Solarforce L2P & Dereelight 3SD XP-E Q5 5C Problem

Hi everyone,

I just ordered a L2P from itc_shop on ebay, and a Dereelight 3SD XP-E Q5-5C from Dereelight.com. So, I do not have another drop-in to test.

The drop-in only works with a single 18650. It has 3 ouputs, 100% 50% and 5%. The light would only turn on with the outer spring. I have tried the following batteries: AW 18650 2200 mAh, AW 18650 2600 mAh, TrustFire and Solarforce 18650.

All have given the same results, so I decided to continue the troubleshooting with AW 18650 2600 mAh.

The problem is when you shake the light hard enough, it changes mode. And if you drop it, it would go into a S.O.S mode, a mode that it does not have.

If you loosen the tailcap half a turn, you only need to lightly shake it for it to change modes.

I have tried adding 1.6mm magnets on both ends of the battery, added copper tape to the side of the drop-in, tighten the switch, padded the side of the battery, and cleaned the contacts with DeoxIT gold. Nothing has worked. I'm stump and would appreciate some help.

Thank you.

^Gurthang said:

Steve,

Have you checked the drop-in to see if the driver board is securely soldered? What you describe is an intermittent contact problem [like that wasn't obvious].

Seems like you've covered MOST of the common cures. If you have a DMM set it for resistence [ohms] and check for continuity between the pill and the driver.

I suspect a cold solder joint, which will show as an open short [max resistance] if you press on the drop-in. That would produce the mode switching you're having.

I've had the same problem w/ a couple of DIY drop-ins..... Now I use single strand 22ga. copper wire to solder a driver into its pill.

Good luck, hope this helps.

Click to expand...

Thank you, Gurthang. The joints look fine and I don't have a device to test the resistance. There was one thing I didn't test with a AW 2200 mAh, that was using 1.6mm magnets, one on each end. That seem to solve the shaking problem, but dropping the light from 2 feet to the ground does make it go into what I call S.O.S mode. It happens once in awhile but not as frequent.

Which brings me to believe that it's the contact springs on the drop-in and the tail switch that's the problem. Perhaps they are too soft or short, so I will try to find a replacement tail switch with a stiffer spring.

The magnets will have to do for now until I find a proper solution. Thanks again. Anymore help is still appreciated.

-----

Anyone else that has this combo, please chime in.

Thank you.

It't most certainly the +spring on the dropin that's on the short side...

LV426 said:

It't most certainly the +spring on the dropin that's on the short side...

Click to expand...

Since I can't test for resistance, and if it comes down to it, I'll will try to re-solder the joints on the contact spring later this weekend.

Thanks.

I have the same problem with yesterday delivered dereeligh cl1h v4 with 3sd q5 5c: shake it, and it switch not to sos, but to flickering "low voltage" warning. It's definitely contacts problem, when tight with force head and tail surround 18650 with paper for more solid overall feel, the flickering on shaking is gone. So, this mean, that voltage watchdog is triggered too early when contact is gone for miliseconds, treating this situation as undervoltage and engage low voltage warning beacon. :thinking:

Just received a pair of L2Ps from itc_shop and have the same problem of mode switching if you shake the torch hard enough. Actually was able to do it with just rotating my wrist up to take a look at the lens, have to rotate rather slow for it not to change.

I don't have a dereelight drop-in but was using a XPG-R5 pill from a DX ultrafire L2.

The problem seems to be is that the battery tube is bored too large and is too long.

All my 18650 batteries rattle inside. CR123A's are even worse. Adding 4mm of magnets helps, but battery still rattles and I bet if I but them on my handlebars and go for a ride they will change when I hit bumps.

The cheap DX ultrafire L2 has much tighter tolerances here, batteries don't rattle in use. Batteries don't even slide out in them if you take the tailcap off, I usually have to flick the torch with my finger on the end to catch the battery. The L2Ps do have better threads and finish but what's the point when your light rattles and changes modes.

BTW, I had to remove the -spring from the pill and add copper tape at the bottom to fully screw on the head.

I'm surprised this has happened given all that I've read hear about the L2's and L2Ps. Is this a recent problem?

edit: the length of the +spring on the pill is 9mm. How long are P60/D26 +springs supposed to be?

