# Safe chemistry LiMN 3.7V rechargeable batteries?



## bleagh (Mar 12, 2011)

Anybody know how these LiMN (IMR) batteries perform compared to Li-ion?
I have seen runtimes of the 18650 but not any of the smaller sizes (16340, 14500, 18350).

And as most of the 14500 and RCR123 Li-ion seem to have overrated capacities, I am really interested in seeing how these LiMN batteries compare.


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## cistallus (Mar 14, 2011)

As a data point, an AW IMR (LiMn) 550mAh-labeled 16340 ran 1.3 hours, and an AW ICR (LiCo) 750mAh-labeled one ran 1.2 hours, in my HDS Clicky on high. I was rather surprised that the IMR did so well. Both cells are relatively new and were at 4.14-4.15V at start of test.


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## rich297 (Mar 14, 2011)

cistallus said:


> As a data point, an AW IMR (LiMN) 550mAh-labeled 16340 ran 1.3 hours, and an AW ICR (LiCo) 750mAh-labeled one ran 1.2 hours, in my HDS Clicky on high. I was rather surprised that the IMR did so well.


 
I'm surprised too! Are the two batteries of approximately equal age and were they each fully charged before your test?


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## 45/70 (Mar 14, 2011)

Just to bring up a common error when referring to IMR cells, IMR cells are LiMn2O4 cells and are often referred to as "LiMn" (Li=lithium, Mn=manganese), not "LiMN". "LiMN" is usually used when referring to certain Li-Ion cells which contain both manganese (Mn) and nickel (Ni) in the positive electrode, which IMR cells do not.

LiMN, or lithium manganese nickel cells, are closely related to (but not quite the same as) the Redilast and AW 2900mAh cells (which are actually Li-NiCoAl), for example. Most of this general family of cells, which tend to also operate at a higher voltage, also contain cobalt in the positive electrode, which IMR cells do not. This fact is mostly why IMR cells are considered to be a "safer" chemistry.

Not nit picking, but rather trying to help keep things more clear when talking Li-Ion cell chemistries. The most common error I see when describing Li-Ion cells, is when running across someone refering to LiFePO4 cells as "LiPo" cells, when in fact "LiPo" refers to "*Li*thium *Po*lymer" cells which are not the same chemistry as LiFePO4 cells however, they are both lithium ion, or "Li-Ion" cells.

With the newer Li-Ion chemistry cells arriving on the scene, even I get the nomenclature mixed up sometimes. Maybe I just did, but I don't think so.

Dave


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## ElectronGuru (Mar 14, 2011)

Great info Dave!



cistallus said:


> As a data point, an AW IMR (LiMN) 550mAh-labeled 16340 ran 1.3 hours, and an AW ICR (LiCo) 750mAh-labeled one ran 1.2 hours, in my HDS Clicky on high. I was rather surprised that the IMR did so well.


 
RCR123A's are more overstated than other LiCo's, but here's the key point. The smaller a cell, the larger the portion of a protected cell's size is taken up by the PCB's. In effect, the part of the cell that actually stores the energy gets smaller. I use IMR's exclusively in this size.


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## rich297 (Mar 14, 2011)

ElectronGuru said:


> Great info Dave!
> 
> 
> 
> RCR123A's are more overstated than other LiCo's, but here's the key point. The smaller a cell, the larger the portion of a protected cell's size is taken up by the PCB's. In effect, the part of the cell that actually stores the energy gets smaller. I use IMR's exclusively in this size.


 
So would you say that, for this size cell or smaller, the IMR's have equal or greater storage capacity than like-sized LiCo's?


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## Colonel Sanders (Mar 14, 2011)

I just happen to have a couple of brand spankin' new protected AW RCR123s that just showed up in the mail last week....haven't even used them yet. I think I'll order a couple of AW IMR RCR123s and do a little test. I have a hobby charger than can discharge as well as charge so it should be easy to find out what the true capacity is of each. I'll let ya'll know.


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## rich297 (Mar 14, 2011)

Colonel Sanders said:


> I just happen to have a couple of brand spankin' new protected AW RCR123s that just showed up in the mail last week....haven't even used them yet. I think I'll order a couple of AW IMR RCR123s and do a little test. I have a hobby charger than can discharge as well as charge so it should be easy to find out what the true capacity is of each. I'll let ya'll know.


 
That would be great! I look forward to learning what your results are.


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## Colonel Sanders (Mar 14, 2011)

I think I will add a Battery Station rcr123 to the comparison as well.


