Lipo vs Lion

crf150rb

1 mW
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Feb 12, 2020
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Hey I am building an electric dirtbike with a qsmotor 3000w kit and need a battery. I was looking at either 3 6s turnigy 20000mah lipos or a 72v 20000mah pack. I am worried that the lion pack wont have the discharge current. Any ideas? Thanks.
 
Voltage difference will affect top speed.

LiPo higher power density will indeed give more oomph for peak usage and lighter weight, but do you really need that? e.g. are you racing for just a few minutes, no actual travel time?

Top notch cylindrical cells will have a longer lifespan.

In the end depends on your use case and priorities.
 
For sure, a much smaller, higher c rate, lipo pack can provide 3000w of power. Though the cells in other packs have improved, you still don't go pulling really high amps from a 10 ah size pack.

In general, if you want light weight, to keep the handling of a bike good off road, you need the higher c rates of lipo. That does not mean you can't use something else, it just means it can be hard to carry a larger one piece round cell pack on some frames. One advantage of lipos is you can carry them in sections, putting less weight in one spot on the bike.
 
crf150rb said:
Hey I am building an electric dirtbike with a qsmotor 3000w kit and need a battery. I was looking at either 3 6s turnigy 20000mah lipos or a 72v 20000mah pack. I am worried that the lion pack wont have the discharge current. Any ideas? Thanks.


What is your controller going to run? Amps?

Do you have any particular cells in mind?
 
You can also run 5 4s packs to get to 72v. Might be preferential not only because of the voltage but also because if a cell ever goes south and you need to replace one of the lipo bricks a 4s pack is cheaper than a 6s. Moot point if you're the type to break down lipo bricks and reassemble them, but if plug and play is the goal it's worth considering.
 
Minor detail but
..a 72 volt (18s) lipo pack operates over a 74 - 65v range. (4.1 - 3.6v per cell)
A 72v volt (18s) Lion 18650 pack operates over a 74 - 54v range ( 4.1 - 3.0v per cell)
..assuming the same capacity in both,
So you have more voltage, power, and speed loss over the capacity range with the Lion pack.
You can obviously increase the Lion pack to 20s to increase the voltages, ..(82 - 60v)
..and you can ensure enough current capacity by choice of better cells
All of which adds cost .
 
Could others please verify or clarify this assertion?

let's assume at rest, or very low discharge rate say under 0.1C

______
li-on packs made from cylindrical cells hold a high percentage of their capacity between 3.6V and 3.0V

while lipo capacity / SoC% maps to much higher voltage range, you should cut off at 3.6V



 
Hillhater said:
72 volt (18s) lipo pack operates over a 74 - 65v range. (4.1 - 3.6v per cell)
A 72v volt (18s) Lion 18650 pack operates over a 74 - 54v range ( 4.1 - 3.0v per cell)
I'm confused. For 18S I only get around 65-66V nominal, the 72-75V range is only for charging.

For nominal 72V, that's 20S, and gets charged at 81-84V

Right?


 
john61ct said:
Could others please verify or clarify this assertion?

let's assume at rest, or very low discharge rate say under 0.1C

______
li-on packs made from cylindrical cells hold a high percentage of their capacity between 3.6V and 3.0V

while lipo capacity / SoC% maps to much higher voltage range, you should cut off at 3.6V


I disagree. Depends on your definition of "lipo".

The "lipo" in my bike like giving capacity down past 3.6v, EV lipo.. ... But yes HK hobby lipo hates anything under 3.8v...

If I cut off at 3.6v/cell, I would not get 10 miles. I get twenty to 3.2/cell.
 
One thing I've noticed using both types is the rest voltage lipos tend to bounce back to a higher voltage.

For example underload my cut off will kill power at 3.0v then Lipo tends to rise back to 3.4v or so where as my 18650 pack will rest around 3.2v after a full discharge both packs a flat at that point good 85% of capacity drawn.

Id say an equivalent 18650 pack can take more abuse for cold than Lipo of simular capacity and discharge rating, the multistar hobbyking packs I had where fragile to the cold and the graphene cells are not much better but in warm conditions they can kick out some serious amps that will make even 10 paralleled of the best 18650 cry for help.

Sony vtc3 i use and found them to be much more robust to temps but have to be aware that they still going to need nannying in cold weather and little exposure as possible to keep cycle life acceptable.
 
OK, for now never mind temp-related issues, assume ambients are tropical.

I also did specifically take propulsion type discharge currents out of the picture, talking **resting** voltages and **under 0.1C** rate usage, so bounceback is minimized.

Ianhill is setting lipo cutoff at 3.0V so that is one data point. Also states resting 3.2V for li-ion is as dead flat as 3.4V resting for lipo.

DogDipstick sets their lipo LVC at 3.2V, and estimates half of capacity is between there and 3.6V LVC but that is under high load.

