3-AA to D adapters vs using D cell batteries? Is it an RCR123 or 16340?

[HighlanderNorth]

First of a few unrelated questions about 2 subjects relating to batteries:

1. I keep seeing these AA to D cell adapters. I've seen ones that hold 1-AA in a D adapter, and one that holds 3-AA's in a D adapter. I read a post where someone claimed there is also a 2-AA to D adapter, but after a Google search I cant find them.

Batteryjunction has the 1-AA to D, and the 3-AA to D adapters, and they have the 3-AA to D adapters running in series(4.5v) or parallel(1.5v). The questions here are: If you compared 2 identical LED flashlights, say a Fenix TK-70, with one using 4- regular alkaline D cells and the 2nd TK70 using 4 of the 3-AA adapters with 3 AA alkalines in each(in parallel), which of the 2 lights would run longer on the various brightness settings before the batteries ran dead?

Also, if you were to compare the same 2 Fenix TK-70's, but instead of using alkalines in the 3-AA adapter and alkaline D's in the other TK-70, you used NiMh AA's in 3-AA adapters in one tk-70 and NiMh D's in the other Tk-70, which light would run longer on the various brightness settings before going dead using NiMh rechargeables ?

In both comparisons above^, the batteries would be the same brand, ie. Duracell AA's in 3-AA adapters vs Duracell D's in one light, and in the other Tk-70 comparison using NiMh batteries, since Sanyo doesnt make D eneloops for whatever reason, lets say you were comparing Tenergy Centura NiMh D's in one TK-70 and Centura NiMh AA's in 3-AA to D adapters in the other TK-70.


2. Next unrelated battery question: When looking for rechargeable RCR123's for the 1st time ever last year, I initially noticed that they were 3v just like their disposable Lithium counterparts, but then I heard about 16340, which are about the same size, but they have voltages of 3.7-4.2 range. But if you put a 16340 with that higher voltage in a gadget that is made specifically for only 3v, then you may likely destroy the gadget or fry it. Then to make things even more confusing and maybe more dangerous, I took a closer look at batteries labeled as RCR123's, but noticed that many of them are 3v, others are 3.6v still others are 3.7 - 4.2v! So it seems a bit irresponsible to label different batteries with completely different voltages with the same name! Wasnt the whole point of calling these higher voltage RCR123 sized batteries by the name "16340", so that it would be obvious that these were different batteries, so that there is no confusion that may(and will) cause people to buy the wrong batteries and fry their gadgets?

Why would companies label their 3.6 - 4.2v rechargeable batteries RCR123's instead of 16340's? Why not only label the 3v Li-Ion 123's RCR123, and name the 3.7 - 4.2v batteries 16340, and be consistent in that labeling? Wouldnt that be the safer, and more responsible thing to do? I mean, when I went to buy 3.7v 14500's, I didnt see them labeled as AA's!

3. Lastly, why doesnt Sanyo make C and D Eneloops?

Thanks...... Patrick

[Lynx_Arc]

The questions here are: If you compared 2 identical LED flashlights, say a Fenix TK-70, with one using 4- regular alkaline D cells and the 2nd TK70 using 4 of the 3-AA adapters with 3 AA alkalines in each(in parallel), which of the 2 lights would run longer on the various brightness settings before the batteries ran dead?

the D cells of course they have over 4 times the capacity of a single AA alkaline

Also, if you were to compare the same 2 Fenix TK-70's, but instead of using alkalines in the 3-AA adapter and alkaline D's in the other TK-70, you used NiMh AA's in 3-AA adapters in one tk-70 and NiMh D's in the other Tk-70, which light would run longer on the various brightness settings before going dead using NiMh rechargeables ?

depends on the capacities of the nimh cells involved and their internal resistance. There are some nimh D cells that have a lot more capacity than 3AAs in parallel and some that may not have much more than that.

In both comparisons above^, the batteries would be the same brand, ie. Duracell AA's in 3-AA adapters vs Duracell D's in one light, and in the other Tk-70 comparison using NiMh batteries, since Sanyo doesnt make D eneloops for whatever reason, lets say you were comparing Tenergy Centura NiMh D's in one TK-70 and Centura NiMh AA's in 3-AA to D adapters in the other TK-70.

I don't know the capacities of those batteries just look them up and add the AAs together and compare them to the Ds.

