Bad experience with 2.5A Convoy S9 from banggood

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Streamtronics
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Bad experience with 2.5A Convoy S9 from banggood

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:

  1. 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…)
  2. 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”
  3. 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).
  4. 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.
  5. 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.
  6. Mode spacing is quite weird, where there’s a big jump from the second to the third mode.
  7. 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.

Edited by: Streamtronics on 06/05/2019 - 08:51
WalkIntoTheLight
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(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
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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 wrote:
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.

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SC31?

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Streamtronics
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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 Smile

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

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Lightbringer
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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…

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Couchmaster
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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
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Couchmaster wrote:
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
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Streamtronics wrote:
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 wrote:
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 Facepalm ), and just to check the fit, ‘cause thicker glass on the 2×AA light requires shaving down the lip of the (also plastic Facepalm ) 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…

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Rexlion
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Lightbringer wrote:
…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. Cool
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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. Innocent

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nydude
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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
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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 Big Smile
  • 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).

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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.

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

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Streamtronics
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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.

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

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

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

You never know how a horse will pull until you hook him up to a heavy load./"Bear" Bryant 

 .................................. "Slow is Smooth, Smooth is Fast" ...................................

       Texas Lumens Flashlights / M4D M4X Deals : sign up - save $$$$  

         Rudeness Level _ mΩ _ {width:70%} _ LightWiki _ LED Tint Chart  

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Streamtronics
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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 :/ 

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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.

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

https://eu.nkon.nl/search/min.-capacity-in-mah/3000-3600/battery-size/18...

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

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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.

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There may be a chance the review was modified.

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

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

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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.

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Streamtronics
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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? 

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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.