Streamlight Argo HP --> 18650 possible?

Just recently I jumped onto the 18650-train.
As I still need a good headlamp (mod) I think about modding an Argo HP, but am not sure if the batt compartment could be bored to the 18,2 mm diameter needed.
Anyone who has an Argo, could You please measure the lamp and give some info?

Or are there any other headlamps using 2 pieces of CR123 batteries?

Or are there any other headlamps using 2 pieces of CR123 batteries?[/QUOTE]

Try the Favourlight 3 Watt (reviewed in flashlightsreview.com).

but the batts are not in line there
(I checked the 3 lights with this batt type mentionned in flashlightreviews)

no way 18650 can fit

well why?
if You posted "the batt compartment has a diameter of xx and thus cant be bored to the 18 mm needed" would have been much more helpful.

Anyone please measure the outer diameter of the batt compartment?

Use a 17670 Li-Ion rechargeable. It fits perfectly. Search the forum for a recent thread w/ pix.

Ha-Ha! (on me) - My first response was going to be: "Look, I've got an HP. I've got a 18650 cell. It just won't go. Not enough material for boring. Trust me." But at yellow's insistance for a more technical answer, I'm starting to think it just might be possible. I still think it's a tough call - you'd have to remove the contact strip support guides plus a little more material from the tube. And you would have to rely on the 18650 to hold the contact strips in place. IE - if you pulled out the 18650 cell to charge it, the contact strips would fall out. Perhaps they could be glued into position. I'm not sure I've got the tools or skills to make it happen. But with an approaching long holiday weekend and a couple of beers, I just may put my HP "under-the-knife".

wow, great photos
awaiting Your findings (and looking on where to get an Argo HP)

I hoped that there might already be some "rattle" with the CR123s + enough material for widening the diameter + the leads be possible to change accordingly (both into the end caps) ...
and it looks like it will be possible.


PS: not willing to use 17xxxs. In my opinion they are completely useless. Not much better than the 14xxx models, but almost the size of the (much better) 18650...

EvilLithiumMan said:

Ha-Ha! (on me) - My first response was going to be: "Look, I've got an HP. I've got a 18650 cell. It just won't go. Not enough material for boring. Trust me." But at yellow's insistance for a more technical answer, I'm starting to think it just might be possible. I still think it's a tough call - you'd have to remove the contact strip support guides plus a little more material from the tube. And you would have to rely on the 18650 to hold the contact strips in place. IE - if you pulled out the 18650 cell to charge it, the contact strips would fall out. Perhaps they could be glued into position. I'm not sure I've got the tools or skills to make it happen. But with an approaching long holiday weekend and a couple of beers, I just may put my HP "under-the-knife".

Click to expand...

Very nice photos! The second one has me a bit confused though. The labeling makes it look as if the positive and negative contacts are shorted together.

Doug S said:

Very nice photos! The second one has me a bit confused though. The labeling makes it look as if the positive and negative contacts are shorted together.

Click to expand...

There is about a 2mm gap between the contacts. It's a little hard to see because of the angle of the camera, but it is the "bright arc" in the photo.

The heck with long weekends and beer, I've started the mod. I'm about 2/3 done and about 90% confident the 18650 cell will fit. (Although now that I'm this far along, I'm wondering if the 3.7V Li-Ion will even drive the 6V Argo to full brightness?) It hasn't all been a bed of roses. Ugly details and pics to be posted in a few hours, I hope.

A 17650, 17670, or 18650 will run in the Argo HP though output will proably be somewhat reduced. I do not think that the HP circuit is set up for buck/boost, and no doubt is a buck circuit.

Bill

Bullzeyebill said:

A 17650, 17670, or 18650 will run in the Argo HP though output will proably be somewhat reduced. I do not think that the HP circuit is set up for buck/boost, and no doubt is a buck circuit.

Bill

Click to expand...

Actually, if it is a reasonably designed stepdown switcher (buck), it likely will be about the same brightness as with the stock 2xCR123. For typical Luxeon Vf, a single Li-ion is nearly fully discharged before the buck would have to stop switching and go into direct drive mode.

Because my posts are always long winded, I'll start with the conclusion:

Good news - the Argo HP can be modded to accept a 18650 Li-Ion cell and still run it at full brighness.

