Kaixen" kits obtained from a group buy. Since I have not found an active group buy and the company does not seem to have a functional website, I can't obtain a kit for more rigorous evaluation. The Kaixen kits from various group buys (not just Volvo forums) have different styles of ballast, and each ballast style may have different components within them.
While there is no evidence to the contrary, I believe that (1) these kits are not designed to work with PWM supply voltage, and (2) that operating outside of design requirements will cause undesirable effects. Until I get my hands on a Kaixen kit I can't provide more information, but I do not recommend running any HID kit without one of the corrective measures listed above.
Jacob