Tuesday, July 5, 2011

18650 BATTERY COMPARISON

18650 BATTERY COMPARISON

Review of Protected Soshine 2800mah 18650 and Protected Trustfire 2400mah 18650



BACKGROUND

The Ultrafire WF504B which was reviewed earlier, uses a 18650 battery.  I also plan on posting up reviews of some other 18650 flashlights in future, so I thought it would be a good to do an article on these batteries.

For those of you not familiar with the term, '18650' refers to a lithium ion battery size.  In theory the battery should measure 18mmx65mm and be cylindrical (I believe the '0' at the end of '18650' is a reference to the shape).  You will often find there is some variation in the actual size of 18650 batteries.  Some 18650 have a protection circuit which will add further length.  Labels and packaging can also affect the size.

18650 batteries are most commonly found inside laptop battery packs, but they have also been taken up by the flashlight community for powering flashlights.  The benefit of these batteries are they can be very energy dense... they can hold alot of energy for it's size.

Before using lithium-ion (li-ion) batteries, it is important to familiarise yourself with the different sorts of li-ion batteries, how to use them safely and how to prolong the life of the batteries.  If care is not taken, some types of li-ion batteries can vent and explode!  At the end of this post, I've included a few articles and threads with further info on li-ion batteries.

I received a couple of different 18650 batteries from Dealextreme for review.  Included were the protected Soshine 2800mah and protected Trustfire 2400mah (black/red/flames packaging).

I was interested to compare these to some other 18650 batteries I have, including the same Trustfire 2400mah, but older and heavily used.


PACKAGING

The packaging for the Protected 2400mah Trustfire batteries is quite rudimentary.  They come in a two pack with shrink wrap around the outside.



The packaging for the Protected 2800mah Soshine batteries are more professional.  They come in a two pack in a clamshell packaging.  A bonus battery case is included.




TESTING METHODOLOGY

These batteries were all initially charged on a Pila IBC charger using the same channel on the charger.  They were then discharged on an Accucell 6 charger at different discharge rates (0.2A and 1.0A).  The Accucell 6 discharges the cell until they reach 3.0V (under load).  You should note some batteries such as the panasonic NCR18650 and NCR18650a can be discharged down to 2.5V.  Since the Accucell terminates at 3.0V, in theory these types of batteries can still be discharged slightly further and provide more capacity. The redilast 2900mah are based on the panasonic ncr18650.

I have included a rough estimate on how heavily used the various batteries are. 

I have to say the older batteries have seen some significant use and moderate abuse.  The unprotected blue 2400mah ultrafire and protected 2400mah trustfire (X), have seen quite a few cycles, some of which they were deeply discharged.  The more heavily used trustfire (X) and was then used with trustfire (Y) in a 2x18650 flashlight (only for a few cyles).  Trustfire (Y) had not been as heavily used as trustfire (X).  Do note; it is NOT recommended to use two poorly matched batteries in a multi-cell light.  I feel this incorrect use of these two batteries, may have result in some damage to both the trustfire cells.


RESULTS






CONCLUSIONS

Under lower current draw (0.2A) conditions the Black/red/flames Trustfire do provide close to the advertised capacity.  Under 1A current draw they still provide around 2200mah or more.  There is some doubt on how well these batteries keep that capacity after many cycles.  My older black/red/flames trustfire have lost a significant amount of capacity, with one developing high internal resistance.  I do have to say these older batteries have been through some abuse. 

For under $10 for two (shipped), they do represent a good buy, if you accept they may not last as long.  (It would be interesting to test my redilast 2900mah after they have been through a similar about of cycles and abuse, to see if these more expensive cells do indeed last longer.)  You should also note some people report there to be variation between various batches of these same batteries.

In my samples of the soshine 2800mah batteries, they are quite short of their rated capacity.  In my tests I only get around 2400mah from these cells.  I have a feeling I have gotten an older batch.  After charging the batteries to 4.20V, they do drop down to 4.13V after resting for a period.  This is a significant drop in voltage and may indicate they are older or used batteries.  Considering the soshine 2800mah are more expensive than the trustfire 2400mah, I feel I can not recommend these batteries.  There are better buys elsewhere.


LINKS:

Here a few articles on 18650 batteries

http://batteryuniversity.com/learn/article/lithium_ion_safety_concerns
http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries
http://batteryuniversity.com/learn/article/lithium_based_batteries


http://www.candlepowerforums.com/vb/showthread.php?312835-Beyond-the-basics-for-Li-ion-safety
http://www.candlepowerforums.com/vb/showthread.php?178133-Are-Li-Ion-Batteries-really-dangerous
http://www.candlepowerforums.com/vb/showthread.php?35282-Li-Ion-FAQ-amp-Safety

http://www.redilast.com/index.php?option=com_content&view=article&id=51&Itemid=85
http://budgetlightforum.com/node/1825



Links for buying the protected soshine 2800mah and protected Trustfire 2400mah:


http://www.dealextreme.com/p/soshine-protected-18650-3-7v-2800mah-lithium-batteries-with-case-black-2-battry-pack-31896
http://www.dealextreme.com/p/trustfire-protected-18650-3-7v-true-2400mah-rechargeable-lithium-batteries-2-pack-20392

3 comments:

  1. Nice in depth discussion on batteries, especially on different discharge and voltage drops. I did some research on what is the best battery to use and still I can’t decide. I’m currently using a hybrid 18650 batteries and it’s doing great; but, may I ask what 18650 you prefer the most?

    Lakendra Wiltse

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  2. i've haven't really kept up to date with the battery scene these days. But these days I'd prefer to buy panasonic or sanyo based 18650. You can buy these unprotected. Or you can also buy them protected and rebrand; e.g. AW, redilast, eagletac, xtar, etc.

    Here is a really good website for information on li-ion batteries, chargers and flashlight:

    http://lygte-info.dk/review/batteries2012/Common18650Summary%20UK.html

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  3. It is cool for this article! Today the battery means power. We need the strong battery pack to run the device.It is hard to find the budget and good battery pack.I found the Gearbest battery pack is good and its price is good.What is your idea?

    ReplyDelete