LED drivers not giving out correct voltage

[Rob Alldis]

I've just bought a bunch of led drivers (12VDC), but they're giving out between 24-32VDC. I'm assuming their faulty. However, testing my old halogen drivers (12VAC), the voltage their outputting on a dimmer (fully on) is only 7VAC. My multimeter seems fine - just getting a bit confused as wasn't expect the old drivers to be giving out less then expected

 

[Shoei]

What's the spec and/or part number of the drivers? You may have the wrong type.

If you're driving LEDs that are 12V halogen replacements you need a driver with a 12V output. You may have a constant current supply which is meant for driving chains of LEDs or it's possible for a 12V driver to output higher voltage with no load. They could also be faulty as you suggest but it would be bad luck for them all to be faulty.

It may help to post a picture of the driver showing any text printed on it.

 

[Lucien Nunes]

Electronic 'transformers' for halogens often deliver a waveform other than pure DC, which your meter may not read correctly, even if the RMS value is correct.

If the LED drivers are 12V CV, then as per Shoei the lack of load may cause the voltage to rise out of spec - Re-check with some load on.

 

[Rob Alldis]

Guys - you’re absolutely right. Tried as suggested with load and output reduced at 11VDC. thanks for the insight - would never have worked that out...!