Solar led light warning, possibility of overcharge and very dangerous situation !

Flashlight Modding and DIY Parts
1

*EDIT :
I test this light two times and it is overcharge 100% just not sure does all do this or only my sample, for now it is better to avoid, or if some member have same, please post your results. You have 2 pictures below, showing 18650 at 4.7V and 4.43V !*

I buy this light HERE.

It arrive with solar panel detached which is only glued with melted glue on center.

18650 li-ion inside and it is not some light weight, it feels heavy in the hand, on site it write that is 1200 mAh, voltage was about 3.8V when arrive… First night I just test it how it will works in different locations and possitions etc… Next day I put it on direct sun all day so it can be filled up…
At night I collect it and want to measure it is charged or not, and guess what ??

DMM is very precise and I don’t have any kind of problems with it, also don’t know what is happen here that voltage is 4.7V, I see no defects on battery so I go out to try… Run a light 5-6 times for 30 sec go inside and measure a voltage, it shows me 4.15V.
So this is just to warn some users I’m not sure why it hit 4.7V it is some mistake or whatever…

Something other I want to ask since this is my first solar light and I don’t know anything about it. I want to use it indoor, and to put solar panel outside :sunglasses: I have some shed for wood and I don’t have electrical installations in it, so I don’t have light, and when I want to go inside and take woods or whatever at night I must to carry a flashlight…
So I was thinking to add thicker conductors from solar panel to pcb but I’m not sure it will this work due to the length of the conductor and how ‘’strong’’ is solar charging and how this work can cell be charged ?

Conductors that are in solar light right now are wide ( with wrap ) 0.9mm ( don’t know thickness of conductor inside don’t write anything on cable ), and I put 2.1mm with wrap, conductor inside is 0.75mm, put 2 meters for both + and -.

Idea is that solar panel be outside.

And light will be mounted inside.

So what do you think can this work with 2 meters of conductors 0.75mm, more precisely can 18650 be charged with solar panel with this long conductors or not ??

2

I think you need to find out why your cell is showing 4.70V when fully charged. That is probably VERY dangerous, and needs to be settled before you go any further. It might be able to adjust output. If so, you need to adjust it to 4.2V cut-off. If need be, maybe you could buy a cheap CC/CV board from eBay and use it with the solar panel to charge the cell up to only 4.2V MAX. Just disconnect the old board and put the new one in, and adjust the voltage to 4.2V and the current to whatever the solar panel is capable of.

Once you make sure you’re not over-charging the cell, I think your idea is good and should work fine. :crown: :+1:

3

Yes I know it can be very dangerous but I don’t know why is this happens, the charger need to have some over voltage protection I don’t know but it is stupid that it don’t have… For example if don’t have you put solar light on sun and don’t use it at night and it is charging every day until the cell explode… Don’t make sense.

4

Yes, especially since even those really cheap CC/CV chargers have (adjustable) cutoff voltage for charging your cells safely.

5

LoL the charger board/circuitry is damned.

I advice you to report that to GearBest, you should get a refund. I once got a rechargeable flashlight whose no-load output charging voltage was 4.46V, got a refund after submitting them a related videoclip I filmed with the aid of a friend where I pinpointed the issue.

Still, take a good look at the circuit board, you may find some replaceable charging IC. A TP4056 is 8 pin, a TP4057 usually is a smaller SOT-23-6 chip, etc. Replacing the chip with a new one should fix the serious and dangerous overvoltage problem.

Cheers ^:)

6

not even sure how it would get to 4.7v without about 15A behind the charging voltage…
probably that reading is a mistake…

wle

7

And or Put a known good, larger cell in the circuit and re test the voltages.

could be a shit cell over charging from tiny capacity?

8

A li-ion at 4.7V on top of a pile of logs ?

9

Ok, I have 2 news one good and one bad.

The good one is that solar charging works with no problem with this about 2 meters long cables from solar panel to pcb then to cell.
And the bad one is that cell is definitely overcharge.

