Retrofitlab V50 Retroquick Projector Kit and Aharon Ballasts

For this review, I’ve ordered what Retrofitlab calls a “complete solution” for P1 HID retrofits, their Volvo V50 (2004-2012) bi-xenon E46-R (D2S) – Halogen headlights combo kit.

TL;DR: Yes, this kit is suitable for P1 retrofits, if installed correctly (especially ground!). Bulb failure warning functionality is not retained, as is the case with all relay harnesses. 

The reason I wanted to investigate this kit in particular is it claims to be a complete solution, their description includes a fun tidbit about the wiper motor (as was pointed out on the SwedeSpeed boards) and it’s in the Netherlands which is where many of the international SKBOWE orders came from.

Email from customer service at retrofit lab
No info on canbus, but at least he acknowledged the SKBOWE…

The product description did not specify how their “Canbus harness” worked, and an answer from their sales team did not do much to clarify, so I figured I’d order a set and see what showed up.

What’s Included

This kit *is* complete, as everything you need for a relay harness install w/projector swap –  For a cool €284,95 (that’s about $325 USD) + shipping, this kit includes:

  • 2x 3-inch D2S “E46” replica projectors (see identification chart) and bulbs
  • 9005/HB3 high beam splitters with solenoid connectors (so you don’t have to make your own like How To: 9005 to 2-wire Bi-Xenon Solenoids)
  • AMP to D2S adapters with grommets and integrated H7-to-9005  adapter.
  • Aharon Speed Start 35W ballasts
  • Relay harness
  • Load resistors

As noted below, the parts I received were average quality, while the kit is priced at ultra-premium levels – you are paying about €75 ($100 USD) for the convenience of not having to source the components individually (e.g. Amazon, eBay, etc.) and presumably, having real support.

Product Description

I believe, especially for those new to HID retrofits, that the product description copy is misleading in several ways so I have annotated it for the uninitiated:

This Volvo V50 retrofit kit contains everything you need to convert your halogen setup into powerful bi-xenon projector headlights.* Custom-made to fit your existing headlights and including all the correct wiring and a selection of OEM-style shrouds, it makes retrofitting quick and easy. And, most importantly, it will take your V50 to the next level – just check out the test pictures! This is way beyond what the majority of OEM projectors can achieve.

The Bosch AL E46 [1] is an incredibly bright bi-xenon projector, enabling you to use D2S OEM bulbs, including the most powerful options from Osram and Philips[2]. You will literally outshine the competition. With available colour temperatures ranging from 4,300K to 6,000K, the crystal-clear 3.0-inch lens throws a low beam with a bright hotspot and sharp cutoff. As for the high beam? It’s like the sun.

Such a light output would not be possible without efficient ballasts, and the included Aharon digital ballast has – as opposed to many other aftermarket units – been tested to generate a full 35W. The Aharon comes in a rugged and extremely compact housing perfect for retrofitting, and its in-wire starter warms xenon bulbs in as little as five seconds. It is also Canbus-proof, so you won’t get any bulb failure readings on your display[3]. This ballast is the perfect complement to the included Volvo V50 wire harness, which connects directly to the original wiring. A high beam splitter is also included, making for easy integration of the bi-xenon mechanism. Power supply is strong, steady and reliable.

* Please note that Volvo V50 is one of a select few vehicles that may also require our custom Canbus harness in order for your dash, lights and wipersto work as normal[4].


[1] The projectors are replicas, not "Bosch" or  "AL"  and the E46 does not exist. They are the correct size and bolt pattern for the P1 vehicles
[2] Misleading, as the kit comes with generic ("$20") bulbs; though it *will* work with Osram and Phillips bulbs if you buy them separately
[3] Misleading, as (per their own footnote) you *will* get bulb failures if you don't get the optional harness.
[4] Note that the dash will not work "as normal" even with the "Canbus harness" (which is really a relay harness + resistors), because if a bulb burns out there will be no indication. I think they meant, there will be no BOW when everything is working. Interesting that they included wipers here.

While misleading, there is nothing patently false in the description, so I will chalk it up to marketing “artistic license”…

What Showed Up

Arrived Dec 26, so it’s literally like Christmas!

Package arrived from the Netherlands in good shape after 20 days (about standard, for priority mail international). I was most interested in the “Canbus harness”, so I tore into that first.

