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Teardown pics of recalled Sunvilla LED-lit patio umbrella battery/solar charger

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Hello, I thought I'd post this here before it gets returned. I got a notice that my patio umbrella has a recall on it, specifically the power module being a fire hazard and has caused at least 5 known fires.

The 5.5mm barrel is both output (there's a switch on the side of the umbrella) and also 5vDC charging input. There's two ICs, but the board is has a splash of epoxy so I can't see the markings. I don't have the skill to tell why this is "dangerous" other than temperature-related failure from being baked in the sun, or the circuit potentially not stopping charging? Having the battery terminals so close together on the PCB without protection circuitry on the 18650s is already questionable.


Product recall page:
"... the umbrellas contain solar panels with lithium-ion batteries that may overcharge, posing a fire and burn hazard."
And according to Costco, there's already been 6 known fires.

Most likely the combination of high temperature and questionable quality cells is to blame. I wonder if the redesign, in addition to using better quality cells, would put them in the post where they'll stay cool.

The positive of the battery pack goes directly to the barrel jack. The negative appears to go to U1 which switches it on and off to barrel jack negative.
This could be a "DW01" type chip that protects the cells from being over discharged.

The solar panel goes to a diode, then resistor, then U2, which is likely a li-ion charge IC (TP4056 type). R2 sets the charge current.

The only major issue with the circuit is U1 might not protect from overcharging. Even on cheap $1 USB charge boards generally have done this correctly.
The max the panel would put out is ~5V, so if U2 was corroded/failed/wrong part then the cell could be overcharged.

Maybe this Big Clive video is relevant:


--- Quote from: canuckcam on June 26, 2022, 02:41:57 am --- I don't have the skill to tell why this is "dangerous" other than temperature-related failure from being baked in the sun,

--- End quote ---

I'm not sure why anyone thinks being baked in the sun wouldn't be enough unless they live in Iceland or something.  Today here in sunny SoCal it is 101F (~39C) and my microinverters are at about 150F (~66C).  I see no reason that a sunbrella battery would be any cooler and I don't think Li-ion batteries do well at 66C.  In fact if they were charged at a much lower temperature, heating them up that much would likely put them significantly overvoltage.  NiMH batteries work in applications like this but they have short but fire-free lives.


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