Bad experience with 2.5A Convoy S9 from banggood

Rexlion · 2019-06-05T20:00:23.000Z

Lightbringer:

…You can always slap on some diffusion film to further blur the hotspot and not only make it floodier, but smoother as well.
….
Peel on. Peel off. The Peeler…

Yep, look for DC Fix diffusion film (I like “Sand” finish). Available everywhere fine diffusion film is sold. :sunglasses:

Lightbringer · 2019-06-05T20:21:57.000Z

I had to (well, wanted to) cover a small window with film to keep out prying eyes yet still let in light, but by mistake got “snow”, which was textured.

Works fine in the beam itself, but leaves small wisps of light around the periphery. Then for s&g got either “frost” or “milky”, forgot which, ’cause whichever it was, it was the only other one they had, and it’s quite nice.

I could easily sell off the excess, but don’t want to step on anyone’s toes here.

nydude · 2019-06-06T04:24:32.000Z

Thanks for posting this. I had the same thought of getting this light as a gift for someone that I didn’t want to have to worry about external chargers and I have always had good luck with Convoy.

Streamtronics · 2019-06-06T10:30:03.000Z

Ok, here’s an update:

Banggood will refund me 19 USD for the S9 after I sent them the video that I linked in the first post
I messaged Simon from Convoy on aliexpress, he offered to send me a new driver. I asked him if the new driver would have the same cheap charging circuit with no real cut-off, he hasn’t replied yet. I’m assuming since it looks very much like a design flaw and not like a malfunction, it’ll be the same.
I ordered an A6 + MC1 from banggood since my brother values the true moon mode more than charging via USB. – OT: I didn’t dare to order the 5A tint again because the last one had such an outright ridiculous light color, so I went for the 3D… apparently my brother and I are part of the minority that actually prefers tint closer to neutral (even if they go into the green slightly) over straight up pink
Since I somewhat know my way around electronics, I’ll have a look at the driver in the S9 soon. Maybe there’s something “obviously” wrong with it, like wrong values in a resistor divider to measure battery voltage (taking into account what mcu is being used… if it’s marked at all. Guess I’ll find out).

pennzy · 2019-06-06T12:35:37.000Z

My S9 stopped charging at about 4.18 . I did not check LVP but gifted it with a protected cell . Very long press for off would be deal breaker if I had kept it.

Scallywag · 2019-06-06T13:43:57.000Z

I also gifted one to a muggle, with a protected 3500mAh cell. Gave the 4x AMC7135 version. The recipient loves it.

Streamtronics · 2019-06-06T22:02:24.000Z

Frankly I didn’t even consider a protected cell. That would make a lot of sense for a muggle. Not sure why I didn’t think of that, but I guess it’s because I’m just not sure where to get high quality protected cells, and if they’d be ok with the current a e. g. BLF A6 draws. Still would rather have a proper charge circuit and LVP in a light and use an unprotected cell than having to rely on the protection circuit attached to the cell. I’m assuming those ICs also aren’t cutting off the charge current once it drops below a threshold? I’d imagine they simply protect against over/under voltage.

teacher · 2019-06-06T22:11:17.000Z

If your in the USA, LiIon Wholesale is a good place.

Streamtronics · 2019-06-06T22:13:22.000Z

Thanks teacher, but I’m actually in Germany sorry, I’ll add that to my profile.

teacher · 2019-06-06T22:17:42.000Z

/\ … Ok I understand, shipping would kill that suggestion.

Streamtronics · 2019-06-06T22:27:18.000Z

I guess I can get Keeppower and XTAR protected cells from the place where I normally order cells from, but they're literally twice as expensive as a Samsung 35E cell... that's a hefty price tag for a tiny PCB with probabably just a tiny IC and a mosfet on it :/

Phlogiston · 2019-06-06T23:57:50.000Z

I’ve no experience with XTAR protected cells, but I’ve found that Keeppower cells tend to be a bit too wide - several of my lights won’t accept them.

I’ve had good results with Eagtac cells - the 3500mAh cells are rated for 10A, with a protection circuit to match, and they worked well in the BLF A6 I used to EDC.

Be warned, though - my Eagtac cells are the old model with the protection circuit at the negative pole. I haven’t tried the new version with the protection circuit at the positive pole yet.

ggf31416 · 2019-06-07T02:15:46.000Z

Streamtronics:

Thanks teacher, but I’m actually in Germany sorry, I’ll add that to my profile.

eu.nkon.nl

Home page | NKON

NKON is a webshop, specialised in batteries, chargers en LED-flashlight. We ship worldwide!

Vaping · 2019-06-07T07:37:00.000Z

thanks for your review of this light, valuable experiences for everyone.
most of my lights are Convoy, never looked at this model

Streamtronics · 2019-06-07T13:32:10.000Z

Found this review on banggood... I don't understand why anyone who actually bothers to measure the cut off voltage would still give 5 stars, even though they clearly found their LVP not working.

BlueSwordM · 2019-06-07T17:53:52.000Z

There may be a chance the review was modified.

Why would he given 3 stars in the written review then?

Phlogiston · 2019-06-09T04:13:41.000Z

Banggood are known for modifying or even deleting “less favourable” reviews.

Lightbringer · 2019-06-09T05:12:42.000Z

What? No way. Get out. That’d be downright dishonest.

Next thing, you’ll be accusing them of luring people in with promises of free gifts, and never delivering.

Streamtronics · 2019-06-10T07:09:08.000Z

I think I’ve heard that about banggood before, and even though I condemn that behavior, I still chose to order from them and haven’t had issues with them so far. That being said, my 3-star review on the S9 (and it only got that because I rated it 5/5 for appearance I guess) is still “processing”. ~~Also still waiting for the promised refund, but I expected that to take a few days anyway.~~ Got my refund now.

Simon from Convoy replied to me on aliexpress and said “It [the new driver] has cut off normally .” and also sent me a tracking number. Not sure what normal means in this case, because if it’s just designed like that… eh, guess we’ll see. Will report back once that has arrived and I got a chance to test it.

OT: Frankly I’m not quite sure about the dangers of a charger that doesn’t cleanly cut off… I suppose if lithium-ion batteries get overcharged, it’ll cause an irreversible chemical reaction (plating), but no idea if the battery will even just accept any current (apart from what’s lost due to self-discharge) when held at the end-of-charge voltage like that. Does anyone have a good resource that explains how bad it actually is for the batteries?

Streamtronics · 2019-06-27T21:37:46.000Z

Alright, here's an update on the replacement driver Simon from Convoy sent me free of charge:

He sent two drivers, both look physically undamaged, and both behave exactly the same way as the one in my S9 did. This tells me that the bad LVP is either baked into the design (aka just bad design), or that a whole batch of drivers have a manufacturing defect (such as a different resistor value in a voltage divider or something). They also both charge a bit high (4.25 and 4.26 V). But hey, at least they're consistent I guess.

I'll get back to Simon on aliexpress later tonight, will see what he says. I'll also have a closer look at the driver later to see if maybe I can replace a resistor to make the LVP function properly.