14500 question

[darklord]

Hi,

I've got a single cell flashlight (Spark) which can run off 14500s, but at present I just use Alkaline or NiMH.

With my limited knowledge I understand a 14500 will give me a higher voltage and allow the light to achieve its highest output, which can't be reached with Alkalines or NiMHs.

But what about run time? If I don't need the turbo output only available with 14500s, am I better off with NiMHs (or even alkies) for longer run time at normal settings?

 

[Str8stroke]

Runtime = Better off with Alkaline.

You will get a longer run time with Alkies. You can drain a 14500 fairly quickly on Turbo (especially depending on the light). If runtime is your goal, try some Energizer Lithium cells.

 

[darklord]

Energizer Lithium cells = great expense!! (in the UK, anyway). Appreciate their lightness and power/capacity, but a non-starter for regular use from the cost viewpoint.

I probably won't use it on turbo much - more likely the medium setting, which is only about 40-50 lumens output from a Cree XPG-R5.

But maybe alkalines and NiMHs still better for that...?

 

[Str8stroke]

You can do what I do. I carry a spare holder in my bag. It holds 4 cells. I usually keep 2 lithiums, 1 NiMH, and one 14500. I usually have a Lithium or Eneloop in my lights already. I like to carry a Sunwayman Dolphin. Great little AA utility light for me.
It sounds easier for me. I have some lights that will only run the 14500. So I have several around to choose from.

 

[darklord]

It sounds easier for me. I have some lights that will only run the 14500. So I have several around to choose from.

Yeah probably! I only have one light - just trying to eek out the most runtime from a cell.

 

[Short_Circuit]

It seems to me that economy is your goal and in that case I'd think rechargeables (14500s) would be the way to go. Buy three or four and a good charger and then you can stop buying batteries period for several hundred cycles. And if you need to leave your light on for extended lengths of time just carry the appropriate number of fully charged batteries with you in a holder. And if you're only using around 50 lumens you should get pretty good run time out of a single 14500 depending on what kind of light you have. Just my two cents worth. If you use your light a lot buying alkalines can get expensive.

 

[darklord]

Thanks, SC.

I've got some NiMH rechargeables, of course, various capacities...1900 eneloops, 2400 Uniross etc. What confuses me is when I look at the 14500s for sale they have capacities like 650, 700, 800 mah.

Errm, as I said, I'm not very clever on the arithmetic of these things!

 

[Timothybil]

I've got some NiMH rechargeables, of course, various capacities...1900 eneloops, 2400 Uniross etc. What confuses me is when I look at the 14500s for sale they have capacities like 650, 700, 800 mah.

The thing to remember when comparing disparate cells like this is not mAh, but mWh (milliWatt hours), which are obtained by multiplying cell voltage times cell mAh capacity. mWh is a truer measure of the total power available from a cell, taking into consideration both cell voltage and cell mAh capacity. As you can see, by using this measure, all of the cells you mention have similar power capacities.

As was said, there are advantages to a higher cell voltage, especially at the higher output levels. But since the OP isn't really interested in those levels, Given that, 14500 and NiMH rechargeable cells are obviously the way to go. Of the two, given that high output levels are not a large factor, I would say that LSD NiMH cells and a good charger would be the way to go. Primary cells are nice to have handy when power is not available to run the charger, but should not be a consideration for day to day use.

Personally, I use a 14500 in my EA11 single AA light, but then I am a devotee of the Tim's Tools school of thought - "More Power!"

 

[darklord]

The thing to remember when comparing disparate cells like this is not mAh, but mWh (milliWatt hours), which are obtained by multiplying cell voltage times cell mAh capacity. mWh is a truer measure of the total power available from a cell, taking into consideration both cell voltage and cell mAh capacity. As you can see, by using this measure, all of the cells you mention have similar power capacities.

14500s being 3.7v....? And NiMH being 1.2v..? OK, that's a simple calculation I can remember!

