What is the best AW battery for high runtime and low self discharge?

I have a Zebralight SC600W MKII L2 and I would to purchase some AW 18650 batteries, but I am in doubt:
I dont know if is convenient to use 3400 mah batteries or batteries with less mah (2600 or 2900 for example).
Have the 3400 mah batteries high self discharge? What battery have the best relation between capacity and self discharge?

For example: after 4 months of storage at 20°C what battery can give me more RUNTIME ? (2200-2600-2900-3100 or 3400 mah).

What is the amount of self discharge for the various 18650 batteries?

I'm sorry for my bad english.
Thank you!

hankc said:

I have a Zebralight SC600W MKII L2 and I would to purchase some AW 18650 batteries, but I am in doubt:
I dont know if is convenient to use 3400 mah batteries or batteries with less mah (2600 or 2900 for example).
Have the 3400 mah batteries high self discharge? What battery have the best relation between capacity and self discharge?

For example: after 4 months of storage at 20°C what battery can give me more RUNTIME ? (2200-2600-2900-3100 or 3400 mah).

What is the amount of self discharge for the various 18650 batteries?

I'm sorry for my bad english.
Thank you!

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First of all: Welcome to CPF! Do not worry about your English. There are many non-English speakers on CPF!

To partially answer your question with a reference: Check out the stickies at the top of any of the forums. Lots of very useful info. For example, read thru the link below which is also in a sticky at the top of this forum:

http://www.candlepowerforums.com/vb/showthread.php?330236-Battery-test-review-summary

In my experience, the AW 18650 cells are quite good. My AW 18650 2900mah cells have survived more than a year in a wide variety of 18650 lights, including the Zebralights. I also have had good experiences with the EagleTac 18650 3400mah cells.

As far a self-discharge, my impression is that the electronic switches in the lights will probably cause more discharge than any self-discharge of a high-quality Li-Ion cell.

Use the links in the stickies or the CPF search window at the top left of the screen for more information such as for 18650 chargers.

Thank you for reply.
Can you quantify the self-discharge of the AW 2900 and Eagletac 3400?
What Is the Voltage of batteries after any months of storage charged? Have you tested it?

hankc said:

Thank you for reply.
Can you quantify the self-discharge of the AW 2900 and Eagletac 3400?
What Is the Voltage of batteries after any months of storage charged? Have you tested it?

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No self-discharge quantification is possible because of the way I use my lights/cells, especially Li-Ion types. Furthermore, any self-discharge in storage is highly dependent on original cell quality and age/wear to begin with.

I have only maybe a couple 18650 cells outside of lights - intentionally so. I rotate thru all my 18650 lights (with cells already in them) at the rate of about one every day or two. Even the 3 or 4 cell 18650 lights will be used enough on certain days of the week to drop the voltage sufficiently for a recharge. I normally recharge at about 3.5-3.7 volts, but sometimes I recharge even above 4.0 volts. At night, I strongly prefer to leave the house with a fresh cell and what I expect to be the full runtime. I quickly check by seeing if the output at different levels is as expected. If not, I either take another light or swap out that cell(s) and charge. Maybe once a month I let a light run down until the low-battery indicator warns me - a reminder of the many different low-battery indicators.

Furthermore, the standby current of an electronic switch has been higher than the perceived self-discharge current - as observed on the couple 18650s that I do have outside of flashlights and then compared with the voltage level in a light that comes up on the rotation. Note that there is a natural drop in voltage after cessation of charge and removal from a charger. The extent of the voltage drop is an indication of the quality of the cell or it's age. I have no equipment to measure the actual capacity of 18650 cells, so I use only a voltage level as an indicator.

The lowest voltage I have observed in a LiIon cell (14500 or 10440) after about a week outside of a light is between 4.0 and 4.1volts - whereupon I recycled them. Fortunately I started with AW 18650s and although they are aging (couple years), none have been recycled yet. Generally I agree with the consensus that if a LiIon cell drops below 4.0 volts in a week, recycle it. Some forum members recommend the recycle cutoff of self-discharge outside of a light of a drop down to 4.10 volts in a week. Keep in mind that this is for aging cells, skipping the many low-quality 18650 cells being sold as new. It depends on the quality of the cell to begin with. If an 18650 cell becomes obviously warm during charging @ 1A or less, recycle it.

addendum: I choose to keep cells in all of my lights rather than no cells in any light except when I intend to use it. Not only do I have several lights on standby duty in the house/car - which I do rotate thru - but when I have a bit more time, I choose the light to use based on the beam pattern. Hunting for a cell when I want light is not conducive to finding whatever made that noise in the dark, inside or outside the house. Hence independent cell self-discharge - separate from a light - has very little meaning for me except to recycle the cell.

The self-discharge is not dependent on cell capacity also? (more capacity = more self-discharge).

