MC-E dropin (Dereelight) + 2 x IMR 16340 = bad?

I was trying different configurations with my lights tonight and don't know if I ruined my Dereelight MC-E dropin in the process. I tried two different configurations before realizing what I did might be bad:

1. 2 IMR 16340's in a FM 1x18650 body with an RPM clicky = no light whatsoever

2. 2 IMR 16340's in a SF C2 body with the SF twisty = low output with purple tint


After the first configuration, I thought the IMR 16340's might be dead but after I saw the purple tint output in the second configuration, I'm thinking I might have done some damage. From what I remember, running IMR's with direct drive could quickly cause damage but I thought it was ok with regulated setups?

With all the different combinations possible where some of them could result in , I'm having a hard time keeping things straight!

Have you tried it in a CL1H or DBS with 2x18650's? I would think IMR16340's would be okay, but I haven't tried that yet.

The only MCE module from deerelight I see is their 3sm 4.6-12v. If that's the module you were using then it should be fine on 2xIMR cells.

gsegelk said:

I was trying different configurations with my lights tonight and don't know if I ruined my Dereelight MC-E dropin in the process. I tried two different configurations before realizing what I did might be bad:

1. 2 IMR 16340's in a FM 1x18650 body with an RPM clicky = no light whatsoever

2. 2 IMR 16340's in a SF C2 body with the SF twisty = low output with purple tint


After the first configuration, I thought the IMR 16340's might be dead but after I saw the purple tint output in the second configuration, I'm thinking I might have done some damage. From what I remember, running IMR's with direct drive could quickly cause damage but I thought it was ok with regulated setups?

With all the different combinations possible where some of them could result in , I'm having a hard time keeping things straight!

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There is nothing in your testing to prove that the batteries aren't dead. the MC-E will draw a lot of current and be such a load to those two little pieces of sshpleep batteries that its quite possible if they were very low on charge, you got no output. Going to the SF with some lesser current draw pill they had enough uumph left in them to give a little purple light. Finish the job and actually test the batteries in something appropriate individually or recharge them and put them in the SF.


Don't know if the IMR's are truly supposed to be safer than Lithium ions but still not the smartest thing to do. The MC-E is a very high current load and those are low amp/hour rated batteries. Don't want to reverse charge one in the process.

Thanks for the feedback...I agree that everything seems to point to the batteries. I hate to admit this, but at the time I didn't have any other batteries to test with. I have several 18650's but don't have any extension tubes and could only find 1 RCR123. I just found another one and have both on the charger so I can test it with something other than the IMR's.

When I created this thread, I only had 1 RCR123 on hand so I wanted to be sure that running this with 2 IMR's was ok before I tried them again after charging. The RCR123's should be finished charging soon...

I would not run an MC-E on two little RCR batteries. Current draw is very high and if one of those batteries does start to reverse charge you can get it to vent or . May just vent from high current draw anyway without reverse charging. What did you intend to run this MC-E with?

The 16340 IMR batteries should according to specification and tests, be well able of handling current discharge of at least 4 A. The MCE pill should give about 2.1 A to the led which means probably between 1 and 1.5 A from each battery. This should be absolutly no problem for these batteries. The run time will however be limited, and be sure not to over discharge the batteries.

I have a DBS that is running with 2xIMR16340 and MC-E and have been using it for some time, it works very well, but the runtime is a bit short.
I have also used it with 2x18650 cells, but I do not like a long DBS.

I have run my MC-E on RC123's and CR123's plus 18650's with no problems. Mine is a 2.4a pill and with two CR123's the batteries do get warm but have had no problems with the six CR cells i have discharged. If something like an Extreme can run a P7 on one CR123 that discharges in 20 min why not run two in an MC-E?

I also use IMR 16340s regularly with my DBS MC-E since first introduced. No problems at all, and I prefer the pocketability of this combo vs. my 2x18650 extension.

