# Lion vs LiPo? Which better, or are they just different?



## peterharvey73

I was wondering why radio controlled cars and planes etc, and mobile phones use Lithium Polymer batteries, whereas flashlights use lithium ion?
How come power tools eg battery operated drills don't use Lithium Polymer?
How are the two types different, and which is better, if any?


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## Shadowww

*Re: Lion vs LiPo? Which better, or just different?*

Li-polymer are lighter and can provide very high currents, but they don't have too long cycle life, they have to be used with very big care, and they're not very safe.
Lithium-Ions, on the other hand, can't provide so much current and are heavier (for same stored energy), but they are much safer.


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## peterharvey73

*Re: Lion vs LiPo? Which better, or just different?*

I just found out that:
Lithium is the lightest metal.
Lithium also has the highest electric potential - meaning the highest potential voltage?

Lithium ion is:
Higher in energy density.
Cheaper to manufacture.
But:
Heavier.
More rigid in shapes and styles.
More internal resistance, for slower discharging, and lower amperages.
Has greater aging, even if not used for 1 year.
More explosive, so requires an IC circuit.

Lithium polymer is:
Lighter.
Moulderble, and flatter shapes.
Less internal resistance for faster discharging and higher amperages, at up to 65C continuously, or 135C in bursts!!!
By comparison, a typical RCR chemistry 18650 can only discharge at up to 5.8 amps.
While an IMR chemistry 18650 at 2000 mAH will discharge at up to 10 amps, though an IMR chemistry 18650 at a puny 1600 mAH can discharge at up to 15C, but for the diminished capacity.
Has less self aging, even if not used.
Less explosive, so no IC circuit required.
But:
Less energy density.
Expensive to manufacture.


Thus, LiPo is used in *radio controlled cars* for their lighter weight and faster discharge rates, for massive amperages, for more power.
LiPo is used in *mobile phones* especially for their flatter shape, and their lighter weight.
While Lion is used in *flashlights *for their greater energy density for longer run times.

Is that right?
The safety business seems to be opposite to what Shadowww posted???


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## shadowjk

Well, LiPos have a soft pouch, so they might not explode as violently. I'd still argue for protection circuit for both though.

The round Li-Ions have been favoured by flashlight enthusiasts because it's easier/cheaper to produce a tube-like flashlight out of aluminium, and we want a metal for heat dissipation with our high power LEDs. For low power stuff, arbitrary plastic shapes are fine, but there we also don't need high power, and the aim is usually cheapness, so both Li-Ion and Li-Po are absent from that.

Someone else here once said that it costs alot more to setup a cylindrical Li-Ion factory than to setup a Li-Po factory, so there are many Li-Po manufacturers out there. This has resulted in wide availability and selection of LiPo batteries offered to the hobbyists that use alot of them, RC.

Some people say that LiPos are more dangerous. Whether that's true, or just a "urban myth" because of LiPos from newly started small Li-Po factory not quite being up to quality, is another question.. I'd definitely use a protection circuit of some sort. In the RC world, there's, I think, maybe 3 different strategies used. Cheapest, use a wristwatch and voltmeter. Set your watch to countdown from 5 minutes. Start it when you take off in your heli or airplane or similar. Land when your watch goes off. Check voltage, if it's very high still, you can increase your flight time for next flight. If it got a bit low, decrease. For $5 extra you can get a buzzer to mount on your RC model, the buzzer goes off at a certain voltage threshold, and you know it's time to land/park/etc... Then we have more advanced stuff, like speed controllers (sits between battery and motor) with programmable cutoffs. When battery voltage drops below a certain threshold, motor power is either cut entirely, or reduced before getting cut. The radio receiver, and the servos are powered "forever", so you can make a engine-out landing with your airplane or heli.

In the flashlight world we've got as wide a range of options with our Li-Ion. Directdrive flashlight, and we can notice the drop in brightness. Maybe. Protected battery, and the batteries cutoff when empty. Intelligent/fancy flashlight and the light itself gives warning signals when battery starts approaching low.

One thing though, outside of hobbyists, in the comercial space, there's always protection circuitry or battery management systems.


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## peterharvey73

Is it true that a LiPo can discharge at 65C continuously, and 135C in bursts?
While a Lion RCR chemistry 18650 2900 mAH can only discharge at 2C or 5.8 amps max???


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## Yoda4561

*Re: Lion vs LiPo? Which better, or just different?*

If treated well lipos are more resistant to violent unexpected explosions, however they're soft and easily damaged in their natural form, and not very tolerant of poor charging habits. If you hold an RC Lipo pack in hand you'll notice it's rather soft and wouldn't be too hard to squish between your fingers, get too agressive with it and you'll get a vent with flame. Newer Lipos seem to be better about this, and cylindrical lithum cells are safer than they used to be as well.


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## shadowjk

LiPos come in all sorts of sizes, shapes, capacities, and power.

LiPos made for cellphones usually have a max discharge rating in the range of 1C - 2C.

LiPos made for RC typically range between 10C and 60C continuous rating.

Li-Ions made for powertool manufacturers have much higher C rating than 2C.

When in doubt check the specs and datasheet for the specific battery model.


