Guys I need your opinion or help on a battery pack issue. This is on my SR90. For those that don’t know, the SR90 has handle/battery pack that contains 6ea 18650 cells. The are stacked 3 + 3 for 8.4v and and for the better amperage. On the end of the battery pack it has a meter with 4 LEDs as a power level indicator. Basically I’ve started noticing the battery pack isn’t taking a full charge. I know this by first seeing only 3 of 4 led’s on the pack light up. And for more accuracy, testing with a DMM shows I can’t get over about 7.85v from the pack. And this is after multiple charge attempts, some lasting about 8hrs. Only went up about .2v.
I’ve had the light about 1.5yr now and have only used it for maybe 1-2hr runtime total. Basically lots of short 30-60 second playing etc. And fortunately I do have a spare battery pack I got on sale for about $30 a few months ago. They normally cost about $90.
So basically I don’t really need the pack since I have a spare. But it’s nice to have.
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So here is the main point of this post - is this battery pack still safe to use or charge? I assume it has a bad cell in the pack. Not sure if I should top it off (up to the 3.8v anyway) every few months or leave it alone for safety. Now I did actually take the pack apart. Mostly anyway. It’s got a contact panel on each end of the pack held into the tube by a metal ring. Between the contact plates are the 6 cells shrink wrapped up all together. The cell pack and the contact panels are not physically connected other than wires and there is some play to pull the pack out an inch Or so and to move the contact panels around a fair amount. Nice heavy gauge wires I noticed. One would have to do-solder the wires from one of the contact panels to totally remove everything from the tube.
Anyway, this tells me someone decent at soldering could/should be able to fully take a pack apart and replace the cells if so desired. This is something I might do eventually or get done.
But back to the original question - is this weakening pack safe or should I just leave it alone totally, regardless if it might drain down enough to totally kill the pack? I’m assuming people use bad packs all the time in old laptops, so I figure its realitively safe. But not sure.
It sounds like it has 3 batteries in series and the triples in parallel (3p2s?), and probably one cell in one of the triples is low, so the one triple with the low cell is causing the overall pack output voltage to be lower.
How are the 3 batteries in series held together? Do they have tabs and are soldered together via the tabs?
Yes it’s (3p2s). The shrink wrapped pack has wires going into each end and a piece of foam glued on to each end. The contact plate is wired so that its wires goes all the way to the other end of the pack. Thats why I cant totally remove eveything from the tube. It will slide out of the tube on either end for an inch or two. Because of the foam glued to each end of the shrink wrapped pack, I can’t see if there is another little plate inside there or just the wires direct soldered to the battery ends. I didn’t want to go to far and not be able to get the pack back together. My soldering skills are limited.
I’ve given the matter much thought, done my homework, 3-part Linear Regression and all that; and I’ve come to an important conclusion: That’s a dangerous undervoltage situation you have there, and the whole pack could vent with flames at any moment. Strontium-90 is very dangerous, as is Lithium! For your own safety, I’ll PM you my snail-mail address, you should wrap up the torch, packs, charger, everything and just mail it over. I’ll be sure you stay safe.
Sorry, you had to mention SR90… And you can use the “bad” pack as long as it makes light, so…
Seriously, if you can take the “bad” pack apart to the level you described, and put it back together again so no one could tell, meaning it fits back in place and the torch lights up, ALL that’s left is some boring soldering and dealing with the shrink-wrap.
Here’s a thought: If you can write your name with a pencil and chew chewing gum, you can hand-solder the wiring you described! You said you have a good pack to use anyway, so why not cut the shrink-wrap on the “bad” pack and replace all the 18650s yourself? Replacing the shrink wrap will take some doing, but you could likely get away with a single layer of wide packing tape if you were really careful (once the pack is reassembled anyway)…
Not trying to lure you over to the dark side of hardware, but you’ve already done the hard part of breaking into the pack. I only assume you can put it back together again, but that’s the only hard part, really. Here on this forum alone are probably a good few dozen people who could verbally and/or photographically make the soldering as easy for you as it really is…
Sorry to push… If it’s outside your comfort zone to stick solder onto battery ends, you could practice on the little strips that join the cells in a laptop pack… Or rip into a dead consumer device & practice on the battery holder…
Once you get the hang of soldering, it’s a really rewarding skill. Just sayin’…….
Imagine the likely scenario: You’ve had the light long enough to have used up this much battery, so the 18650s you get today will likely have both deeper capacity AND a wider current path, which means your little fist-full of sunlight will get even brighter, and may even last a little longer! You’ll be repeating the process on the spare before you know it!
I think you should do it.
