Bad experience with 2.5A Convoy S9 from banggood

Streamtronics · 2019-06-05T12:48:12.000Z

Hi, I just ordered a Convoy S9 for my brother (who’s not a flashlight enthusiast), and I’m making this thread to tell you about my bad experience with this S9.

I ordered the 2.5A version of the S9 on Banggood.
My goal was to get a sleek A6-style “tube” light that takes a standard 18650 and is USB rechargeable. The S9 seemed to check all the boxes.

Here’s what I found:

Battery cutoff voltage is supposed to be 3.0V (as per product description), and red LED should already start at 3.3V. Red LED starts at 3.0V, starts blinking at 2.7V and flashlight never actually turns off in a controlled way, it just gets dimmer and keeps running (and discharging the battery!) down to below 2.5V. Here’s a video showing the LVP in action (or rather, not working properly…)
The USB charge circuit isn’t much better either. It charges a bit high (4.23V, which is still fine though), but it’s one of those cheap circuits that never actually shut off. The red LED that’s on while charging just slowly fades out and the blue one fades in as the charge current naturally gets lower. A proper, safe charging circuit would measure the current and shut off at something like 50 or 100mA and not continue to “trickle charge”
The micro-usb socket is really tight, hard to plug a cable in, even harder to pull it back out (lots of force on that probably SMD-mounted usb socket).
The rubber flap that protects the usb socket is pretty floppy and comes out easily, doesn’t instill a lot of confidence. The switch feels quite mushy and needs to be pushed in quite hard to activate.
The “moon” mode ist really way too bright to be called moon mode, blinding even when using it right after waking up in the middle of the night.
Mode spacing is quite weird, where there’s a big jump from the second to the third mode.
The brightness of the light varies depending on battery voltage, even in lower modes (I expected a more regulated output, it shouldn’t be too hard to do that in a light that costs >20 USD)

So yeah, I’m particularly disappointed about the low voltage protection, since charging a cell that has been discharged to under 2.5V can be dangerous… and since we’re in 2019 and not 2009 I expected a better charging circuit with a clean cut-off. Come on Convoy, one of those ICs can’t cost more than 3ct.

WalkIntoTheLight · 2019-06-05T15:46:34.000Z

(1) and (2) sounds bad. It’s really cheap LVP and OVP. Make sure to always shut off the light, and personally I wouldn’t use the built-in charging. Not a deal-killer, but wasted features if they don’t do them properly.

(3) - (7) just sound like poor design choices, not necessarily problems.

Just buy a BLF A6, and get a separate $5 Xtar MC1 charger.

Streamtronics · 2019-06-05T16:06:48.000Z

Yeah, I agree. 1 and 2 are the main issues in my eyes, since my brother didn’t want the clutter of a separate charger and I thought USB charging in general worked well since the only other light I have with USB charging (Fenix TK20R) cuts off the charging cleanly, as it should.

WalkIntoTheLight:

I wouldn’t use the built-in charging. Not a deal-killer, but wasted features if they don’t do them properly.

Well, I mean the reason I got that light in the first place is because of the USB charging so it’s definitely a deal-breaker for me/my brother.

I do have a BLF A6, but mine came with an awfully pink tint (supposedly 5A, was basically salmon colored light), and I don’t think my brother would appreciate that… but yes, in case I can’t find another sleek light with usb charging I’ll definitely go for the A6. Proper moon mode and LVP are important features.

Does anyone else have a recommendation for an alternative? I really hope banggood doesn’t act up now and refunds me the full amount, since the light just doesn’t work as advertised.

Lightbringer · 2019-06-05T16:09:21.000Z

SC31?

Streamtronics · 2019-06-05T16:45:20.000Z

Good suggestion, nice form factor, but 10 lm as lowest mode sounds a bit annoying though, and brother wouldn’t appreciate mode memory with no direct access to lowest mode. Also a warmer tint would be preferable I guess. But it does look like a handy little light

Lightbringer · 2019-06-05T17:01:13.000Z

Yah, well, that’s why people have dozens if not hundreds of lights, ’cause no one light does it all.

Lightbringer · 2019-06-05T17:03:58.000Z

For fitty bux, though, the MH20 might fit the bill.

2-stage switch, direct to turbo and direct to moonlight, click on/off for memorised level, usb rechargeable, fairly NW to CW (at least not Angry Blue™), so…

Couchmaster · 2019-06-05T17:47:16.000Z

Love my Nitecore MH20’s, they seemed costly at @$47 as you note, but saw them yesterday for sale at $87. To OP, have you contacted Convoy? That dude seems on it and conscientious. I would imagine he’d want to know the issue and also take care of you.

Streamtronics · 2019-06-05T17:55:42.000Z

Couchmaster:

To OP, have you contacted Convoy? That dude seems on it and conscientious. I would imagine he’d want to know the issue and also take care of you.

I haven’t considered getting in touch tbh, I assumed it’d kind of be a big company that wouldn’t bother with just one customer complaining. I might look up how to contact them later, thanks!

As for the MH20, that thing looks great (I mean, just visually, I really like the looks lol), but price wise quite a bit too expensive and also probably too throwy (the S9 is actually a bit less throwy than the A6, which is preferable in this case. Tight spots are pretty annoying indoors imo). Thanks for the suggestion though!

At the moment the A6 + MC1 seems to be the best choice… I guess being able to sleep at night knowing your battery won’t catch on fire is more important than wanting to avoid an external charger lol

Lightbringer · 2019-06-05T18:19:17.000Z

Streamtronics:

I haven’t considered getting in touch tbh, I assumed it’d kind of be a big company that wouldn’t bother with just one customer complaining. I might look up how to contact them later, thanks!

Him. Simon at Convoy. He’s wonderful.

Streamtronics:

As for the MH20, that thing looks great (I mean, just visually, I really like the looks lol), but price wise quite a bit too expensive and also probably too throwy (the S9 is actually a bit less throwy than the A6, which is preferable in this case. Tight spots are pretty annoying indoors imo).

Nah, you want throwy, you get the MH20GT.

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

I just got a glass front for a LuxPro 4×AAA light (had plastic :person_facepalming: ), and just to check the fit, ’cause thicker glass on the 2×AA light requires shaving down the lip of the (also plastic :person_facepalming: ) reflector, but in this case it dropped right in.

Fired it up with just nekkid glass. Tight saucer-sized hotspot with evil urine-yellow corona from the G3. With film, a nice sofa-sized blur.

Peel on. Peel off. The Peeler…

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.