The “canbus harness” is just a relay harness with integrated load resistors

As I suspected, their “Canbus harness” is just a relay harness, with load resistors. There is no capacitor so it won’t work with the US/NA DRL, but I don’t think thats a thing in the EU so no fault there. I was relieved to see the relay harness has all necessary elements for a P1 install, rather than a DDM-BOW3 style eliminator.

Resistor pack marked as “C30” reads 5.4 ohms

The resistors are marked “C30”, which considering the options which were not marked, I assume means a nominal 30W draw. I read 5.4-5.5 ohms, which is inline with the 25W threshold and my 5 ohm recommendation . Someone did their homework :-)

Actual current draw through only the load resistor was 40W at 14V

The load resistors are a unique design, and it sounded like there was something loose inside of them so I cracked one open and it is filled with what appears to be salt?

Internals of load resistor
The load resistor is packed with what looks like salt

Not sure if that’s for heat, or moisture, but it is surely a unique design. I do worry about vibration slowly grinding the crystals down into powder, leaving that ceramic element banging around inside the aluminum case, but that is probably many thousands of hours away. Nice quality on the high-temp wire insulation, though I was not impressed with the case itself, strain relief, or grommet. I would have preferred to see thermal epoxy over salt.

Note the ferrite inline with the HV leads. Nice!

Anyway, moving on to the ballasts. I had not heard of Aharon before, but they feel nice, comparable to Morimoto XB series. Some interesting features:

  • There is an integrated “Canbus” module inline with the supply lead
  • There is a ferrite inline with the hard-wired ignitor (not replaceable)
  • There is a ground tab on the mounting bracket, although the case is not connected to ground and there is no provision for making contact through the case. Perhaps this is an attempt at RF shielding?

The reason I compare it to Morimoto, despite it not having replaceable ignitors, is that it looks very similar to the XB AMP ignitor (down to the cable braid):

Aharon vs the Morimoto XB ignitors. Same factory? Or at least same tooling?

Although advertised as a 35W ballast, it draws nearly 60W of power, so it is likely running bulbs hot.

Inline “canbus” on Aharon ballast, un-potted.

It does run off the signal PWM directly, as it has an integrated “canbus” error eliminator which was poorly potted using silicone inline with the power feed. The back cover of this unit was not glued, and the silicone potting pulled of easily. This design will not protect against condensation and corrosion in an automotive environment for long.

This module has two 16V  10,000UF 105c capacitors the and a single silicon diode, as well as a choke, MOV, and a few resistors for an RC filter. I did not reverse engineer the circuit yet, but based on the size of the choke this is tuned for a much higher (1KHz +) PWM frequency.

I do NOT recommend using the Aharon ballasts without the relay harness in P1 vehicles even if it seems works – 20,000uF at 16V is not enough capacitance for 80Hz PWM. Subsequently, the single diode is subject to large current spikes gets very hot (PWM only, it’s fine on the relay harness):

142F (60c) without the heat of the engine, etc. This will get worse as the capacitors degrade.


  • This relay harness + load resistor kit is a safe way to retrofit a P1 with HIDs, and the included projectors are drop-in including bi-xenon  functionality.
  • All components included – this is a true “plug-and-play” kit (aside from having to drill a hole in the housing cover, of course)
  • Now that SKBOWE is out of production, this is a great alternative especially if you are in the EU
  • Average component quality, some aspects similar to Morimoto, though projectors are replicas.

Overall: 4/5 stars: -1/2 for cheap silicone potting, -1/2 for no screw holes in ballast case.



All 100 SKBOWEv2 units have shipped! Sorry, I do not have plans to produce more at this time. You may contact me if you are interested in a notification if they become available again. Sorry if you missed it, but I was upfront about the quantity being limited to 100!

So what should I do?

You could build the circuit yourself, as it is an open source design… But if that isn’t an option, per the Retrofit Guide, a relay harness is the only safe way to retrofit. Unfortunately you won’t get factory bulb-failure functionality (either always on without resistors, or always off with them).


  • 100 units sold
  • 0 units returned in 83.1 years of car-install time (30330 days, and counting)
  • 100% testbench pass rate (no defective during manufacturing!)

Where did they go?

