18650'S - UltraFire vs Laptop cell battery.

[Maros]

I bought the O-like 400mW 405nm bluray torch and just received it about a week ago. I also have 6 cells i took out of an old laptop battery which are 18650's.

I was just curious what the difference is between the two. Are they supposed to be the exact same battery? Can I substitute the old laptop 18650's for the ultrafire in my 405 torch?

The ultrafire puts out about 2.4v, The amount of amps it puts out is extremely variable, it starts out at about 2.5A and gets down to around 200mA. This seems pretty odd to me.

The laptop cell puts out about 3.8v, It starts out at 16.5A and gets down to 1.4A but it gets hot in the process. (This is just testing one of the 6 cells, The others registered about the same but that was just quick spot testing).

*** Edit ***

So, not sure what this is about, I know this is the wrong area for this but, I had my ultrafire plugged in to charge all night and tested it this morning with my DMM a few times and now my 405nm is fading to pretty much nothing when I click it on. Hopefully this is just the battery dying?

 

[Drew]

2.4v is too low, sounds like the battery is toast. Any charged 18650 should be around 4.2v static (no draw). The laptop cells should be the same if they have the same dimensions. 3A is about the highest draw you should put on this type of battery, 16.5A is dangerous as lithium batteries have been known to explode. 3A might even be high for a laptop battery as different cells are made to discharge at different rates and laptops are long running devices

 

[Cyparagon]

STOP!!

You will very likely blow up your batteries and sustain serious injury if you short-circuit them with your ammeter like that! :undecided:

18650s Should not be discharged faster than 4A or so. Max current is NOT something you should test. Its a bit like testing the max speed of your car on the open road - it might not end well. Your O-like violet will not need much current. Either battery will work IF you charge it first and IF you haven't killed them already with your "test". ~4.2V is charged. 2.4V is not.

 

[BShanahan14rulz]

When you test the current, in the 5A or 10A range of a multimeter, you are connecting the two electrodes with a piece of solid wire, about 3mm to 4mm in diameter. You are basically shorting the battery with a piece of wire.

Li-Ions can discharge many many amps in a short-circuit situation. However, they can only safely discharge much fewer amps, so the output must have a load, not just a short. Try not to do that test to anymore batteries, and if you can afford to, recycle the ones that you've already shorted. They may have sustained internal damage that would exhibit itself in various ways later on, such as poor performance, slow charging, and exploding while charging.

 

[Maros]

Fail - Well ... that's good times. Hadn't had any issues but at least now I know. Time to order a new 18650 I suppose. Is this true for any type of battery or just these 18650's / Lithiums?

 

[BShanahan14rulz]

almost all batteries don't like being shorted, it's just that lithium primaries and secondaries are capable of much higher currents, and hence much higher powers. Not to mention their "catastrophic failures." When's the last time you saw an alkaline or an Eneloop explode like a pipe bomb or spit fire like a blowtorch?

 

[LarryDFW]

Maros;

A fairly new laptop cell in good condition should deliver 4.2 VDC.

Laptop cells have a finite life of ~ 5 years, or 300 charges,
whichever comes first.

All multi-amp cells can malfunction when directly shorted.

I've seen ni-cads catch fire.

Educate yourself on cell handling, before you abuse them.

Larry

 

[Maros]

Lol I've not seem them do that, In person any way. Is it possible to put some sort of test load between the DMM leads and the battery? Or is that just the same or not worth it?

 

[chipdouglas]

the best bet is to just do voltage tests. but that isn't fool proof either. i have had batteries read full juice but deliver no current. =(

michael.

 

[Seoul_lasers]

I bought the O-like 400mW 405nm bluray torch and just received it about a week ago. I also have 6 cells i took out of an old laptop battery which are 18650's.

I was just curious what the difference is between the two. Are they supposed to be the exact same battery? Can I substitute the old laptop 18650's for the ultrafire in my 405 torch?

The ultrafire puts out about 2.4v, The amount of amps it puts out is extremely variable, it starts out at about 2.5A and gets down to around 200mA. This seems pretty odd to me.

The laptop cell puts out about 3.8v, It starts out at 16.5A and gets down to 1.4A but it gets hot in the process. (This is just testing one of the 6 cells, The others registered about the same but that was just quick spot testing).

*** Edit ***

So, not sure what this is about, I know this is the wrong area for this but, I had my ultrafire plugged in to charge all night and tested it this morning with my DMM a few times and now my 405nm is fading to pretty much nothing when I click it on. Hopefully this is just the battery dying?

Any Li-ion cell putting out 2.4v is a bomb in the charger! Get rid of the cell and replace with a protected cell or new cell.
3.5v is generally cut off for 0 charge.

 

[Cyparagon]

According to the label on a couple of batteries I'm looking at right now, the cutoff is 2.8V.

 

[BShanahan14rulz]

2.7V, 2.8V, 2.6V, either way, if it's below 3.6 resting, charge it.

Also, there's a thread already on how to judge the health of your Li-Ions, and it's stickied, IIRC.