Bad news - the mod is pretty much irreversible. I don't see CR123 cells going back in after all the material that has been removed. (Although one might be able make a spacer to enlarge the 16mm CR123 cells diameter to 18mm)

Long winded part:

Start by completely disassembling the Argo HP. The positve battery cap is a snap fit, not threaded. It's on pretty tight, but using a pair of padded jaw pliers with a "twist and pull" motion will remove it without damage. Remove the bezel, lens and two screws that secure the LED module. The module is also a little bit of a tight fit. Just use a small bladed screwdriver and carefully work it out along the circumference, "coaxing" it to the front.

Now the ugly part. I was hoping the battery contacts would easily slide out of their retaining rails, but no such luck. The contacts have a pair of "teeth" on them that pretty much ensures once they are installed, they stay that way. Another problem is that the contacts aren't very thick, so they became a little bent up during removal. I had to reshape them and grind down the rough spots. If anyone discovers a neater way to remove them, please share.

Once you are down to the shell of the body, you can start boring it out. It took me about 90 minutes of filing with a rat ******* file to remove enough material for the 18650 cell to fit. (It may not have been a rat ******* file, but I like to say "rat *******") (place rim shot here) (OK - I stole that line from another post, but you still laughed, right?)

Because there are no longer any guides to hold the battery contacts, you have to rely on the 18650 cell to keep them in place. So you want the final fit to be snug. (But not so snug the positve contact cuts through the cell's insulation. Talk about a disaster! Wish I had a protected cell for this project, but I don't). If I end up with a short, I'll be kissing my Argo goodbye.

When assembling the light, start by placing the positive contact on the cell and installing from the positve side. Install the positive end cap. Now carefully slide in the negative contact strip. Be sure leave a little bit of the negative contact strip sticking out beyond the threads so it makes contact with the battery cap. Before installing the PCB/LED module, measure the
voltage on the contacts, verifying 3.7V is present.

As far as charging goes, I'm leaving the cell installed and using alligator clips. I don't think it's worth the risk of monkeying around with removing and reseating the contacts to do a charge.

Here's some pics:






ELM

Nice work. Since you have had a chance to examine the construction of this light, you can answer a question I have wondered about. How would you rate the watertightness of this headlamp?
If you had it to do over again, would you do the same or settle for using the lesser capacity 17670 cells?

posted a thread modding argo hp with Sbin and 17670 awhile back.
excellent little light! used it for several extended run jobs underneath a truck. ran for 5-6 hours, still had plenty of juice left.

http://candlepowerforums.com/vb/showthread.php?t=134811

Doug S said:

Nice work. Since you have had a chance to examine the construction of this light, you can answer a question I have wondered about. How would you rate the watertightness of this headlamp?
If you had it to do over again, would you do the same or settle for using the lesser capacity 17670 cells?

Click to expand...

The Argo HP is rated as being "water-resistant", not "waterproof", so you really shouldn't dunk it in a sink full of water. Of course, you shouldn't really try to stuff a 18650 cell into it either.

My Argo failed the dunk test - a small amount of water entered the positive cap end, despite there being an o-ring. But I'm pretty sure I have compromised it's seal by having it off a dozen times during this mod. First time I removed it, it took a healthy "twist-and-pull" to get it off. Now it's a lot easier to remove and even has some play to it when installed. The bezel and negative (threaded) cap were completely dry.

Would I do the mod again? Certainly. It's the challenge. It's the knowledge that I now have as much Li-Ion capacity (2400maH) as is practical. Did I risk ruining the Argo HP? Certainly. But when you rip into a flashlight like a chimp into a cupcake, that's the risk you take.

Thanks!

my hat is off to you ELM!!!!
now eating my words

got the HP just a day ago

... boy, this light is SMALL!
I thought I got a wrong one when I opened the envelope (till now, 2 pcs. Cr123A was the size of a SF 6P to me ...)
be4 starting with getting the interior out, I wasnt even sure if the other driver might fit in ....

After removing these contact plates, my 18650 got into the body till to the "reels" mentionned. When they are removed, no problem. And I think there is still some material left to widen a bit and put the contact plates (with a little cutdown) back in. Just have to be epoxied, but ...
Much better than my 1st idea of outside wires.
When it comes to emitter and circuit, there really is enough space for a realistic heatsink, board, on/off/level switches in front of the emitter (light will be switched by turning the head).
The now not needed hole for the original switch will hold an extending rod of aluminium, mounted to the heatsink inside, to get some heat away.

If ever finished, what a small, but powerful light, able to run for the full battery power without overheating