12v Lighting - which cable

[Maybedaisy]

http://www.ebay.co.uk/itm/Channel-L...arts_Vehicles_CarParts_SM&hash=item5aeaca321b

I am installing these lights at my stables. They run through a blue sea systems fuse box direct from a leisure battery so no transformer needed. ( we don't have mains electric )

What is the best cable to use ?

Thanks in advance

 

[skotl]

You didn't say what length you wanted but automotive cable is probably the best match. Something like this; http://www.ebay.co.uk/itm/12V-24V-A...T-TWIN-THIN-WALL-CAR-CABLE-WIRE-/171029176356

Note that this is 16A which is overkill for the lights you linked to - you only need 0.5A (~5W) so feel free to google "automotive cable" and pick the length that best suits.

 

[ericmark]

As stated at 0.4 amp load is not a problem what is more of an issue it being heavy enough to prevent physical damage. It does not need to be auto cable standard 230v flex will use standard clips and may be easier to use than auto cable. Also round cable will seal in a gland better.

 

[Maybedaisy]

The second one is more what I am looking for. The longest run from light to fuse box is about 10 metres.

Do you have a web link for the second one so I can have a better idea. tks

 

[ban-all-sheds]

A clickable photo with a link to a website.

Do you have a web link for the second one so I can have a better idea. tks

 

[Maybedaisy]

Ha, ha ! Doh ! tks Maria

 

[SimonH2]

http://www.ebay.co.uk/itm/Channel-Letter-Stage-3528-SMD-3-LED-Light-20-Modules-3m-/390486176283?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item5aeaca321b

I am installing these lights at my stables. They run through a blue sea systems fuse box direct from a leisure battery so no transformer needed. ( we don't have mains electric )

And how do you propose to keep the voltage across the lights down to 12V ?

12V is only the nominal voltage of the battery. Even off-charge and under light load, the voltage will be above 12V. Under charge it can be as high as 14V.

Most of these LED strings just us a simple resistor to set the operating current. This might only be dropping say 4V or less, so 1/2 a volt extra (eg 12.5V instead of 12V) will significantly increase the operating current above what the LED chips are designed for.

 

[ericmark]

12V is only the nominal voltage of the battery. Even off-charge and under light load, the voltage will be above 12V. Under charge it can be as high as 14V.

Most of these LED strings just us a simple resistor to set the operating current. This might only be dropping say 4V or less, so 1/2 a volt extra (eg 12.5V instead of 12V) will significantly increase the operating current above what the LED chips are designed for.

This is a very real problem when using items designed for mains on battery. I would think a 7812 voltage regulator would do the job and when the voltage is low then the LED lights will likely still work OK.

However unless you try running on 10 volt you will not know. Other option is a simple 5 ohm resistor.

However in this case since the advert clearly says

Suitable for cars, boats, caravans, etc.

I would not expect anything needs to be done if using standard regulator to charge battery. They are not designed to work from a mains supply but are designed for battery supply as would be found in cars, boats, caravans, etc.

 

[SimonH2]

This is a very real problem when using items designed for mains on battery. I would think a 7812 voltage regulator would do the job and when the voltage is low then the LED lights will likely still work OK.

However unless you try running on 10 volt you will not know. Other option is a simple 5 ohm resistor.

A 7812 has a fairly high dropout voltage - probably better to pick a low dropout one.

However in this case since the advert clearly says

Suitable for cars, boats, caravans, etc.

I would not expect anything needs to be done if using standard regulator to charge battery. They are not designed to work from a mains supply but are designed for battery supply as would be found in cars, boats, caravans, etc.

I'd take any statement like that with a pinch of salt unless the vendor verifies in writing that they are suitable for up to 14.4V. Even then I'd verify by measurement that the current drawn at that voltage was within the specs before using them. From the photo, it does look like they just have a resistor for current control, that means potentially overdriving by (rough guess) 50% in a vehicle with the engine running.

There are a lot of people who work on the basis of "car is 12V, this is 12V, therefore it's suitable" with no idea of the technicalities.

I could be wrong, that might be a constant current chip rather than a resistor. But I doubt it, when I've seen stuff with active current control it tends to quote a permissible voltage range rather than a single figure.

 

[riveralt]

http://www.ebay.co.uk/itm/Channel-Letter-Stage-3528-SMD-3-LED-Light-20-Modules-3m-/390486176283?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item5aeaca321b

At less than a fiver a throw (shipped free), made in China and proudly displaying the CE and RoHs signs - what can possibly go wrong?