Newbie Modder: diag battery problem

[ckc]

This is my first mod, and I've hit a snag, and not where what I should do next..

I have a Mag 2D which I put in a "prebuilt" P7 drop in (it's not a drop in for a Mag, so I had to mod the reflector to fit..)

I got it all working with a 2x 18650 setup, and it was working good however...

I turned it on this morning (8 hours after completion), and nothing.. opened it up ,and one of the cells was leaking, and both were reading low (0.8 and 1.2 volts)

the light was not left on over night.. and the batteries were fully charged last night..

1) is the leaking cell salvageable?

2) is there something I can check to see the cause of the drain??

 

[LukeA]

The cells are dead and are unsafe to attempt to charge, and no good charger will even accept them at that voltage.

Never use a lithium cell that has dropped below 3.0V.

 

[Conte]

Whoa, that's odd.

Yeah, those cells are toast. RIP.

So, you're saying you left the cells in the flashlight, and 8 hours later, this happened ?

Where did you get this "drop in"?
Where did you get the cells ?
Are the cells protected ?

Is the mag stock for the most part with the exception of the dropin?
For example, does it have a stock switch ?
Is the reflector the only thing you modded to fit ?
What form of tailcap mod did you do to accommodate the 18650 cells in the mag ?

Is it possible that the cells popped while you were testing the light, and you did not notice, cause you did not open the light up after you tested it ?

All I have is questions right now. With more input we might be able to help you troubleshoot the problem.

For now, I think it's safe to say, at the very least, you're poor batteries are garbage.

 

[ckc]

So, you're saying you left the cells in the flashlight, and 8 hours later, this happened ?

Yup..

Where did you get this "drop in"?
Where did you get the cells ?
Are the cells protected ?

it's from deal extreme..
http://www.dealextreme.com/details.dx/sku.14413

the Cells came from battery Junction (Trust Fire 2400 mah with the charger..) Note.. I have NOT contacted B.J. yet as I was not sure what was wrong. plus considering it's a modded light, I wasn't sure if it was my fault..)

the cells were protected.. (edit well again.. I just checked them and it says "short-circuit" and "over-current" protected..... but is there a "over-discharge" protection????)

Is the mag stock for the most part with the exception of the dropin?
For example, does it have a stock switch ?
Is the reflector the only thing you modded to fit ?
What form of tailcap mod did you do to accommodate the 18650 cells in the mag ?
[/quote

I had to mod the switch, and the battery holders, and the tail cap (recessed).. pretty much a complete mod (except the heat sink was attached to the reflector, which is non focusing)

Is it possible that the cells popped while you were testing the light, and you did not notice, cause you did not open the light up after you tested it ?

maybe... the light was only on for about 10-15 seconds each time when I was putting it together....

All I have is questions right now. With more input we might be able to help you troubleshoot the problem.

For now, I think it's safe to say, at the very least, you're poor batteries are garbage.

thought so.. Thanks..

 

[spencer]

If they are protected then they shouldn't be at that voltage. On the other hand I have heard that the ___Fire batteries have less than great protection.

 

[ckc]

Is there an easy way to find out if the light is draining the battery when it's off?

 

[Conte]

Is there an easy way to find out if the light is draining the battery when it's off?

Not unless you have a multi meter.

both were reading low (0.8 and 1.2 volts)

This statement suggest that you indeed do. Set is to test of resistance (ohms). Set is to the lowest setting too, x1 if you got it, then try and test for resistance between the pos and neg terminals in the flashlight that the batteries connect too. When the switch is off, it should read ZERO, if you get any reading at all while the switch is off, you found your part of your problems.

The other way is to, while you have the batteries in, with the tail cap removed. Set your meter to read Amperage draw (DC-A). Set it to at least a 1 amp or greater setting if you have it. If you have a cheap meter that is limited to say 200 - 500ma that that will do for short bursts. In this setting bridge the gap between the Battery negative, and the flashlight body in lieu of the tailcap. The Pos probe will connect to the body. With the switch off, again, you should have ZERO reading. Otherwise, if it reads, then again, you've found part of your problem.

The other part of said problems being WHY it is shorting out.

The question you have to ask yourself is: would any for your mod between the batteries and the drop in be causing a short of some kind?
Which is why I ask what kind of mods you've done to the switch.

I ask how you modded the tail cap, because, perhaps it is possible that a sloppy job, or wrong choice of spring made to tooo tight a fit, to that when you put everything together, you perhaps crushed and damaged the protecting PCB's causing THEM to short out and ruin the batteries.

if you are going to buy some new batteries, I would maybe suggest some AW cells or something that other CPF members can confirm as being trust worthy.

 

[ckc]

Not unless you have a multi meter.

I do (a nice one..) and I'll give what you suggested a try..

I ask how you modded the tail cap, because, perhaps it is possible that a sloppy job, or wrong choice of spring made to tooo tight a fit, to that when you put everything together, you perhaps crushed and damaged the protecting PCB's causing THEM to short out and ruin the batteries.

Ahhh now there is something.. I recessed (with a lathe) the standard metal spring that the mag had (and built an insert for the hole in the middle).. it is a tight fit (tension/pressure wise). that may be the culprit.. I could cut the spring shorter, and reduce the pressure on the battery once the tail cap is on.

 

[ckc]

just an update... I have not checked for a short/drain yet..

but i took another look at the cells before I tossed them, and found out that one is still good.. when I wiped it off and put it on the meter.. it was measuring 3.9 volts.. I guess the oil and the contact points were bad and one was not reading right.. after charging it (10 mins) it read 4.1 on the meter..

so only one cell has gone bad.. maybe it's not the light then???

 

[Conte]

Check out my Mag C Tail mod here:

http://www.candlepowerforums.com/vb/showthread.php?t=255089

Heh, if it was me, I would kind of hope that is it a Crush PCB, then that mean's the rest of my mod is fine.