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## saeckereier (Mar 14, 2011)

16340 protected are 16340 + protection circuit. The Circuit doesn't take away space, it usually makes the cell bigger by 1-2mm which is why sometimes protected cells have fitting problems. There was a nice chart somewhere showing the size variations.


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## srfreddy (Mar 14, 2011)

saeckereier said:


> 16340 protected are 16340 + protection circuit. The Circuit doesn't take away space, it usually makes the cell bigger by 1-2mm which is why sometimes protected cells have fitting problems. There was a nice chart somewhere showing the size variations.


 
Not true-AW's are the same size as Cr123's.


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## ElectronGuru (Mar 14, 2011)

rich297 said:


> So would you say that, for this size cell or smaller, the IMR's have equal or greater storage capacity than like-sized LiCo's?


 
For the 16340 size, I've seen tests and examples showing each as having more, but always just a bit more. There's enough variance between examples that I would state the conclusion more like: _near enough as makes no difference_. 

LiCo + PCB's have enough drawbacks that they need significantly more capacity to make them worthwhile to me.


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## rich297 (Mar 14, 2011)

ElectronGuru said:


> For the 16340 size, I've seen tests and examples showing each as having more, but always just a bit more. There's enough variance between examples that I would state the conclusion more like: _near enough as makes no difference_.
> 
> LiCo + PCB's have enough drawbacks that they need significantly more capacity to make them worthwhile to me.


 
I seem to learn something new everyday at this forum. Thanks for the info.


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## cy (Nov 21, 2013)

45/70 said:


> Just to bring up a common error when referring to IMR cells, IMR cells are LiMn2O4 cells and are often referred to as "LiMn" (Li=lithium, Mn=manganese), not "LiMN". "LiMN" is usually used when referring to certain Li-Ion cells which contain both manganese (Mn) and nickel (Ni) in the positive electrode, which IMR cells do not.
> 
> LiMN, or lithium manganese nickel cells, are closely related to (but not quite the same as) the Redilast and AW 2900mAh cells (which are actually Li-NiCoAl), for example. Most of this general family of cells, which tend to also operate at a higher voltage, also contain cobalt in the positive electrode, which IMR cells do not. This fact is mostly why IMR cells are considered to be a "safer" chemistry.
> 
> ...



how can one identify LiMn2O4 cells by voltage in end product?


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## 45/70 (Dec 3, 2013)

cy said:


> how can one identify LiMn2O4 cells by voltage in end product?



Hello cy. You brought me back from the dead! 

Determining Li-Ion cell chemistry by voltage measurement is a bit difficult. The various LiCo as well as LiMn cells will all charge up to pretty close to whatever voltage at which they are charged (ie. the CV voltage of the charger used). LiFe cells are different in this respect, as the voltage drops significantly when the cell is removed from the charger. The rested voltage after charging at a 3.60 Volt CV is typicaly 3.35-3.45 Volts, depending on the individual cell and the amount of time the cell has rested. I've never tried this (and would not recommend it!) but I believe even if a LiFe cell were charged at a 4.20 Volt CV, the voltage would still eventually drop to within this range. Again though, LiFe cells are the exception in the Li-Ion family. All other Li-Ion chemistry cells, asuming they are in good condition, charge to very nearly the CV Voltage of the charge. Only LiFe cells drop in voltage.

The only way one mght determine LiMn cell chemistry through voltage measurement would be to observe voltage characteristics during discharge at significant current load. This would likely not work all that well either, as some of the newer LiCo formulations retain voltage well under load as well.

So, to answer your question, you can't, really. Hope this helps, LOL!

Dave


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## cy (Dec 20, 2013)

45/70 said:


> Hello cy. You brought me back from the dead!
> 
> Determining Li-Ion cell chemistry by voltage measurement is a bit difficult. The various LiCo as well as LiMn cells will all charge up to pretty close to whatever voltage at which they are charged (ie. the CV voltage of the charger used). LiFe cells are different in this respect, as the voltage drops significantly when the cell is removed from the charger. The rested voltage after charging at a 3.60 Volt CV is typicaly 3.35-3.45 Volts, depending on the individual cell and the amount of time the cell has rested. I've never tried this (and would not recommend it!) but I believe even if a LiFe cell were charged at a 4.20 Volt CV, the voltage would still eventually drop to within this range. Again though, LiFe cells are the exception in the Li-Ion family. All other Li-Ion chemistry cells, asuming they are in good condition, charge to very nearly the CV Voltage of the charge. Only LiFe cells drop in voltage.
> 
> ...



thanks .. let's say cells are charged to 4.2v each .. typically LiCo will drop very little for a brand new cell. then progressively drop further as cells age. what's the typical drop for LiMn2O4 from 4.2v per cell?

