Are 18350's a good choice?

[pae77]

I was wondering if anyone is using 2 unprotected 18350s instead of a single 18650 and, if so, how they are working out? I was thinking of trying a pair of them in a Solarforce L2P with a DX XPG 5 mode P60 module. Will this combination give me any warning, such as starting to dim noticeably, so I can tell when I should change out the batteries?

 

[dhouseng]

They don't give any warning. You will never know when to stop using the light. When it dims it means the voltage is already way below the recommended discharge voltage, which means damage to the batteries. Without protection you wont get full potential out of these batteries.

 

[lemlux]

I use an 18650 in an old 3P body I've bored out to 3/4" = 19.05 mm. The 18350 is a much stronger power supply in that light than a 16340. I have 3@ new 18350's that deliver between 877 and 923 mAh discharged at 337 mA (the only analysis discharge rate available to me) I drive both LED drop-ins and a wolf-eyes 3.7V LA that came with a single 18500 cell flashlight 5 or six years ago.

Just be sure to change batteries when the light dims or goes into low power flashing mode.

 

[Slickseth]

Using unprotected 18350 cells in series is a bad idea. I've ruined 2 pairs of brand new cells this way. One of them will always end up overdischarging. If you want to use them in series, you need to add a protection pcb to each cell. Dealextreme sells the pcbs for this application. They are a little tricky to install, but once you figure it out, it works like a champ. You will need to order the proper shrink wrap to insulate the cells once the pcbs are installed.

 

[pae77]

Adding PCB's to them sounds like a good idea if it is not too difficult or expensive. Does it require soldering? Any suggestions re where one might find clear detailed instructions on how to set it up correctly that would be appropriate for someone who is not very experienced doing electronics mods?

(My first soldering iron and some related gear just recently arrived and I'm just about to start learning and practicing soldering.)

 

[Slickseth]

Soldering a pcb to a li-ion *probably* isnt a good project for someone who doesnt have much soldering experience. However, after some practice, it shouldnt be too difficult. Please educate yourself on the SERIOUS dangers associated with li-ion cells before even considering such a task. That being said... proceed at your own risk.

The pcb is actually intended to be spot welded to the cell, and not soldered, however, I have soldered directly to li-ion cells many, many times with no adverse affects.

If you order the pcb's, they come with the positive lead attached, and if youve ever disassembled a protected cell, you will understand exactly how to connect it.

Heat is your enemy when soldering diretcly to a battery. This is ESPECIALLY true of li-ion cells. I cannot stress this enough.

Whenever I solder directly to a cell, I make sure that the cell is freezing cold before I solder to it. Placing the batteries in the freezer for an hour or so will do the trick. Make sure that you use a very hot soldering iron (at least 40w). Do not let the tip linger on the surface. You just want to create a small flat dab of solder between your terminal and the battery surface and be done.

Here is a link to the PCB: http://www.dealextreme.com/details.dx/sku.26112

 

[pae77]

Thanks for the additional info.

Yes, I wouldn't attempt to solder either magnets or batteries until I have gotten some practice in on easier and safer projects and acquired some soldering skills. So I won't be trying this for a while.

But a bit further down the road it sounds like a good project to try. At least I chose the right power soldering iron (40 w) to get.