Question about protected cells in parallel - RE overcurrent

[Mooreshire]

Short version: How does running multiple cells in parallel configuration effect current draw and overcurrent protection? :thinking:

Long version: The (Trustfire 3000mAh Red with Flames) 18650 protected cells I purchased in anticipation of modernizing my caving lights can't run the TURBO mode of my new ZebraLight H600W. I have a Kavelight (by kevinm) ordered which will run double the number of diodes up to very high currents but do so with four such cells in parallel. I do not know what the TURBO mode of the H600W is drawing current wise, but anticipate the drop-ins I've planned to use in the Kavelight to draw similarly high amounts of power. I would very much like the piece of mind of overcurrent cell protection while caving as I foresee the cloud of toxic smoke a lithium battery fire produces as being downright life threatening in an enclosed space. Does running cells in parallel pull full current from each cell or do they only have to provide a fraction of the current as shared by each cell? Will the protection cut in just as quickly with multiple cells in a parallel configuration as if there was only one cell in the pack? Would I just be better off considering lower capacity cells with higher protection thresholds?

 

[hellokitty[hk]]

The Trustfire 3000mAh probably isn't very good at holding up a voltage under load, and that's probably why it's not working on turbo.
In parallel with identical batteries, each battery provides an equal fraction of the current, and that's the current that the protection circuit will be looking at.

 

[TEEJ]

Ow

I would NOT put "Trust it to Catch Fire With Flames" on my head in a cave.

:D

The "Trust it to Catch Fire With Flames" can be made with differing internal resistances, so that the difference between the cells can lead to the creation of HEAT, and is one of the primary causes of fulminating flashlights.

In a single cell light, the cell could have too little flow to allow high amp draw applications, and prevent the turbo activation as kitty mentioned above.

In SERIES, that same scenario can get very ugly, very fast, and if it sets your head on fire when in a cave, you might get ugly fast too.

In parallel, its not AS bad, but you are STILL looking at now FOUR cells that can't keep up with this current instead of one.

IE: It may not be able to fully power that driver....and there are FOUR unreliable cells to worry about a malfunction for...


Again, considering the risk/benefit ratios here...spring for some real 18650's instead of the "Trust it to Catch Fire With Flames" cells.

AW, Redilast, Callies Kustoms, etc, all handle draws better than the flaming specials.

You'll potentially find the H600W with a good cell is all you need...at least as a back-up for the Kavelight...albeit MORE LUMENS are always nice.

I don't know what protection the Kavelight has built-in, but you can't count on the flame's protection circuits, its just too risky under a caving scenario. I have not been in a Washington cave...but on the east coast, we have a lot of limestone caves, and shale cracks, etc...and the idea of squeezing through a ~ 18" high 10' wide crack that's 50 yards long...knowing I HAVE TO get through to the other side to escape if there's a fire...and that the small space will concentrate any fumes released, the smoke might screen my vision/hide my route...and all I can do is wriggle a bit at a time to move at all...in the dark, with no helmet, well, for me...I'll spend a few bucks to NOT have that as likely to happen.

:eek:

Besides, the "Trust it to Catch Fire With Flames" can burn the house down while on the charger, even if the light is protected up the whazoo.



:devil:


I used to be in a club where we did regular caving on the East coast...and a flashaholic in a CAVE is like an alcoholic in a bar...I mean, where ELSE is a light more appropriate?

:devil:

 

[Mooreshire]

The Trustfire 3000mAh probably isn't very good at holding up a voltage under load

I would NOT put "Trust it to Catch Fire With Flames" on my head in a cave.

Thanks a lot for the info. Back on Ebay they go I suppose. Also I get a big F- on graph reading apparently, as I recall having briefly perused a lovely 18650 comparison site and concluded that the CatchFires were a good bang for my meager budget - fail.

Thanks for all the information regarding the complexity of the issue and ineffectiveness of those cells. I'll try not to faint examining the prices of higher quality batteries and hopefully I can find a good deal on ten cells which will kick *** in such lamps.

More information or suggestions of course welcome.

 

[Shadowww]

Thanks a lot for the info. Back on Ebay they go I suppose. Also I get a big F- on graph reading apparently, as I recall having briefly perused a lovely 18650 comparison site and concluded that the CatchFires were a good bang for my meager budget - fail.

Thanks for all the information regarding the complexity of the issue and ineffectiveness of those cells. I'll try not to faint examining the prices of higher quality batteries and hopefully I can find a good deal on ten cells which will kick *** in such lamps.

More information or suggestions of course welcome.

3000mAh Trustfire cells are a good bang indeed. Their internal resistance isn't anywhere near "high" either, they are very close to high-priced Sanyo & Panasonic cells in that matter.
They are 2600mAh instead of 3000mAh though, but quite stable 2600, not something like Ultrafire 3600mAh cells which really are anything between 1500 and 2200 mAh.

Here's test of them, side-by-side (if your monitor is wide enough, otherwise one under another) with AW 2600mAh (more like 2400mAh) test:

 

[HKJ]

A lot of people has reported that the quality of the 3000 mAh TrustFire has dropped.
I will have to redo that test with a new set of batteries.

 

[Shadowww]

A lot of people has reported that the quality of the 3000 mAh TrustFire has dropped.
I will have to redo that test with a new set of batteries.

Did they reported that for genuine TF's (with hologram) or fake ones (without), though? Might be same story as with DX's fake batch of 2400mAh TF's.

 

[HKJ]

Did they reported that for genuine TF's (with hologram) or fake ones (without), though? Might be same story as with DX's fake batch of 2400mAh TF's.

I did not note if it was with or without hologram, but both batteries from Manafont and from Dealextreme has been rapported as lower capacity than my chart shows.

 

[Mooreshire]

Thanks everyone! Those TrustFires, now back on eBay priced at a negligible loss to me (or PM me - $21 free US shipping for four, two still in wrapper, eight total available), do in fact have some sort of a hologram sticker on the wrapper with the TF logo.

I've now set my sights on Orbtronic's Panasonic 3100mAh cells which claim an 8.5A cutoff. Anyone know offhand what the turbo mode is pulling on my H600W? I estimate my planed Kavelight won't pull more than 5A.

 

[hellokitty[hk]]

A lot of people has reported that the quality of the 3000 mAh TrustFire has dropped.
I will have to redo that test with a new set of batteries.

I ordered a pair of the holographic (I think) TF3000 from manafont a week and a half ago, I only have the imax b6 so I'll simply do a capacity test and see how well matched they are. I'll try to pay attention to the voltage, but it'll be by eye and it won't be super accurate.

 

[Colonel Sanders]

The SC600 pulls no more than about 3a or so (less on a fully charged battery.) I think it's safe to say that the H version pulls no more than the SC.

But yes, when you have two cells in parallel the current is split between them. So if you had a regulated 3a, for example, two cells in parallel would only see 1.5a each.

P.S. I own no cells with the word "fire" in them (what a dumb name to have on a Li-Ion cell!)