LiFePO4 in 4x series 12v configuration when charged to 14.6v (100%) without BMS voltage will drop to 14.25v range or 3.56v from 3.65v .. a drop of about 3% or about same as LiCO

it's nice to know if you overcharge LiFePO4 to 4.2v ... cells will take that abuse without going into thermal runaway. LiFePO4 typically takes wild abuse of charging to 7.25v range to catch on fire. which is a HUGE advantage for LiFePo4.

besides tolerance to wild abuse .. LiFePO4 voltage matches nicely with 12v PB charging systems. fact is the world is already flooded with devices that mate to 12v PB or multiples of. being able to drop-in a 12v LiFePO3 battery is a HUGE advantage!


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## StorminMatt (Dec 21, 2013)

cy said:


> besides tolerance to wild abuse .. LiFePO4 voltage matches nicely with 12v PB charging systems. fact is the world is already flooded with devices that mate to 12v PB or multiples of. being able to drop-in a 12v LiFePO3 battery is a HUGE advantage!



Another unique quality of LiFePO4 among Li-Ion chemistries is the fact that LiFePO4 has a voltage plateau. Most Li-Ion batteries experience a linearly decreasing voltage as state of charge decreases (similar to alkaline batteries). But on discharge, LiFePO4 behaves alot more like nickel-based batteries (ie NiMH, NiZn, NiCad) in the sense that it maintains a very constant voltage during discharge. This is certainly an advantage over lead acid, which also experiences a drop in voltage with state of charge. Voltage regulation circuitry can be greatly simplified (or even eliminated) as a result. Of course, unlike lead acid (and like NiMH), state of charge cannot be determined by a simple voltage reading.


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## RetroTechie (Dec 21, 2013)

rich297 said:


> So would you say that, for this size cell or smaller, the IMR's have equal or greater storage capacity than like-sized LiCo's?


More like: @ high drain, IMR cells can put a greater % of their capacity to good use. Which makes them perform on par with higher-capacity cells. This is especially true for small sizes like 16340, since it's easier for devices to reach a point where you're talking 'high drain'.

On the flip side: once that energy has drained, it's "lights out" quickly for an IMR cell (similar to LiFePO4 cells). That is: drained at a high power level means drained, period. With regular LiCo cells, there's more room to drain a cell at low power after it ran out of steam on high.


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## BVH (Dec 21, 2013)

Just look at this flat discharge test of my 100 Ah LiFeP04 brick cells: (I used 2 cells in Series and extrapolated to 9 cells in-Series - how I use them, because my electronic load would not handle that Amperage at the higher Voltage)

starting pack............29.76V - immediately dialed in 85 Amps and tapered down to 63 Amps over 45 seconds. Remained at 63 amps for balance of test.
At 5 minutes.............28.67
At 10 minutes...........28.58
At 20 minutes...........28.49
At 30 minutes...........28.43
At 40 minutes...........28.35
At 50 minutes...........28.24
At 60 minutes...........28.06
At 63 minutes...........28.0
At 67 minutes...........27.9V - 3.1 VPC






StorminMatt said:


> Another unique quality of LiFePO4 among Li-Ion chemistries is the fact that LiFePO4 has a voltage plateau. Most Li-Ion batteries experience a linearly decreasing voltage as state of charge decreases (similar to alkaline batteries). But on discharge, LiFePO4 behaves alot more like nickel-based batteries (ie NiMH, NiZn, NiCad) in the sense that it maintains a very constant voltage during discharge. This is certainly an advantage over lead acid, which also experiences a drop in voltage with state of charge. Voltage regulation circuitry can be greatly simplified (or even eliminated) as a result. Of course, unlike lead acid (and like NiMH), state of charge cannot be determined by a simple voltage reading.


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## cy (Dec 21, 2013)

StorminMatt said:


> Another unique quality of LiFePO4 among Li-Ion chemistries is the fact that LiFePO4 has a voltage plateau. Most Li-Ion batteries experience a linearly decreasing voltage as state of charge decreases (similar to alkaline batteries). But on discharge, LiFePO4 behaves alot more like nickel-based batteries (ie NiMH, NiZn, NiCad) in the sense that it maintains a very constant voltage during discharge. This is certainly an advantage over lead acid, which also experiences a drop in voltage with state of charge. Voltage regulation circuitry can be greatly simplified (or even eliminated) as a result. Of course, unlike lead acid (and like NiMH), state of charge cannot be determined by a simple voltage reading.