But I’m just …
Dim
I appreciate the info and suggestions. And yes I think I could likely get the pack fully apart and yeah I’m sure I could get it back together. I would take photos to make sure I remembered how the wiring was done. One of the contact panels just have a very simple - & + wire connection so I’d pretty pathetic not to be able to that piece apart and back together again. That way I could break it down even more to see how the wires are connected to each cell. The other contact board has several wires connected to it.
I guess I’m just not sure if its worth it at this point. It would likely take $30-40 worth of batteries and parts to fix it. If I used the light for work or a regular bases, it would be a no brainier to obviously try to fix it. But I do have a spare battery pack and only use the light for fun.
That aside, I still might give it a shot just too see if I can do it. I’ll look at it some more in the morning and see if I want to fully break it down.
Well, killed the pack. Much more to it than I thought. It had special triangular plates soldered to all ends and including between the two stacks. How some got to them to solder I have no clue. And it even has a pretty serious circuit board on one end. Anyway I pulled out the cells. They are green and labeled as ICR18650NM MH28822 1K10182941 182713. Anybody have a clue what these cells are?
Oh between the two stacks there was what looked like brown corrosion or gunk. And all three top cells read about 4.07v and all three bottom cells read about 3.51V. So I’m assuming there was a contact issue between the stacks stopping the lower stack from charging.
ICR18650NM:
Yes that’s the cells. Are they panasonic or what though? Are the decent cells I wonder?
I just googled the item number, ICR18650NM, and got this: ICR18650NM Datasheet … Pertinent details, 2000mAh, 3.7v “full”, Fast-discharge Current 1C. Translation: wimpy-wimpy-wimpy. I don’t know your situation, but if I paid close to $400 for a flashlight, I’d be a little PO’d if the batteries could only flow 2A at their “fast” discharge rate…
But nevermind me! There are SO many better batteries now, your future really does look “bright”!!
I call that “MISTER Root Cause”!!
You’re getting Very Good at this!
If you haven’t already ripped into the pack, maybe cleaning the gunk (there’s a technical name for that, but I can’t spell it) and putting everything “in order” would restore the pack to its “original glory” (at 2Ah) without further ado…?
Yeah I saw that 2A on one site last night too. Looks like a cheap Chinese cell. It might be weird, but I was actually thinking about trying to just stick two King Kong 26650’s in there. Would be much easier for me to wire up. The would have slightly less capacity, but they would handle the amps just fine I would think.
But yeah I killed the pack. When I was trying to “carefully” take it apart, one wire contacted something it shouldn’t and sparked. I said screw this and started quickly snipping wires before I accidentally blew up a cell. This pack actually had its own circuit board and the two contact board in addition. The thing has more wires than one would think needed for a battery pack. And the triangular plates to contact all the cells together. Both contact boards are very straight forward with negatives and positive terminals. If I can discard the extra circuit board, then I fell confident I could safely install a couple 26650’s. I figure the circuit board is sometime of monitoring system, but not sure. The battery pack has its own removable power indicator that screws on and off the pack. And that part has the port for plugging the charger in. Assuming the chargers have voltage/amperage metering capability, I can’t see where the flaw in design would be to do the simple 2 x 26650 wired direct to both contact boards, thus bypassing the other circuit board entirely. I would think the power meter cap would even still work.
So am I thinking wrong? I did take photos of most of this if it would help.
Not Panasonic, but maybe OEM. Mostly OLD… That’s only good for Dimbos and Engineers, not batteries!
I wonder why their Page Title and Features Block list the C as “2200mAh”, but the Details block says “2000mAh”… 10% is more than “ooops”…
This one still shows it as “full” at 3.7v. Meaning your 2S pack should only give you 7.4v… But the 3P means ~6A max. for your LED…
Just to be thorough, your Luminus SST-90 (if that’s your emitter) can take 9A within spec, and the Vf is only 3.9… Meaning the pack is producing more V and less I than your emitter needs… Strange…
You can do better, in 2013, by simply raiding a “dead” laptop pack. If you have one of those “smart” chargers and some time, you could do a LOT better.
That’s what I think, anyway. But I’m still choked up over the price of the torch with these batteries in it!! Probably the best they could get at the time, I’m sure, but uh…. We’ve moved on since then…
Full disclosure: I have no clue, nor any way to get one, as to what happens inside a ~$400 flashlight!!!
