Convoy s21a burned molten rear spring/bypass

Hi everybody,

I bought two convoy s21a sst40 flashlights for a buddy of mine. Its the one with the 4 mode driver(6 amp max). Both lights have the rear spring/bypass burned and they are not springy anymore. I guess he accidently put both samsung 50e batterys in the wrong way. It does state on aliexpress that the light has reverse polarity protaction.

Does anyone know if this driver does have reverse polarity protaction? And Im going to fix it now. The light still works, I tried charging the batteries and both seems to work fine.

Is there anything I need to think off safety wise?



Below is from the Convoy flashlight Store. So it appears to have reverse polarity protection.

So I wonder what happened?

Material: Aluminum Alloy
LED: luminus sst40 6500K white tint and 5000K neutral white
Low voltage warning: Yes
Reverse polarity protection: Yes
Lens type: Ar-coated glass lens
Reflector: orange peel
Mode memory: Yes
Tailstand: Yes
Battery included: No
Required battery type: 21700 or 18650 lithium battery
Required battery quantity: 1pcs
Driver: 4 modes 0.1–3–30–100 / 12groups, max current output 6000mA, Temperature protection management inside
Length / Diameter : 123mm / 26.6mm
Weight: 88g

Yeah I thought maybe its only the 12 mode driver that has the reverse polarity. If you only buy the 4 mode driver it does not say reverse polarity anywere. So if it does have it something else is the problem.

Interesting. Here’s the 4 mode driver:

And you’re right, it doesn’t say anything about reverse polarity protection.

But the the 12 group driver doesn’t say anything about reverse polarity protection either:

Seems strange that this happened if they’re supposed to have reverse polarity protection. Luckily replacing springs and adding bypasses is not that hard to do.

I have several of the 12 group driver, but I don’t want to test them just in case. Maybe contact Simon and ask him about it?

Yeah I send him a message. no reverse polarity is the only thing I can really think of what happend. But the driver seems fine and works like it should. So maybe there is reverse polarity protaction but it still can do damage to te tail spring? As its a pill so if you would reverse the battery it blocks current going into the driver so it just makes the circuit from the spring into the body to the tail, but I do not know if it works like this.

I don’t think any reverse polarity protection would have made a difference. A current that’s strong enough to anneal a spring has certainly enough power to fry a driver. And there is no damage done at the front side of the light.
My guess is that the bypass of the tail spring got loose and touched the inside of the switch housing. Creating a (very local) short. Did you add the tail spring bypasses yourself or did you receive the the lights that way?

Im pretty sure my buddy reversed the battery on both his lights as the have identical fried springs on both switch sides. The lights came with spring bypass but I did check them because sometimes they are not that well soldered. I have another s21a but im not going to reverse the battery to test the polarity protection :money_mouth_face:

I replaced the springs and bypass on both now and it is working again, but both switches are not springy enough, going to the modes requeres very little force and not how it came. The switch it came with is a omten yls-16.

I have a couple of omten hgj-16 spare switches. Does anyone know if these are the same? They look the same but maybe different amp ratings.