The first time I hook up the light after being off for a long time, it will run at least 10-15 minutes. However, at some point there will be a little smoke coming from the battery and/or battery holder and then it will shut off. Then when I disconnect & reconnect it will run for maybe a minute before smoking and shutting off again. It seems like the longer I wait with it off, the longer it will run when I reconnect it. When I connect my cheapo multimeter (rated for 10A) to try to measure current, it will turn on briefly and then shut off almost immediately. During this time the measured current will rapidly increase. I’ve seen 3.5A & 5.2A before it shuts off. I’m measuring 14.4 V on the battery pack (after total running time of about 30 minutes since last charge.)
Can anyone explain whats going on and how I might fix it?
Isn’t the input supposed to be a clean 12V instead of 4 cells resulting in max 16.8V?
Edit:
Maybe the led (+ driver) consumes more than 50W, resulting in over discharge current kicking in. Only 50W results in about 3.5A per battery, which should be no problem. Temperature plays a role as well too, that’s why the faster you reconnect (higher temperature), the faster protection kicks in. Battery holder may not be able to handle 5A, hence the smoke… Just a guess, I’m pretty much a noob.
Edit 2:
What’s the light going to do if the input voltage is higher than 12V? Will the output be significantly more than 50W? I don’t know…
Hey, thanks for responding. I’m a noob too. So maybe we can combine our powers and actually seem smart… either that or blow something up.
I’ve seen other similar lights that appear as though they are rated for any voltage from 12-24 V. So I assumed that anywhere in that range would be fine. The first time I hooked the light up with freshly charged batteries (I’m assuming 16.8 V) it ran fine. It ran probably 10 minutes before I shut it off.
I also thought that maybe the smoke was coming from the battery holder. And it might be. The wire that connects the batteries is a very thin, bare piece of metal (silver in color). I thought maybe that was getting hot and melting the plastic it was up against. I couldn’t figure that out. I should probably take the batteries out and see if the holder melted at all.
Here’s what I assume is happening. Let me know what you think. When I connect the multimeter in series, it has a fast acting current shut off that turns it off nearly immediately. But when the multimeter is not connected, the protection circuits in the batteries open the circuit as a result of being too high in temperature/pressure/whatever. If this is right, it would suggest the current draw is higher than the multimeter is rated for… supposedly 10A. That would surprise me a little because then the light is drawing something like 150W.
those holders are junk.smoke is the springs heating up.look on ebay for the blm/blossom ones.
at over 5a and lousy contact the ptc on one or more cells may trip.the protection may be at its limits too.
open the light and post the driver pic.some really cheap n nasty ones dont even have a driver!
Okay, first off, if the light is rated a 50W, your cells are at 14.4V (and that’s after use, fully charged, about 16V), then if you are measuring 5.2A, you are seeing 75W-84W, far above spec.
If you aren’t certain of the authenticity of the Panasonics you are using, then it may be that one or more of your cells has a bad or weak protection circuit.
Check the springs on your battery carrier; if they are discolored or warped, that’s an indication that they are heating up to glowing hot, due to the current. I would recommend beefing up wires and making certain you have a quality carrier with good springs and wiring.
Like suggested, make sure that your floodlight actually has a proper driver; if not, I would recommend installing one. I hope it would had a driver, as many of the super-cheap 50W COB-style emitters I’ve seen require 30+V to operate but there are 12V options available.
My experience with mains-powered LED flood lights like yours has shown that they are typically driven at about half the rated wattage. Replacing the driver with a good unit is usually inexpensive and easy to complete.
Would it be possible to post pics of your setup? I’d like to see what you have, as I’ve thought about building a portable flood light similar to that.
Here are some pictures. If you click on them it should take you to the full resolution image.
The light with batteries.
Cover removed.
Reflector removed.
Driver.
Battery holder. Notice the melted plastic and discolored wire. The other battery holder that I got at the same time (but haven’t used) doesn’t look like that.
when the battery holder is melting you got a lot voltage sag
the lower the voltage the more current gets drawn
and thisDriver simply shuts off when the voltage gets too low
just measure the voltage inside the light when it shuts off and measure how much you loose direclty compared to the cells terminals
Thanks for the suggestions. I think the voltage sag was the cause, which was made worse by the cheap battery holder. I kludged together a low resistance holder with 5 cells in series. The light ran for 71 minutes with no problem. Below is the data from the battery side. On the LED side, I was measuring 30.6V, ~1.3A for about 40W.
I am considering repeating the test with 6 cells in series to increase the voltage at the end of use. This will put the initial no-load voltage at 25.2 V. Will that be a problem for the driver which is rated for 12-24V? I doubt the driver will see more than 24V with it drawing current.
Fun work!
Could you, essentially, use a flashlight battery tube for your “holder”? Reduce resistance everywhere possible and have a solid reliable carrier for your cells.
