I use aluminum strips around a P60 to help remove heat. I know this helps and will always do it but is it something that really has to be done or something that helps with heat sag and durability?
The reason I am thinking about this is I have a friend who wants a SF L2i and he wants to use 18650 batteries. No problem so far except that the L2i has to be loaded from the head end as I describe towards the end of this thread Solarforce L2i too tight with 18650
Now done that way the battery fits perfectly. The problem is that I can’t give a guy a light that has a bunch of crap wrapped around the dropin if he is going to be handling the dropin.It’s not proper. If he was going to be loading batteries from the tail then I would have no problem properly heat sinking the dropin. Every other light I give to people has Al strips in the head. This guy wants the L2i and nothing else. I don’t blam him because it is also my favorite.
If I give him this light will it have real world problems or just suffer some extra heat sag?
Without decent heasinking he will severely reduce the lifetme of the emitter and possibly driver if he likes to use the flashlight for extended periods. If anyone would use it for 20 sec at a time with a few min pauses in between it would probably not matter at all. Why the L2i cannot be loaded from tail? o.O (i don't own one)
It's shorter and wider than 18650 accepting host should be. So if loaded from tail, the battery will hit the ridge (ring, or whatever) between body and head and not go as long as it needs to go so that tailcap could be tightened. When loaded from head, it can be inserted so that the ridge (ring, or whatever) does not interfere and the battery sits "higher" in the tube and cap and head han be tightened.
Hmph.. I can't really explain it. Not sure if I could explain it in my own language, let alone a foreign one. Buy one and you'll find out 
Everyone loves them (I have one, second on the way).
Got it. Would not be nice if you find a pvc tube to cram inside as a guideline where the battery should go? My ex romisen RC-C8 came with such tube stock...
You did a fine job of explaining it. It is also explained in the link from the first post, towards the end.
Has anybody ever seen a failure that they can say was caused by not wrapping a p60? I know the emitter will dim as it gets hot and that’s not good but a fried driver or emitter?
Budgeteer, I was thinking the same and I have a trip to the hardware store planned. A piece that would fit nicely on there with an ID that will allow an 18650 would be the answer. I just have to see if any standard sizes work.
The strips are pretty easy to put in or take out and usually you can remove the drop-in without messing with the strips, so I would just explain to your friend why they are there and that he should leave them in place.
I always tought to go to the lathe guy to machine some inserts exactly for the dropins and p60 hosts. The only problem (and a big one) is that those have to be made individually... you would not believe how far from standard these tolerances go...
That is probably what I will be doing if I can’t make a sleeve that’s nice. I know the guy probably wouldn’t mind but it seems a little half assed for me to tell someone to mess with something every time they change the batteries. That’s just me though, I can’t do it. I just wish he wanted an L2. I don’t blame him though because the L2i is sweet. Doesn’t bother me changing the batt with the strip in but when you do it alot, which you do if you have to change the batteries that way, the strips do tend to creep up and start splitting on the reflector flange. If you put them in right then it is pretty tight too. Not bad for removing every now and then but doing it often might be a pain.
How 'bout this stuff...
I got a roll of 3M Al foil tape from local Lidl for less than 2 euros. Use it in my high voltage dropin. Seems to work ok. Glue does smell a bit weird when hot, though.
Yeah, different hosts will have different inner diameters and the drop-ins will have different diameters too. Even with the same brand: I have a Solarforce L2i that needs a different number of strips than a Solarforce L2 with the same drop-in.
Would be nice at 1st tought but on second i suspect the glue would act as a nice insulator and adversely affect the heat transfer.
I wrapped the dropin in my P60 host with flat, tightly folded aluminuim foil and then used a small bit of the aluminum tape to hold it tight while I pressed the insert into the head with a clamp. Because great care was taken to ensure the aluminum was wrapped flat with no creases and considerable force was used to insert, the aluminum compressed nicely making good contact with the inside of the head. Of course, it is now very difficult to disassemble the head if I ever need to work on it again.
I would agree about adhesive on the aluminum tape hindering heat transfer. The adhesive seems to be rather thick on aluminum tape so personally, I rely on it in this application.
I use a coca cola (or another brand :p) tin can that i've cut open. Works perfectly
I have had no problems loading 18650 batteries in my 3 L2i's
You just have to be careful that things are lined up when you put the tailcap on.
OTOH, I would not gift a light with 18650 batteries; that's why I bought the L2i's. Gift them with 3xAAA in them.
I'm not comfortable with the adhesive either and I may have missed it but you've not mentioned the drop-in your friend plans to use. I was doing some run time tests Sunday evening with a couple of lights including the L2i. With the 3-mode Ultra Fire XM-L drop-in using 3 x AAA NiMH, 20 minutes passed before the light dimmed with useful light continuing (dimming) for about another 10 minutes. So, of course 18650 is the only way to go and the heat concerns are valid, espeically with this drop-in.
At the same time, I also began a run time test with an L2P/UF XM-L, leaving it sitting on the ottoman. (I.E., no heat transfer from flashlight to hand) When I picked it up, maybe 15 minutes later, I dropped it like a hot potato. It was too hot to hold for more than a one count, hotter than I have ever had one of these get. I knew immediately why because I had swapped several drop-ins in and out of this particular host over the past week and had not re-wrapped the XM-L. I will never doubt the importance of addressing heat issues with high-power P60 combinations again. It was the first time I actually could not pick up the flashlight - it was that hot.
Maybe we could talk about the efficacy/manner the human body plays to wick heat from a flashlight.
sorryforthelongrambleFoy
+1
I'm all against giving a li-ion based flashlight to those who do not understand how li-ion works and what is a worst case scenario. I gift only AA/AAA flashlights and push them to those i feel pretty confident they are not to be trusted with li-ion based technology. Call it playing it safe.
Hi Foy;
I need to think through that statement in bold, not sure I'm 100% correct, would like more input on this. If the light was so hot you could barely handle it, then it was doing a good job of heat transfer. That is what copper or alum foil is supposed to do. The situations where emitters/drivers get damaged are when they get way too hot before the light itself does; your hand does not feel it because the driver is not getting the heat wicked away to the body of the light.
If the host was so hot you could barely handle it, then what you have is a well-driven XM-L. They do get hot! Better foil wrapping will only make the body hotter, it's not going to save your hand when you touch it.
Thanks for running that test. I was wondering how 3xAAA would work running an XM-L at 3A or so. Seems like a really high draw for such a little battery, but I guess they are up to it.
Realistically a wrapped light should get hotter than one that isn't because the wrap is transferring the heat to the body. If the light was hot, then the heat was leaving the drop-in as it should. What you don't want is a light that doesn't feel hot because then the LED must be baking inside with no way to dump the heat.
About the only way to tell for sure is to an infrared temperature scan, which someone on CPF did that seemed to show a wrapped drop-in distributed heat better than an unwrapped one. I wish he had kept doing more study, because it was kind of hard to tell just from the thermal pictures and I think he was just using foil.
+1 on all that. If your flashlight is hot, that is a good thing. So why was Foys unwrapped light too hot to touch? Maybe because the aluminum reflector, which we can’t forget is there, transfers the heat to up near the bezel area. The heat then escapes the light in a more concentrated area, making this area hotter than if the energy was spread out over the whole head.