Batteries for LED flashlights

[Superorb]

Last month I picked up about 8 packs of Duraloops (white top, Japan). How do they compare to the CR123a and the 15800 batteries? I'm looking for some LED lights, but I don't know if I should invest in some new batteries/chargers and get a different flashlight altogether. Any advice?

 

[SilverFox]

Hello Superob,

Welcome to CPF.

The Duraloops are NiMh chemistry, the CR123A is lithium chemistry, and the 15800 is lithium ion chemistry.

The NiMh and Li-Ion chemistries are rechargable, the CR123A is a primary cell and is not rechargeable. However there is a R-CR123 Li-Ion cell that is rechargeable.

The nominal voltage of a NiMh cell is 1.2 volts, the primary lithium cell is 3.0 volts, and the Li-Ion cell is 3.7 volts.

The Duraloops have a capacity of around 2000 mAh, primary lithium cells come in at a little over 1550 mAh, and I am not sure what the capacity of the 15800 Li-Ion cell is. The R-CR123 cells seem to be coming in at around 600 mAh of capacity.

As an official CPF member I will pass on the official CPF advice... You can never have enough flashlights, batteries, or chargers...

Tom

 

[Superorb]

Thanks for the input. How do the Duraloops compare to the R-CR123a's or the 15800 rechargeables as far as runtime is concerned?

 

[SilverFox]

Hello Superorb,

Once you get past the voltage differences, it looks like the Duraloops have the highest capacity. Capacity is directly related to run time.

The Duraloops have a capacity of 2000 mAh, the R-CR123 cells have a capacity of abot 600 mAh, I couldn't find 15800 cells, but the 17800 cells have a capacity of about 1100 mAh.

In theory, if your light had a 1 amp draw, the Drualoop cells would give you about 2 hours of run time, the R-CR123 cells would give you about 36 minutes, and a 17800 cell would give you about 1 hour and 6 minutes of run time.

Tom

 

[Superorb]

Hello Superorb,

Once you get past the voltage differences, it looks like the Duraloops have the highest capacity. Capacity is directly related to run time.

The Duraloops have a capacity of 2000 mAh, the R-CR123 cells have a capacity of abot 600 mAh, I couldn't find 15800 cells, but the 17800 cells have a capacity of about 1100 mAh.

In theory, if your light had a 1 amp draw, the Drualoop cells would give you about 2 hours of run time, the R-CR123 cells would give you about 36 minutes, and a 17800 cell would give you about 1 hour and 6 minutes of run time.

Tom

Gotvha. So, the higher voltage delivers brighter light for less time, but the Duraloops deliver less brightness for longer? I'm not too good with the electrical stuff. I suppose mah is capacity and Voltage is how much power the batteries can deliver at one instance in time?

 

[Oznog]

But you can't "get past" the voltage differences.

2000mah @ 1.2v NiMH= 2.4 watt-hrs (plz do not state this as w/hr)
1100mah @ 3.7V lithium = 4.07 watt-hrs

The lithium will should outlast the NiMH by a long shot.

It is not uncommon for batt mfgs to lie out their asses about the batt mah capacity to vendors (we're looking at you, KD/DX). Also depending on the flashlight ballast, a light may be unable to use the lower end of the charge on lithiums as the voltage drops below what the LED needs. NiMH has little voltage drop so this doesn't come up.

The batt voltage does not determine flashlight brightness, because the light's ballast changes the voltage to whatever the LED needs. A 1.2V light must be boosted to the 3.7v-ish needed by the LED anyways. It could drive it with more voltage/current than another light running off a 3.7v lithium. There's no telling which will be brighter that's up to the light.

 

[Superorb]

Wow, confusing now. So a rechargeable Lithium will be longer lasting while delivering more volts.

BTW, how can a light boost a 1.2v battery to 3v+?

 

[vali]

Wow, confusing now. So a rechargeable Lithium will be longer lasting while delivering more volts.

BTW, how can a light boost a 1.2v battery to 3v+?

Try these topics:

http://www.candlepowerforums.com/vb/showthread.php?t=220187

http://www.candlepowerforums.com/vb/showthread.php?p=2632695

 

[SilverFox]

Hello Superorb,

Let's move from talking about single cells to talking about how they are used in a flashlight...

Many LED lights contain a circuit that regulates the voltage and current going to the LED. Depending on the requirements of the regulation circuit, a number of battery combination's are available.

If the circuit steps the voltage up, you can run an LED off of 1 Alkaline or NiMh cell. If the circuit drops the voltage, you can run an LED off of 2 Li-Ion cells. Some circuits do a combination of both.

LED's require a certain voltage to work for flashlight use, and they work best at a constant current. LED's will glow at low voltages, but we expect a little more than a glow from our flashlights.

If we look at a battery pack to power a flashlight that has no voltage regulation circuit in it, I think you will begin to get this concept.

We can take 3 NiMh cells, put them in series, and this battery pack will have a voltage of around 3.6 volts, and, in the case of the Duraloop cells, a capacity of 2000 mAh. If you set 3 NiMh cells end to end on a table, you will have an idea of the shape of this light. It will be long and narrow.

On the other hand, we can take 1 Li-Ion cell and end up with about the same voltage. There are many options on capacity ranging from the R-CR123 cells at around 600 mAh, to 18650 cells with up to around 2500 mAh. In the case of using an R-CR123 cell as the battery, the flashlight would be a little fatter than the other one, but much shorter. This ends up being a very compact package for a flashlight.

That should give you a starting idea about size differences, now let's look at available energy.

The battery pack made up of 3 NiMh Duraloop cells would have around 7.2 watt hours. The battery pack made up of 1 R-CR123 cell would have around 2.2 watt hours.

Now, if your light uses 3.6 watts, the light powered by the Duraloops will last around 2 hours, and the light powered by the R-CR123 will last around 36 minutes.

Now you have to look at how you are going to use the light. The light powered by the R-CR123 battery will easily fit into your pocket and may be readily available when you find yourself needing a light. The other light will most likely end up on a shelf or in a tool box and when you need a light you will have to go find it before being able to use it.

Many people find that they use both types of lights, and as you can see, there are an infinite combination of variations between these two examples.

Tom

 

[Superorb]

Thanks Tom and Vali.

So what are the Pros/Cons of using a light with an 18650 cell as opposed to some Duraloops?

 

[SilverFox]

Hello Superorb,

Now you have come to the point where you can begin to understand the information available on CPF. You can go the the LED section and see what others have to say about various lights. You can do the same for headlamps, incandescent, and specialty lights. There are even people who are not satisfied with what the manufacturers make, and they will custom make improved lights.

Browse, study, and enjoy.

Tom

 

[TakeTheActive]

...I'm not too good with the electrical stuff. I suppose mah is capacity and Voltage is how much power the batteries can deliver at one instance in time?

Please explain V)olts, A)mps, R)esistance, W)atts, and C)apacity

 

[Superorb]

^^ Thanks. I've got a TON of reading witht his and the Welcome Mat. I'm going to start another thread ina minute.