I bought some cheap solar powered motion detecting street lights off Temu. They aren’t working properly and would like to fix them, but I don’t really know what I’m doing as I am not an electrician and I’m not familiar with how the control boards and stuff work.
A little more detail about the problem with the lights. They’re 544 LED diode powered by (3) 18650 batteries.
I got them and let them sit in the sun for a day or so to charge then at night I turned them on. I left them on a constant on dim mode that goes full bright when senses motion. Then the next day when the sun hit the lights turned off as normal and charged all day, but the following night they didn’t turn back on until you hit the on button and then they act like they should. I also tested them by taking them in a dark place during the day, turning on the light, checking the motion sensor, walking outside, then walking back in. Doing this they seemed to work just fine, but when they’re exposed to sunlight for too long, is when this seems to reveal the problem.
Does anyone know what could be causing this and if there’s a way to fix it?
I know they’re cheap lights and are probably not worth the time to fix but I have them and I would like to make them work if it could be relatively easy.
I’m not an electrician but I’m pretty competent and if someone wouldn’t mind walking me through this I would really appreciate it. TIA
I hate to be that person, but generally accepted wisdom is not to buy lithium cells (or products containing lithium cells) of unknown provenance.
It may well be just a terrible electronics design and not fixable.
The behaviour you describe regarding length of time in sunlight is odd… I’m just guessing, but perhaps there’s a BMS that’s triggering from overcharge from the solar panel and needs resetting from the switch?
Do you have a link or picture of the lights? I’ve had quite a few different solar lights over the years, some are just rubbish and not worth fixing! Particularly the ones that aren’t waterproof.
There’s a bunch on Temu. You might post a direct link.
I’d guess those 2 statements are your problem. My experience with solar NiMh lights is not great.
For SINGLE 18650 solar powered lights the batteries are ALWAYS poor quality, (don’t believe the exaggerated claims) and the solar panel is inadequate to recharge them well.
Only a few months in the peak of summer do they work without an external recharge. I’ve even put external charge ports on the ones that work well enough to tolerate so I don’t have to open them up all the time.
For 3x18650 AND 544 LED, I think the electronics equation doesn’t pan out. A single day in the sun may have been woefully inadequate.
Most useful first option I think - Open it up, however you need to do that, get at the batteries and check the charge state. Are they in parallel or series? If possible remove and test. If not possible can you charge them in place?
Fixing failed electronics in devices like this is not worth the headache.
Replacing crap cells with good ones can possibly turn complete junk into somewhat annoying but functional devices if the rest of the electronics are functional.
Replacing the cells may not be too hard, or it could be a headache not worth getting in to.
Ironically, the cheapest crap is usually also the easiest to get into, barely weather-sealed, etc.
I got a pair of nice motion-lights where one went mental, and I tried cracking it open (literally), and to this day haven’t. It’s a solid hunk of THICK plastic for the back end, and like a ¼ in glass plate in front, epoxied to the back. Dremelled off the edge/ledge that the glass fits into, and tried prying off the glass. Sent little chips flying, so yeah, ain’t gonna lose an eyeball trying to crack it open.
Maybe more Dremel work later, but never got arsed enough to do it.
Cheap crap? Yeah, pull a few microscrews, and whatever doesn’t drop off can be pried off. “Weatherproofing” might just be a drain-hole in the bottom.
Thank you everyone for your advice. I want to try to respond to everyone’s input here to streamline the situation and let you all know that I appreciate all your input.
First, Gravelmonkey, thank you for your input and yes I don’t doubt that the first two sentences might be the highlight of the problem and I know trying to repair them is probably just as humorous, but color me stubborn I guess. Haha
Also if you could elaborate more on what a BMS is so I can understand what you mean and what I can look for & diag that would be cool. TIA
Secondly, smurcod. Thank you for the warm welcome and I will post a picture to this response at the end.
Thirdly, flydiver. Thank you for the education on these electronic components as I know next to nothing about them.
What kind of power should the solar panel be outputting in order to determine whether is adequately charging or not?
I did check the charge on the batteries and found them to be @ 3.7-3.9v and yes they are wired in parallel. They are bound together by a thin steel strip that seems to be pin welded to the ends.
I also checked the solar panels at peak sunlight and if my memory serves me correct it was outputting like 6.7v.
Also I had one light fixture with dead batteries due to the solar panel ground wire being broken. I proceeded to re-solder it and the light seemed to charge up within the hour. Based on this experience I assumed the panels were outputting adequate power. ¯_(ツ)_/¯
Last but not least, lightbringer. Thanks for your input as well. That seems like a real pain in the arse to get into. Makes me feel better about the cheap & easily accessible cheap lights I bought. Haha
What size is it roughly? I have had one light like that, but smaller. It didn’t last long, like you found, the 18650 batteries were hard wired in. From memory it failed and was coming on during the day - an indication the solar panel likely wasn’t working.
The number of LED’s seems a bit suss- 544 just doesn’t make sense. They must have an extremely low power output.
Yeah, but those reflectors only scavenge such a small percentage of light that’s shooting sideways as to be almost negligible.
I got a 17W(real) light with COB emitter that also has a shallow plate around it. The COB would have to have something like a 170° emitting angle for any light to hit it.
I looked up “544 LED motion detection street lights” on Temu and what came up was a bunch of “504 LED motion detector street lights” I always love the fictional lumen and watt counts that come with these. I don’t own or use one similar to that light but have used a couple of these 1000000LM LED Solar Motion Sensor Light Bright Garden Outdoor Street Wall Lamp | eBay to light entryways. They are cheap ($6), bright enough to light up an area about 15-20 feet from the door, and easy to install. These are chip-on-board type LEDs so a bit more efficient than individual LEDs with the same couple hundred lumen output. The only downside of the new ones over the ones I replaced is that the light turns on low at dark and lights up brightly when anyone approaches. However they will not work all night long so early in the morning are worthless. The old ones replaced only turned on when approached so lasted more than all night long, I think that is the same problem as the ones you have. They discharge too much being lighted on low all night long and can’t be recharged enough by the solar cells to work correctly. I live in an area with intense sunlight (the Mojave Desert) so if they wouldn’t work here, they wouldn’t work anywhere.
This is an absolutely valid reason to tinker with something! Just wanted you to clarify this is a hobby activity.
Battery Management System: the safety/“brains” of the battery, a well designed one will prevent overcharging voltage, over-discharge, over-current, over/under temperature. My wild speculation was the BMS was shutting the battery pack down on an overcharge situation after many hours in the sun, requiring a press of the button to reset it. I am just guessing though.
Tricky without knowing the design specs of the panel. A solar panel is made up of individual silicon cells, just like a battery is made up of individual cells. Joining these in parallel & series allows a panel of the required voltage/wattage. A single silicon cell produces an open circuit voltage of about 0.6V, this falls to about 0.45V under load.
Most of these Chinese solar products on the market have woefully inadequate solar panels (keeps costs down). To charge 3x 3.7V 2.5Ah 18650 cells (combined 28Wh) in e.g 6 hours, in perfect sun conditions, you’d need at least a ~5W panel.
You have main components of the light system: charging panel, storage, output LED, and the electronics around them. It’s pretty much a ‘package’ with little you can do to change them except maybe the batteries.
If the panel is inadequate then it doesn’t much matter what battery you put in. Where the panel is located (input) relative to the light output is also a factor. I find this a frustrating factor since many of the places I want motion activated lights simply don’t have decent light much of the time, so won’t charge properly.
You certainly can learn a lot with this kind of experiment by asking questions. I learn best by hand on tinkering.
