Just moved house and have a problem with exchanging all 12V 35W halogen bulbs, with 12V 5W LED bulbs.
The latter work well for about 5 minutes, then start to (very weakly) flutter. After another 5-10 minurtes, some of the bulbs turn off. When I switch off, and then on again, the bulbs light up - again for another 5-10 minutes, and then the problem repeats itself. I note on the transformers concerned (see attachment), the phrase 'for 20-105 watts'. This is achieved with 2 halogens (70W total), but not for 2 LED bulbs (10W total). Is this the problem? Why should too LOW wattage give problems with the trafo?

 

View attachment 142175

Just moved house and have a problem with exchanging all 12V 35W halogen bulbs, with 12V 5W LED bulbs.
The latter work well for about 5 minutes, then start to (very weakly) flutter. After another 5-10 minurtes, some of the bulbs turn off. When I switch off, and then on again, the bulbs light up - again for another 5-10 minutes, and then the problem repeats itself. I note on the transformers concerned (see attachment), the phrase 'for 20-105 watts'. This is achieved with 2 halogens (70W total), but not for 2 LED bulbs (10W total). Is this the problem? Why should too LOW wattage give problems with the trafo?

I'm kinda guessing your LED kit wants DC.

 

I'm kinda guessing your LED kit wants DC.

Thanks, but no, it requires AC.

 

It may be a solid-state inverter that requires a minimum 20W load for proper operation.

 

It may be a solid-state inverter that requires a minimum 20W load for proper operation.

The one I ripped was just a 2 transistor astable driving a CT primary - it would most likely keep going with no load.

A dimmable PFC type would be more complex.

 

Well, there must be some reason it has a minimum power rating of 20W.

 

And what you describe may be overheating, cooling down, then overheating again,

 

Simple way to find out...hook another load to the transformer...

if it works then it needs a minimum load, if it shuts down even faster then it is overheating.

 

Hello,

There are some protections in the transformer that will kick in:



This is from an other brand with the same specs.

Bertus

 

Hello,

There are some protections in the transformer that will kick in:

View attachment 142311

This is from an other brand with the same specs.

Bertus

Many thanks! Bob