Now if Dereelight would only produce the requested 2x18500 extension we'd have the perfect balance of output, size & runtime.

jenskh said:

The 16340 IMR batteries should according to specification and tests, be well able of handling current discharge of at least 4 A. The MCE pill should give about 2.1 A to the led which means probably between 1 and 1.5 A from each battery. This should be absolutly no problem for these batteries. The run time will however be limited, and be sure not to over discharge the batteries.

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Batteries in series draw the same current. Both batteries would draw 2.1A not 1 to 1.5A each. Batteries in parallel would draw half the total load current in theory if they were equally matched.

That is part of the problem. If the batteries are in good shape and fairly equally charged and not run down to the point of shut down then it is no problem. Two batteries do not have to be at the same charge level and same output voltage under load to be forced to draw the same current to that load. That is how a weak battery gets reversed charge in a stack in the first place.

With non protected RCR's if one of the 2 batteries is in bad shape or more run down than the other, it can reach to the point where it collapses its voltage and starts to reverse charge off the other battery trying to maintain constant current into the load that has a regulator.

Running fresh batteries and topping them off regularly as some of you do may help to prevent this, but that is not to say one day some where some one wont have a battery that is going bad or just happens to be more discharged and the first symptom of that is a high pitched whine and then when running a high current draw light. It has happened before and will happen again. The use of smaller and smaller batteries (the RCRs in particular I don't know about these special IMR's that are supposedly "safer") to run higher current loads increases the likely hood of that. Just running batteries hard shortens their life and there is nothing to say that any pair will degrade in performance equally, it just doesn't work that way.

So for you guys who say you have done it with no problems, that is not proof that there will never be a problem by running a 2 amp load from a little RCR battery pair. It is a risk, its your risk, do whatever you want, but don't dismiss it as not being a risk.

There is a reason that they came out with these IMR batteries in the first place.

Absolutely good points. The ideal setup for the DBS MC-E is 2 x 18650's. But, the DBS MC-E runs each die of the four-die MC-E LED at 525 mA. Typical current draw from 2 x RCR123's is 1050 to 1100 mA. Near the end, the current will go up to about 1250 or so... this is only during the last minute or two. For those who must use RCR123's, I have recommended AW's RCR123's. He has stated that the maximum safe limit for them is a 1400 mA draw... the DBS MC-E stays under that limit. This is the 2.1 amp MC-E version I'm talking about, which is the only version I have sold. Dereelight came out with a 2.4 amp version, but after discussing it with me (and the fact that people would use 2 x RCR123's because they'll fit) they decided to go back to the 2.1 amp version. They now only sell the 2.1 amp version.

The IMR 16340's will handle the 1100 mA load effortlessly. The down side is that they do not have any protection circuitry, so they will be drained down too low in voltage if you don't limit the runtime to about 20 minutes or so. IMR's will have a short life expectancy if continually drawn down to less than 2.5 volts (and especially if left in a low voltage state without being recharged).

Thanks for all the feedback! I charged both the IMR's and the AW RCR123's and both sets work fine in the SF C2 body and the Dereelight C1H body. So the problem I was having with setup #2 was due to the IMR's being drained right at the cutoff voltage for the dropin (oops!)...

BUT, even with the batteries charged, it still doesn't work in the FM body. I figured it must be a connection problem since it worked with the other bodies so I took the batteries out and found that the dropin is sitting loosely between the body and the head. I can't be the first person figuring this out given the popularity of the FM bodies so I'm guessing I missed something obvious in the sales thread.

One option is to use the spring that the other Dereelight dropins use but this isn't recommended per the Dereelight site (heat buildup). I seem to remember someone talking about this issue with the Malkoff dropins and it was resolved using a washer or aluminum foil. I'm going to do a little searching...

MrGman said:

Batteries in series draw the same current. Both batteries would draw 2.1A not 1 to 1.5A each. Batteries in parallel would draw half the total load current in theory if they were equally matched.

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Wrong, the orignal poster was correct.

The pill delivers 2.1 amps at the VF of the LED, 3.4-3.8 volts.

Two batteries put out >7.4 volts, the converter will pull less than 2.1 amps.

Measured at the tailcap my Dereelight MCE pulls 1.08 off of 2 RCR123s.

Jay T said:

Wrong, the orignal poster was correct.

