Review: C20 DIY EDC flaslight host from FastTech

TSellers - you might be having battery bounce, particularly if your intermittent problems happen while you’re skiing. Try raising the switch inside the tailcap like Keltex did to increase pressure on the spring. It’s a pretty common problem among mtbers using torches for night riding and a stiffer or longer spring usually fixes the problem.

I got my C20 yesterday, looks really nice. Threads are well machined and run smooth, o-rings are lubed as stock. I haven’t had time to pull it apart yet (busy building a milling attachment for my lathe), but I’ll get stuck into it when my programming clip arrives. The only downside I can see is that the pill material under the star is pretty thin. I might see if I can add some copper to the pill to help out with that - I just found a nice 2in copper pipe cutoff which should help :slight_smile:

Thanks Matt,

I’ll give your suggestion a try. One of the things I noticed was the light powers on as soon as the tailcap makes contact. I also noticed my solder job for the ground looks iffy, I’ve tried 3 times, and even scored the edge of the pill with a dremel, but I’m just not getting a good weld there. That’s why my theory that the battery bounce is actually moving the driver inside the pill. When I check continuity it is always positive but that doesn’t mean it just hasn’t reseated itself when I unscrewed the cap.

So if I do get this problem solved, now I wondering about something else. I see that FT has a 4.35 charger SKU’d up now. If I were to use a 4.35v cell with the 8* driver do you think it would result in any brighter light, or does the driver regulate it so that it would not make any difference?

it would (in theory) keep the light regulated for longer, not brighter

Thanks janko, think I’m just looking for a reason to justify starting to use the 4.35v cells!

no worries :slight_smile: Tracking down an intermittent electrical problem is a pain in the bum, that’s for sure. Another way to troubleshoot would be to smack the light when it’s on with the tail cap on and off (with a nail or something between B- and host), as you could have something not quite right in your switch too. One way of making a good -ve connection on the driver is to just solder a piece of bare wire between driver -ve and pill. That might help too.

Thanks, co-incidentally I just finished soldering again. Also this time I didn’t like the look of the solder bridge on the star that tells it the mode, so I redid that as well thinking maybe the mode was getting confused with a bad solder. So I tried your suggestion and gave it a few smacks while it was on and all good, but in the past it fails after it’s been on for awhile so I can’t be sure yet. I sure hope it works this time because for the first time the emitter is perfectly centered which is nice.

Also since I posted earlier I did find a previous thread where they said this driver does not really benefit from a higher voltage feed, and it can be worse in fact, apparently at 6v for example it’s only 60% efficient with tons of heat as the result. So in fact I’m thinking maybe the best cell for this light would be an a123 18650 LiFePO4 cell and not a Li-Ion.

Update: the intermittent problem was due to bad ground between driver and pill. Seems OK now.

Thanks very much for the review! Frontpage’d and Sticky’d.

great, glad you got the problem sorted. My build is still stalled, but I’m hoping to start making progress this week or next.

Thanks Matt,

BTW there are a couple of features I’v some to appreciate with this host now that I’ve had a chance to also do the Convoy S3 host as well:

  1. Can unscrew the top section to access pill easier.
  1. Pill has better slots to use to extract or insert it, and you can screw it in from the driver side of the pill. (S3 has tiny pin pricks that my circlip pliers cannot hang onto and you have to screw it in from the LED side, on my first attempt I ended up transferring heatsink compound onto the LED).
  1. Pill has keyway slot to match tab on the Nanjg driver (you have to grind it off, and discard the included retaining ring, if using Nanjg with the S3).
  1. The finish is more scratch resistant ( EG: when compared for example to the black of the XPower host they sell).
  1. Tighter spot than the S3’s OP reflector.

In my mind the areas that could use improvement are the thickness of the metal, it sort of feels like a tin can for guage, and the drivers on the two that I have built needed to be sanded down to get them to fit into the pill. Maybe even the finish could be upgraded, and I do like that glow ring under the lens of the S3. If they did all those they could charge more, I think it would still be a great host at twice the price, and even better still if they were able to find a different switch.

