1.When switched on, a halogen bulb draws high current because the filament is cold and hence has a low resistance. Shortly after ignition the current decreases and eventually stabilizes at about 4,5 Ampere. This process takes about 100 ms.
A ballast however behaves completely different. Most ballasts do not immediately draw current after switched on. After a short while the current consumption looks quite unpredictable and eventually the system stabilizes around 3 Ampere. But in many cases the car's on-board computer has already decided that something is wrong and disconnects the power.
The trick is to make a ballast that behaves like a halogen bulb.
2.Another problem is the noise produced by the ballast. The ballast contains a switched mode power supply that produces noise. This noise can confuse the CAN-bus system with unpredictable results like windows that open automatically (or don't close anymore), wipers that start moving, the car's radio that produces noise etc. etc.
This noise can be eliminated by a warning canceller that can be used in combination with the ballast.
These special capacitors suspend the electrical noise that possibly is generated by ballasts. Also it cancels false board computer warnings. Is mainly used in conjunction with budget ballast but can also be used with other ballast types .

Features:
- As high as 35W power supply, greatly reducing vehicle power system load, the power loss save 50%
- Quick and safety ignition, internal voltage protection.
- Short-circuit protection
- High performance of insulation, waterproof and quake-proof: the circuit boards are enveloped by silicone (only High End ballasts will use silicone in insulation
- This ballast build-in digital technology.
- It can solve the Canbus error code problem.

Description:

- Output power in stable state: 35w(saving 40% power)
- Luminous flux: 2500~3500 lumen( decided by color temperature ,the higher the temperature .the lower the lumen)
- Output power :reach 70% in cold starting in 2s,reach 80% in 4s,reach rating output power in 8s.
- Maximum input electricity: string electricity 6.5A, reach 3.2A in 4s, 3.2A  in stable state.
- Hot starting electricity: less than 4.0A
- Instant ignition voltage: 23000v~25000v
- Ballast lifespan: 3200+ hours
- Anti-electromagnetism disturb: reach S95/54/EC standard
- Output voltage frequency: 250HZ
- High voltage interior integration design
- Open circuit protection: automatic protection in 1s
- Shorti circuit protection : automatic protection in 3s
- Function of waterproof, dustproof, anti-vibration
- Protection of less or over voltage
- Protection of anti-electromagnetism
- Constant power designed , more applicable to bulbs