FAQ
TL;DR: For street‑legal daytime running lights (DRL), look for RL/E‑mark approval; typical charging voltage is 13.8–14.7 V, and “it should be min. 13.8 V, max. 14.7 V.” [Elektroda, helmud7543, post #17147794]
Why it matters: This FAQ helps drivers choose legal DRLs, avoid inspection/police issues, and protect battery health on short trips.
Quick Facts
- DRLs should carry RL and E‑mark on the lampshade to be considered approved. [Elektroda, Davvvi, post #16943436]
- Using lights without approval is “at your own risk” and nothing has changed legally per forum experts. [Elektroda, enhanced, post #16943768]
- Enforcement is real: police/diagnosticians may pull registration and fine for improper lights. [Elektroda, kkknc, post #16943813]
- Typical alternators are strong; swapping to LEDs may not noticeably help charging. [Elektroda, kkknc, post #17145437]
- Healthy system voltage target: about 13.8–14.7 V while charging. [Elektroda, helmud7543, post #17147794]
Are COB waterproof LED strips legal as daytime running lights?
Only if they have DRL approval markings (RL and an E‑mark) on the lampshade/housing. COB strips without such markings aren’t considered approved and are used at your own risk. Forum guidance stresses approval on the lamp itself, not just seller claims. If there’s no approval, expect potential inspection or police issues. Check the product for embossed RL/E# before installing. [Elektroda, enhanced, post #16943768]
What markings should I look for on legal DRLs (E4, RL)?
Look for the RL code and an E‑mark (e.g., E4) molded or etched on the lamp’s lens or body. Users in the thread selected units specifically marked E4 and RL to stay compliant. Without these markings, the lights are not considered approved DRLs. [Elektroda, Davvvi, post #17145431]
Are flowing turn signals combined with DRLs legal?
Legality hinges on approval. If the combined DRL/indicator lamp lacks proper approval on the lampshade, you use it at your own risk. Forum contributors caution that nothing changed: no approval means potential trouble during inspection or traffic stops. Choose units with visible approval markings. [Elektroda, enhanced, post #16943768]
Can I get fined or lose my registration for non‑approved DRLs?
Yes. Contributors report growing attention from diagnosticians and police. You might drive for years without issue or get penalized soon after installation. The remedy is simple: use approved lights and mount them correctly. “There is to be approval and proper assembly.” [Elektroda, kkknc, post #16943813]
Will adding DRLs help my battery on very short trips?
Usually not. A modern alternator already handles the load well, so switching to LED DRLs brings little charging benefit. One user with short weekly mileage considered DRLs for battery relief; advice given was that alternators are large and gains are minimal. [Elektroda, kkknc, post #17145437]
What charging voltage should I see while driving?
Target around 13.8–14.7 V. If voltage sits below ~13.8 V, reduce load or service the system. An expert notes, “it should be min. 13.8 V, max. 14.7 V.” Edge case: constantly below 13.8 V indicates a fault needing diagnosis. [Elektroda, helmud7543, post #17147794]
My voltage drops under 14 V when cruising—is that a problem?
Yes. A forum expert states that while driving, voltage must not drop below 14 V, and falling below harms battery life. Persistent lows point to charging faults that matter more than headlamp type. Fix charging issues first. [Elektroda, Strumien swiadomosci swia, post #17147833]
Do I need proof or a certificate with the lights, or just the marking?
For inspections and roadside checks, the approval marking on the lamp is decisive. Users warn that lack of approval can complicate insurance after a collision. Choose lamps with visible RL/E‑mark to avoid disputes. [Elektroda, Davvvi, post #16943528]
Is it okay to install cheap DRLs if they ‘look fine’?
Appearance isn’t compliance. Some install low‑cost sets and drive without issues, but enforcement varies. You could be fine for years or get cited quickly. Approved lights and correct placement are the safe path. [Elektroda, kkknc, post #16943813]
Will LED DRLs noticeably reduce alternator load on a 1999 diesel?
Impact is small. The bigger variable is whether your alternator holds proper voltage. If charging sits in the 14.2–14.7 V band, LEDs won’t materially change your battery balance compared to proper system health. [Elektroda, helmud7543, post #17147794]
How long does it take to replace energy used during engine start?
Expect a few minutes. One expert notes the battery needs “a good couple of minutes” to recover what it gave in about two seconds of cranking. Short trips may never fully replace that energy. [Elektroda, helmud7543, post #17147794]
What’s a quick 3‑step way to check charging before buying DRLs?
- Measure battery voltage at idle with lights off; confirm around 13.8–14.7 V.
- Switch on major loads (headlights, blower); recheck for stable voltage in range.
- Rev slightly; ensure voltage rises if low, or diagnose if it stays under ~13.8 V. [Elektroda, helmud7543, post #17147794]
Where should I mount DRLs to avoid trouble?
Follow approved mounting and aim for sensible, glare‑free placement. Forum contributors stress that proper assembly matters alongside approval. Poorly aimed or blinking retrofits draw attention from inspectors and police. [Elektroda, kkknc, post #16943813]
Do flowing indicators inside headlamps cause extra scrutiny?
Yes if unapproved. Combined DRL/indicator assemblies without markings invite inspection issues. Users report that authorities are increasingly attentive. Choose marked units only, even if the feature looks great. [Elektroda, kkknc, post #16943813]
What if my lamp has no visible approval, but the seller claims it’s certified?
Assume it’s unapproved. Forum advice is clear: approval must be on the lampshade/housing. If it’s missing, you assume the risk of fines or failed inspection regardless of vendor claims. [Elektroda, enhanced, post #16943768]
Can DRLs alone fix weak charging on short weekly mileage (6–20 km)?
No. The core issue is insufficient run time to replenish start energy. As one expert explains, the battery needs minutes to recover a two‑second start. Verify charging voltage and address faults first. [Elektroda, helmud7543, post #17147794]