The self-discharge is important for me because I would have always any backup charge batteries to use in case of emergency and don't want charge it every 1 or 2 months. The best for long term storage is the use of primary CR123 batteries but the SC600W work only with rechargeable 18650.

Anyway, I think I will try a pair of AW 3400...

hankc said:

The self-discharge is not dependent on cell capacity also? (more capacity = more self-discharge).

The self-discharge is important for me because I would have always any backup charge batteries to use in case of emergency and don't want charge it every 1 or 2 months. The best for long term storage is the use of primary CR123 batteries but the SC600W work only with rechargeable 18650.

Anyway, I think I will try a pair of AW 3400...

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Frankly there are too many significant advancements in 18650 cells in order to achieve the higher capacity vis-a-vis any significant correlation between capacity and self-discharge. ie: witness the introduction and evolution of the latest Panasonic cell bundled inside of most higher capacity 18650 cells intended for consumer use. Use the excellent HKJ 18650 evaluation as a starting point.

Perhaps you are attempting to transfer some NiMH knowledge over to LiIon 18650 cells. For a NiMH cell, there is a good correlation of higher self-discharge with higher capacity. However the NiMH cell technology is relatively stable. The low-self-discharge NiMH cell was the last major change.

The situation with Li-Ion cells is much more dynamic. The main driver for Li-Ion, Lithium-xxx and specifically 18650 cells are electric cars and laptop battery packs. Electric car/aircraft modelers are driving the development of Li-PO cells primarily because of the very high current discharge ability. In general, there is a lot of investment into Lithium-xxx technology.

As for CR123 sized cells, be they CR123a or RCR123 something cells, I gave up on those. I sold or gave away all lights that would only accept a CR123 size cell. The usable capacity of an RCR123 is simply too small and the run time is too short to bother with. I would rather use a 1xAA or 1xAAA light rather than any 1xCR123 light if I thought that I needed the small size. and if I run out on a trip, AA or AAA batteries are readily available in most countries (Mignon/Micro in Europe).

Ok, thank you so much!
About CR123: I have flashlights that accept 2 or 4 CR123 or 1 or 2 18650. I have at home any primary CR123 batteries to use just in case of emergency (for long shelf life).

I think the 3400 mAh AW 18650 might be best simply due to its capacity, even if self discharge is a problem, i think the high capacity would negate that

tobrien said:

I think the 3400 mAh AW 18650 might be best simply due to its capacity, even if self discharge is a problem, i think the high capacity would negate that

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I believe this to be true. I've had a few cells sitting around and I check the voltage on occasion out of curiosity.

An Eagletac 3400 protected sitting in my garage with NO use since July: started at 3.94v, still 3.94v as of right now. I also have one in a PD32UE in my car. It has been at 4.00v all thru summer and winter so far, now measures 3.98v with very little use over that time period of about 8 months.

The OP actually asks a good and interesting question.

There are some general rules of thumb for li-ion cell 'features'. Regarding self-discharge, typically li-ion cells lose 5% in the first 24 hours, then 1-2% per month if stored at 21°C. Protection circuits add to the self-discharge rate by around 3% per month. Self-discharge increase substantially with temperature, doubling for every 10°C higher temperature.

However this is the general rule and I have not seen any testing to see if there is any significant difference between the lower and higher capacity cells.

Generally to get higher capacity in a cell, the membranes used to separate the anode and cathode are made thinner to allow for more cell area and so a higher capacity. As has been shown in Ni-Mh cells, the LSD cells have been lower capacity than non-LSD due to having a thicker membrane to reduce charge leakage and so self-discharge.

This would logically lead to the possibility of high capacity li-ions having higher self-discharge, but I have not seen this quantified anywhere. A long and difficult test to get reliable results.

However as this information is lacking, I would go with 3400mAh cells and worry more about any parasitic drain if the light uses an electronic switch.

If they generally lose 3% per month, I wonder why my Eagletac is still showing the exact same voltage after about 8 months (stored in garage, 45°-90° range)! Maybe I should use it in a light for a brief moment to see if changes at all. OR the voltage is not an accurate indicator in this case.

So which technology works better in an nightly duty flashlight? Li-Ion Panasonic or Li-Co AW?

I believe AW does not produce cells, they just have an assembly plant that rewraps Panasonics and other brands.

All batteries have a trade-off between capacity (mAh) and max. amps continuous discharge (A). You will never find a cell that has the highest of both values.

The new Panasonic 18650PF is a good tradeoff between the two (2900mah and 10a). but if you are just looking for high mAh you should go with one of the Panasonic B cells that do 3400mAh.

Long-term storage is ok, but you may have to recharge them every 6 months or so. I wouldn't plan on keeping them for more than 2-3 years, because by then the tech will be much better and your cells might have degraded a bit.