The pill delivers 2.1 amps at the VF of the LED, 3.4-3.8 volts.

Two batteries put out >7.4 volts, the converter will pull less than 2.1 amps.

Measured at the tailcap my Dereelight MCE pulls 1.08 off of 2 RCR123s.

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If you are stating that my "restating" of the 2.1 amps current draw from the batteries is incorrect, I agree. I think I misunderstood Jenshk's intent of his message and thought he was trying to say that the batteries were each supplying half of the LED's required load current at 1 to 1.5 amps.

I don't think you disagree with me that batteries in series must all deliver the same current, the currents are not additive, only the voltage. If you say the current draw at the tailcap is 1.08 amps, both batteries draw 1.08 amps and the total voltage is somewhere above 7.4V and definitely less than open circuit value of 8.4V. That would make more than 7.4 watts. If the LED was at say 3.4V and 2.1 amps that would be 7.14 watts and the rest would be dissipated across the driver (0.26 watts) and that sounds a little low but just for the sake of example, The power put out by the 2 batteries equals the power consumed by the total load of the LED and driver and that makes sense.


Whether its one or twelve batteries in series, whatever the current is through one is the same through all be it 1 amp or 12 amps they all see the same current. That was my point.

Thus if one drops out voltage and the regulator is trying to maintain current it could reverse charge and possibly go poof. It would not really matter if it was being driven with 1 amp or 2 amps if it got to reverse charge, it would probably still go poof. The need for protected or IMR batteries is still the main point.

I have been using AW RC123's in the 2.4a version but will take advise from those who know but i am still confused as to how the Extreme runs down a single RC123 in 20 mins on max power with no recorded problems?

electric sheep said:

I have been using AW RC123's in the 2.4a version but will take advise from those who know but i am still confused as to how the Extreme runs down a single RC123 in 20 mins on max power with no recorded problems?

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The short answer to that is because a single battery type system can't ever reverse charge the one battery. That is a big part of preventing the problem right there.

I'm running 2xAW R123's in my DBS with the MC-E 2.4A. It's drawing 1.5A at the moment when I measure it. That's about the most you want to draw from these batteries last I checked with AW. The batteries are reading 4v. Since this pill is regulated, when the voltage drops, say to 3.7v, it should start drawing even more current (and if the batteries were fully charged, the current draw would be a little lower.) So this could get a little dicey. At least these are protected cells, but it would be more ideal to run 2x18650's or 2xIMR16340's. The only problem with 2xIMR16430's is you could over discharge them, as I believe the MC-E pill has no over discharge protection. So one would have to use care there.

I may keep running AW R123's (protected) and just keep it topped off.

The 2.1A MC-E pill should keep the current draw at a safer level for R123's.

I have a Dereelight MC-E (2.1a) lamp module on the way from Dereelight.

My plan is to drop it into a Solarforce L2 w/extension to hold two black AW protected 18500 cells.

Some questions... as long as the light isn't run for long periods of time, but perhaps used for 10-15 min at a time, will heat generation not be a problem?

Also, are the non-IMR cells capable of doing a reasonable job driving this lamp assembly?

I have two P7 lamp modules (one a Malkoff) that run well with a single IMR 18650, but the Dereelight MC-E isn't likely to run well with a single cell, is it?

DHart said:

I have a Dereelight MC-E (2.1a) lamp module on the way from Dereelight.

My plan is to drop it into a Solarforce L2 w/extension to hold two black AW protected 18500 cells.

Some questions... as long as the light isn't run for long periods of time, but perhaps used for 10-15 min at a time, will heat generation not be a problem?

Also, are the non-IMR cells capable of doing a reasonable job driving this lamp assembly?

I have two P7 lamp modules (one a Malkoff) that run well with a single IMR 18650, but the Dereelight MC-E isn't likely to run well with a single cell, is it?

Click to expand...

Should be fine at those runtimes... 15 minutes might be pretty hot, you'll just have to see.

Two regular protected Li-Ion 3.7V 18500's will handle the current fine. The MC-E module won't run with a single cell... needs at least 4.6V and up.