RCR123 vs. IMR123?

[recDNA]

I have a Dereelight Javelin head that I use in a "shorty" format holding one CR123 sized battery. The D26 drop in is the single mode 4.2 volt XP-G by Dereelight.

I've noticed that using a AW RCR123 the draw is 1.4 amps at the tailcap but with the AW IMR123 the draw goes up to 1.8 amps.

Of course I'll get more runtime with the RCR123. I tend to use my "shorty" only for short bursts anyway. In fact I almost never "click" it, rather I just hold and depress a little utilizing the forward clicky function.

My question is approximately how many lumens am I losing on an XP-G running 1.4 amps vs. 1.8 amps with the IMR battery?

 

[joe1512]

If you already have both batteries, can't you find out for yourself? You wont exactly be able to compare them side by side of course, but you can certainly see if there is a significant difference.

I would guess you will notice a bit of difference but not much. At higher amperage the emitter is going to have diminishing returns, so its a lot less difference than from 0.6 to 1.0 for example.

Then, based on how we see lumens, it would require a 2x increase in lumens for us to consider it 20 to 30% brighter.

With those 2 factors in mind, if you think runtime is important, I'd go with the RCR123 over the IMR unless you can tell a significant difference in output which I'd think is unlikely.

 

[hoongern]

One thing to think about, I'm not sure that you'd actually get more runtime with the RCR123 over the IMR123. Have you tested it? Afaik, the RCR123 looses A LOT of capacity > 1Amp discharge rates, whereas the IMR123 remains consistent ~ 500+mAh

 

[recDNA]

If you already have both batteries, can't you find out for yourself? You wont exactly be able to compare them side by side of course, but you can certainly see if there is a significant difference.

I would guess you will notice a bit of difference but not much. At higher amperage the emitter is going to have diminishing returns, so its a lot less difference than from 0.6 to 1.0 for example.

Then, based on how we see lumens, it would require a 2x increase in lumens for us to consider it 20 to 30% brighter.

With those 2 factors in mind, if you think runtime is important, I'd go with the RCR123 over the IMR unless you can tell a significant difference in output which I'd think is unlikely.

I would really need to see them side by side.

I have seen posters who know the efficiency of the XP-G R5 determine mathematically the approximate lumen increase at the LED. That was the type info I was looking for.

I prefer the safety of the IMR chemistry at high with high amp use and I only need to charge my IMR once a week so runtime isn't a problem at my level of use.

If, however, I am told there is only a 10 lumen difference then naturally I'd go for the runtime and go with the RCR. I'm a little concerned that the draw is kind of high for an RCR also.

Mostly, I'm just curious but not curious enough to purchase another shorty for a side by side test.

 

[45/70]

I'm guessing that hoongern may be right. IMR's hold up so much better at high discharge rates, that you may be surprised to find they actually provide longer runtime at 1.4-1.8 Amps. You're right though, at lower discharge rates, LiCo's will last longer. Sorry, I can't help you with the lumen estimate.

Dave

 

[Bullzeyebill]

Do you have an 18650 body you could try with the head? I would be interested to see the current at tailcap with the larger Li-Ion cell. It might be closer to 1.8A's, indicating that your drop in is working at its rated output with a Li-Ion cell that can supply the current.

Bill

 

[ShineOnYouCrazyDiamond]

Just be aware that you are running those RCR123 cells pretty hard - close to 2.5-3C.

Above 1A the RCR123 cells have about 500 mAh capacity, which means at 1.4A draw you are getting close to 3C on the cell.

The IMR16340 has a lower internal resistance compared with the RCR123 and can push more power into the same load - as you can see with the 1.4 vs 1.8 current draw.

My rule of thumb for R123 size cells is - less than 1A you are safe with RCR123 cells, over 1A you should be using IMR 16340 cells.

 

[old4570]

1.8 VS 1.4 = 23% only problem is that the gain with higher Amps is not consistent , but rather a diminishing gain [ depending on all the variables ]
So it may most likely be less than that , possibly closer to 17% [ of the top of my head and working from my own exp ]

 

[recDNA]

Do you have an 18650 body you could try with the head? I would be interested to see the current at tailcap with the larger Li-Ion cell. It might be closer to 1.8A's, indicating that your drop in is working at its rated output with a Li-Ion cell that can supply the current.

Bill

I don't have a bigger body but I could test it anyway with just the head and the 18650. I'll let you know. In the mean time Ive been convinced to stick to the IMR battery. I run the same head with 2 AA L91's also. Right now I'm EDCing it so I'm using the shorty body for 1 X IMR123

 

[turboBB]

If you take a look at the runtime charts in my SC30 review, you'll see that even a LiFePO4 bested standard LiIon RCR and the IMR came out tops.

I do not know what the current draw was and I have a feeling that my particular Ultrafire 16340's are underperformers. I can never really get them to charge above 4.15v and they usually fall immediately to 4.12v shortly after coming off the charger.

I'd stick w/the IMR's unless the PCB is a big deal for you.

Cheers,
Tim

 

[jasonck08]

Definitely go IMR.

I literally measured about 360mAH capacity from the AW RCR123 750mAH cell @ a 1.3A discharge rate (which is a little more then 2C from the actual capacity).

The cell is HORRIBLE at high discharge rates.

I don't think I've ever tested a Li-on cell that does so poorly at a 2C discharge.

AW advertises them as "High current" RCR123's. I wouldn't ever recommend discharging these above 1C, or the capacity of the cell will be pathetic.