# Solar powered motion sensor light question **URL:** \ **Category:** Factual Questions\ **Created:** [September 10, 2023, 12:52am UTC](https://boards.straightdope.com/t/solar-powered-motion-sensor-light-question/989858 "2023-09-10T00:52:31Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![velomont](https://avatars.discourse-cdn.com/v4/letter/v/8491ac/32.png) [@velomont](https://boards.straightdope.com/u/velomont)\ **Post date:** [September 10, 2023, 12:52am UTC](https://boards.straightdope.com/t/solar-powered-motion-sensor-light-question/989858/1 "2023-09-10T00:52:31Z")
We have a shed in our backyard to which I attached a solar powered motion sensor light. It is probably ten years old. Tonight I noticed for the first time that it is significantly dimmer. It has 10 x 10 LED (I believe/assume) bulbs. For the experts out there, what do you think is the cause? Is it the solar panel, the rechargeable battery, or the bulbs. I would appreciate an expert opinion before I go off spending $ on a solution or replacement. Thanks ---
**Author:** ![FinsToTheLeft](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/finstotheleft/32/2930_2.png) [@FinsToTheLeft](https://boards.straightdope.com/u/FinsToTheLeft)\ **Post date:** [September 10, 2023, 1:29am UTC](https://boards.straightdope.com/t/solar-powered-motion-sensor-light-question/989858/2 "2023-09-10T01:29:58Z")
My money would be on the bulbs or the drivers. If the panel wasn’t working well, the battery would still charge (albeit slowly) and give off normal voltage. If the battery were failing and not giving enough voltage, the light would likely not work at all. Incidentally, I have the same type of light that I bought at Costco about 10 years ago to light the side of the house where the garbage bins are and it still works well after all these years. ---
**Author:** ![velomont](https://avatars.discourse-cdn.com/v4/letter/v/8491ac/32.png) [@velomont](https://boards.straightdope.com/u/velomont)\ **Post date:** [September 10, 2023, 1:56am UTC](https://boards.straightdope.com/t/solar-powered-motion-sensor-light-question/989858/3 "2023-09-10T01:56:31Z")
Thanks for that but what are “drivers”? ---
**Author:** ![GaryM](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/garym/32/241_2.png) [@GaryM](https://boards.straightdope.com/u/GaryM)\ **Post date:** [September 10, 2023, 3:29am UTC](https://boards.straightdope.com/t/solar-powered-motion-sensor-light-question/989858/4 "2023-09-10T03:29:16Z")
A “driver” is an electronics part that controls the voltage and current going to the light array from the battery. It may also control the charging of the battery from the solar cell. ---
**Author:** ![Princhester](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Princhester](https://boards.straightdope.com/u/Princhester)\ **Post date:** [September 10, 2023, 7:19am UTC](https://boards.straightdope.com/t/solar-powered-motion-sensor-light-question/989858/5 "2023-09-10T07:19:11Z")
The problem is that it could be any of the above. There are several ways of implementing this sort of circuit, and any of the solar panel, battery, or LED’s can cause the LED’s to operate but dimly. LED’s will run (dimly) off remarkably little voltage, so it could be that the solar panel is not charging the battery, and the battery is gradually running down but still supplying enough to tickle the LED’s into operating a little. It could be that the battery isn’t holding charge. I’d think this the least likely as a ten year old light probably has NiCads or NiMH’s and they are notoriously long lived in these applications. Or it could be that the LED’s are getting old and consequently dim. Armed with a screwdriver and a multimeter it is something that could be diagnosed by someone who knows what they are doing in minutes but the described symptoms aren’t enough to be able to say anything meaningful. ---
