I like the idea of finding and reusing old cells. I know the safe operating voltages and the dangers of using batteries that aren’t testing in the mid 3v on the multimeter. I have an xtar wpII mk. 2, which seems a pretty idiot proof charger for safely charging unprotected cells. I see one or two more 18650 lights in my future. I really think a Sky Ray King is one of them, but I think I need protected cells only. So these questions are to determine if there’s a good choice for that second light so I can use these batteries. I’d like the most power and decent regulation for the buck, and ideally it’d run more than one unprotected cell safely- but I don’t think there’s a good light out there that runs more than one unprotected cell safely. Anyway…
1. I understand correctly about the only safe way to use a laptop pull 18650 cell is in a single cell flashlight right?
2. How do you know when to stop using an unprotected cell in a light and recharge it? Till the light cuts off? If not what’s a good rule of thumb?
3. Building on question 2… Are there any lights that have their own protection built in, that cuts the light off below certain voltages for people that use unprotected cells?
4. Now keeping in mind #1, are there any lights out there that you can use more than one unprotected cell in provided you use matched cells? Lights that have voltage cutoffs? Or some sort of built in protections. I guess it also have to be a parallel light, if this sort of thing exists.
Okay, I’m not buying anything right now, but what do you guys/gals use your unprotected or recycled cells in?
1. Parallel cell configurations are safer. I use a set of matched cells salvaged from a laptop pack in my King clone with no issues. Of course, all cells came from the same pack and had matching voltage. I marked them all as a set and keep those with the King and always charge them together.
2. If your light starts to get dim, then charge the cells. I have never discharged cells to this level though, and always pull/recharge my cells frequently.
3. Yes, some lights do have over-discharge protection that will automatically dim the light or blink a warning when the voltage gets too low. I would not rely on this to be my primary indicator of low charge.
This style light doesn't work with flat top cells (such as laptop salvage) and would need a solder blob added to the positive contact to help make ocntact with the driver...
Less safe, but never causing any issues; I have a low-powered XR-E drop-in installed in a 502d host (P60, 2x18650 series connected) that is too short to take protected cells so I use a pair of matched laptop cells and have never had any problems. This light does not see heavy use; it has a warm-white emitter and I only use it when grilling to get a better idea of the color of the meat I'm cooking. The pocket clip has been removed from this light though, so there are vent holes to prevent pressure build-up if a cell vents...
Let someone else comment on the safety of the King on unprotected cells first. It's what I use, and it works for me...
Yes, you would need to extend the positive pole of your cells to fit. I was able to do this by soldering small brass machine nuts onto the positive caps on the cells. Be careful doing this; make sure your soldering iron is hot, and work quickly so you do not overheat and damage the cells. I use soldering paste as it has a low melting temperature and bonds easily and quickly. Apply a small blob to the positive pole of the cell, heat it with the soldering iron and swirl it around to evenly and thinly coat the surface but remove the heat as quickly as possible. Scuff one side of the spacer you are soldering on and pre-tin it with the soldering paste. Place it on the pre-tinned cell post and heat the nut with your soldering iron until you see it settle into place, then immediately remove the heat and let the part cool.
when you can get two protected sanyo cells for $10 or so, I really cant see the point in risking soldering cells to make them work.
Use the laptop pulls in lights that have a spring/positive post. In a high draw light like a skyray king, it would cost $20 to have four good matched protected cells, bodging cells to work in a potentially dangerous manner just strikes me as folly.
There are plenty of cheap nanjg based single cell lights out there, from mild to wild, edc sized, c8, c12, the whole convoy range at fasttech barring the l2, if your confident enough in your soldering skills to risk soldering cells, why not get a diy host, driver and emitter and build your own light. You’d be able to use your laptop pulls and have the satisfaction of building your own light.
I’m with keltex78 on this. Only thing I would add. If you do use laptop pulls (or any aging cells) in the SRK, don’t lock out the light by unscrewing the head. The cells will remain at the same voltage as long as they remain connected. Disconnect them and some of them are bound to want to self discharge more rapidly than the others.
I’m no expert, but I don’t see much risk in putting a small dab of solder on the center of the positive terminal as long as:
You have decent soldering experience so that you can do it quickly and not run solder down into the vent gaps.
The terminal is undamaged and in the intended raised position (not smushed down).
I refrigerate cells before and as an extra (probably unnecessary) precaution.
I appreciate the concern, but I have soldered before guys. That said, I was most likely going to go with the spacers anyway. Oh and it has nothing to do with cost. I know where to get good protected cells, and that they’re cheap. I own a few already. I started this thread to get a little better understanding of what it means to use unprotected cells. Thanks for all the replies.