About 3/4 went to the US (expected, due to extremely expensive shipping & tariffs abroad), the rest to basically Europe:

  • USA – 73
  • UK/Great Briton – 7
  • Netherlands – 7
  • Ireland – 3
  • Canada – 3
  • Poland – 2
  • Germany – 2
  • Estonia – 1
  • Finland – 1
  • Sweden – 1

Kinda bummed none went down under :(

In the USA:

  • VA – 9 (some local)
  • CA – 6
  • NY, CO – 5 each
  • WA, PA, FL – 4 each
  • TX, TN, MI, MA, GA – 3 each
  • UT, OR, OH, ME, CT, AL – 2 each
  • WI, RI, NE, NC, MD, KS, IN, IL – 1 each


Batch 3 Sold Out – Batch 4 In Production

The last of Batch 3 sold out today, so I have opened SKBOWE Batch 4 up for preorders, estimated ship date is October 15th 2018, though they may ship before that if I can find time to finish them. The boards are populated, but they need to be potted and get the harness & connectors. This will be the last batch, since I am out of PCBs, enclosures, and 9005 connectors. Get them while you can!

Volvo Halogen to OEM Bi-Xenon Headlight Housing Swap for S40 and V50

This advanced tutorial describes how to re-wire the OEM Bi-Xenon headlight housings to work with Volvo P1 vehicles originally equipped with halogen headlights. The SKBOWE is tapped into the headlight harness outside of the headlight assembly and powers the OEM ballast, so no holes in the housing or cover are required.


Many years ago, I described how to re-wire the factory bi-xenon headlight assemblies as part of an project to facelift a ’05-06 S40 to the new style (’07+) front bumper and headlights with LED city lights. These assemblies are hard to find and very expensive, but offer a unique look (compared with pre-facelift and halogen-facelift) and are technically “DOT Approved” to pass inspection (as they are stamped D2S on the lens).

Note that this mod does NOT give you ABL (active bending lights) or auto-leveling functionality – the motors inside of the OEM bi-xenon housings remain disconnected and unpowered. THERE IS NO PRACTICAL WAY TO GET THIS ENABLED ON A HALOGEN CAR – you would need to change the headlight type in the CEM, add the leveling sensors (which is a lot of re-wiring) and pins in the CEM harness, plus the GDL modules. Sorry, short of creating your own system from scratch, it’s just not practical.

Unfortunately, the original project pre-dated the SKBOWE and the importance of the additional ground was not understood at the time, so eventually (within 3 years) the under-sized capacitor filters I provided failed and took out the WMM. However, with some tweaks to that procedure (described here) to allow using a SKBOWE, the process is just as safe as using an aftermarket ballast.

Install Process

There are two important mods to OEM equipment to make this mod work:

  1. The headlight harness (From the car, with the connector that plugs into the back of the headlight) must be modified to allow inserting the SKBOWE inline on the low beam wire; and
  2. Inside of the OEM bi-xenon housings, connect the pins that are missing in the halogen harness so that the OEM ballast can power up.

Step 1 – Tap Halogen Harness for SKBOWE

To avoid having to drill a hole in the headlight housing and having extra connectors (power in and power out) the cleanest way to get the SKBOWE inline with the low-beam supply is by tapping the OEM harness.

While it is possible to cut the connectors off the SKBOWE and crimp it directly inline, it’s better to just add a pair of 9005 connectors so that you can remove the SKBOWE in the future and go back to stock (just disconnect the SKBOWE and connect the male+female together).

Tapping pin 4 ground and pin 9 low beam with 9005 connectors to allow SKBOWE install outside of headlight housing
Modifications to the headlight harness to connect an SKBOWE without drilling holes in the headlight housing.

You’ll need to find two wires within the split-loom that goes to the headlight connector. you can do the tap anywhere along the split loom, in the image above it’s shown right at the connector for clarity. The pins are:

  • Pin 9 (+) – the low-beam power supply, green/white on my 05 (check your VWD to confirm)
  • Pin 4 (-) – the ground for the headlight housing

The female 9005 (“supply”) goes on the car side, the male 9005 (“output”) goes on the connector side. You can get the connectors for cheap by cutting up a 9005 extension. I like to use heat-shrink butt-connectors for this type of splicing, to keep everything firm and waterproof.

