How much safer are AW High Drain IMRs compaired to AW lithium-ion?
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mrartillery
Enlightened
IMR's are unprotected, in some circumstances is a good if you need them for a high amperage drain situation. But to somewhat answer your question, everyone doesnt use IMR's for that reason, they're not protected.
"Everyone doesn't use..." I guess you mean to say, "Not everyone uses..." The former means that no one uses them, which isn't true.
As I understand it, IMRs don't need to have a protection circuit because they are inherently safe and can't go
because of their internal makeup. Since protection circuits could conceivably fail, I would venture to say that IMRs are safer. As my Li-Ions age I plan to replace them with IMRs where possible (not all sizes are available yet, though).
jasonck08
Flashlight Enthusiast
The chemistry of IMR batteries make them safer then traditional LiCo. They can't vent, and flame like LiCo cells can. They can still get damn hot and melt your flashlight and maybe cause something to catch fire, if you short circuit one.
A good protected LiCo cell if used properly is pretty safe. 99% of laptops use 18650 LiCo cells and millions of laptops are sold every year.
Probably the only reason single LiCo cells are dangerous is because people don't handle them properly. Most of the accidents we've had here on CPF were user error.
1) WAY over charged the cell and leaving it unattended in a cheapo charger.
2) Combining good cells with junk cells in a high drain application
3) Combining cells that have a very low charge with cells that have a very high charge, in a high drain application
4) Short circuiting the cell.
I don't think I've heard of a single accident when using a LiCo cell in a low drain single cell LED light that is mass manufactured.
Use caution, especially in any high drain lights! If you don't at the very least have a multi-meter don't use ANY Li-ion cells! If your going to run mutliple LiCo cells in a high drain application frequently, it would be wise to invest in the tools to measure your cells capacity (mAH). Something as simple and cheap as the Turnigy Accucel-6 can do this for less than $50.
IMR's can be overdischarged because there is no PCB. My understanding is that they are not quite as picky as LiCo cells as far as overcharging and overdischarging them. But still the recommended voltage range for most IMR cells is 4.20-2.5v (about 3.3v resting voltage is the lowest you should bring the cell without recharging it). But then again, even AW's 18650's can be way over discharged. I've had a cell go down to 2.3v under about 1A load and the IC never kicked in to terminate the discharge...
A good protected LiCo cell if used properly is pretty safe. 99% of laptops use 18650 LiCo cells and millions of laptops are sold every year.
Probably the only reason single LiCo cells are dangerous is because people don't handle them properly. Most of the accidents we've had here on CPF were user error.
1) WAY over charged the cell and leaving it unattended in a cheapo charger.
2) Combining good cells with junk cells in a high drain application
3) Combining cells that have a very low charge with cells that have a very high charge, in a high drain application
4) Short circuiting the cell.
I don't think I've heard of a single accident when using a LiCo cell in a low drain single cell LED light that is mass manufactured.
Use caution, especially in any high drain lights! If you don't at the very least have a multi-meter don't use ANY Li-ion cells! If your going to run mutliple LiCo cells in a high drain application frequently, it would be wise to invest in the tools to measure your cells capacity (mAH). Something as simple and cheap as the Turnigy Accucel-6 can do this for less than $50.
IMR's can be overdischarged because there is no PCB. My understanding is that they are not quite as picky as LiCo cells as far as overcharging and overdischarging them. But still the recommended voltage range for most IMR cells is 4.20-2.5v (about 3.3v resting voltage is the lowest you should bring the cell without recharging it). But then again, even AW's 18650's can be way over discharged. I've had a cell go down to 2.3v under about 1A load and the IC never kicked in to terminate the discharge...
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Are IMRs LiMnNi? The safest type of lithium cell are LiFePo4. However the voltage is 3.2v instead of 3.7v.
I'm also pondering hard which cells to get between the 3 types. If i were to get LiCo cells, i will use LG unprotected and get a good charger. If not i will get LiFePo4.
AWs are really way overpriced. That's what stopping me from getting them.
I'm also pondering hard which cells to get between the 3 types. If i were to get LiCo cells, i will use LG unprotected and get a good charger. If not i will get LiFePo4.
AWs are really way overpriced. That's what stopping me from getting them.
Compared to what? Follow the leader products of inferior quality? They are way cheaper than a new manufacturer approved LiIon cell phone battery.
mrartillery
Enlightened
"Everyone doesn't use..." I guess you mean to say, "Not everyone uses..." The former means that no one uses them, which isn't true.
As I understand it, IMRs don't need to have a protection circuit because they are inherently safe and can't go
Perhaps my statement was misinterpreted, yes IMRs do have a safer makeup, but what I was saying is, they have no protection feature to keep from over discharging which is why they are not suited for everyone. Voltage needs to be monitored to keep this from happening as a protected li-ion will shut off when the voltage gets to low. And to say no one uses them would be very foolish on anyone's part, so now that the informalities are out of the way the discussion can resume.
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Mr Happy
Flashlight Enthusiast
That's not a good debating tactic. You are imposing your own meaning on what someone said, a meaning which is clearly not intended, and then arguing against the unintended meaning. Please don't do that, it's not friendly.
alpg88
Flashlight Enthusiast
- Joined
- Apr 19, 2005
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- 5,660
I beg pardon. I wasn't debating it, I was correcting the faulty grammar and explaining that the two phrases have entirely different meanings.
45/70
Flashlight Enthusiast
I think the biggest reason some people prefer LiCo over LiMn, is that LiCo's have far superior capacity at current rates of 1C or less, eg. a 1600mAh LiMn 18650 vs. a 2600mAh LiCo 18650. That's why I have never owned any LiMn cells. That may change, if I ever require higher current capability.
As far as LiMn and LiFe cells being called "safe", they have the same capability to "vent with flame" as LiCo chemistry cells. It just takes more abusive conditions to cause them to vent. There is a thread around here somewhere with a picture of a LiFe pack that blew up, it really didn't appear any different than a blown LiCo pack. It just took a more severe situation than LiCo's would have tolerated, to cause the cells to vent.
It would be better to call the LiMn and LiFe cells "safer" rather than "safe". Also, as has been mentioned, LiMn and LiFe cells don't normally offer protection circuits. Any cell that packs as much power as any of the Li-Ion chemistry cells do, has the potential to be dangerous. Think about it.
Dave
mrartillery
Enlightened
Thank you, enough said! :thumbsup:
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