Primaries vs Rechargeables Question

[VirtualMe]

Hi everybody. I had been wanting to buy a LED flashlight for a long time, over a year. I decided to do some looking around a couple weeks ago and found these forums. Within about 5 days I bought a Fenix L2D Q5. I got it last week and I love it! I grinned like a little boy when I turned it on turbo, aimed it at the ceiling in my room, and there was plenty of light to see everything and read a book! Could probably read a book like that on medium, definitely on high. Now I'm already thinking about buying a L0D Q4 or maybe the L1D body for EDC.

Anyway, all that is besides the point. Why is it, from reading here, that it seems to me people advocate NiMH rechargeables over standard AA Alkalines but either don't recommend, or the performance is much worse, of CR123As vs RCR123As?

 

[Black Rose]

At this point in time, CR123A primaries still have higher capacities (more than double in some cases) than their RCR123A equivelents.

 

[Niconical]

You already have a L2D, and you'd like a L0D, or maybe a L1D body.

Running them well on rechargeables doesn't have to be a complicated matter.

1 pack of AA eneloop, 1 pack of AAA eneloop, plus 1 good charger.
I would recommend the LaCrosse BC 700 for a beginner. (Which BTW, includes me!)

I don't know in which country you live, so I will just list a US place in dollars.
The batteries and charger are available from here....

www.thomas-distributing.com

or here....

www.amazon.com

 

[Marduke]

It's fairly simple.

NiMH cells vs alkaline:
NiMH give longer runtimes, and brighter, more constant output than alkaline cells. They are also very safe for beginners and non-technical people. No matter how much you mistreat them, the worst you can expect is to ruin a $2 cell. Just about any alkaline power device will work with NiMH, and most by far will work MUCH better.

RCR123 vs CR123 primary:
RCR123's have less capacity than CR123 primaries, meaning less runtime (1/3 to 2/3 of primary cells). They are also not as user friendly for beginners, and require special safety precautions for charging and use. Not all CR123 devices will accept RCR123's because of the voltage difference or size difference (cheap RCR123's are longer). If you mistreat one, you can be out as much as a $9 cell, and possibly have a fire/explosion.

 

[Misterbean]

Another reason is that nimh batteries have a much flatter discharge curve than alkaline batteries.

on the other hand lithium primary batteries have a decently flat discharge(much flatter than alkaline). Li-ion batteries have a flatter discharge curve than primaries but the disparity isn't as big as nimh/alkaline.

 

[VirtualMe]

Thanks for all the replies. It's all beginning to make sense now. What's the deal with 18650's then? It's Li-ion too right? Do they just have more capacity than RCR123s?

And thanks for the suggestion Niconical. I already bought a Vanson BC-1HU. I haven't opened it yet though, so I could return it if it's not all that great.

 

[Marduke]

A 18650 is about the same size as two CR123 primaries, just 2mm wider. At this size point, you get about the same energy as two CR123 primaries, and about double two RCR123's. Besides packing in more energy, you get a rechargable format, and it's safer since you're only dealing with a single cell instead of two. With a single cell, you don't have to worry about matching up multiple cells, with potentially surprising consequences

 

[mdocod]

Li-ion batteries have a flatter discharge curve than primaries but the disparity isn't as big as nimh/alkaline.

A long time ago, this myth got started, and has yet to be extinguished, I think i may have even played into this myth a long while back (OOPS!). So don't feel bad, i think it's a very common misunderstanding. A quick study of the discharge graphs of CR123s and various li-ion cells that Tom has tested will reveal that they both are semi-similar depending on the load in question. In many cases, the CR123 actually has a flatter discharge. but both are awesome energy storage solutions

Eric

 

[jerry i h]

1) go ahead and use the Vanson. You will love it.
2) AA/AAA alkys vs. NiMH is way different from the CR123 question.
3) Li-ions are again a way different kettle of fish, unrelated to the AA/AAA or CR123 issues. Whew...
*if you have a torch that uses AA or AAA, it is probably designed for alkys. Using an Energizer Lithium will give you more life and more light, in many, but NOT all, cases. NiMH's are often preferred, because, in the long run, they are cheaper to use because you just plug 'em in to recharge. Your torch may or may not be brighter with NiMH's over alkys.
*if your torch is incan, NEVER sub a rechargeable for the CR123. For LED torches, it may or many NOT work with RCR123: in each case, you must query the manufacturer as to suitability.
*In most cases (yes, here goes that qualifying, weasel words again), you may NOT use Li-ions as a substitute for alkys or NiMH's.
You may uses a Li-Ion, but only if the manufacturer says you can.
The relative merits of the competing chemistries are irrelevant. It is more important to know exactly which battery types will work in your specific model of torch

 

[half-watt]

...A quick study of the discharge graphs of CR123s and various li-ion cells that Tom has tested will reveal that they both are semi-similar depending on the load in question. In many cases, the CR123 actually has a flatter discharge. but both are awesome energy storage solutions

+1. only at very low current draws is Li-ion flat until near the end of its discharge curve. at higher draws it appears to be linearly decreasing. its slope is dependent upon draw (i.e. greater draw/load and the slope is steeper).

these statement are true, to a greater or lesser degree, of other chemistries also, though there are some exceptions (e.g. NiCd being very flat under much a higher percentage of its rated/recommended max. draw until near the very end of its discharge curve when there is a "knee" to the curve as it is sometimes called.).

alkalines initially and for a longer period of time than other chemistries have a characteristic discharge curve that appears to be decreasing somewhat exponential in nature, until it eventually becomes what appears to be a more linear curve after the cell voltage has dropped significantly.

it is obligatory to check out SilverFox's excellent plots,found elsewhere on these Forums, of the discharge curves of various types of cells.