Step 2 – Prepare the OEM Bi-Xenon Headlight Housing

As shown in the wiring diagram below, the HID ballast in the OEM housing is grounded through pin 10 on the headlight connector, which is not populated in the halogen car-side harness. So inside of the housing, you need to connect pin 4 (the halogen and high-beam ground) to the wire that runs to pin 10 (the HID specific ground).

wiring diagram for 2007+ bi-xenon headlight housing s40 v50
Wiring diagram for the facelift S40/V50 bi-xenon headlight housing, 12V section (ABL/AL not shown)

The cleanest/easiest way to do this is by cutting the brown wire going to the four-pin HID connector as close as possible to the main headlight connector’s pin 10 (leaving as much length as possible) and then crimping it into the the the high-beam connector ground, which is visible if you remove the round cover on the top of the headlight.

Alternately, you could use another butt connector, cut the high-beam ground, and crimp everything back together.

Step 3 – Install the SKBOWE

The final step is to install the SKBOWE normally, per the installation guide, including the ground prep and mounting (zip ties or inside of wheel liner on bracket) – but instead of connecting it to an HID ballast, connect it to the 9005 connectors you added in step 1.


One Year Anniversary

That’s right, we are coming up on the one-year anniversary of the SKBOWE pre-order with 70 units sold and a total of 15,535 car-days (estimated) installed! To celebrate, the remainder of Batch 3 has been discounted to the pre-order price ($99)! Batch 4 later this year will be the last production run, so get yours while you still can.

AC vs DC HID Ballasts

A customer recently asked if SKBOWE was comparable with AC and DC HID ballasts, a confusing question because every HID ballast I’ve ever seen has been marked for 12V DC in, 85V AC out (bulb side). Turns out there actually are “DC” output HID ballasts, and they should be avoided as D2S bulbs are specified for AC drive only.

AC vs DC

As discussed on the issues page, HID bulbs are arc lamps that run a fixed current through two electrodes in a sealed quartz capsule. The voltage drop is about ~85V after ignition (20kV) and warmup. Like any arc lamp, electrons jump off the negative (-) electrode, and impact the positive (+) electrode, causing the (+) side to run hotter and wear out faster. To counter this effect, all OEM ballasts and most aftermarket designs send AC current to the electrodes, alternating each electrode between (+) and (-), so that both electrodes wear evenly.

Because the input power from the car electrical system is nominally 12V DC, there are two stages required to output the necessary power to an HID bulb:

  1. Step up 12V DC -> ~120V DC, using a boost converter with a flyback transformer, rectifier diode, and filter capacitor,
  2. Chop the 120V DC into 85V AC (RMS) using a set of push-pull MOSFETs (H-Bridge)

However, Chinese cost-cutters, in an effort to produce increasingly cheaper ballasts, figured they could get rid of the second step and feed DC directly to the bulb. The result is lower component count, but a bulb that will burn out very quickly due to rapid erosion of the positive electrode. It will also result in a lopsided, unstable arc that will “dance” and not locate at the center of the reflector foci.

Some Ebay Sellers are starting to market the difference, but price is almost always the most reliable indicator.

Some eBay sellers are starting to market the difference between AC and DC.

How to avoid DC ballasts

Price is usually a giveaway, though some manufactures have figured this out and are now up-pricing DC ballasts to make huge profits. Because DC ballasts are cheaper manufacture without the DC to AC stage they sell for very low prices, say, below $35 for a kit. AC ballasts require a large inductor and HV regulator for DC to AC conversion and are more expensive to manufacture. High-end Digital 35W AC Ballasts can’t be produced at that price, let alone sold for anything close. Without special equipment it’s hard to test at home, so make sure to order from a reputable company that specifies an AC output.

Also it doesn’t help for online shopping, but AC ballasts are significantly heavier than DC ones:

Weight of AC vs DC ballast


The what NOT TO BUY post has an example of a DC ballast. The Morimoto XB is an example of a good AC ballast. When I get some free time, I will update the ballast selection page with measurements from the ballast collection.

SKBOWE Batch 3 Ready to Ship

Of 25 units potted so far in Batch3, 12 have sold, and 13 are ready to ship! There are still two AL Gen2 bi-xenon pigtails available as well.

There are another 17 units of PCB assemblies ready for potting, but without an ETA on when they will be finished, they are being pushed to Batch4.

SKBOWE Batch 4 is ready to pot

When these are complete, I am waiting on 8 units worth of capacitors which are backorder until Mid-April, to round out all 100 SKBOWEs.  Based on average monthly sales, total remaining inventory should cover until October or November. After that, the future of the SKBOWE project is uncertain…