I've always had a love-hate relationship with NiMHs which, apart from eneloops, never have the reliability of performance I'd hope for. Some cells fail prematurely, capacity is always in doubt, 'confidence' is not their watchword.

Would 14500s be more reliable? I certainly find my 18650s quite reliable.

 

[ChrisGarrett]

14500s being 3.7v....? And NiMH being 1.2v..? OK, that's a simple calculation I can remember!

I've always had a love-hate relationship with NiMHs which, apart from eneloops, never have the reliability of performance I'd hope for. Some cells fail prematurely, capacity is always in doubt, 'confidence' is not their watchword.

Would 14500s be more reliable? I certainly find my 18650s quite reliable.

I run li-ions in my CR123A and AA light and it just comes down to brightness vs. runtime. One can get a lot of lumens out of smaller lights than they can with their primary power sources. Two issues are runtimes being a bit lower and heat.

Runtime can be mitigated with carrying a small plastic snap case with 2/4 spares. If you need to have a lot of light in a small package and if you're willing to regulate your usage on high, by dropping down to medium, or low after 5-10 minutes, then that might be the better way to go for some of us.

Li-ions need some further attention relative to primaries, or NiMH batteries.

Pick your poison.

Chris

 

[more_vampires]

Thanks, SC.
I've got some NiMH rechargeables, of course, various capacities...1900 eneloops, 2400 Uniross etc. What confuses me is when I look at the 14500s for sale they have capacities like 650, 700, 800 mah.
Errm, as I said, I'm not very clever on the arithmetic of these things!

Perhaps look at it this way:

On one hand, you've got a Toyota Prius hybrid car. Good gas mileage. Environmentally responsible (maybe.)
On the other hand, you've got a pedal-to-the-metal muscle car that can only run on 104+ octane (at the bare minimum.)

One gets the commute to work. The other only drives a quarter mile at a time and gets a new entire engine every 3-5 trips.

Make sense?

RCR123 has lousy capacity, basically because it's a rechargeable version of a non-rechargeable battery (and they are not even strictly voltage compatible.)

NiMH can give steady current discharge pretty well, but is only pushing 1.2v nominal.
Lion 14500 has to do 4.2v fully charged so something's got to give. In this case, the capacity.

 

[darklord]

Li-ions need some further attention relative to primaries, or NiMH batteries.

Hi Chris, and what "further attention" might that be?.... You mean they just need more 'care' in charging/maintenance?

 

[reppans]

Maintenance will be the same as your 18650s - no over: charge, discharge, current, etc.

I'm a runtime fanatic and use sub-/low-lumens 90% of the time and like 14500s in my 0.9-4.2v lights. Although they are still about the same watt-hrs of energy as a NiMh, I prefer running 14500s for a few reasons: brighter max (when I need it), voltage checks are an accurate indicator of state of charge, and greater efficiency with well regulated boost/buck drivers (ie, lower modes stay at spec regardless of voltage). I guess it's less efficient to boost V up ~150% than to buck V down ~25% to the Vf of the LED (3 something volts).

 

[bob_ninja]

Here is simple short summary:
- "LSD" category NiMH cells have solved most of the problems with the old technology that was much fragile, Eneloop being the best in class. There are other re-branded versions like Amazon that are cheaper.

Use LSD NiMH for reliable/longer lasting operation when performance is not top priority. So if you don't care about max lumens or peak output then NiMH is perfect.

- LiIon primary advantage over LSD NiMH is IR that provides more peak power. So if you want max output/performance than LiIon is better choice.

In general, LSD NiMH is just as reliable and has low SD as most LiIon.

 

[yellow]

.
14500 and NiMh have (roughly) the same energy stored in the cell
(voltage * capacity)

* the 14500 can be used with the same charging equipment as your 18650s
* when there is a difference in boost mode, then with the 14500 the output will be brighter.
* At all other levels there is zero difference (runtime, output, ...)
* 14500 is lighter (if that is a concern)