There are many L2P owners out there and I'm surprised that no one has really brought this up. I've seen only a few threads that talk about the L2P's body being a bit too long and wide, but no one has really mention it interfering with multi-mode drop-ins.

Regarding the 9mm height of the +spring, I don't know if it's the typical normal length, but I decided to find my own solutions.

Solution 1: No modification to drop-in or flashlight
You have to use two magnets, one on each end of the battery. I used 1.6mm magnets from lighthound.com with an AW 18650 2200 mAh battery, and it seems to solve the problem, but if you shake it hard enough or drop it, the low voltage warning will come on.

Solution 2: No modification to drop-in or flashlight
Buy some #4-40 x 3/4" flat head slotted screws from Home Depot. It comes with 8 screws and 8 nuts. Then I cut a screw to about 9mm, attached the nut and place it inside the +spring. What this does is it stiffens the spring. Shaking problem is gone, low voltage warning still persist, if you drop your light.

Solution 3: Modification to the drop-in
There's no store that I know of that sells +springs for p60 size drop-ins. So, I found an old xenon bulb for my WF-500 and took the +spring from it. The spring is about 15mm in height and the diameter of the end that contacts the drop-in is just about the right size.

The tricky part was desoldering the +spring from my drop-in. I used some desoldering braid and managed to get it to a point where it was thin enough for me to use a razor to scrap it off. It didn't come off completely clean, part of the contact on the drop-in teared off. Then it was a matter of just soldering the longer spring on.

This solution does solve the shaking problem, but it does still go into low voltage warning (looks like S.O.S) occasionally if you drop it.

Maybe next time, I will probably use a heatgun to melt the solder off the spring.

Solution 4: Modification to the flashlight
I have not tried this method yet. Instead of modifying your drop-in, perhaps you can just add a longer spring to the -spring on the tailcap, though I don't know what this will do to the resistance.


Any Solarforce L2 and L2P users that experienced this problem, please let us know.

Thank you.

Update
I just received a Solarforce R2 3-mode drop-in from lighthound.com.
The +spring is about ~10.5mm, compared to the 9mm on the Dereelight, and it's also a bit stiffer.

I used an AW 18650 2600 mAh (flat top) for the quick test and it did not change mode when shake or dropped.

I guess every p60 drop-in is different. I really like the color rendition of the Q5-5C and most likely will order more from Dereelight, the only problem is they'll have to be modified to work in my L2P.

The bore diameter of the L2p is slightly bigger than expected. I've contacted Solarforce about this and potential issues it may cause.

@maz, thanks for the solutions and update. Seems the spring stiffness is the issue or body too long depending on how you want to look at it. Solution 3 seems the only real option, I might loose magnets during a battery change and the tailcap spring seems rather long already.

To rely on spring stiffness doesn't seem like a good design to me as spring stiffness will fade with use.

I hope my pair of Nailbender neutral whites will work, should have them by Tues.

Maybe they should advertise only for use with solarforce drop-ins. :thumbsdow

@jake. Thanks for the confirmation on the bore diameter. Do you know if the battery tube length is longer for the L2P vs L2? L2P vs 6P?

From another thread I found that the L2P body tube is longer than the L2 by almost 2mm. I have 1mm magnets and 2 of them does seem to stop the mode changes.

My solution to the battery rattle is to line the inside of the tube with tape. I stuck 9 pieces of desktop tape (some type that I've had for a few years that doesn't leave sticky residue) a little longer than an 18650 battery on top of each other with the bottom piece longer than the rest. Peeled them off by peeling off the bottom one and cut the ends to clean things up, bent it into a u shape, then slid down into the tube. I used the flat backside of the clear plastic casing the L2P came in to do this tape layering.

Result is it holds the battery, though some of my batteries I have to rotate a bit for it to go in without too much resistance.

Also thinking about soldering a magnet to the end of the tail spring. Since my magnets are 1mm thick it will be easy to adjust as needed by adding or subtracting magnets to make future drop-ins work.

Really surprised to have to do this to such a highly praised light. BTW, the inside of the body tube seems to taper a little bit towards the head (narrower).

jake25 said:

The bore diameter of the L2p is slightly bigger than expected. I've contacted Solarforce about this and potential issues it may cause.

Click to expand...

