Streamlight SL Series: Charging questions

I'm a long time user of Streamlight products in the fire service (LiteBox, Vulcan, Survivor, etc.), however this is my first experience with the SL Series, and so I'm looking for some feedback from experienced users.

I recently purchased an SL-20LP with the 120v charger, and I'm seeing a few things regarding the charging that seem odd to me.


- It seems to take a really long time for the charge indicator LED to go from solid red to flashing red. I dropped the flashlight in the charging sleeve overnight for its first charge, as recommended, and even after 12+ hours the indicator remained solid red. I took the flashlight out of the charger and left it on for two hours to run it down (not all the way, but certainly enough), dropped it back in the charger overnight, and 10 hours later the indicator was flashing as expected. Okay, seems to finally have acted normally, however...

- Once the indicator was finally flashing, indicating a full charge, I took it out and used it for roughly 2 minutes. I dropped it back in the charger, and 2+ hours later the indicator is still solid red. Seems to me that going from a full charge, to using it for barely 2 minutes, should not trigger a charge cycle that is taking 2+ hours. The battery is pretty warm to the touch; not hot, but toasty warm.

- This is the oddest thing of all, though. I unplugged the charger's adapter from the wall with the flashlight still in the charging sleeve, and the LED charge indicator remained solid red. I would expect that the indicator would turn off if power were removed to the charger. Not only did it remain on, but after pulling the flashlight out of the charger, it remained solid red, and the flashlight itself was inoperable! I had to remove/reinsert the battery to "reset" it, at which point it worked normally.


Have any SL-20L/LP owners experienced anything similar with your flashlights? I'm especially curious about the way the flashlight seems to "lock up" and become inoperable if you remove power to the charging sleeve while the flashlight is still in it. Seems odd to me that this is some sort of design flaw that has persisted for so long. What happens if there's a power failure or you have the charger installed in a vehicle, two scenarios where the flashlight would almost certainly be in the charging sleeve when power is removed. Are people removing their batteries to reset the flashlight? I can hardly believe that is the case.

What the heck is going on with this thing? I suppose it's possible that I got a bad flashlight and/or charger, although the flashlight does seem to operate normally aside from these weird charging quirks. The date code on the flashlight is May 2017 and the charger June 2017, so it's not old stock that has been sitting around for a while or some old design. These are brand new, factory fresh!

Thanks in advance for any feedback!

I sent an email to Streamlight customer service to inquire as to whether any of that was normal behavior. Unfortunately they didn't give me a direct answer, but they did recommend that I return the flashlight if I had any concerns about it.

It doesn't seem normal for a top off charge to take more than a few hours at most. This thing was sitting in the charging sleeve for 20+ hours and the indicator remained solid red with the battery quite warm to the touch. No bueno.

Upon closer inspection, I noticed that the plastic switch assembly was cracked due to what looked like over-torquing of one of the screws. Could be coincidence, or the cause, but either way it's a damaged item so back to Amazon it goes for a replacement.

I'd still be interested in anyone's experience with these flashlights while I await the replacement and determining how that one behaves.

Replacement light got here on Monday afternoon. The serial # was just five units higher than the original light, which wasn't surprising. Close visual inspection yielded no defects, everything was intact. Didn't even turn it on after putting the battery in, instead I dropped it right into the charger and left it there undisturbed for 10 hours until the charge indicator LED went from steady to blinking (full charge). Pulled it out a little while later and tested the switch functions, levels of brightness, beam focus, etc. with everything checking out.

So while the light itself is defect free and is working great, it turns out that I was able to reproduce the same quirky behavior with the charging routine. Must be an inherent defect in the charging circuitry, either with the "smart" charging sleeve, or the switch/charge assembly on the light itself.

Unplugging the wall wart with the light still in the sleeve caused the charge indicator LED to remain solid red, and the flashlight was inoperable after being removed from the charging sleeve, with the LED remaining lit. Battery pull/reinsertion was the only way to clear the condition.

So while this is normally not a big deal for routine usage of the light, as most of us have reliable utility power, it is kind of crappy in the sense that if the power goes out, the flashlight is probably the first thing you'd reach for. Well, in one sense at least the charge indicator LED remains lit so you can find it easier in the dark LOL! However it's obviously a huge PIA that you first have to unscrew the tail cap to pull/reinsert the battery before you can get the darn thing to actually turn on. :duh2:

I also notice that even if you only use the light for a few seconds with it previously being fully charged, that it sits there for hours with the LED steady after reinsertion. I know Streamlight makes a point of stating in the operating manual that "There is no danger of overcharging the battery.", I'm a bit skeptical. Turning the light on for 10 seconds on a full charge, then reinserting it into the charger, should not result in a full charge cycle lasting hours. It should go into full charge mode, then within 10-15 minutes go into maintenance charge mode.

I'm going to attempt to get in touch with someone at Streamlight who has a working knowledge of the charge circuitry in these lights to see if maybe this is something they're just not aware of. I find that hard to believe, the SL-20 series being around for so many years, but who knows. I'm not optimistic that I'll actually get to speak with anyone other than maybe a customer service supervisor, but I'm pretty tenacious so maybe I'll get lucky and will wind up getting in contact with one of their technical guys or an engineer. If not for my sake, for the sake of future models and product development.

I know this was a boring thread that no one had anything to add to, only suffering through my droning on about a light that's not even that popular, but it was somewhat cathartic, so thanks to those who took the time to read it.

I don't have any answers but I did read it, lol. It almost sounds like the charger is timer based. Pretty weird stuff.

I own the protagonist 2-L, HL-X but not any with a built in charging system.

Lol protac 2-L not protagonist. Though it might have a new nickname.

The charger definitely has some sort of smart circuitry, but I'm just not sure how smart it really is. The first time I put it on the charger it took roughly 10 hours for a full initial charge. The second time I dropped it in the charger, the full charge cycle only lasted a few hours, so it's definitely not a timer based circuit.

I don't really know what to make of it. As long as the light keeps working well, I guess I won't worry about the charge time too much.

The thing with the flashlight locking up and becoming inoperable if power is removed to the charger, that's a more puzzling issue that I'd love to get an answer to.