Modifying Lights to LED

LadyInBed

LadyInBed

Well-Known Member
Joined
2 Sep 2001
Messages
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Location
Me - Zumerzet Boat - Wareham
montymariner.co.uk
I have finally got round to replacing the florescent tubes with LED's.

3 Mtrs warm white LED strip £9.99
RS Voltage regulator, MC7812CT 12V 1A £3.84 (for 10 but only need 4)

I am putting 3 strips in the two main saloon lights
4 strips in the light over the galley
2 strips in the passage light to the aft cabin.

LEDLights_zpscf9df395.png
 
gregcope said:
Forgive the ignorance, but what is the voltage regulator for?

Are those LEDs not 12v?
Click to expand...

Yes 12v LED's but with engine running the 12v could start to approach 15v.
Then given that the alternator could be a bit noisy and produce spikes I decided that for a few pence, the regulator wouldn't do any harm.

PS Since I took the pic I have redone the wiring to the regulator so it doesn't look so untidy :o
 
LiB. Yes I too bought the 3 metre LED strips. I tried them at 6v;9v and 12 volt and got acceptable lighting from the 9volt and 12v have not considered a voltage regulator,nor yet where to fit them on board . I bought them originally for the engine bay but I think I need better wiringsystems before I try anything more complex.


ianat182
 
ianat182 said:
LiB. Yes I too bought the 3 metre LED strips. I tried them at 6v;9v and 12 volt and got acceptable lighting from the 9volt and 12v have not considered a voltage regulator,nor yet where to fit them on board . I bought them originally for the engine bay but I think I need better wiringsystems before I try anything more complex.


ianat182
Click to expand...

I've a growing number of lockers lit with led strip and rechargeable 9v pp3 batteries. Works well without having to run in power.
 
LED strip light

Well I would not worry about the possible high voltage when engine is charging batteries. The strips are made to cope with car battery on charge (14v) so risk it. olewill
 
From the data sheet:

The input voltage
must remain typically 2.0 V above the output
voltage even during the low point on the input
ripple voltage.

So when you are on battery without engine or charger you will only have 10V or just over at the light.
How does that affect light output?
 
Troubadour said:
How does that affect light output?
Click to expand...

See pics above (3 strips of 15 LED's)

Here are the numbers:
I/P to Light Unit before Reg = 12.7v
O/P from Reg = 10.6v

4 strips of 15 draws 452mA call it 450
3 strips of 15 draws 398mA on one light and 415mA on the other, call it 400
2 strips of 15 draws 295mA call it 300
I'm not sure why it isn't linear, maybe switch resistance and component tolerance?

Compared to Fluorescent 2 tube unit which draws 715mA

I will see how it goes, I can always ditch the Reg if I decide that they need to be a bit brighter.
 
LadyInBed said:
See pics above (3 strips of 15 LED's)

Here are the numbers:
I/P to Light Unit before Reg = 12.7v
O/P from Reg = 10.6v
Click to expand...

As mentioned in an earlier post, you need at least 2 volts above 12v for the 12v regulator to function properly
At 10.6V output the regulator is not regulating anything at all. Try switching on a transistor radio on AM band and listen to the oscillations.
 
LadyInBed said:
See pics above (3 strips of 15 LED's)

Here are the numbers:
I/P to Light Unit before Reg = 12.7v
O/P from Reg = 10.6v

4 strips of 15 draws 452mA call it 450
3 strips of 15 draws 398mA on one light and 415mA on the other, call it 400
2 strips of 15 draws 295mA call it 300
I'm not sure why it isn't linear, maybe switch resistance and component tolerance?

Compared to Fluorescent 2 tube unit which draws 715mA

I will see how it goes, I can always ditch the Reg if I decide that they need to be a bit brighter.
Click to expand...

Thanks for posting this, the man selling these at the boat show said the savings over flourescent tubes would be minimal but this looks like it might actually be worth while after all.
 
Curiosity got the better of me so a quick solder and measure came up with this..

Input voltage into a boost/buck power supply - 13.3v' all current measure on the way in with a DC clamp meter, so maybe not hugely accurate but shouldn't be too far out.
This was for a strip with 30 x 5050 warm LEDs
Output 10v. 50mA
10.5v. 75mA
11v. 90mA
11.5v. 125mA
12v 150mA
12.5v. 175mA
13v.* 220mA

Started to get a bit warm when cranked up to 16v.

Light started to tail off s bit under 11v but still pretty bright.

Something satisfying about measuring things:cool:
 
I have now tried the 4 x 15 LED unit without the regulator the result was:
I/P Voltage now down to 12.49v (must recharge the battery!)
The current drawn was between 860mA and 930mA (differences due to switch resistance).
This is more drain than the Fluorescent tubes so some sort of regulation is required.
Will order LM2940-12 (and capacitors :D ) and try again.
 
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