I have some spare 12v led lights, I want to use them in a stable powered from a car battery, I don't know if they are A/C or D/C will they work with either, ps they used to be at home and have a transformer in the fitting which I would do away with if powered by battery.
12v led's from battery
- Thread starter algas
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OK. have a look at the output on that original transformer. It will tell you if it is a plain old transformer (gives you AC) or if it is some sort of power supply that delivers something else.
PS The LEDs will probably work on either AC or DC. You could try them on your battery, if they don't work, swop the wires round - what could go wrong?
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Not to be too gloomy, but I have had LED lamps explode. Caution when doing the experiment is advised. (Flying glass is a possibility if that's what they're made of.)
It's reasonable enough to issue that warning but, although I have also experienced LED bulbs/lamps exploding (most commonly plastic, rather than glass, fortunately!), I very much doubt that connecting a 12V DC supply to a "12V LED" could precipitate such an event, even if the LED was designed for AC only. I would have thought that, at worst, it probably simply wouldn't work.
Kind Regards, John
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I agree it's most likely to be fine. But it's not your eyes which I was suggesting protecting, it's the OP's.
Indeed. As I said, it was perfectly reasonable for you to give the 'warning'.
Kind Regards, John
The 'transformer' may, apart from providing the drive voltage, also be a current control device. Without current control, either external or built-in, LEDs will run to self-destruction. I suggest you supply a photograph of all information contained on the transformer so an informed response can be given.
True, but it would be very wrong if a LED lamp/bulb intended to be driven by a current-controlled source was described as a "12V LED" - such a description should, for obvious reasons, only be used in relation to a product which has internal current control and is designed to work when 12V is applied to it (which is what virtually all 'consumer' LED lamps/bulbs are).
Kind Regards, John
I don't know if that is true (have had very little dealings with 12V LEDs) but if, as usually seems to be the case, they are designed to work on AC (and maybe also DC), given the crude (largely unsmoothed) rectification they are likely to contain, when fed with 12V (RMS) AC, they are likely to see something approaching the peak of that voltage, namely around 17V.
Kind Regards, John
Most of us have fitted 12 volt led strip in the back of our vans.
Never measured voltage but ok so far
Never measured voltage but ok so far
That's what I would expect.
In terms of LED lamps/bulbs, as far as I am aware, eric might well be right in saying that many ELV LED lamps/bulbs are designed for boats/caravans, and as such commonly are rated for a voltage of 10-30V (or something like that), so that they can be used with 12V or 24V batteries, off or on charge - which is very different from what big-all suggested. However, as I've said, I personally have minimal experience of ELV LEDs of any type.
Kind Regards, John
Yup had LED tape in the back of my van for the past 2 years - still going strong.
Not sure about the output of a 12v battery as I’ve never measured it but I do know the alternator puts out 14.5v ish volts and they survive that seemingly fine so shouldn’t matter if the battery output is slightly more than 12vdc
Not sure about the output of a 12v battery as I’ve never measured it but I do know the alternator puts out 14.5v ish volts and they survive that seemingly fine so shouldn’t matter if the battery output is slightly more than 12vdc
i run 9-12v 10w led chips direct no control but a large bit of ally bar as a heat sink from a bosch 10.8v[peak 13v] powertool battery and i prefer a battery a bit lower on power as you get a far far greater run time[about 2 times ] with a say perhaps 10% less bright
indeed you get fantastic run times with 2 in series with a working range off 18-24v with a 18v battery that gives out around 21.5v at the high end
indeed you get fantastic run times with 2 in series with a working range off 18-24v with a 18v battery that gives out around 21.5v at the high end
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This firm specialises in caravan and boat LED lamps however I don't think we are talking about specials we are talking about lamps you would buy in the local supermarket.
The units could be AC or DC and they could use capacitors as current limiters, however for 12 volt it is very unlikely that is the case, much more likely is a simple resistor. So the big question is if the extra voltage from a battery will overload the device?
A lead acid battery has a nominal voltage of 12, but it can be anywhere between 11 - 14.8 volt depending if on charge or not and what state of charge. If not charged and used at same time then 11 - 13 volt, but we don't know if solar panels are being used.
So to use LED lamps designed for a power supply then what we want is to reduce voltage to 12 volt or under, you could use a 12 to 12 volt inverter, but that seems a bit of over kill, would be better buying proper battery lamps. The other two options are resistors or diodes, a 1 amp diode would reduce voltage by 0.6 volt so two diodes will reduce voltage enough, I have in the past put them in in-line fuse holders, most LED packages will still give out a far amount of light at 10 volt and we would not want to bring a lead acid battery to below 11 volt, so most likely you can use standard domestic LED lamps on a battery.
It may be the wiring is enough to reduce the voltage, and it is unlikely the lamps will be damaged if lit long enough to measure the voltage, they may even work without fitting some voltage reducer, the question is do you pay £8.50 for a 3 watt lamp you know will work, or £1.70 for one which may work? (Looking at MR16 replacements) one point is the special bulb for battery use is around 100 lumen per watt, the cheap one designed for domestic is around 70 lumen per watt, in fact with volt dropper less than that, so you would need a larger battery, for same amount of light.
So question is really is it worth using domestic 12 volt lamps with all the messing around required, or just get the proper ones?
The units could be AC or DC and they could use capacitors as current limiters, however for 12 volt it is very unlikely that is the case, much more likely is a simple resistor. So the big question is if the extra voltage from a battery will overload the device?
A lead acid battery has a nominal voltage of 12, but it can be anywhere between 11 - 14.8 volt depending if on charge or not and what state of charge. If not charged and used at same time then 11 - 13 volt, but we don't know if solar panels are being used.
So to use LED lamps designed for a power supply then what we want is to reduce voltage to 12 volt or under, you could use a 12 to 12 volt inverter, but that seems a bit of over kill, would be better buying proper battery lamps. The other two options are resistors or diodes, a 1 amp diode would reduce voltage by 0.6 volt so two diodes will reduce voltage enough, I have in the past put them in in-line fuse holders, most LED packages will still give out a far amount of light at 10 volt and we would not want to bring a lead acid battery to below 11 volt, so most likely you can use standard domestic LED lamps on a battery.
It may be the wiring is enough to reduce the voltage, and it is unlikely the lamps will be damaged if lit long enough to measure the voltage, they may even work without fitting some voltage reducer, the question is do you pay £8.50 for a 3 watt lamp you know will work, or £1.70 for one which may work? (Looking at MR16 replacements) one point is the special bulb for battery use is around 100 lumen per watt, the cheap one designed for domestic is around 70 lumen per watt, in fact with volt dropper less than that, so you would need a larger battery, for same amount of light.
So question is really is it worth using domestic 12 volt lamps with all the messing around required, or just get the proper ones?
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