not true .. state of charge can be determined easily by a simple voltage reading. for single cell that takes a precision volt meter which the average consumer doesn't have. but for four cell in series like for 12v Motorcycle LiFePO4 batteries. it's easy to determine state of charge with a VOM. 

currently the fastest selling LiFePO4 batteries are for motorcycles. speed of adoption has taken a number of major battery mfg by surprise. due to almost flat discharge curve coupled with LiFePO4's ability to tolerate wild abuse from overcharge. Some 12v LiFePO4 mfg have elected not to use any BMS at all. others are using a very_sophisticated BMS using MOSFET to disconnect main buss under certain conditions. 

current doing a long term test for Optimate Lithium LiFePO4 battery charger. which balances cells without external balance leads. 

here's a state of charge chart for 12v LiFePO4


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## StorminMatt (Dec 21, 2013)

cy said:


> not true .. state of charge can be determined easily by a simple voltage reading. for single cell that takes a precision volt meter which the average consumer doesn't have. but for four cell in series like for 12v Motorcycle LiFePO4 batteries. it's easy to determine state of charge with a VOM.
> 
> here's a state of charge chart for 12v LiFePO4



As far as determining the state of charge based on voltage, you can see here that there's only a .2V difference between 80% and 20% state of charge with 6V (or around half a volt for 12V). This is FAR, FAR, FAR less than you would see with, say, LiMn, LiCo, or lead acid. And it is well within the range of error you would get using even a very accurate DVM due to such factors as a little oxidation on the terminals or leads. With LiFePO4, a better way to measure capacity would be to know how much current you have been drawing for how long.

Anyway, speaking of the use of LiFePO4, it's also finding use for off grid solar power. Compared to lead acid, it not only has a more stable voltage. It also lasts longer and is less maintenance intensive. And it takes up FAR less space (and weighs less) for a given capacity. There is also no worry about losing a battery that never gets fully charged (say, due to extended cloudy/rainy weather in the short days of winter) from sulfation. LiFePO4 is more expensive than flooded lead acid. But it is actually quite cost competitive with AGM batteries.


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## cy (Dec 22, 2013)

StorminMatt said:


> As far as determining the state of charge based on voltage, you can see here that there's only a .2V difference between 80% and 20% state of charge with 6V (or around half a volt for 12V). This is FAR, FAR, FAR less than you would see with, say, LiMn, LiCo, or lead acid. And it is well within the range of error you would get using even a very accurate DVM due to such factors as a little oxidation on the terminals or leads. With LiFePO4, a better way to measure capacity would be to know how much current you have been drawing for how long.
> 
> Anyway, speaking of the use of LiFePO4, it's also finding use for off grid solar power. Compared to lead acid, it not only has a more stable voltage. It also lasts longer and is less maintenance intensive. And it takes up FAR less space (and weighs less) for a given capacity. There is also no worry about losing a battery that never gets fully charged (say, due to extended cloudy/rainy weather in the short days of winter) from sulfation. LiFePO4 is more expensive than flooded lead acid. But it is actually quite cost competitive with AGM batteries.



yup discharge curve is almost flat once voltage makes initial drop .. so yes a very accurate volt meter would be necessary to determine state of charge. note in 12v or 4x series configuration voltage differences is multiplied. so a voltmeter with normal accuracy range will work fine. 

for all practical purposes 12v LiFePO4 operates at 13.3v range within 1/2v .. cost effectiveness of LiFePO4 is a hard sell vs AGM for most stationary applications. but for motorcycles it's one of the most cost effective way to drop lbs. 

someone that's riding a $10k+ motorcycle think nothing of spending $250+ for a 12v LiFePO4 battery that will shave say 6-10lb+ from their bike. it's the fastest selling 12v LiFePO4 batteries sector that I'm aware of.


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## abies (Jan 11, 2014)

45/70 said:


> Just to bring up a common error when referring to IMR cells, IMR cells are LiMn2O4 cells and are often referred to as "LiMn" (Li=lithium, Mn=manganese), not "LiMN". "LiMN" is usually used when referring to certain Li-Ion cells which contain both manganese (Mn) and nickel (Ni) in the positive electrode, which IMR cells do not.
> 
> LiMN, or lithium manganese nickel cells, are closely related to (but not quite the same as) the Redilast and AW 2900mAh cells (which are actually Li-NiCoAl), for example. Most of this general family of cells, which tend to also operate at a higher voltage, also contain cobalt in the positive electrode, which IMR cells do not. This fact is mostly why IMR cells are considered to be a "safer" chemistry.



On batteryspace, it seems there is a confusion between LiMnNi and NiMn2​O4​.
I suppose IMR are of better quality than these?


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