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Lithium batteries: the essential basics.

GVLLD M981

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I'm going to add my report on lithium batteries I originally posted someplace else, because it's very relevant to building lasers. It would make a good sticky, but I don't know how to do that, here. Not all lithium batteries are the same, and so they have industry standardized codes for the different types, for different uses.

Regular Lithium Ion and Lithium Polymer batteries fall into the first category. The primary difference between them is that the cylindrical cells use a liquid electrolyte, and a metal body, while the soft pack batteries use a polymerized electrolyte, so they can be housed in foiled plastic envelops. Here is how the coding of lithium batteries breaks down, starting with the lower discharge rate, higher capacity, standard type batteries, ICR:

ICR: LiCoO2 (Lithium Cobalt Oxide)
It's important to remember that this type of battery is UNSAFE to over discharge, and are the most prone to failure, and the primary symptom of failure involves a huge ball of fire that burns your house down. They are ALWAYS used with some kind of protection circuit to prevent this, albeit part of the device using the cells, like your mobile phone has. Caution should be used when deploying ICR batteries. On the other hand, the high discharge types don't suffer from from over discharge related failures, and are meant to be practically shorted out. These are most commonly used now, for portable vaporizers, like "vape pens", so they are fairly common, just expensive. These, however, have about half the capacity of the older type lithium cells. And ALL lithium batteries require a special charger that will NEVER allow the total voltage to exceed the maximum allowable voltage, they reduce the charge rate accordingly when the batteries reach that voltage, then decrease it to keep that voltage until they don't take any more current. Electronics meant to use lithium batteries will usually have this built into them. For other uses, you can buy cells with protection pcb's built into (or onto) them.

High Discharge Capacity

IFR: LiFePo4 (Lithium Iron Phosphate) One unique thing about these is that they have 4 times the number of charge cycles or lifetime.
IMR: LiMn2O4 (Lithium Manganese Oxide)
INR: LiNiMnCoO2 (Lithium Iron Phosphate With Nickel/Manganese Oxide)

Primary cells (non-rechargeable, but usually have twice the capacity of rechargeable batteries)

ER: Li-SOCl2 (Lithium Thionyl Chloride)
LS: Li-SOCl2 (Lithium Thionyl Chloride)
CR: Li-MnO2 (Lithium-Manganese Dioxide)
BR: Li-(CF)x (Lithium Carbon Monofluoride)
FR: Li-FeS2 (Lithium-Iron Disulfide) - 1.5 to 1.8V "Energizer Ultimate"

The numbering usually refers to the size of the battery, a 14500 refers to "AA" size of 14mm x 45mm, a 18650 is 18mm x 65mm, and so on. At least with ICR, IMR, INR, and IFR types. So, "AA" size 3.7V primary cells are ER14500 or LS14500.

I'm going to add a breakdown on C rating.
There are a couple of factors to consider when trying to quantify capacity and discharge capacity, how much current, and how fast. The "C" number is the minimum time the battery can be safely discharged completely in, quantified in fractions of one hour. So when they give you the capacity in mAh, they are telling you the 1C for the battery. So a 5Ah battery can be discharged completely if discharged @ 5A for one hour. This way you can multiply the mAh capacity by the C number to calculate the maximum sustainable discharge rate, in amps, with the time you can do it in, as the given.
Let's say we have 2 identical looking packs, same size and weight, same capacity, 5Ah, but we'll make the first one a 20C and the other a 30C. The 20C battery can be discharged in (60/20=3) 3 minutes @ (20x5=100) 100A. The 30C battery can be discharged in (60/30=2) 2 minutes @ (30x5=150) 150A. Likewise, an identical battery with a 60C rating can be discharged @ 300A in a minute flat.

More info on lithium batteries here:
https://en.wikipedia.org/wiki/Lithium_battery

I have an NUBM44 with a 4.5A driver running on just two, AAA size IMR 10440 cells, currently! That's a hell of a lot of laser for those tiny batteries, but they can do it! They just don't do it for very long, but a few minutes on a charge is fine for a laser pointer. Currently, only EFEST sells high discharge capacity cells in this size, IMR 10440. But if you are trying to force as much laser as possible into the smallest host you can get it into, these are the way to do it.
 
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BobMc

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Terrific information, will be printing it out. :thanks:for posting it. :)
 

GVLLD M981

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No problem, I just hope it made sense. That part about "C" rating is a bit hard to explain. I wish I could make it a sticky, everyone should know the basics, since lithium batteries are what makes high power laser pointers possible. And they are damn dangerous if misused. I read many horror stories that ended with the house burning down on my r/c forum, scary business, lithium batteries can be.
 

CurtisOliver

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When Hap or ElectricPlasma sees it they may choose to sticky the thread for you as only mods can. :)
 

paul1598419

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Thanks, This was like going back to Wikipedia and reading about the various Li-ion batteries again. + rep.
 

GVLLD M981

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I found this the other day and it seems relatively thorough.

Types of Lithium-ion Batteries ? Battery University
That was one of the many resources I studied when I was learning up on the subject, along with everything else I could find. It was sort of a study project of mine, once. I thought I could condense it down to something I could post, and so I did. Most of you already know about the batteries, but lots still don't, and if they are going to mess with them, they should know the risks. Like a gun, don't mess with one if you don't know what you are doing, you know? Or an over powered laser pointer, too, for that matter. They give new meaning to "you'll put someone's eye out with that thing!".
 

paul1598419

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I've read that before, too. It is a decent enough listing of different types of Li batteries and their pros and cons.
 




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