(SOLVED) Rebuilt Torch Burns Hotter Than Before

Hello everybody,
I am eager to build my first torch from the ground up, but I am learning the electronics and components functions first and also waiting on parts. So, for practice, I decided to completely disassemble a torch I have and reassemble it.

I desoldered all wires, removed the star from where it was mounted, removed and desoldered the driver, and cleaned off all the solder with a desoldering bulb. I wanted soldering practice and the feel of actually building a light so I reassembled everything as it was.

The problem is it gets WAY hotter than before. Actually too hot to hold and I know something's not right because it actually melted a plastic piece that sat over the star. The battery was too hot to hold also and this is what worries me most; I don't want to blow up.

What could be causing this? Is it possible I used higher resistance wire? It looked the same gauge to me but I don't know for sure. I checked the following before I posted:

-made sure the driver and LED were connected correctly and there are no shorts
-made sure that everything was making contact as before so the heat dissipates through the head
-made sure I didn't use too much solder that would cause more resistance

Thanks a lot for any help.

Re: Rebuilt Torch Burns Hotter Than Before

What type of LED is in the light and what type of cell(s) does it use? Do you have a DMM to measure the current?

Re: Rebuilt Torch Burns Hotter Than Before

Mike S said:

What type of LED is in the light and what type of cell(s) does it use? Do you have a DMM to measure the current?

Click to expand...

It's a single XP-G R4 and it is running on a single 18650. The max Vf on the XPG is 3.25 @ 1.5A and I'm just wondering if slight differences in the wires I used could be causing it. Strange that the same connections would run hotter. I unfortunately do not have a DMM (yet).

Re: Rebuilt Torch Burns Hotter Than Before

Are you saying you desoldered all the components from the driver board?

You may have created a short circuit somewhere along the line, which is, I think, the most obvious problem. I would suggest stop using it. If there is a short, the current drain coul d be high enough to cause a cell to go into thermal overload and catch fire.

Re: Rebuilt Torch Burns Hotter Than Before

John_Galt said:

Are you saying you desoldered all the components from the driver board?

You may have created a short circuit somewhere along the line, which is, I think, the most obvious problem. I would suggest stop using it. If there is a short, the current drain coul d be high enough to cause a cell to go into thermal overload and catch fire.

Click to expand...

I didn't remove the components from the driver, just removed positive and negative leads to the driver. I am definitely not ready to desolder microcontrollers and stuff like that. Is it possible that I created an unintended bridge on the board and am getting heat that way?

Re: Rebuilt Torch Burns Hotter Than Before

Does the light use AMC7135 chips or some other low side current sink driver? It sounds to me like the cathode wire from the LED is shorting out, so it's now being driven directly off the cell.

Check the cathode wire and make sure there are no cuts in the insulation and that the ends of the wire aren't touching something they shouldn't (pill, MCPCB, battery tube etc).

Re: Rebuilt Torch Burns Hotter Than Before

Soldering the negative output wire is sometims tricky. On some popular multi-mode boards, the negative output is right next to negative input and any solder bridge is going to run the LED directly off of the battery.

SOLVED

Thank you for these suggestions. I went ahead and desoldered everything from the board. I made a reference on paper, removed the components and cleaned everything up. While removing, I did notice 2 things : a slightly frayed negative lead connection and possibly some misplaced solder on the board itself.

I don't know for sure if or which of these was the culprit, but after I painstakingly got it back together, I am very happy to say it seems normal. It gets warm but not scorching hot. So, I got more than I bargained for, but definitely the practice I needed.

Thank you guys for helping out on what to look for, you are a light saver!