IMR Cells?

[pobox1475]

I have been away from forum and purchasing new lights for a while. Just caught wind of the JetBeam RRT-01 and it looks like a nice EDC. Traditionally I have been using AW black label RCR's in all my 123 sized lights. What are the advantages of IMR cells? It appears more than one size of them can be used in 123 lights. Is this the case and if so what are their size #'s?

 

[tandem]

IMR use a safer (not safe, just safer) chemistry that is well suited for high drain applications (which probably does not describe the RRT-01). IMR cells are popular with pocket rocket fans who need cells that can safely deliver several to many amps of current.

Safer means they have advantages for series use in lights in that if something goes wrong and one cell does become seriously imbalanced it is less likely to vent profusely (leading to blow-ups in sealed tube flashlights) than a standard LiCo li-ion.

Downsides: For a given size, IMR cells have less capacity than LiCo due to the different chemistry. Another practical downside of IMR cells is that they aren't protected; some folks might actually want to rely on the protection circuits of protected LiCo cells to provide a low voltage cut-off. As some lights incorporate low voltage cut-off capabilities, this downside is light specific. In any case to avoid cell damage either the light or user should be terminating IMR cell use before they are too deeply discharged.

I use LiCo and IMR cells in multi-cell (series) lights all the time and fairly interchangeably. I don't need IMR cells for high current (yet) nor do I reach for them for safety concerns - I just happen to have some that I mostly use in a 1xCR123A sized SureFire light or 2x 18350 when I want to power Malkoff drop-ins at higher voltage with a still-short 6P sized flashlight. I don't have any RCR123 li-co cells.

For bigger lights when I want both higher voltage and more capacity than 2x IMR could delivery I use Li-Co 2x18500 and less often even bigger lights with 2x18650 cells, not IMR based, and I don't fret any more about safety when using these lights. Then again I check all my cells with a voltmeter before use and after charging, and I only use high quality Li-Co based cells in multi-cell lights.

As an old hand no doubt you know this but for newbie readers: always check with the light mater to be sure your light can handle the higher voltage 2xli-ion presents (as much as 8.4 volts) as compared to 2xCR123 (6 volts). Not all can take those additional 2.4V without going :poof:

 

[pobox1475]

Thanks, that shed some light on things for me. I thus far have only used single protected AW Li-ion cells. 17670 in Quark 123x2, 18650 in Jet 3M, etc...

 

[snakyjake]

With the different chemistries you are trading runtime, safety, or high output. Research LiCO (protected), LiMN, and LiFePO4. I've read about multi-cell lithium and LiMN batteries dangerously venting. LiFePO4 is safe, but compromises runtime and high output. LiCO is a dangerous chemistry and protection via circuit doesn't have my full confidence (haven't seen any testing and I'm not comfortable with the risk).

For me, my next light will be optimized NiMH (i.e. Zebralight).

 

[tandem]

If you look at my postings in this subforum probably you'll come to the conclusion that I am something of a safety nerd when it comes to hobbyist/enthusiast use of li-ion cells in flashlights. I plead guilty.

Despite that I have no issues at all using li-ion cells in multi-cell lights. I am comfortable with the risks involved after taking what steps I can to minimize risks:

- invest in known good quality cells with a proven track record
- invest in known good quality chargers with proven track record
- invest in good quality lights with proven track record and solid engineering
- charge cells only when I'm physically present (easy to do during the work day for me)
- make voltage check after charging and before insertion into lights a regular habit
- don't take safety for granted, assume anything can happen
- lock out lights when not in active use (tail cap slightly unscrewed)
- don't allow my kids access to my high output lights

Li-ion cells are in many products. There are li-ion cells in all of my portable construction tools (IMR cells); 18650's are in my laptop and wife's work laptop. LiPo cells and batteries are in our cell phones and other portable devices. These products have been made safer thanks to engineering and documentation work done by the product maker.

With flashlights we are to some degree our own systems integrator. Provided one is willing to take on the product "design" and documentation challenge (even if documentation is oral), there is no reason why through careful selection of base components a li-ion powered flashlight system assembled by the user can't be safe enough for regular use by properly motivated persons.

If my AW/Panasonic powered Malkoff driven flashlight charged by a Pila charger is unsafe for household use then so are our laptops and other li-ion powered devices.

Would I feel comfortable handing over to my wife or kids a flashlight of questionable heritage powered by an UltraFire charged by a no-name never reviewed (or reviewed and found lacking) charger? No, I would not.

 

[Joe Talmadge]

IMR use a safer (not safe, just safer) chemistry that is well suited for high drain applications (which probably does not describe the RRT-01).

I have not been following the RRT-01 threads closely enough, but I thought I've seen numerous mentions of IMR 18350s delivering more light output than ICR/LiCo... Certainly the RRT-01 does impose a bit higher drain than LiCo battery manufacturers recommend, though not by too terribly much

 

[Raze]

AW IMR 18350 are rated at "3.7V 700mAh", at least that's what it says on the red label/wrapper.

The charger I use is the Xtar MP1 single-bay charger, with a dummy CR123 cell I got from light hound. So far the charger has been excellent at terminating the charge at 4.15 for my AW protected 18650s,

When the LED indicator turns green, I immediately remove the 18350 from the charger. Using Cottonpicker's mini voltmeter, I tested the 18350 and it reads "4.22".

Is this safe voltage termination for the IMR 18350?


Sent from my iPhone using Tapatalk, please pardon typos.

 

[Joe Talmadge]

Yes, that's within spec

 

[jasonck08]

When the LED indicator turns green, I immediately remove the 18350 from the charger. Using Cottonpicker's mini voltmeter, I tested the 18350 and it reads "4.22".

Is this safe voltage termination for the IMR 18350?

The spec for voltage during the CV stage is 4.20v +/- 0.05v. So 4.15-4.25v is considered acceptable.

 

[Raze]

Thanks all for the help. I just need to make sure I don't drain the IMR too much right? That's what I've read at BatteryUniversity.com




Sent from my iPhone using Tapatalk, please pardon typos.

 

[turboBB]

Correct, however given it's LiMn based, the lowest discharge voltage is 2.5V but ideally you shouldn't let it drop that low so as to prolong cycle life.

This is for your Alpha shorty I assume? If so, my AW IMR 18350 should be here tomorrow after which I'll add to the shorty runtime chart.

 

[Raze]

Correct, however given it's LiMn based, the lowest discharge voltage is 2.5V but ideally you shouldn't let it drop that low so as to prolong cycle life.

This is for your Alpha shorty I assume? If so, my AW IMR 18350 should br here tomorrow after which I'll add to the shorty runtime chart.

You assumed correctly!

I love the Alpha Shorty but I guess I'm still babying the AW IMR as I don't quite have the general idea of how long I can use the light before popping the 18350 back to the charger. It's quite a hassle to keep removing the battery for checking what's left in the tank.

I really appreciate the effort you took for your review and run times, especially for the Shorty. Mine's MC18-B though, maybe you can help me ballpark the runtime for a Shorty with the MC-E on the 18350?

Thanks!


Sent from my iPhone using Tapatalk, please pardon typos.

 

[turboBB]

Wow, that was fast! Just got home and the battery is already here (shipped from NY right across the river) and charging up now. ;)

I'll have runtime for you later tonight and basically whatever the results I get you can assume MC-E will last a little longer.

EDIT: @OP - apologies for the OT but looks like your original q's have been addressed so hope you don't mind the segue.