18650 and 16340 in the same light, At The Same TIME?

[ACHË]

Recently I saw a video on YouTube about using one 18650 and one 16340 in series in the same light(a Fenix).

Is this safe?

Could it be used in other lights that accept 3 cell configurations like the JETBeam M1X and RRT-1 with cell extender?

 

[AnAppleSnail]

Recently I saw a video on YouTube about using one 18650 and one 16340 in series in the same light(a Fenix).

Is this safe?

Could it be used in other lights that accept 3 cell configurations like the JETBeam M1X and RRT-1 with cell extender?

Not really. One cell will go dead, and if the other cell has enough capacity then it'll deep drain the other one. You want your li-ions to be paired as closely as possible.

 

[TooManyGizmos]

~
Your question was ........... "Is this safe?"

ABSOLUTELY NOT

(for either you or your battery)


(and yes - I was yelling)

~

 

[kramer5150]

No... Thats one of the most unsafe ways to use Lithium rechargeable cells.

I hope others don't follow that youtube members advice.

 

[jp2515]

Yes you did see it on Youtube but no don't try it at home!

 

[Kraid]

Terrible idea. The batteries won't like it. And they might tell you about it by "Venting with Flame". Look THAT up on youtube...

Here, check this out.
http://www.youtube.com/watch?v=jjAtBiTSsKYhttp://www.batteryuniversity.com/partone-24.htm

 

[Ray_of_Light]

When you connect battery in series, they MUST have the same capacity; voltage CAN be different.

When you connect batteries in parallel, they must have the same voltage, and their internal impedance MUST be inversely proportional to their capacity.

Not abiding these rules only brings all kind of problems, and is straight dangerous.

Anthony

 

[TooManyGizmos]

When you connect battery in series, they MUST have the same capacity; voltage CAN be different.

When you connect batteries in parallel, they must have the same voltage, and their internal impedance MUST be inversely proportional to their capacity.

Abiding these rules only brings all kind of problems, and is straight dangerous.

Anthony

Anthony ,

Should there be a ...... "NOT" ..... before your last sentence ?

~

 

[jirik_cz]

Actually it shouldn't be dangerous if the 16340 cell is protected. The protection circuit will just disconnect the battery and prevents it from over discharging.

On the other hand, it just doesn't make sense to use this combination. The overall capacity in series connection is limited by the capacity of the weakest cell (16340).

You should rather try 2x17500 or 2x18500 cells in lights supporting 3x CR123 configuration.

 

[Ray_of_Light]

Anthony ,

Should there be a ...... "NOT" ..... before your last sentence ?

~

You Right! Thanks.
You wont' believe the frustation of sitting in front of the computer in this tropical heat...

Edited.
Anthony

 

[MattK]

DO NOT DO THIS.

DO NOT TRY THIS.

DO NOT EVEN THINK ABOUT TRYING THIS.

DO NOT EVER:
MIX OLD AND NEW BATTERIES.
MIX USED AND UNUSED BATTERIES.
MIX BATTERY TYPES, SIZES AND CHEMISTRIES IN SERIES OR IN PARALLEL.
ATTEMPT TO CHARGE NON-RECHARGEABLE BATTERIES.


etc....

 

[kramer5150]

Actually it shouldn't be dangerous if the 16340 cell is protected. The protection circuit will just disconnect the battery and prevents it from over discharging.

On the other hand, it just doesn't make sense to use this combination. The overall capacity in series connection is limited by the capacity of the weakest cell (16340).

You should rather try 2x17500 or 2x18500 cells in lights supporting 3x CR123 configuration.

No... Protection circuits CAN and DO fail. Its not safe to continually deplete the cell and "bump" it into the cell protection. The protection circuit should be thought of as an added fail-safe, not the only failsafe.

x2 to your other comments though.

 

[45/70]

First, let me say that this should never be done. :shakehead Even when using cells that have properly working protection circuits, under a light current load, the circuit may not trip and the 16340 cell could be over discharged, or worse, reverse charged.

When you connect battery in series, they MUST have the same capacity; voltage CAN be different.

I can go along with this, to a point. With Li-Ion cells of the same type and potential capacity however, cells having the same voltage should be at the same capacity level, therefore the voltage should not be different, to any significant degree anyway.

When you connect batteries in parallel, they must have the same voltage, and their internal impedance MUST be inversely proportional to their capacity.

I'm not too sure about this though, as pertains to Li-Ion cells. Li-Ion cells generally, can be discharged in parallel without any ill effect. Li-Ion chemistry cells can be parallel discharged as well as charged, as long as the voltage is within +/- 0.5 Volt, which is potentially a considerable difference in capacity. In either scenario, the cells will balance themselves rapidly if there is a full 0.5 Volt difference, however the voltage potential will equalize so fast with Li-Ion chemistry cells, that it is not a problem, provided the +/- 0.5 Volt rule is adhered to.

NiCd and NiMH cells are a different story. While they can be discharged in parallel reasonably well, provided they are in a similar SOC, due to the nature of their chemistry, they cannot be parallel charged. Mr Happy explained this to me in another thread, which I will never be able to find, but the current flow through NiCd and NiMH cells differs considerably between cells with different IR, voltage potential etc. making parallel charging of these chemistry cells impractical.

It's hot here as well, Anthony. I woke up to an 80 F morning. It's too hot to convert to C, so you'll have to live with Fahrenheit today. Oh, and no A/C here, and the forecast is for 96F. On top of that, today I have to work outside, most of the day.

Dave

 

[ACHË]

Thank You...

That's exactly what I thought...

I guess I'll PM this YouTube user, because last time I checked, he had like 30,000 subscribers and if ONE of them follow this advice and ONE protection circuit fails.....

Well....somebody's going

Thanx Again

 

[jasonck08]

Thank You...

That's exactly what I thought...

I guess I'll PM this YouTube user, because last time I checked, he had like 30,000 subscribers and if ONE of them follow this advice and ONE protection circuit fails.....

Well....somebody's going

Thanx Again

Someone should create a video response explaining why you should NEVER do this.

 

[^Gurthang]

Yes, absolutely a response / demonstration vid..... using the original vid poster.... w/ just such a light strapped to his [...]

Narrator: Kids, DON'T TRY THIS!....

*light switched on

UN-,MATCHED Li-ION BATTERIES ARE HAZARDOUS

*light pops and begins to vent

HERE WE SEE THE HAZARD, THE BATTERIES HAVE FAILED AND ARE VENTING CATASTROPHICALLY! :fail:

* light bursts into flames

OOH.... TOO BAD! GUESS THIS FELLOW SHOULDN'T HAVE TRIED HIS OWN IDEA. GAME OVER FOLKS....DRIVE HOME SAFELY.

 

[kramer5150]

Justifying something is safe because failure has not personally occurred is NOT legitimate justification. Safety is not something to chance with.

 

[old4570]

Simply "NO!"

Unless your looking to blow off your hand :laughing:
In which case feel free to ignore all the nay sayers :wave:

:shakehead

 

[carbine15]

Nutnfancy did this on one of his fenix light youtube videos. I protested but to no avail.

this is the video. It happens at 28:23
Good news is that he uses AW protected cells. One 17670 and one 16340.