ZL SC600 HI--problem with pogo pins?

Okay, my first complaint about the HI. (And let me say that I generally love the thing.)


The pogo pins dent the sheet-metal buttons on the positive end of my cells.
Once the ends are dented, then a shock to the front or back of the light, while it is running, turns the light off.


I have this problem because I use the light on the handlebars of my bike as a head-light for the bike.


Every time I hit a significant bump--not pot-hole, not a bone-breaker, just a medium-sized bump--my head-light turns off and I'm in the dark.


Or sometimes it shifts down to a very low mode. Then when I switch it to H2 again it works fine. Until I hit another bump.


I tried to reproduce it at home by turning the light on, and whacking the side of the head against my hand. No problems. Stayed stable.


Then I tried hitting the back of the tailcap or the front of the bezel so that the force was in line with the long-axis of the battery.


The light immediately shut off. Or sometimes it throttled down to low. Sometimes one hit bumps it to M, then another hit bumps it to Low.


The cause seems pretty clear: the pogo pins are not maintaining contact with the cell when there is a shock down the length of the light.


When I put in a cell with an undented positive terminal, it works fine: I can hit the bezel with my hand repeatedly and not turn off the light.


Trouble is, if the light takes a *real* blow to the ends (e.g. being dropped from waist height and landing on the bezel), then it dents the terminal.


So a big shock to one end causes the pogo-pins to dent in the sheet metal. And after that, small shocks to the end cause it to lose contact.


See if you have this problem yourself. By the way, my cells are red-label AW IMR 20amp 3000 mah cells. Flat-tops.

That happened to me too when I dropped my light from waist level. It dented both ends of the battery and I noticed the light would shut off if it received a blow/shake to either end. I took a screw driver and gently propped up the sheet on the positive contact of the battery. It fixed the problem until the next few times I drop the light. I love the light but that is my only complaint. I have ncr18650ga cells

No problems with mine, but I've been pretty easy on it. But I would like them to go back to springs just to diffuse any possible issues going forward before it gets worse. I don't care about longer/protected cells not fitting, but it would solve that "issue" as well.

A+ for effort on reducing the size, but good old springs just make more sense to me.

markr6 said:

A+ for effort on reducing the size, but good old springs just make more sense to me.

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I think this is where I end up as well. They should go back to springs.

They were right to try the pogo pins--if you want to be innovative, then you have to try new stuff.

But you also have to change your mind when the new stuff does not work.

Yeah, I wouldn't say it's a 100% total failure. But after a few drops I may start getting concerned. Better safe than sorry IMO. Wouldn't be surprised if we see all springs in the future.

As an interetsed zebralight observer (don't own yet but will) a picture would help explain what you're talking about.

Thanks for opening this thread subject, as it would be great if we could catalog and describe any related incidents.

Have there been any recorded failures that occurred *without* the light being dropped onto a hard surface or by a similar impact?

Beckler said:

As an interetsed zebralight observer (don't own yet but will) a picture would help explain what you're talking about.

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Beckler, check out this review by selfbuilt. It's for the SC600 III, but uses the same setup as the HI. The 8th and 9th photos he took show the pogo pins, which are used in place of traditional springs to hold the battery snugly. They're sort of like mini springs, but don't have much travel at all.

roger-roger said:

Have there been any recorded failures that occurred *without* the light being dropped onto a hard surface or by a similar impact?

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I doubt it, since the unprotected cells fit nicely and the pogos take up a little slack. But I would also like to keep tabs on any other incidents regardless of use.

markr6 said:

Beckler, check out this review by selfbuilt. It's for the SC600 III, but uses the same setup as the HI. The 8th and 9th photos he took show the pogo pins, which are used in place of traditional springs to hold the battery snugly. They're sort of like mini springs, but don't have much travel at all.

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Interesting, thanks. I didn't know they had that design, I like it - looks like it's mostly an attempt to increase electrical contact area. If they decrease spring force then contact will suffer. Seems like problem is with 18650 cell and insufficient material strength. So it may vary by cell if some have stronger contacts. Anyone want to drop test dozens of batteries?

Edit: of course it could be the flashlight contact springs are too soft, causing them to "bottom out" if they're still protruding a bit at bottom out. So maybe a fix is easy.

markr6 said:

I doubt it, since the unprotected cells fit nicely and the pogos take up a little slack.

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Yeah, I doubt it, too. Until the sheet-metal positive terminal on the 18650 is dented, the fit is excellent. The pogo-pins have just enough travel so that the battery is held snugly under spring-tension when the tailcap is screwed all the way down.

