3800 mAh q?

vinny

Newly Enlightened
Joined
Oct 12, 2010
Messages
73
I thought id post this in here and see what you guys think,



I recently received some ultrafire LC18650 3.7v 3800 mAh batteries from an ebay seller, the problem im having is finding the maximum safe discharge rate for these batteries, ive searched everywhere i can think of and cannot find the information i need.



Basically i need to know if they are safe to use in a 2d mag rop hi drawing approx 4.4amp (not measured draw, but researched) Ive got a feeling that they are probably low discharge rated and therefore not safe to use with the rop high, although i have been using them with the rop high and they seem to be working and recharging fine.



If theres a slight chance that they will blow up in my light ill upgrade to imr's or whatever is best for my requirements.



Any info or help will be appreciated.



thanks vinny.
 

Stephen Wallace

Enlightened
Joined
Mar 10, 2011
Messages
628
Location
London, UK
The discharge rate of Li-Ion batteries is often quoted in terms of multiples of capacity - 2C is a relatively common rating, meaning that if you have a battery with 2000mAh capacity, it should be able to support a 4 amp discharge rate.

Now, before anyone starts screaming at me, that is purely an example, and I am not suggesting that these particular Ultrafire batteries can support a 2C discharge rate. ;) Fact is, I honestly don't know what discharge rate these batteries will support.

So, that being the case, why am I even bothering to post? Now comes the point.

No way, no how, are these batteries 3800mAh capacity. The highest capacity 18650 Li-Ion cells from reputable manufacturers (Panasonic, Sanyo etc.) have a capacity of 3000mAh. The highest capacity available from dealers popular with flashaholics (AW, and more recently, Redilast) are rated at 2900mAh. There just aren't any true 3800mAh 18650 cells out there at this time. As such, any discharge rate calculation based on capacity is invalid with these cells, as you simply do not know what the true capacity (obviously you can measure the true capacity of the cells with the right equipment - you might be shocked at just how widely the true capacity differs from the quoted capacity).

Having said that there are genuine 3000mAh cells available, don't be tempted by the Ultrafire 3000mAh cells - I made that mistake myself, which is why I am posting this. The measured capacity of the cells was considerably lower.

I would strongly suggest relegating these cells for use with LED powered flashlights with a lower current draw, and getting something more trustworthy for your ROP.
 
Last edited:

jasonck08

Flashlight Enthusiast
Joined
Sep 16, 2007
Messages
1,516
Location
Redding, CA
Highest capacity cells out are the Panasonic 3100mAh cell along with LG/SDI/Sanyo's 3000mAh 18650 with ~3.78v nominal voltage and 4.35v charge voltage. Cheap companies lie about capacity and often times will sell you a garbage cell or even a recycled cell.
 
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