Rechargeable Battery Questions

[I came to the light...]

I've heard from some people that there are certain Li-ion batteries that drop their output to 3.0 v within 12 ms of activation, and others that do not and are around 3.7-4.2V fully charged.

I've also heard about protected and non-protected, the latter of which can explode under circumstances I'm not quite sure of...

Are the "protected" ones the ones that automatically drop their voltage to 3.0V, or are these completely different things? I take it only 3.0V Li-ion rechargeables are the only rechargeables able to be used in the Fenix P3D.

Also, a quick question about low self-discharge Ni-Mh rechargeable AAs - I have heard that there are only a few brands, and the only brand I've heard named is the Eneloop. What are the other brands? Which is the "best"? And, most importantly and most simply, are they the same as all other AA Ni-Mh batteries in all other factors?

 

[Marduke]

Taken from the Welcome Mat

Q: What do protected/unprotected mean in regards to Lithium-Ion?
A: As mentioned in the "what is double-tapping" question, a "protected" Li-Ion has a small electronic circuit integrated into the cell packaging. It protects against common dangers, such as overcharge, overdischarge, short-circuit (overcurrent), and temperature. These cells are safer to use, both individually and in batteries. They are less likely to ignite and cause personal or property damage, a phenomenon known as "venting with flame." Unprotected cells do not have this protection circuit, so they can have more capacity and current capability than protected cells. Some cells, such as 10440 (AAA), are too small to accomodate a protection circuit and are only available in unprotected form. Users must decide whether they prefer to stick with protected cells or accept the bigger responsibility and danger associated with unprotected cells.

Q: What are the different types of Lithium-Ion?
A: Lithium-Ion is a rechargeable family of cell chemistries. Ordinary Li-Ion types are referred to simply as Li-Ion, RCR, or by their metric size designations (see the question "what's up with these five-digit batteries?"). When they have just been charged, they have an open-circuit voltage of about 4.2V (make sure your charger terminates at 4.20V at the most). They have a nominal voltage of about 3.7V, after a bit of use and under a moderate load. They should be charged when they reach about 3.4V-3.5V. To make Li-Ion a more suitable replacement for primary (nonrechargeable) CR123As, with their 3V nominal voltage, some manufacturers add some sort of circuit or dropping resistor into their 16340-sized cells, giving them a lower voltage intended to mimic that of primaries. These have reduced capacity compared to primaries or even ordinary 3.7V Li-Ion, but they serve their purpose. A relatively new type of Li-Ion is LiFePO4, or Lithium Iron Phosphate. With a resting voltage of about 3.2V-3.3V, it has lower voltage (and slightly reduced capacities) as compared to the classic Li-Ion discussed above, can handle significantly more current, and is safer. For example, CR213a-sized LiFePO4 cells can handle about 5A, whereas the same current would require an 18650-sized Li-Ion cell or greater. LiFePO4 is available in 16340 (CR123A), 14500 (AA), and 18650 sizes.

Q: What's up with these five-digit batteries?
A: Cells of various types can be referred to by their standardized size codes. The first two digits are the cell's diameter in mm, the second two digits are the cell's length in mm, and the "0" usually found at the end indicates a cylindrical cell. An ordinary AA cell, for example, is 14mm in diameter, 50mm long, and cylindrical, so it would be a 14500. Other common sizes are 10440 (AAA), 26500 (C), 16340 (CR123A), 17500, 18500, 14670, 17670, 18650, and more.

The P3D can use any RCR123, including 3.7v ones

 

[I came to the light...]

Thanks, seems like you answer all of my battery questions

So I now understand the flexibility, but which Li-ion cells are best in the P3D? LiFePO4 seems like the safest and best (I'd want to stick with protected cells).

 

[Marduke]

Thanks, seems like you answer all of my battery questions

So I now understand the flexibility, but which Li-ion cells are best in the P3D? LiFePO4 seems like the safest and best (I'd want to stick with protected cells).

Some of AW's 3.7v protected li-ion would probably be the "best" for it. He sells them over the the Market Place.

 

[I came to the light...]

Those seem good, but they are only 750 mAh. I've seen a lot of protected RCRs, like ultrafire's, that are 880 mAh.

 

[mdocod]

almost all li-ion RCR123s are in the 500-600mAH range when actually under any realistic load, so don't concern yourself with the higher ratings from ultrafire, the track record of ultrafire is pretty bad around here for cells, odds are you would get a cell that doesn't work at all, let alone deliver 880mAH.

The P3D doesn't make a very good rechargeable setup as it doesn't support 18mm cells and won't regulate on only 3.7V properly... Trick to really taking advantage of li-ion cells is to buy a light that was designed for them from the ground up. Like the DereeLights. Best bet is to go with AWs 3.7V protected RCR123s here... AW is a great dealer, he sells quality cells, and handles customer service issues quickly and very fairly.

 

[I came to the light...]

Are you saying that the cells deliver greater mAh under smaller loads? (presumable b/c of heating etc.)

Is AW the exception to this "500-600" rule? (you're speaking very positively of him and he claimes 750 mAh in his latest versions)

I know the P3D isn't ideal, but from what I understand it is the best of the P series on rechargeables: doesn't lose any modes, and the only change is around 1/2 the runtime (but they're rechargeable, so that's OK ). I'm planning to mainly use CR123s on the P3D, but have rechargeables so I don't eat up batteries around the house.

 

[mdocod]

600mAH is pretty common across the board for all RCR123s. Here is a link to a li-ion shootout done by Silverfox:
http://www.candlepowerforums.com/vb/showthread.php?t=117117

towards the bottom are 4 RCR123s tested, all test in the 500-600mAH range in applications around 0.5-1A draw. Unfortunately, even the 750mAH rating is pretty optimistic, but at least it isn't as overstated as other brands, I have seen RCR123s rated 900+ mAH, I kind of doubt that they are any better considering that all the cells tested (with many various label capacities) all came in at around the same capacity.

The advantage of the AW cells is that they are specifically designed to be as safe as possible, they are probably the safest 3.7V RCR123 on the market. They have some safety features that other cells may or may not have. At $6 each they are a good deal from a reputable dealer. AW stands behind his products.