What Power Cell/Battery & Why?

[radar696]

Okay I did a little searching and didn't find anything specific along this line so here goes.

I'm actually looking for opinions comparing rechargeable cr123's to the 18650's but I would like for everyone to place their opinions about any and all primary cells vs. rechargeables; any size and which you prefer and the reason why.

I will be needing to pick up a few cells here in the next couple of weeks and for myself I'm looking for the one that will give the longest run-time as compared to the brightest light.

I will be using them in a Olight M20 for camping. So I will have no place to recharge while there and wish to only have to carry a few to get by on.

Thanks for looking.

Radar:candle:

 

[etc]

I use 18500 backed up 123 cells.

I also use AA Lithiums (L91) in the backup capacity, with NiMH being primary

 

[Lumencraft (Matt)]

I'm not completely sure what will work best in your situation, but I will mention this. 18650s are one of the most widely used li-ion cells because they have a great size to power ratio.

 

[brucec]

I prefer primary CR123. Small, light, good capacity, 3V vs only 1.5V, don't explode, and you can drain them until they are dead. Li-ion rechargables are potentially dangerous, especially in the sealed airtight tube of a flashlight, and you can't drain them all the way. However, they are good in larger capacities, such as 18650, where there are no primary equivalents. But, I'm not an electrician or police officer so a single CR123 primary can last me for months and I don't need a low cost rechargable solution.

 

[HKJ]

I prefer primary CR123. Small, light, good capacity, 3V vs only 1.5V, don't explode, and you can drain them until they are dead. Li-ion rechargables are potentially dangerous, especially in the sealed airtight tube of a flashlight, and you can't drain them all the way.

I believe that the primaries are more dangerous than the rechargeable LiIon batteries. But as long as your use quality cells and do not mistreat them, there are no real risk with either.

 

[45/70]

+1 on Li-Ions being safer in use than primaries. The danger with Li-Ions is when charging, which of course is a non-issue with disposable primaries. As HKJ said though, with good quality cells treated properly, matched in series applications etc, there really isn't a problem.

Dave

 

[yellow]

protected Li-Ions, or none

1 18650 vs. 2 CR123:
* light is same size
* single 18650 light can not have full and empty cells mixed,
* less small parts to bring along (spare cells)
* 18650 has more power inside (roughly: 18650: 2.5 hours on full, vs. 1.5 hours with 2 CR123a rechargeable Li-ions)

CR123 light gives the opportunity to purchase single-use cells, while the 18650 is rechargeable only
(if this is of importance for You to decide)

... imho the single 18650 beats all other setups
(maybe except for a 2 18650 light, if the added size does not matter)

 

[mdocod]

We need to make sure we are getting the terminology right so we understand what we are dealing with here first... With that said, hence forth, lets call a CR123 a CR123 and know it is a primary non-rechargeable cell, and lets call a lithium cobalt (rechargeable) cell that happens to be the same size as a CR123, a R123, or RCR123, or, if we want to get fancy, call it a 16340 LiCo cell....

The problem with trying to compare CR123s, to RCR123s, to 18650s, is that, each has advantages in certain applications. Depending on the way a particular flashlight is designed, it may have more or less runtime, or totally different behavior all-together on different possible cells that could be used in it....

For lights like the M20, you have to make a decision:
1. Use RCR123s, get regulated output through the entire discharge, and then it suddenly shuts off with no warning, runtime is ~1/2 as long as it would be on CR123s.
2. Just use CR123s, and spend a lot on replacing cells all the time without a rechargeable option, get good regulated runtime with a trailing output of dimming output at the end to let you know you need to change the cells. Also, realize that we have had far more reported incidence of CR123 explosions than we have had of li-ion explosions.
3. Use an 18650, and get steadily dimming output with a runtime exceeding that of the 2xCR123 configuration because of that steady dimming. (dims to ~50% output towards the end of the discharge)

There are some lights out there, that are designed specifically for use with an 18650, and will not dim during the run, but their runtime won't really be any better than they would be on 2xCR123 cells, but who cares, it's rechargeable and regulated!

----------------------------

here's some general considerations that apply to a broader range of scenarios.

At low drain rates, 2xCR123s will have more stored energy than a single 18650, at higher drain rates, the 18650 beats the 2xCR123s.

RCR123s just have poor energy storage compared to the other options.