I go with another test today just to be sure that is not mistake about, put into charging and monitoring often with DMM at situation. As it is charge I checking for about 45 min - 1 hour to see the results and voltage is slowly increasing all the time 4.2 => 4.25 => 4.3 => 4.35 etc… I stop for about 4.43V where I record a picture as a proof :

So we have situation that only my sample overcharge or all other do this, I will change topic name and warn people about this, since this is not good at all, also I will ask Gearbest to send me one more sample to test and see does all do this behavior or only my faulty sample.

After that I hit it for 5-6 times of work and voltage stops at 4.19V.
This solar light have motion sensor and night sensor which I like, so @DavidEF solution with CC/CV board will not do the job, so I will give one more try to this one if GB send a new sample if not I will not mess with this in a room full of wood.

10

This is could be an easy to solve issue, but it all depends. GearBest should refund you anyway, I believe. First of all, what I said before:

A possible way to fix the issue.-

Connect the battery to the circuit board via a DC/DC buck module. Like one of the following CC/CV XL4015 buck boards:

Attach the output/input battery leads from the solar light circuit board to the buck module, and tune the desired output voltage to the battery in it (left side trimpot). I recommend not going above 4V to maximize battery life in spite of only being able to attain a lesser capacity from the battery. You will not need to adjust the current potentiometer because the output voltage from the solar led board is limited to 4.7V or maybe a tad higher. This will prevent the XL4015 module to work in CC mode since it needs nearly 6V of input to regulate in constant current mode (tested by myself; I have a blue module and a few red ones), but this is no issue because the solar light circuit board will adjust output voltage to limit output current in any case. With this we have solved the battery charging problem.

Then there's another problem: to allow the solar light circuit board to drain current from the battery. This can be accomplished by attaching a set of leads from the battery to the circuit board, restricting the current direction from battery to board via schotty diode(s). This will produce a small voltage drop, though it can be limited by using multiple schottky diodes in parallel and selecting low Vf units. A handful of 1N5823 - 1N5825 or equivalent diodes would do, for example: https://www.ebay.com/itm/10pcs-10SQ045-10A-45V-Schottky-Rectifiers-good-quality/282397972819 A handful of 10SQ045 diodes, go big or go home LoL!

Finally, I'd get some new cells for it. That 1200mAh POS cell is more than probably dangerous dead meat already.

Cheers ^:)

11

If you’re getting new cells anyway, just use a protected cell?

12

Mmm, that is actually a nice idea. One or more, if vidramon aims to increase the led light battery life.

I'd go with protected high voltage cells (like Samsung 28A/30B/32A, Sanyo UR18650ZTA or LG C2/D1/E1 cells), it would increase life cycle since protection circuits usually cut-off a bit above 4.2V. Problem is… good luck finding protected high voltage cells from a trustworthy provider.

In any case, here is a nice 1S BMS: https://www.aliexpress.com/item/1S-15A-Li-ion-BMS-PCM-Battery-Protection-Board-PCM-for-18650-Lithium-Lion-Battery/32839338685.html

Cheers

13

My ‘’fight’’ with GB support was last for couple of days but my victory in the end was inevitable, it was just a matter of time.
At the end I get refund for this light.

Barkuti, thanks for you for your explanation but I was not considering to fix this light. Why ?

1. Must order new parts from China and must wait for 20-30 days to arrive
2. Must replace cell now - additional cost
3. Must spend time for working on this
4. Light was paid about 6.5$ when I add cost of new components + time it will get out very expensive, I think for that money that I can find other solar light that is working with no problems

The most interesting parts were these :

Any pay attention on this !

It is safe especially in my shed for firewood :smiley:

I don’t know here is pic of board if someone can to recognize something just say, there does not write anything on this 8 pin chip so I don’t know what is this. If someone can tell does this really don’t have any kind of ovp and lvp it will be great !

14

Be careful of those ultra cheap devices and gadgets having li-ion. Some are ticking time bombs. Already have a lot of stories of venting and starting property fires, particularly with the bigger packs. E-scooters is a very good example and their issue is big because of their very big packs.

Quite a number of these stuff are really meant for the domestic market in China, but conveniently and entrepreneurially exported to other countries on these “gadget” websites. These will also find their way into budget retail stores.