Len Salisbury Posted August 4, 2017 Share Posted August 4, 2017 I acquired a COB led from a friend to illuminate the dials on my Boxer 59 plate. and it does the job very well, mounted on the steering column. The only problem I have is that the strip gets VERY hot and falls off the bracket that I have made for the job. I blew the led the other day and it is now useless so have ordered new ones from Amazon and should arrive today. This COB was wired to a cigarette lighter socket plug in. Can anyone advise me as to whether the led gets hot (and I mean hot) or should they remain cool. I have used double sided tape, super glue and was going to use Gorilla glue before I rendered the led kaput. Link to comment Share on other sites More sharing options...
Keithl Posted August 4, 2017 Share Posted August 4, 2017 Len, You need to reduce the voltage to reduce the current and hence heat. Have a read of this thread and specifically the posts by Allan (aandncaravan) towards the end. http://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/21w-Flourescent-modified-to-2w-LED-1-50-How-to/45945/ Keith. Link to comment Share on other sites More sharing options...
Agaric Posted August 4, 2017 Share Posted August 4, 2017 All the COB leds that we install have large heatsinks on them, they need to be mounted with heatsink paste, same stuff you use to mount computer chips. They have a high failure rate when not installed properly. Last year we had to replace 96 of these in 32 fittings hung in a sports hall, for 2 of us it took nearly a week all because of poor installation. Link to comment Share on other sites More sharing options...
mgnbuk Posted August 4, 2017 Share Posted August 4, 2017 I have used a couple of these to replace incandescent lamps, as stated in the earlier thread detailed. Leds really require a constant current driver, but I found that an inexpensive voltage regulator (when set at a voltage that provide the required current) gave cool running. These units require, at most, the stated operating voltage & if this is exceeded by a even small amount the current (and therefore heat generated) increases rapidly with no increase in brightness as you would expect with an incandescent lamp if "overdriven". A 12v Led needs to be fed no more than 12v - a motorhome "12v" system will only give a true 12v if the battery is just about flat & not on hook-up ! On hook-up, the "12v" system is usually 13.5v-ish & can go to over 14v - a 12v rated Led on such voltages will just cook, as you have found. I was trying to run 18v rated Leds off power tool 18V rechargeable batteries & the 18.75v from a fully charged battery was too much - a regulator set to 17.75v sorted it. On a later conversion, I ran a 24v rated Led from the 18v (nominal) battery - the measured current was slightly under the Led rating & it ran cool, but was not much dimmer than at full rated current. I would replace the Led & mount a regulator in series with the supply to it. Adjust the regulator to give an output to the Led of 11.5 - 11.75v & all should be well. Details of suitable regulators are given in the earlier thread. Nigel B Link to comment Share on other sites More sharing options...
Len Salisbury Posted August 4, 2017 Author Share Posted August 4, 2017 Thank you all for your replies. The COB leds arrived and I wired it in to the cigarette plug and the same problem has arisen again. The voltage at the Power Pack is 12.75 at the Cigarette socket ENGINE NOT RUNNING 12.59 but as soon as the engine is started the voltage is 14.25. I was thinking last week in Devon but did not have my meter with me to measure the current when engine was running. I am going to contact Auto Electrician as it is above me to fix. I did send Allan from aandcaravans yesterday asking for advice/fix but no reply so far.Thanks again. Link to comment Share on other sites More sharing options...
Len Salisbury Posted August 5, 2017 Author Share Posted August 5, 2017 If the COB was wired into the lighting circuit that lights a bulb would I still get the same result, over heating? Link to comment Share on other sites More sharing options...
aandncaravan Posted August 5, 2017 Share Posted August 5, 2017 Len I did reply via the PM you sent. As stated above, the problem is these are not designed for vehicles, despite all the 'Auto' pictures on the advertising, they are designed for a very specific 12v input, not a Car batteries 13v.output, even 12.5 volts will get them warm. You therefore should run a voltage regulator if using them for any length of time in a vehicle, especially with the engine running and the Alternator putting out 14.4v. They work fine as interior lights without regulators in my van because the 'charger' is a lower voltage power supply that only puts out 13.2v (to extend battery life) but my friend has big issues with his Standard fit LED lights on his Solar Powered Motorhome. He has a permanent 14.8v on the supply rail to charge the AGM batteries which the Hymer standard fit LEDs do not seem to like at all, running hot and suffering short life. I don't think he would get away with fitting COB LEDS!! In your Motorhome the entire 12v circuit, including lights, will rise to 14.4v when the Alternator starts spinning. Derek Uzzell found a supplier of COB leds that were much better made than the ones I first proposed in my COB thread, as they had an Alloy 'heat sink'. They are probably more suited to your set-up? Photo below of one made up with a Voltage regulator attached. See full thread here : http://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/21w-Flourescent-modified-to-2w-LED-1-50-How-to/45945/ Link to comment Share on other sites More sharing options...
Len Salisbury Posted August 7, 2017 Author Share Posted August 7, 2017 Allan from aandncaravans is sending me a Regulator by post to over come the problem of heating when the engine/alternator is running. I have made up a bracket of 2 aluminium strips and attached strips of double sided tape to mount on top of the steering column shroud.The COB is attached to the long piece of plastic number plateby sicky tape.so all should be ok once the Regulator arrives. I have plugged it in to a 12 volt power pack and nothing has fallen off and the COB is warmish engine not running is not connected to van's electric. Brilliant lighting and no reflection. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted August 8, 2017 Share Posted August 8, 2017 I spoke to Aten Lighting at this year's NEC Show regarding the implications of using 12V LED flexible strips for lighting when a motorhome was being driven or on 230V hook-up with the on-board battery charger running. I was told that their LED strips were ‘rated’ to run at 14V, so there MIGHT be problems above that voltage. However, they said that they had not received any complaints so far. I’ve used 12V LED strips to illuminate my Ducato-based Rapido’s instrument-cluster and also to improve the lighting in the motorhome’s rear garage. Obviously I don’t have the garage lighting on much, and I usually leave the LED-strip instrument-cluster lighting off most of the time. When I have the latter on for a long period the LEDs do warm up noticeably, but this has not affected the strip’s adhesive backing (yet!) and the strip is still firmly attached to the underside of the plastic ‘shroud’ above the instruments. I can well appreciate, though, that running a 12V COB panel unregulated at above 14V would result in heat-related issues. Link to comment Share on other sites More sharing options...
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