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## Xero416

Sorry to bring up an old thread but as far as I understand there is an incredible amount of misconception around lithium ion and lithium polymer. I've seen many of these threads on RC plane forums. From the sound of it they are the same thing with different casings. Lithium ion or "Li-ion" is a lithium ion battery with a solid case in most cases, such as those found in laptop and phone batteries. "LiPo" or "Lithium Polymer" is the same thing, a Lithium Ion battery but in a soft "polymer" casing. Note almost all Lithium battery cases are technically polymers anyway... 

If they are the same thing, electrically speaking the case would make no difference.
The original use of "polymer" referd to the polymer electrode according to Wikipedia
http://en.wikipedia.org/wiki/Lithium_polymer_battery

Also...
"The name "lithium polymer" (LiPo) is more widespread among users of radio-controlled models, where it may indicate a single cell or a battery pack with cells connected in series or parallel. The more general term "lithium-ion" (Li-ion) is used almost everywhere else, including consumer electronics such as mobile phones and notebook computers, and battery electric vehicles." (Wikipedia, July 2014)

I have a question though, what is all this 1c and 2c and 20c everyone is talking about when in concern of battery discharge rates and what rates they are capable of safely discharged at? is the c for coulombs?


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## archimedes

Xero416 said:


> Sorry to bring up an old thread .... I have a question though, what is all this 1c and 2c and 20c everyone is talking about when in concern of battery discharge rates and what rates they are capable of safely discharged at? is the c for coulombs?



http://batteryuniversity.com/learn/article/what_is_the_c_rate


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## sadtimes

The "C" rating is how much current the cell can supply and receive safely. 

Take the number before the C (if there is no number it is 1) and multiply it by the mah of the cell (or pack) and that is your number to not exceed.

Example, a 1000 mah battery with a 2C rating can handle 2 amps... there will be a C rating for discharging, burst discharging, and charging.


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## IonicBond

Li-Ion is a generic class of battery that can come in somewhat different chemical properties that affect the energy-density, size, and stability.

LiFePo4 is at the lowest energy density scale, and is the most stable, and is physically large comparatively. At the highest end of the scale, LiCo02 is the most energy-dense, the smallest, but the most unstable. A slight error with lifepo4 will not result in an incident, other than battery damage. A slight error with licoo2 will not only damage the battery, but can easily create a safety incident. In between these two extremes are other slight chemical makeups like those currently in use with powertools.

It is important that if you work with any of these types is to know that lifepo4, takes LOWER VOLTAGES than the rest, so don't accidentally abuse them.

LIPO is merely a polymer bag to contain the internal battery plates and separators, and is not truly a battery definition at all, however it has become a manufacturer slang term.


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## StorminMatt

I should add that LiPo batteries seem to have another advantage compared to conventional Li-Ion batteries. And that's a flatter discharge curve. While it's still not as flat as, say, LiFePO4, it's considerably better than your average Li-Ion battery. It's not uncommon for LiPos to start at a fairly conventional 4.2V and be pretty much fully drained at 3.7-3.8V. This is considerably flatter than conventional Li-Ion batteries, which are pretty much fully drained in the 3.0-3.5V range.


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## IonicBond

Yep - although this is kind of my point about being aware of marketing slang. A LiPo is a li-ion battery contained in a POlymer bag. You could put any chemistry in there, so it pays to make sure that if you are buying a LiPo, you are actually getting the chemistry you bargained for, and not just the bag description.


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## the forger

IonicBond said:


> Li-Ion is a generic class of battery that can come in somewhat different chemical properties that affect the energy-density, size, and stability.
> 
> LiFePo4 is at the lowest energy density scale, and is the most stable, and is physically large comparatively. At the highest end of the scale, LiCo02 is the most energy-dense, the smallest, but the most unstable. A slight error with lifepo4 will not result in an incident, other than battery damage. A slight error with licoo2 will not only damage the battery, but can easily create a safety incident. In between these two extremes are other slight chemical makeups like those currently in use with powertools.
> 
> It is important that if you work with any of these types is to know that lifepo4, takes LOWER VOLTAGES than the rest, so don't accidentally abuse them.
> 
> LIPO is merely a polymer bag to contain the internal battery plates and separators, and is not truly a battery definition at all, however it has become a manufacturer slang term.




So I've been researching and studying for months now. I'm trying to develop a garment with a built in battery pack for charging my phone... I'm really excited about the lipos but they sound dangerous. So far my prototypes have been li-ion. Do you think lipo batteries are safe enough to have on your person? And if so where do I go to buy high quality ones that are safe.


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## Phlogiston

If you're going to build a LiPo cell into a garment, you're going to need physical protection for it against damage. Think about what happens if someone bumps into something and the LiPo cell suffers internal damage or a rupture in its soft polymer casing. You could easily be looking at a fire after that, and injuries from burning clothing can be horrific. 

Personally, I'd stick with a Li-Ion cell that comes in its own hard casing, whether cylindrical or prismatic, and build that into a larger hard casing to protect both the cell and whatever electronics you add. 

One example of that design pattern would be a user-replaceable mobile phone battery. Those have a hard plastic shell of their own, often in a flat form-factor, and then the hard casing of the phone itself acts to give them further protection still.


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## NoNotAgain

Both Milwaukee Tool and DeWalt have hoodies, and jackets that use their brands tool batteries to provide heat to the garmet as well as a charging port for a cell phone.

Readily removable for replacement or recharging.


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