Jake,
Any word on fix?? This noob really wants to purchase a L2P (host or w/ drop-in) but will wait for a fix (narrower body?). Ready to spend $

double-d said:

Jake,
Any word on fix?? This noob really wants to purchase a L2P (host or w/ drop-in) but will wait for a fix (narrower body?). Ready to spend $

Click to expand...

The reality is that this issue may not be fixed anytime soon. To me, the L2P is still a fantastic value and very good flashlight. The easiest solution I think is to go to the hardware store and find some kind of tubing that can go around the batteries. That's been a method I've seen on many occasions even on custom flashlight body tubes that were designed to use different battery types.

mellowman said:

From another thread I found that the L2P body tube is longer than the L2 by almost 2mm. I have 1mm magnets and 2 of them does seem to stop the mode changes.

My solution to the battery rattle is to line the inside of the tube with tape. I stuck 9 pieces of desktop tape (some type that I've had for a few years that doesn't leave sticky residue) a little longer than an 18650 battery on top of each other with the bottom piece longer than the rest. Peeled them off by peeling off the bottom one and cut the ends to clean things up, bent it into a u shape, then slid down into the tube. I used the flat backside of the clear plastic casing the L2P came in to do this tape layering.

Result is it holds the battery, though some of my batteries I have to rotate a bit for it to go in without too much resistance.

Also thinking about soldering a magnet to the end of the tail spring. Since my magnets are 1mm thick it will be easy to adjust as needed by adding or subtracting magnets to make future drop-ins work.

Really surprised to have to do this to such a highly praised light. BTW, the inside of the body tube seems to taper a little bit towards the head (narrower).

Click to expand...

Heating magnets can destroy the magnetism. do it with great caution.

High quality electrical tape is also good. Few rounds around the cell doesn't cause problems with chargers but most likely you can't use those cells in other lights.

I have the same L2P host and dreelight drop-in. Like others I ended up using a cylindrical magnet as a spacer to make up for the short spring / long body tube issue. As far as the battery rattle I came up with a very sophisticated fix. I shoved a thin piece of cardboard in that sucker. Works fine.
On the other hand I'm not really sure why Solarforce decided to make such an oversized body tube, both length and width are much more than needed.

Still a fantastic light. Especially for the price.

mn_doggie said:

Heating magnets can destroy the magnetism. do it with great caution.

Click to expand...

Yea, decided against that idea when I measured the resistance of a couple magnets stuck together, some 5+ ohms. Adds too much me thinks.

Anyway, I stiffened the module + spring by adding aluminum foil. The foil is wound up in the spring pretty good and with the spring tension should hold it fine. I waved and shook it about in my hand and couldn't get the foil to move.

Also moved the tail cap switch up when replacing the tail cap button to a GITD one. So the tail spring is now closer to the body. Seems the switch itself was screwed down more than it needs to be (about a mm) for the tail cap to be flush with the torch. This helped a lot, now I can't get the mode to change at all no matter how hard I shake.

You can tape your batteries to stop the battery rattle but if you have other torches/flashlights to put the same batteries into you now have a problem because they are too thick. So my solution was to stick the tape inside the torch body instead. Alternatively you could create a sleeve from some plastic or cardboard.

It's a shame a host like this has these problems but I think that is why it is rather cheap. An equivalent host cost 2-3x has much. Enough to pay for a nice custom drop-in.

mellowman said:

It's a shame a host like this has these problems but I think that is why it is rather cheap. An equivalent host cost 2-3x has much. Enough to pay for a nice custom drop-in.

Click to expand...

As a whole, I still very much like the L2P with the problems it has. To me, it is still a great value and well made host in general. The problem is that Solarforce decided to make the body a little longer than the standard L2 body for some reason. I also wish the inside diameter was a little smaller as well since even 18650s will rattle in it. The issue has already been made known to Solarforce and I have faith that they'll adjust their manufacturing process to fix these problems.

IN general , the L2 series of lights are a little generous in there length ...
I have found that if you carefully stretch , the springs ...

DONT try to pull against solder joints , hold with pliers both ends ..

The L2's are a little too long in the body , so if you 'shake n bake' , the battery will lose contact momentarily , hence the switching of modes ...

One of the tiny reasons I like the Xtar 18700 , it fills up the L2 body a little better than other batteries ..