2. Next unrelated battery question: When looking for rechargeable RCR123's for the 1st time ever last year, I initially noticed that they were 3v just like their disposable Lithium counterparts, but then I heard about 16340, which are about the same size, but they have voltages of 3.7-4.2 range. But if you put a 16340 with that higher voltage in a gadget that is made specifically for only 3v, then you may likely destroy the gadget or fry it. Then to make things even more confusing and maybe more dangerous, I took a closer look at batteries labeled as RCR123's, but noticed that many of them are 3v, others are 3.6v still others are 3.7 - 4.2v! So it seems a bit irresponsible to label different batteries with completely different voltages with the same name! Wasnt the whole point of calling these higher voltage RCR123 sized batteries by the name "16340", so that it would be obvious that these were different batteries, so that there is no confusion that may(and will) cause people to buy the wrong batteries and fry their gadgets?

labeling was done prior to all the differences existing I believe. The RCR label was used for the first lithium ion rechargable 123 sized battery even though it wasn't an exact replacement at 3.7-4.2v range the label stuck.

3. Lastly, why doesnt Sanyo make C and D Eneloops?

Thanks...... Patrick

Sanyo did make a C or D eneloop but I think it was AAAs in parallel in a battery container as a D cell? It was never offered in the US. The problem with trying to market C and D sized nimh batteries is the cost of them plus a decent charger plus taking into account fast enough charging to make them compete with AAs and lithium ion battery solutions makes for a large expense. Imagine it takes 4-5 eneloop AAs to equal a eneloop D cell that would be about $10-$20 a battery then a charger that can charge a 8000 to 10000mah battery up in decent time perhaps 4 hours would cost another $50+ now you have around $100 for 4 batteries plus charger something that cannot compete with buying 4D alkalines for $4. Someone would have to be running through a lot of batteries to make that cost of about 25 recharges works for them.

[45/70]

Just to comment on "RCR123" vs. "16340". "RCR123" is a bit of a misnomer IMO. What it suggests is a rechargeable CR123 cell, of which there is no such thing.

A CR123 cell is a lithium primary cell which contains actual lithium metal, or "metallic lithium". These cells are not rechargeable. As has come up before here on the Forum the designation, or name comes from the NiCd days. These cells were two thirds (2/3) the length of an "A" cell and approximately the same diameter (an "A" cell is actually 17mm in diameter and 50mm long, or a "17500"). Individually these cells were referred to as one (1) two thirds (2/3) A cell. In reference to lithium primary cells of this size, "CR" means the cell contains a cathode which contains metallic lithium (symbol for whatever reason is "C") and is round (R).

Nowadays the 16340 designation as well as the other numerical sizes, 14500, 18650 etc. are used primarily for designating Li-Ion cells (although not necessarily), which by the way, contain no lithium, only lithium ions in their chemical formula. In the case of a 16340 cell the cell is 16mm in diameter, 34mm long, and is round (0). Some distributors confuse the last digit when the cell is xx.5 mm long and simply use eg. 17335, meaning the cell is 33.5mm long. This is not really correct as I believe a cell ending in "5" rather than "0" means it is a prismatic (non cylindrical) cell.

Anyway, RCR123 and 16340 mean the same thing, usually a Li-Ion cell that is the same size as a 2/3 A cell. Perhaps AW has the best alternative to "RCR123", he just calls them "R123" cells, meaning a rechargeable 123 size cell, which of course, would by necessity mean a Li-Ion cell.

As for the 16340 size, in the case of Li-Ion cells, there are actually four different types with three different charging requirements. The most common is the LiCo, or lithium cobalt oxide cathode type (also called ICR or LiCoO₂). These cells charge with a 4.20 Volt CV stage and have a 3.6-3.7 Volt nominal voltage under load. There are also LiMn, or lithium manganese oxide cathode types (also called IMR, or LiMn₂O₄). These cells are also charged with a 4.20 Volt CV, and have a similar nominal voltage.

There are also two types of "3 volt" 16340 cells. The most common nowadays is the LiFe, or lithium iron phosphate cathode type (also IFR or LiFePO₄ and sometimes LFP). These cells require a 3.6 Volt CV stage and have a nominal voltage of 3.2-3.3 volts.

The second type of "3 Volt" Li-Ion cell seen in 16340 size is the traditional LiCo type cell as described above, but with two diodes installed under the positive nipple. One of these diodes causes a voltage drop when the cell is under load, providing a lower voltage closer to 3 volts, although, as with any cell, depending on the load this can vary a bit. Normally the voltage of these cells is about the same as a LiFe cell under load. The second diode is installed in the reverse direction, to allow the cell to be charged (diodes only allow current to flow in one direction). Due to the voltage drop in the charging circuit, a 4.4-4.5 Volt CV stage is required to charge these cells. Behind the diode, the cell is actually being charged with a 4.20 volt CV.

The only distributors that I am aware of that supply these LiCo type "3 Volt" cells anymore, are Tenergy and Soshine. Long ago AW offered these and not too long ago, Bateryspace under their "Powerizer" brand. I suspect both have discontinued carrying these type "3 Volt" cells due to the confusion with LiFe cells and also the danger of accidentally charging a traditional LiCo cell with a 4.4-4.5 Volt charger.

Dave