 

[half-watt]

...AA/AAA alkys vs. NiMH is way different from the CR123 question...Li-ions are again a way different kettle of fish, unrelated to the AA/AAA or CR123 issues...You may uses a Li-Ion, but only if the manufacturer says you can...

good words. most Mfr's list the permitted range of Vin (input voltage) the the light will run on w/o any damage to the electronic components in the light. knowing this range will help you (OP, that is, not jerry who already knows all this) know if you can safely run a certain type of battery w/o "frying" the electronics in your lights.

remember, a nominal Li-ion cell voltage is ~+3.7VDC (and up to +4.2VDC right off a charger). this is for a SINGLE cell, so multiply the voltage by the number of cells in series that will be placed into your light.

keep in mind also, that though some lights can take an appropriate physically size Li-ion cell in place of cell of another chemistry (e.g. a 14500 Li-ion cell can replace an AA sized alk. or NiMH cell - in terms of physical SIZE only, *NOT* voltage), in some cases, depending upon the light's electronic design (the Mfr. ought to explain this in their specifications which are often reproduced on a webpage advertising or selling that light) the light may a) either function properly if it was designed for such, b) "fry" fr/overvoltage, or c) lose some of it's operating modes until the Li-ion cell voltage drops a bit, e.g. some Fenix lights can handle a Li-ion cell, but lose the lower levels of light o.p. [output] until the Li-ion cell voltage drops a bit nearer the end of its discharge.

hopy you continue to enjoy your new adventure in the lighting hobby.

 

[Darkpower]

1) go ahead and use the Vanson. You will love it.
2) AA/AAA alkys vs. NiMH is way different from the CR123 question.
3) Li-ions are again a way different kettle of fish, unrelated to the AA/AAA or CR123 issues. Whew...
*if you have a torch that uses AA or AAA, it is probably designed for alkys. Using an Energizer Lithium will give you more life and more light, in many, but NOT all, cases. NiMH's are often preferred, because, in the long run, they are cheaper to use because you just plug 'em in to recharge. Your torch may or may not be brighter with NiMH's over alkys.
*if your torch is incan, NEVER sub a rechargeable for the CR123. For LED torches, it may or many NOT work with RCR123: in each case, you must query the manufacturer as to suitability.
*In most cases (yes, here goes that qualifying, weasel words again), you may NOT use Li-ions as a substitute for alkys or NiMH's.
You may uses a Li-Ion, but only if the manufacturer says you can.
The relative merits of the competing chemistries are irrelevant. It is more important to know exactly which battery types will work in your specific model of torch

I agree with what you said and I just want to add that having a suppy of alkalines is essential for emergencies (power outages). NiMh have a self-discharge that even the best (eneloops) can't match the alkaline shelf life.

Unless you want to maintain a rigid regiment of battery maintenance by performing charge-discharge cycles on NiMh sitting on the self; you might find that the NiMh that you charged 6 months ago have either gone flat, or have less charge left in them then a cheap disposable alkaline.

I live in a hurricane zone and so I use NiMh and CRC123 for every day use. But I keep a hefty supply of primaries such as Akalines, Lithium's (AAA and AA L91 L92) and CR123s on hand for a prolong outage. I have a generator as well, but I don't count on running a 6.5 KVA generator just to charge up a few cells. Hence Alkalines or primary Lithiums are an important part of emergency lighting supply.

 

[VirtualMe]

Thanks for all the info! You guys are great!

One last question. I've seen this hinted at but I haven't seen an outright answer yet. I've read about being careful to not over discharge Li-ion batteries. Do I have to be careful to not over discharge NiMH batteries too?

 

[Mr Happy]

One last question. I've seen this hinted at but I haven't seen an outright answer yet. I've read about being careful to not over discharge Li-ion batteries. Do I have to be careful to not over discharge NiMH batteries too?

Yes, but for a different reason.

When NiMH cells reach the end of their charge, the voltage decreases very rapidly towards zero. If you have a light that takes two or more cells, it will usually happen that one cell is slightly weaker than the other one and will discharge first. What can can happen then is that the stronger cell takes over and pushes current through it, in effect reverse charging it. This is bad for NiMH cells and prolonged reverse charging will damage them.

What makes it doubly bad is that LED lights often have a regulator circuit that pulls more current to maintain brightness as the batteries run down. So you might not know that one cell is discharged and being damaged until it is too late.

Therefore when using NiMH cells in a multi-cell light, it is always best to swap out the cells and recharge them as soon as there is even a hint of fading.

 

[jerry i h]

Well, I occassionally over-discharge my *nergizer AA NiMH's (like last night ). Just stick 'em into the charger, and they will spring back to life. However, each time you do this, you shorten the lifespan and capacity of your expensive rechargeable batts somewhat, so try not to do this too often.
My SOP is to always have a set in the charger, and swap 'em out whenever I can remember.