DogDipstick said:
Depends on your definition of "lipo".

The "lipo" in my bike like giving capacity down past 3.6v, EV lipo.. ... But yes HK hobby lipo hates anything under 3.8v...
What do you mean by that last? That there is little capacity below that voltage? Or that you think they are being damaged by being drawn lower?

Could you please link to the "EV lipo" in your bike, never heard of that.

Just because a given chemistry is packed in pouch format, often called prismatic form factor, that's got nothing to do with the "LiPo" label, if that's what you mean.


 
Take cold out of the equation and Lipo does tend to hold it's power towards the top of the graph then drop of sharp, my graphenes for example will drop to 3.8v fairly fast then hold there to 3.6v for a while and drop off again fast to 3v at the end.

My 18650 pack don't do that as much it does hold most of its capacity around mid range but the graph looks less flat in the middle and not so steep at the start and end.

It's easy for a novice to blast Lipo down to 2.8v when warm as they fall off fast at the end in this regard 18650 is easyier to manage specially as the bms tend to be run with them and Lipo packs go naked but a decent wh meter and volt gauge will allow monitoring of them and that's enough if you read the signs all around us.
 
john61ct said:
DogDipstick said:
Depends on your definition of "lipo".

The "lipo" in my bike like giving capacity down past 3.6v, EV lipo.. ... But yes HK hobby lipo hates anything under 3.8v...
What do you mean by that last? That there is little capacity below that voltage? Or that you think they are being damaged by being drawn lower?

Could you please link to the "EV lipo" in your bike, never heard of that.

Just because a given chemistry is packed in pouch format, often called prismatic form factor, that's got nothing to do with the "LiPo" label, if that's what you mean.

... You have never heard of an "Electrical Vehicle " ? ( EV) ( Production designed and sold vehicle with electric traction) ( Chevy Bolt, Tesla S, Audi E, many many more in production today)
Yes, Not all "lion" is "cylindrical" and not all "lipo " is "pouch" format.

For simplicity I generally refer to the square pouch cell advertised by HobbyKing as "lipo" and this is not in direct regard as to the chemistry. This is a "HK lipo" in my vernacular. Includes Graphene Turnigy HRB Nanotec Multistars, ect. Generally a powerful but low quality cell that puts out current but will puff badly when taken below 3.8v regularly. Yes, the full mAh is there but they puff if you use it all. So generally ( on my rcheli) I dont go below 3.6v, (or 35% SOC or less) in hopes that my packs dont PUFF like mad ( like I know they do) from high amps/ mAh taken from the pack. These are cells without mutch regulation, sold for more than they are worth IMO, with replacement warranty, for the average consumer, on websites in China like "HOBBYKING".

For simplicity I generally refer to the square pouch cell ("EV Lipo" as in "Electric Vehicle" Lipo) advertised by LG and OEM like Chevy and Kia as "lipo" and this is not in direct regard as to the chemistry, but the common vernacular used in these forums with other commonly known traits of the cells. However, like the cells on my bike, they are generally a "true gel electrolyte" lipo. I run these down to the min of capacity, the SOC map shows about 6Ah below 3.6v, 6 Ah between 3.6v and 4.05v... and 3+ Ah above 4.05v. ( My LGX P1.5B cell, 15Ah 1.2mOh) These are cells produced by LGX Chem, made for a real electric vehicle, for on the road, long term durable good, NHTSA standard. The cells in my ebike were made in Korea and assy in Ohio. These cells are only commonly beginning to be available to the consumer who does not want to recycle one out of a junkyard.... ine came from junkyard. Much higher quality control goes into EV production than HK production. Billions more I bet.

Yes, not all pouches are really " lipo" and not all cylindrical cells are " lion" but for the general consensus, I figured you guys would understand the differences with context. Many cells have very different SOC vs Voltage mappings I have found.
 
OK thanks for clarifying.

I of course am aware of the EV pouch cells, did not realize any makers refer to them as lipo, and yes just reinforces the fact that term has nothing to do with the actual chemistry.

For clarity I posit the following categories for the various form factors, keep hard boundaries between them.

1. LiPo, for hobby packs only.

2. Pouch cells vs 3. Cylindricals

and 4. EV packs specifically, which can be composed from either

5. Prismatics, for pouches but hard-cased with posts or bolt terminations

All of these used independently of the cell chemistry.

 
DogDipstick said:
So generally ( on my rcheli) I dont go below 3.6v, (or 35% SOC or less) in hopes that my packs dont PUFF like mad ( like I know they do) from high amps/ mAh taken from the pack.

Many cells have very different SOC vs Voltage mappings I have found.
Yes, but the only way to compare precisely and objectively is to use **resting** voltage.

And in practice testing at very low C-rates.