So it's only when the terminal gets dented that there is that extra millimeter (or 0.75mm?) of travel that allows for a break in contact.

The trouble with tightening the whole thing up *more* is that I don't want a lot of shock transmitted into the body of the 18650.

That's why I am not tempted, e.g., to drop a blob of solder into the divot on the positive terminal to take up the slack. Yes, it would take up the slack. But it would transmit shock into the cell itself. I would rather have the sheet-metal on the terminal fail than have the container of the 18650 fail.

Like I said: I'm glad they tried it. But I think springs are superior.

(There's a separate question about amperage: part of the selling point about pogo pins was that springs have more resistance and don't carry the high amps as well. Maybe? Maybe they just need to source a new spring? Or provide a wire current-bypass the way that Vinh does when he hot-rods his lights? Not sure. But I can't believe it is impossible to get a spring that will carry the current, too.)

lampeDépêche said:

Maybe they just need to source a new spring? Or provide a wire current-bypass the way that Vinh does when he hot-rods his lights? Not sure. But I can't believe it is impossible to get a spring that will carry the current, too.)

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I think one of my cheaper lights, I can't remember which, uses the dual spring design for more current. So ZL could probably get away with that. And couldn't they make the springs a little shorter? Even one less "twist" just to say they tried to make it shorter? Just and idea. I'll continue to enjoy my SC600w HI and SC63w in the meantime...but watch me drop it tonight and dent a battery now that I said that.

They may go to a hybrid design in the future like the 63w. It has the pogo pins at the head and a spring at the tail cap. Having said that I've not had any issues with my MK3 HI after a few drops but I do have the dented cell from it.

Maybe I missed it but are you using unprotected battery ? as these are 65mm which means they are shorter compared to protected which are 69mm.

marinemaster said:

Maybe I missed it but are you using unprotected battery ? as these are 65mm which means they are shorter compared to protected which are 69mm.

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Yes, OP states unprotected. Many people are having this issue with a range of unprotected batteries including the ga's recommended by ZL.

One of my NCR18650GA had developed a dent on the top contact, this probably from the SC600w MKIII dropping onto a desktop. That light had seen only light duty, with no further symptoms showing.

roger-roger said:

One of my NCR18650GA had developed a dent on the top contact, this probably from the SC600w MKIII dropping onto a desktop. That light had seen only light duty, with no further symptoms showing.

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So do us a favor, if you like, and turn it on to H1 or H2, then give it a few smacks on the tailcap or bezel, straight in line with the long-axis of the battery.

See if it kicks down into a lower mode.

markr6 said:

No problems with mine, but I've been pretty easy on it. But I would like them to go back to springs just to diffuse any possible issues going forward before it gets worse. I don't care about longer/protected cells not fitting, but it would solve that "issue" as well.

A+ for effort on reducing the size, but good old springs just make more sense to me.

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+1. I much prefer springs and don't need the additional current that inspired the switch to pogo pins. Dump the xhp emitters and go back to springs.

The trouble is when companies make changes like this they spend a lot of $ on research and development and they hate to go back to the tried and true solutions. Could even involve somebody losing a job. Bottom line is now they use the pins even in models that don't have the current needs to require them. I doubt they will go back.

lampeDépêche said:

So do us a favor, if you like, and turn it on to H1 or H2, then give it a few smacks on the tailcap or bezel, straight in line with the long-axis of the battery.

See if it kicks down into a lower mode.

Click to expand...

Sorry, I no longer have that set up on hand. Otoh that seems a good test, and hopefully others will be in the position to give it a go.

I'm definitely interested in the results and this subject in general, as I'm about to take a second go at the SC600w MKIII HI.

Someone suggested dropping an o-ring into the light that sits around the pogo pins. With the right thickness it should cushion the battery on a drop while not impeding electrical contact.
Didn't try it myself but sounds like an easy fix.

All kinds of hacks. But the issue is, this is a fundamental oversight or negligence in the design. The tabs on unprotected cells are Not designed to take a load. That is why they are deforming. They were never meant to be used that way. They are designed for attaching tabs or establishing a no-load connection. If Zebralight was responsible they would have made the battery tube just a little bit longer so that one could use unprotected button-top cells. They have willfully designed a flawed product. If there is ever a short causing a fire they will have no chance in a court of law. I personally have many Zebralights as they have been my favorite brand. This design, that starts damaging a brand new $8.00 cell the moment you place it in a light is irresponsible.