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LED Light Replacement
Your interior lights, if left on, can kill a battery. So replace them with LED's
by Jonathan Edwards

Whilst working on my Esprit I noticed how much the interior lights put a drain on the battery, after having some experience in LED lighting I thought that I would replace some of the lamps inside the car with direct LED replacements I had seen advertised by a company on the internet.

Basically LED lamps have almost complete superiority in comparison to their filament counterparts, this it outlined below :

1)  LEDs draw a fraction of the electrical current required to produce roughly the same amount of light that a filament gives off.  In my tests the old filament lamps rated at 5 watts drew about 0.36 Amps when activated, the equivalent LED replacement draws anywhere between 0.02 Amps & 0.04 Amps depending on colour, a current rating of up to 1/18th of the old style lamp !

2)  Filament lamps by design create a lot of heat, you'll notice they are hot to touch.  The heat causes carbonisation on the glass bulb (most bulbs will have a black dusting on them) - LED replacements create next to no heat.

3)  LED lamps have a quoted life expectancy of approximately 100,000 hours which equates to 11 years of constant use !  Basically they should outlast the length of time you'll have the car and is much, much longer than any filament lamp will last.  In comparison the light does not diminish over age as it does in filament lamps either.

4)  LEDs are available in a variety of colours such as green, blue, white, red and amber which gives the user more choice when picking interior light colours.  Another advantage is that they also work well with clear lens modifications on things like side repeaters, you just have to buy an amber LED lamp replacement.

Some only work in one polarity (after all they are LEDs), and the axial / tubular ones have to be faced to get them to shine in the correct direction.  The major downer is that they are more expensive than filament lamps but when you weight it all up and take the benefit of extreme long life and very low current draw they still become an attractive alternative.


Old lamp with a yellow light New LED white light Old Door light New red LED replacement

When altering the current drain on a circuit it is usually good practice to re-rate the fuse for the new current being drawn.  You should check with the user manual what fuse is fitted (usually 5 Amp for the interior lighting circuit) - in my opinion you can leave the rating as it is because of the nature of variable load circuits.  You can probably drop the rating to 3 Amps which will take into account the lighter load current on the circuit, I have left mine at 5 Amp however.


When altering the current drain on a circuit it is usually good practice to re-rate the fuse for the new current being drawn.  In this case I chose not to alter the fuse rating (5A) because it's there mainly to protect the wiring (which hasn't been altered), other systems also run off of this fuse as well as some of the interior lighting.  Finally in the event of an over current fault the lamps act as fuses anyways just like filament lamps do, as you increase the current they tend to self destruct long before they cause any damage.

My lamps were purchased from www.ultraleds.co.uk (Car / Motorbike 12v Led Bulbs section) who make a wide selection of lamps in different colours for direct replacement in 12V systems like those found in cars.  They commonly come with a choice in the number of LEDs that make up the lamp, basically the more LEDs you have the brighter (extra current drain is next to nothing) but also the more LEDs the more expensive.  Below is a list of original filament lamps, their lens colour and their LED replacements :

Standard colours are linked, other colours are available but not tested to fit correctly.

Filament Lamp LED Replacement
(2)  Driver & Passenger foot well (clear) (239) 39mm 6 or 9 LED versions*
(2)  Door lights (red) (239) 39mm 9 LED versions
(1)  Bonnet Illumination (clear) (239) 39mm 6 or 9 LED versions*
(2)  Rear Luggage compartment (clear) (239) 39mm 6 or 9 LED versions *

(2)  Rear Number plate Illumination (clear)
(239) 39mm 6 or 9 LED versions
(3)  Ventilation panel illumination (501) Wide angle recommended
MORE TO FOLLOW * Denotes a slight modification needed to lamp holder, see below.

I managed to buy virtually every single axial lamp UltraLEDs supply and none would fit these interior lamps correctly, being either too large or too small.  In reality you have to use the smaller size in order for the lamp to fit back into the trim so re-bending the spring connector to make a good connection onto the lamp is the way to go about this.  It takes just a few seconds and a pair of pliers to do the job, it is totally reversible if you want to change back, you simply exaggerate the bends in the clip the directions as shown above in the photo.

LEW's Verdict

The facts speak for themselves really - the current saving is huge and I much prefer the new light colour, especially from the white lamps.  What it means in practice is that you can work on the car and so on without any real concern about battery drain - replace all of the interior lights and the whole lot will draw less current than just 1 of the old lamps !  Granted you can pull a fuse to stop the lights coming on but in my car pulling that fuse also cuts out other things like the ECU and the clock which I find annoying.  The lamps are expensive that is for sure but I'm happy with what I have got and will be kitting out some more lighting sections in due time.

This mod was performed by Jonathan Edwards on his 1997 Esprit V8.

If you have any comments, feel free to e-mail me with at admin@lotusespritworld.com


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