2D type, Double D (D2) or round 12v fluorescent tubes are found in many Caravans, Motorhomes and RV's. These are a bit more difficult to replace than standard bulbs but they are doable. All fluorescent's have an electronic starter and this must be by-passed to wire in an LED replacement. You can still use the light fittings original switch once the electronic starter has been by-passed to convert a 2D type 12v fluorescent tube to LED.
To convert from Fluorescent to LED, you should first consider both the power draw and the light output. The 2D type or often referred as a D2 Fluorescent tube will either be an 11, 16 or 21 watt, there should be some marking on the D2 to indicate which. From our experience it seems that the D2 11 watt tend to be the originals and the 16 or 21 watt are the most common replacements. To be viable to convert to LED you would want to save near half the current power draw AND have the equivalent or better light output, otherwise there’s no real point. As a general rule Fluorescent's produce 100 Lumen of light per watt, so an 11 watt Fluorescent produces around 1100 Lumen.
We've seen many “off the shelf” products out there and we don’t believe there’s an “off the shelf” product yet that will achieve this. Most of the “off the shelf” 2D type 12volt fluorescent tube replacements we’ve seen use either the 3528 or 5050 type LED’s and in our opinion these only do half the job. To get around the same light output as an 11 watt Fluro you would need an LED fitting with a minimum of 216 - 3528 SMD's or 72 – 5050 SMD’s.
Let's explore this point further, to get close to the equivalent light output for an 11 watt fluro in LED you would need 72 5050 SMD’s, the current draw would be 13.2 watts and produce around 1140 Lumen. We've even seen some stores promoting replacements with 36 or 48 SMD's and whilst the power draw will be less, so will the light output.
As you can see by this example you won’t achieve any power saving and if you use less than 72 5050 SMD's you'll get much less light output . In the case of an 11 watt D2 you’ll actually use more power. In all honesty if your D2’s are 11 watt then there’s not much point in replacing them. But, if they are the 16 or 21 watt type, then it might be worth considering.
OK, so there has to be something better.... “common off the shelf” as stated above not yet. However, at madaboutled.com we've been experimenting with some different options and our latest development is a new light fitting to take the place of a D2 Fluorescent tube or to convert older type dome lights found in older caravans and RV's. We make these fittings ourselves and they can use either 3 or 4 G4 Disc type LED's or G4 LED Bulbs.
We've named the new fittings a G4 Triple Cluster and a G4 Quad Cluster
. Eventually if there’s enough demand we’ll have these manufactured, but until then we're happy making them. They are more a labour of love as they can take over 20 minutes just to assemble one.
The G4 Clusters as designed to use Multi Volt G4 Disc Type LED's and for a D2 Fluorescent replacement we recommend using the new generation LED called 5630 which are 3 times brighter than the 5050’s and overall use much less power.
Why Multi Volt? Multi Volt circuitry provides a uniform level of intensity for reliable and safe illumination across a range of DC inputs from 10 to 30 volts DC. Our new Multi Volt G4 LED Discs can be safely connected to 12 or 24 volt DC battery systems without modification, providing better performance by automatically compensating for low or high battery outputs and or voltage drops caused by longer cable connections.
To put this into prospective, one 5630 SMD is three times brighter than a 5050 SMD. 36 – 5630 SMD’s will use only 9 watts of power and 3 x 5630 12 SMD Discs are the equivalent of 108 – 5050 SMD’s in light output. As a replacement for a 16 or 21 Watt D2 these are worth considering (more light and around half the power). Again though as a direct replacement for an 11 Watt 2D type 12volt fluorescent tube there’s not enough power saving to warrant it, unless you want to just upgrade.
The other thing to consider is the colour output of the 5630 SMD compared to a D2 Fluorescent. D2’s are generally on the lower side of “Cool White” and the 5630 LEDs are on the higher side. This means that they have a little more of a “blue” tinge and can take some getting adjusted to. That said, they are very bright and once you get used to them, anything else will seem dull.