I’ve got a Convoy M2 host arriving today, so looking forward to giving that one a try.

Edit: Sorry about the numbering on the list, for some reason I couldn’t seem to get it to number consecutively.

On hosts that have pills without the notches, I use the edge of a small file to make the notches. Since the brass is soft and can be removed quickly, the process is very easy and you end up with good results.

Thanks for that. I’ll either do that, or if there is a bit in my Dremel kit that is good for making dimples, I may give that a try, as I’m using the dremel to take the tab off the driver anyway. I’ll probably end up doing that later today if the M2 arrives as the tracking says it will.

interesting feedback. I actually ground a couple of slots in the driver side of the pill after reading your earlier posts, so that was a lot of help. I agree that the body is pretty thin, but then again it’s small and light, so there’s always a trade off. We’ll see how well it stands up to abuse :slight_smile:

I just finished assembling the Convoy M2 host. The dimples in the retaining ring on the pill for it, and on the tailcap, are sufficient for my circlip pliers to get just enough purchase to make it work, so in that regard the M2 has been better than the S3. I’m thinking that the S3 is supposed to have better dimples but just suffered from an absence of QC at the manufacturing plant.

Was thinking bout buying one of the C20’s and they are sold out!

The OP version is available:

http://www.fasttech.com/products/0/10002463/1198400-18650-diy-edc-led-flashlight-host-with-switch-refl

Also, more expensive options exist:

The Convoy S2:

http://www.fasttech.com/products/0/10002463/1277401-convoy-s2-diy-edc-led-flashlight-host

...and S3:

http://www.fasttech.com/products/0/10002463/1277402-convoy-s3-diy-edc-led-flashlight-host

...and this X-Power host with much more aggressive knurling:

http://www.fasttech.com/products/0/10002463/1278500-x-power-118650-edc-led-flashlight-host

Doesn't sound so good... See rest of thread below...

Thanks keltex those all look nice. I guess i have been over looking that x-power host. Thats a good looking light also.

Thanks

That's the one that's identical to the Xiaozhi light from CNQG. I finally got the clip installed on mine (very very nice, but what a pain to get those nuts on!) and have been fiddling with the tailcap switch. I hope they have a better sized switch with it (in FastTech's photos it's a black switch and mine is white - hard to tell, but it does seem larger than mine)! My switch is ridiculous! It's way too small and "floats" around inside the tailcap. Nice host though once the switch is fixed.

-Garry

Ok, I just finished re-assembling the tailcap switch on my Xiaozhi after a thorough cleaning of all threads and contact points. I managed to get my switch centered well and tightened the $%#@ out of the retaining ring to hold it in place tightly. It now work flawlessly (so far)! And to top it off, there is NO more driver whine (Nanjg 105c)! It used to whine annoyingly on low and medium and now I can't hear anything even up against my ear!

So the FastTech Xiaozhi gets my approval as a good solid host and manageable even if the switch is still too small.

-Garry

P.S. I didn't place an o-ring under the tailcap yet to allow tailstanding. Not sure if I want to touch it again though!

+1 here first one I ordered from FF tailcap pcb diameter was way undersized for the fitting after lots of adjustments its just acceptable, My initial impression perhaps they ran out of correct size switches.
second one ordered same problem…
So if anybody is contemplating getting one of these unless they have increased the diameter of the switch pcb be prepared for lots of adjustments and frustrations, good light spoiled by a poor 50 cent part.
YMMV
B

@apt323

That xPower is one of the first I purchased, and is now the least favourite of the C20, S3, and M2 hosts that I have used so far. At 60 degrees it has the narrowest beam of the 4 (not meant as a negative), the second O ring often catches the tailcap when you are screwing it on and obstructs it, the head section caught one of the other O rings and simply tore it apart, the finish scratches very easily, on closer inspection the finish looks to me like it is a matte polyurethane powder coat (and the threads have no coating at all like the anodized lights do). It does not take a protected cell. Personally, I will not be getting another one as long as there are better choices, even at that price point.