A quality LED module produces a crisp, sharp colour.
For example, a Red LED should give a strong Fluorescent Red or Poppy Red colour not a wash-out red like hot pink, magenta, dark magenta and, in some cases, a purple/violet hue. A Green LED should be a just a touch lighter than a strong Apple Green moving slightly towards Lime Green. Blue is actually a little more difficult to define. It should be in the a bright mid-blue range slightly tending towards Cobalt Blue. Amber has a significant variation in range and can be anything from Yellow, Gold Yellow to Orange.
In some cases, manufacturers and even individual production batches can vary because of the difference in the mix of compounds used to create particular colours. The high quality manufacturers have more consistency in colour as they only use a particular mix and don't vary it because of price fluctuations in the cost of the required compounds.
Yes and no. While the power rating - sometimes stated in watts, lumens, candela or milli-candela {mcd} - may determine the amount of brightness of the light source, there is much more to it. The shape and type of the lens is important (both in the reflector and the fresnel), heat management, and the quality of the control circuitry are all part of the total package.
If given a chance to visit a modern light-house, ask about the wattage or lumen power of the lamp then ask at what distance can the light be seen. These and similar questions will quickly show that, in the case of a light-house, the construction and quality of the lens actually plays a more important role in light output in both brightness and focus than the actual light source. So you see, it is the the total package that counts not just the power of the light source.
First thing to note is the effectiveness of a warning light does not determine its overall quality. Second thing is thinking about what a warning light is actually designed to do. The short and most obvious answer is to "warn someone of the presence of a hazard using a visual agent to attract their attention".
When we want to avoid danger (a hazard), we usually employ a very simple solution by using “Time and Distance" as a protective agent. The greater the warning time and the farther we are away from a hazard means one is generally in a safer position.
When anything is moving, proximity to a hazard is again a function of time and distance. The faster something is travelling, the more distance it covers in less time. That equates to a diminishing response window in recognising a hazard exists and taking appropriate or corrective action to avoid it (or avoid you when your hoping the "hazard" will see you, reduce speed and take appropriate action). It is not exactly rocket science. It really is simply giving notice or getting noticed at distance.
The effectiveness of a warning light should be tested at about 12 pm (Noon) on a clear sunny day and at some distance away from the device. The distance is determined by the device’s application. In some cases, it may be a stipulation in law or regulation depending on that application. For vehicular use or similar, an example would be a graduated testing range of 50, 100, 200 to 300 metres minimum. Using this methodology will give a fairly reasonable indication of daytime effectiveness.
In many cases, 300 metres in the bright daytime conditions will be at the upper limit of the clearly distinguishable visual range for even a quality incandescent light (halogen or strobe) and some quality single or dual LED modules. However, a good quality LED lightbar with several adjacent modules simultaneously activating should be noticeably visible to 500~600 metres or more.
The light of early morning or late afternoon will always present problems for a warning light because of the angle of the Sun: either by looking into the Sun; glare from window glass; or, light reflecting from or through the lenses. Do not bother testing under these conditions because the Sun will always win. Another testing issue is heat haze. This condition will also affect distinguishable visual range.
Particular colours are more suited to either day or night. Red is a good day colour whereas Blue, Green and White are good night colours. This is why many emergency services use Red and Blue. Amber is a good day/night all-rounder. However, some colours can only be used by certain agencies and/or in certain circumstances.
Conspicuity is the term generally used for the brightness and noticeability of lights.
At night and close-up, any light will be bright to the naked eye. Noticeable differences will show-up in colour clarity, light output and beam focus the farther one moves away. Night testing should be done at even greater distances than that of daytime because distant vision (and therefore reaction time) is obviously lessened because of the dark. However, a device’s effectiveness will quickly become apparent: especially, when comparing one model/brand against another.
A panel style LED module is good for directional and focused light output - very good for distance - but these do not have a good angular spread. A standard rotating beacon, omni-directional strobe or a LED unit giving the general effect of a rotating or strobe beacon will provide the best 360-degree visibility. It is possible a combination of multiple devices or systems could and, in some cases, should be used.