**Author:** ![Princhester](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Princhester](https://boards.straightdope.com/u/Princhester)\ **Post date:** [September 10, 2023, 7:29am UTC](https://boards.straightdope.com/t/solar-powered-motion-sensor-light-question/989858/6 "2023-09-10T07:29:21Z")
> [@FinsToTheLeft](#): > > My money would be on the bulbs or the drivers. If the panel wasn’t working well, the battery would still charge (albeit slowly) and give off normal voltage. If the battery were failing and not giving enough voltage, the light would likely not work at all. You can’t assume any of this. The problem is that an LED which nominally runs off say 3v will run ever more dimly down to a voltage less than half that. And as you would know, LED’s require very little power. Meaning that if the panel stops supplying power (such as through a corroded or broken wire or contact) the battery will keep powering the LED’s for ages, ever more dimly. The same reasoning applies to a failing battery. And the drivers are typically very simple and solid state. A low voltage DC circuit like this will not usually have any electrolytics that may half-work. Which means (a) the circuits tend to be reliable and (b) tend to either work or not. The electronics are IMHO easily the least likely to be the problem. ---
**Author:** ![FinsToTheLeft](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/finstotheleft/32/2930_2.png) [@FinsToTheLeft](https://boards.straightdope.com/u/FinsToTheLeft)\ **Post date:** [September 10, 2023, 9:23am UTC](https://boards.straightdope.com/t/solar-powered-motion-sensor-light-question/989858/7 "2023-09-10T09:23:45Z")
> [@Princhester](#): > > You can’t assume any of this. I certainly can assume this, but I have appropriate diagnostic tools to check to see what voltage the panel is putting out, which is the only unsealed part on my unit as it’s connected to the light with a plug. Practically speaking units like this are not economically repairable. If it is no longer performing properly, it needs to be replaced. ---
**Author:** ![Princhester](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Princhester](https://boards.straightdope.com/u/Princhester)\ **Post date:** [September 10, 2023, 9:33am UTC](https://boards.straightdope.com/t/solar-powered-motion-sensor-light-question/989858/8 "2023-09-10T09:33:01Z")
Depends if you are the type of person who regards sealed boxes as an insurmountable obstacle or a challenge. I have repaired several of these sorts of things economically by such trivial measures as reinstating corroded connections or removing corrosion from battery terminals. IME more often than not outdoors items like this fail due to moisture ingress that is often trivially repairable if you know how. ---
**Author:** ![FinsToTheLeft](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/finstotheleft/32/2930_2.png) [@FinsToTheLeft](https://boards.straightdope.com/u/FinsToTheLeft)\ **Post date:** [September 10, 2023, 11:52am UTC](https://boards.straightdope.com/t/solar-powered-motion-sensor-light-question/989858/9 "2023-09-10T11:52:52Z")
> [@Princhester](#): > > IME more often than not outdoors items like this fail due to moisture ingress that is often trivially repairable if you know how. You can, I can, but many people cannot. ---
**Author:** ![MindsEye\_Watering](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mindseye_watering/32/3619_2.png) [@MindsEye\_Watering](https://boards.straightdope.com/u/MindsEye_Watering)\ **Post date:** [September 10, 2023, 1:24pm UTC](https://boards.straightdope.com/t/solar-powered-motion-sensor-light-question/989858/10 "2023-09-10T13:24:47Z")
Batteries are often easy to replace in solar lights. I have [several of these](https://www.amazon.com/gp/product/B01MR4OO9U/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1) and all of mine have standard AA rechargeable batteries accessed by a gasketed cover plate. Since there is probably little that you can do for repairs except replace the batteries, I would start there. ---
**Author:** ![velomont](https://avatars.discourse-cdn.com/v4/letter/v/8491ac/32.png) [@velomont](https://boards.straightdope.com/u/velomont)\ **Post date:** [September 10, 2023, 1:30pm UTC](https://boards.straightdope.com/t/solar-powered-motion-sensor-light-question/989858/11 "2023-09-10T13:30:53Z")
Thanks for the info everybody. Now it’s time to do a personal cost/benefit analysis to see what I’ll do. I will probably just go out and buy a replacement. ---
**Author:** ![Jackmannii](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jackmannii/32/311_2.png) [@Jackmannii](https://boards.straightdope.com/u/Jackmannii)\ **Post date:** [September 10, 2023, 1:32pm UTC](https://boards.straightdope.com/t/solar-powered-motion-sensor-light-question/989858/12 "2023-09-10T13:32:00Z")
> [@"FinsToTheLeft](#): > > Practically speaking units like this are not economically repairable. If it is no longer performing properly, it needs to be replaced. My take also. Ten years is a pretty good run.