Car battery too powerful for LED MR16's

[visualchillout]

This claim was made by a popular ebay seller (female) today.

My original (filament lamp) boat lighting (boats use a 12V car battery supply) pulled 28 Amps when all the lights were switched on. Just fitted a mixture of white 4500K (heads-bathroom), and warm white (3200K) MR16's and total current all switched on 3 Amps. Stonking - no more flat batteries.

I know that these 12V LED lamps can be destroyed if an electronic transformer suitable for halogen lighting (white box few inches long) is used because these power supplies only chuck out 12V if the load is between min & max stated on the transformer (usually wattage). Because LED's draw so little, the transformer will go over-voltage and puff!!! no more LED's.

So with a nice rock steady feed from a 12V car battery, one would think that this was the perfect means of supplying the LED MR16's. Allegedly not. The lady assistant claimed that she has had many returns from a big warehouse customer who did not use the recommended LED psu's. Claimed that the supplies they used were too powerful. And I will have the same problem.

Surely, the LED circuitry only pulls what it needs, but I think what she was getting at is that the large surge currents destroy the LED's. I'm dubious but only time will tell.

Have any forum members heard of this claim?

 

[Adam W]

You need a constant voltage or constant current driver. With many LED lamps this is built into the lamp, with some it's built into the transformer, and with some it's separate (sometimes soldered onto the wire).

 

[visualchillout]

Yes I know.

In the advert it says :

PLEASE NOTE THAT ALL MR16 BULBS REQUIRE A DRIVER/TRANSFORMER CAPABLE OF DELIVERING A CONSTANT 12 VOLT VOLTAGE.
How more constant can you get than a car battery!!!

 

[Adam W]

If you feel you've installed them correctly (in accordance with the manufacturer's instructions) and they're still not working as they should, that would be an issue for the manufacturer.

 

[visualchillout]

Just to clarify - I installed all 15 of them a few days ago and have used them quite a few times and all is fantastic, bright & efficient.

It was her warning today that, from a car battery, I WILL HAVE FAILURES - and that surprised me.

 

[robikaz]

If you feel you've installed them correctly (in accordance with the manufacturer's instructions) and they're still not working as they should, that would be an issue for the manufacturer.

Yeah car battery is 12V but if started in engine its more sometimes even 14V... And if MR16 is very sensitive to voltage it will fry out...
Why don't you use only separate LED's...? You can take 4 of em whenever you want ant put it how you want, and buy a cheap resistor for 4 LED's in series on 13V.... That will do the trick ;]

Good luck ;]

 

[visualchillout]

You're right - just like a car alternator + voltage regulator = around 14V max on batteries engine running. I wouldn't have thought a couple of extra volts would hurt. Problem is they don't specify a max voltage.

I think she was more hinting at the large current capability of a car battery (300+ Amps). But then surely the LED's (60 off per MR16 equiv to 50W but consumes 3W) have a current limited supply. And I'm guessing that there's a full-wave rectifier directly on the MR16 pins since these bulbs work either way round so this would drop 2 lots of diode = 0.7V x 2 = 1.4V.

I thought about the DIY route that you are proposing some time ago. But I need serious light levels and TBH, building electronics to survive the harsh salty marine environments that a boat is exposed to at sea - well forget it - unless you encapsulate everything in resin to protect against the elements.

 

[robikaz]

yeah, nice thinking and these are quality lightbulbs, should do the sea trick ;]

you already said that you connected 15 of MR16's and they are working... Keep it for test purpose for now, and see what happens ;]

 

[telectrix]

i think the problem, if any will arise from the charging voltage on the battery when the engine, and hence it's alternator is running. you will be getting 14V+ and the waveform is as rough as a badger's arse. some sort of stabilized power supply is required, but as you say, salt environment. a possible solution would be to have a spare battery running the LEDs. when nearly flat, swap batteries.

 

[Adam W]

I don't get why you can't just use drivers like the manufacturer recommends, instead of arguing that powering them off a battery should be alright instead.

 

[visualchillout]

I installed the LED lamps about a week ago. It was only today that I learnt of the 'potential problems' using 12V batteries during a discussion about a completely different MR16 application.

 

[Rubert Glascock]

I realize this is an old thread, but it looks like the easy solution to the problem caused by unstable 12v power supplied from any 12v battery connected to a charging system would be to install a 12v voltage regulator between the battery and the lighting. There seems to be some confusion between the necessity for transformer/driver and voltage regulator from one application to another. The transformer/driver is required under the assumption that the power supply is 120/240 and needs to be “stepped down” to 12v. The “stepping down” function of the transformer is similar, yet very different than the function of a 12v voltage regulator. In general, voltage regulators regulate voltage that is “in the ballpark” from the source(in this case a 12v battery). Sorry for getting knit picky, but it seemed like it would help to clarify the different applications and specific functionality of the components involved.