The final thing is not to be immediately taken-in by initial brightness, abundance of flash patterns and other “bells and whistle”. Some may be useful; others will never be used. Keep in mind, both alternate and simultaneous flash patterns are useful in particular circumstances. However, professional users do concern themselves with changing flash patterns while driving.
Stand back, analyse what your purpose is for obtaining a warning light, where and when it will be used. Check if there are any legislated requirements and regulations including particular colour usage: especially concerning motor vehicle registration, traffic, maritime and navigation regulations, if that is where a device is to be used. Specially accredited lights are used in hazardous material situations and mining applications: check the certification.
Then make an informed decision.
Lights should really only be fitted by qualified persons.
Poratble dash lights, visor lights and such are not meant to be permanent windscreen attachments. So people tend to think it is OK to just plug them in and use them. Where there are several other devices fitted, whether or not emergency response related, take heed of advice given in the full suite of all device documentation and that given by qualified persons: such as, an auto electrician.
A user-come-installer needs to understand that attaching any electrical device to a vehicle requires an understanding of the interrelationships and dynamics of its whole electrical system. The more one adds, the more load is placed on particular wiring line, looms, their respective fuses and the vehicle's entire system.
Therefore, our advice is to always consult with a qualified person.
Read any and all safety instructions concerning a device's installation and use.
LEDs and strobes produce high intensity light outputs, which can cause temporary blindness and night blindness. This may cause loss of sight sufficient enough to stumble or not notice another hazard. Staring at high intensity light sources at close range can cause permanent eye damage. Therefore, avoid looking directly into or staring at a light source.
Some devices produce flashback (reflection off vehicle glass, external objects or mist/fog) in low light situations. Under such circumstances, reduce speed and drive according to the conditions and visibility.
For you own safety and that of other passengers, never simply lay a device on the dashboard. Always affix the product as directed by its documentation, eg: with its straps or suction cups, as the case may be.
Suction cup mountings should be fitted to very clean glass with no ridges (like those usually found around mirror mounts or with demister lines). Both the glass and the cup need to be free of greasy substances. Therefore, use proper cleaning cloths and agents like methylated spirits. After cleaning the glass and the suction cup, dab a drop water on each cup to ensure a proper vacuum seal and check them periodically.
Additional caution is well advised when installing product in places other than a front windscreen. For example, fitment of a dash light by its suction cups to a rear or side window or simply tucking it into the roof lining is most certainly not advised nor condoned.
The dynamics of forces involved with sudden changes of direction at speed or in collisions, at any speed, make proper device fitment something to consider seriously when considering anchoring locations and mechanisms (like brackets). While some product may be light in weight, they can still become a missile and cause serious injury or death.
Any device and its wiring is to be laid away from any areas where they will interfere with deployment of an SRS airbag or activation their sensors. Non-compliance might reduce the effectiveness of the airbag through tearing or obstruction and, thereby, contribute to serious injury or death. Deployment areas for side curtain or rear seat air bags including their deployment sensors also needs consideration with regard to warning device wiring and anchors points for the same reasons.
Periodic checking of all fitments, both temporary and permanent, must be conducted to ensure they are tight, undamaged and still fit for purpose.
Brackets and straps, where used, should be of metal construction and of a thickness conducive to the weight of the device. Therefore, advice from a qualified persons must always be sought.
For example, any rearward bracketing strap for any device fitted to a vehicle used by Code2 Australia is, at the minimum, constructed of 3mm mild steel or 5mm aluminium and anchored by using high tensile nuts and bolts. Any device's rail, frame or holding bracket fitted to a side or rear anchoring strap is no less than 1.6mm mild steel; again anchored using high tensile nuts and bolts. Washers or spacers are used in all cases to mitigate load stressing.
Always consult a qualify person because specifications and parameters will vary for different devices and vehicles.
