Anyone have any thoughts what is going on here, and how to remediate?
I have a largish backup power supply usually used for security systems -- 17AH battery, charger, SMPS in a big box producing 12V 5A max. The idea is to use it to power 12V LED strips for load shedding lighting.
I had it set up with 8x strips, each drawing about 1/2A. It worked fine -- no problems. The LED strips were a little too orange, so I tried some others, too cold. But everything working fine.
A got in a new set of 8 strips, hooked them up in largely the same way - a little more efficient in terms of wiring... but 4 strips wired in parallel to another set of 4 strips a couple of meters away.
Now as soon as I power it they flash, with a faint electronic click click from the power supply. Off/on/off/on maybe eveyr 1/2 second.
Now is where things get weird. Hooked it up through my DMM to check current ... 2.8A DC, but also 2.8A AC.... although 11.4 VDC and maybe 200mV ripple. And the flashing stopped. They came on solid. If I wired through some cheap thin crocodile clip leads they behaved.
So clearly the PSU does not like something about the semiconductor load. Needs a little resistance, maybe.
Now it gets weirder. If I disconnect the battery (i.e. powered by SMPS only) it works fine. If I power directly from the battery it works fine.
But combination of battery on charger with SMPS ... flashes.
I currently have it through 8x 10R 10W paralleled resistors to give it a bit of plain resistance, it works fine except I can hear the PSU is not that happy -- a very faint buzz and almost imperceptible click-click.
I thought maybe some high frequency noise was causing something to go unstable ... tried a 50V 6800MF electrolytic cap across the load, no difference.
So -- what is going on, and more importantly, what can I do about it?
I have a largish backup power supply usually used for security systems -- 17AH battery, charger, SMPS in a big box producing 12V 5A max. The idea is to use it to power 12V LED strips for load shedding lighting.
I had it set up with 8x strips, each drawing about 1/2A. It worked fine -- no problems. The LED strips were a little too orange, so I tried some others, too cold. But everything working fine.
A got in a new set of 8 strips, hooked them up in largely the same way - a little more efficient in terms of wiring... but 4 strips wired in parallel to another set of 4 strips a couple of meters away.
Now as soon as I power it they flash, with a faint electronic click click from the power supply. Off/on/off/on maybe eveyr 1/2 second.
Now is where things get weird. Hooked it up through my DMM to check current ... 2.8A DC, but also 2.8A AC.... although 11.4 VDC and maybe 200mV ripple. And the flashing stopped. They came on solid. If I wired through some cheap thin crocodile clip leads they behaved.
So clearly the PSU does not like something about the semiconductor load. Needs a little resistance, maybe.
Now it gets weirder. If I disconnect the battery (i.e. powered by SMPS only) it works fine. If I power directly from the battery it works fine.
But combination of battery on charger with SMPS ... flashes.
I currently have it through 8x 10R 10W paralleled resistors to give it a bit of plain resistance, it works fine except I can hear the PSU is not that happy -- a very faint buzz and almost imperceptible click-click.
I thought maybe some high frequency noise was causing something to go unstable ... tried a 50V 6800MF electrolytic cap across the load, no difference.
So -- what is going on, and more importantly, what can I do about it?
