Small solar security light with 18650 battery

[bob-n]

There are a lot of small solar security lights on the market. They come with a 1-watt or 2-watt amorphous panel, an 18650 LiIon battery, and 5 watts to 20 watts of LEDs. For example:

https://www.ebay.com/itm/100-LEDs-Outdoor-Solar-Powered-Sensor-Light-Security-Flood-Motion-Garden-Lamp-US/352554056804

s-l300.jpg
Does anyone here have first-hand experience with any of these devices or anything similar? Do the panel and electronics correctly maintain the battery, or is it at high risk for overcharge and undercharge? Seems very dependent on available light and amount of time it is used, which is so hard to control.

I appreciate any comments at all. Thank you.

[scrambler]

I have several solar light in our garden and they all work great.
That said, the only way to get a sense of whether the specific one you are looking at has enough battery and charging capacity for your use, is to get the specs and make the calculations.

On the link you mentioned:
The spec say it has 100 x 0.1W leds, that is 10 Watts of lights consumption
This mean one hour of these would consume 10Wh

They say the panel is 5.5V x 200 mAmp, that means 1.1 Watt max power, If you count an average of 4 hours at full power per day (probably 3 in winter 5 in summer),
that is a charging capacity of around 4.4 Wh (watt hour) per day

They say one battery of 3.7V by 2.6Ah, that is a battery capacity of 9.62 Wh (Watt hour)

The solar panel can therefore only charge about 50% of the battery every day. It will eventually charge the battery up to 100% if the light is not used / triggered too much (less than the charging amount)

6 hours of best charge condition would be 6.6 Wh that would power the 10W light for 0.66 hour (39.6 mn or 2376 sec).
The light activation is said to be from 10 to 120sec
if set to 10 seconds, that means 6 hours of charge would provide 238 activations
If set to 120 sec, 6 hours of charge would provide 20 activations

That does seem plenty for a night, and it means that most nights the light will use less power than the charge provide during the day, and therefore will eventually charge the battery to full. That does suppose you are not on a street with tens of people (or animals) going by triggering the light at night
When the battery is full, with 9.62 Wh, it could power the 10W light for 0.962 hours or 346 x 10 sec events or 29 x 120 sec events.

These also represent how many times the light can go on on a single charge, so you can use that to calculate how many days it will last if there is no sun for a few days.


Overall, it does seems like the system is reasonably sized for a night motion sensing lights, as long as you don't expect it to get on more than the numbers mentionned above