The differences in ESR, efficiency / heat production factor, voltage sag and bounceback involved

make accurate and consistent mapping impossible while using high C-rates charging or discharging, over say 0.2C

The puffing may be more due to that, rather than going to a high DoD%

prevented by using a gentle, say ten-hour discharge rate.

Not talking about practical real-world guidelines for the propulsion use case, just testing the battery technologies independently of how they are used.

 
I dissagree with alot of these ( following) assumptions. Also the


john61ct said:
OK thanks for clarifying.

I of course am aware of the EV pouch cells, did not realize any makers refer to them as lipo, and yes just reinforces the fact that term has nothing to do with the actual chemistry.

For clarity I posit the following categories for the various form factors, keep hard boundaries between them.

1. LiPo, for hobby packs only.

2. Pouch cells vs 3. Cylindricals

and 4. EV packs specifically, which can be composed from either

5. Prismatics, for pouches but hard-cased with posts or bolt terminations

All of these used independently of the cell chemistry.


..also some of the following assumptions too.. like the 0.2C thing... I think I know where your "0.2C" mention came from, but.... For instance my charger makes a PID controlled SOC map for any cell with a 0.5C and a 1C discharge/charge cycle... Well accepted in the hobby community and tested extensively by battery users/testers like me. Everything you need to know is in those two discharges and the SOC vs capacity is mapped accurately.

The puffing may be more due to that, rather than going to a high DoD%

No, no. I know what puffs my HK lipos.

It is called a Gaui X7 and a KDE 700XF, along with the 12Kw and the 250Wh drained in under 3 min, 150mph +. They dont puff if you only go to nominal or storage under high demand. I can really puff pretty much any pair of lipo on demand in 3-4 ( 4 min) flights. Visual puffing and IR damage, with lost capacity to follow.

About 40C discharge on a 5Ah pack @ 200A and 1000Wh gone in (10) min.
 
You have all gone well off topic..
The OP was quite specific... HK Lipo compared to a commercial “Lion”. ( presumably 18650/21700). Packs
You only have to look at a common capacity discharge graph to see that the Lipo is 90% discharged at 3.6v, with any further discharge just pushing the cell “ over the voltage cliff”. And into a condition that will shorten its life ...or worse.
The 18650 Lion graphs clearly show that you have to discharge down to 3.0v or less to get that same 90% capacity.
Many 18650 cell data sheets suggest the cell should be discharged to 2.5v for its rated capacity.
So fundamentally on a 20 S pack, at end of discharge, there could be as much as 12 volts difference between the two chemistries !
Note, this also implies that a lipo pack of the same 20s and Ah capacity, will actually discharge more “Wh” of energy than an equivalent 18650/Lion pack.
There are many other pro and cons for each type , but this is simply the discharge voltage data.
 
Hillhater said:
look at a common capacity discharge graph to see that the Lipo is 90% discharged at 3.6v
If anyone can link to such graphs where the discharge rate is well below 0.3C, ideally 0.1C

I'd greatly appreciate it.

 
https://batteryuniversity.com/learn/article/discharge_characteristics_li
And if you take the time to follow what Drkangel has done with his “Capacity Mapping” of numerous cells .
https://endless-sphere.com/forums/viewtopic.php?f=14&t=54202&hilit=Capacity+mapping
And this thread is very relavent also..
https://endless-sphere.com/forums/viewtopic.php?t=62932
 
I'm sorry I must have misunderstood.

From this

Hillhater said:
You only have to look at a common capacity discharge graph to see that the Lipo is 90% discharged at 3.6v, with any further discharge just pushing the cell “ over the voltage cliff”. And into a condition that will shorten its life ...or worse.
I inferred that discharge charts reflecting these assertions were common.

As in, published by the battery makers.

 
john61ct said:
I'm sorry I must have misunderstood.

From this

Hillhater said:
You only have to look at a common capacity discharge graph to see that the Lipo is 90% discharged at 3.6v, with any further discharge just pushing the cell “ over the voltage cliff”. And into a condition that will shorten its life ...or worse.
I inferred that discharge charts reflecting these assertions were common.

As in, published by the battery makers.
No, my meaning of “common” chart, was that they are known and readily recognised by anyone who claims to be familiar with those types of cell.
Are you Uncomfortable with referring to a “generic” discharge profile since we do not know the specific “Lion” cell being compared ?
 
I have no interest in the li-ion chemistry charts, (I guess you mean cylindricals?)

I was specifically asking for ones that verify the assertion that hobby **LiPo** cells hold insignificant mAh capacity below 3.6V

even at low discharge rates, say 0.2C to 0.1C

 
Sony 4.2Ah lipo pouch discharged at 0.2A
hBi6Bb.jpg


Or this...
https://electronics.stackexchange.com/questions/32321/lipoly-battery-when-to-stop-draining
 
thanks, that "mAh per mV drop" metric is very interesting, but the timeline going right to left. . .
 
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