I’m just…
Dim
Yeah I was surprised the light didn’t have panasonics. It did get it a little cheaper than retail, but still paid $325. The SR90 itself has pretty much been passed in performance. Mine thus has had mutilple upgrades. First was a dedoming. That brought my Kcd up to about 195kcd from 140Kcd stock. But it’s lumens dropped from the 1900’s to 1400’s. Next I talked Vinh into installing a custom copper based SBT70 in it. Now that was a huge improvement. Kcd jumped to 325k and lumens back up some to the 1700’s. So it is an impressive light again and justifies me keeping it running one way or another. It’s monster sized, but that monster head gives an impressive beam. My TN31vn is pretty much top dog now in throw at 495k. But the SR90’s beam and spill is still simply amazing to see. More impressive “visually” than the TN31vn.
Plus this light was my “dream light” when I first got into this hobby. So its got sentimental attachment.
I guess basically as long as I have my one good battery pack I’m good to go. As long as Olight still has their SR series lights with compatible battery packs, there is no need to run out and get another one or truthfully to buy a bunch of cells to fix this one. I’ll likely just keep the case and components for a “just in case”.
Sorry to hear that. As we just covered in another thread that wouldn’t actually likely happen with LiIons… That spark means your pack won’t be able to get an ISafe rating, so don’t take it to any chemical factories! If your King Kong upgrade can’t be made to spark like that after you build it, this could be amazing “on the job”!
When I shorted 3 cells in a Dell Inspiron pack, I got pictures…
The wire-whacking may make it difficult to do this, but it’s pretty important to track down what that “extra” circuit board does. My guess would be it’s a protection AND monitoring circuit (maybe half of a 2-part set) which interfaces with that charging port and status display you mentioned.
“Thinking wrong”?? Not IMNERHO! I’m thinking you’re probably right (and I’d wager Olight would love to know too), but I’d still try to track down what that “extra” circuit board does…
It was probably not a Good Idea to whack all the wires that way… But even that’s not “wrong”!!! You will get lots of practice soldering now!! Plus, tracing all the cut wires will help improve a lot of processing skills too… It might be easier to retrace them ASAP, while the “uncut” view is still fresh…
I’m thinking your thinking is launching you on a pretty amazing-looking career as a hacker/modder/hot-rodder, which puts you in some amazing company. And I should remind you not to test your work by pointing it at anything you don’t want to go blind!
So it’s a “Texas EDC”? :bigsmile:
Unfortunately I know I lack the steady hands and good eyes needed to do any serious modding. Been there and tried that. Simple soldering jobs I can handle. I gave up the more advanced stuff when I last attempted to stack 7135 chips to a 16mm board. Ain’t no way that’s happening. My hands/eyes arn’t capable of attaching tabs the size if an ants leg to another ant sitting on a dime. Nope. That sucks because I have pretty good hand eye coordination and mechanical knowledge and experience. But not on something so tiny.
So I leave the serious stuff to the pros like Tom E and Vinh.
The electrical I didn’t totally murder on the pack. Just a couple wire snips to get it mostly apart. Its still 50% intact now. And I took a few shots along the way. So I’m 90% sure I could figure out the wiring if needed.
But it will likely be a back up just in case all of sudden every Olight pack disappears off the planet after my good pack decides to die.
Oh, and I actually think the cells are all fine. I’m going to try cleaning them up, the tips mainly to remove old contacts remains, and carefully try charging them up. The three sitting at 4.0+ volts especially should be fine. The three 3.5v ones are more questionable, but still likely fine. I’m still thinking they had a contact issue or perhaps that circuit board thing failed some how and stopped those three from getting charged. Either way, I’ll likely keep them for backups in case of serious power outages or if Armageddon ever happens 
I think the circuit board is likely a balancing array to make sure all the cells remain identically charged, thats the only reason for more than two wires I can think of.
Assuming that balance board is good, I would suggest the best bet is to find 18650’s that fit and get it rebuilt the same as standard but with better cells. I would expect that the driver is not direct drive so I wouldn’t expect the cells to improve output, only increase available runtime and keep it in regulation for longer, you’d have to fiddle with the driver to exploit the increased output potential of the new cells.
From my experience, I wouldn’t be discouraged from soldering just based on having difficulties stacking 7135s.
That’s something I tried recently, and it was, indeed, very frustrating, even with some experience soldering.
It’s not an easy thing to get the solder to jumper across a gap like between the tab on the original 7135 and the one being stacked, especially with the top one moving around.
Soldering other stuff is pretty much “a piece of cake” compared to that :)!!
It’s like everyone says… practice, practice, practice, and also, I think that for stacking 7135s, you have to find the technique(s) that work best for you, with the specific equipment you’re using.
Thanks for the input guys. When I got bored one afternoon I might try rebuilding the back in one form or another. It’s too cool of a system to discard with the built in power level indicator etc.
Here are a few shots for those who are curious what the guts look like -
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