100% discharge rate capacity

Batteries, Chargers, and Battery Management Systems.
goatman   10 kW

10 kW
Posts: 775
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: 100% discharge rate capacity

Post by goatman » Feb 06 2020 7:49pm

so I made another chart, the dashed line in the middle is 97%.
the peak at #1 is 10amps 100%
the peak at #2 is 0.6amps 100%
the valley at #3 is 3amps 95%

if you read the exchange of ohbse and me, I mention he operates at 97% 100% 97% at peak #1

when he cruises at 1200 watts that's 1.25amps or 98% of peak 2

Image

I was just talking about the 30q wolf pack at 20 amps/5 amps cell if my chart is right it would spend most of its life below 97% around 3 amps

5amps 97% 3amps 95% 1.8amps 97% 0.6amps 100%

there must be someone running a 30q luna wolf pack at 20 amps , no PAS that can kill this theory

john61ct   1.21 GW

1.21 GW
Posts: 3756
Joined: Dec 18 2018 2:06pm

Re: 100% discharge rate capacity

Post by john61ct » Feb 06 2020 10:12pm

If you define EoL (destroyed) as 80% SoH, that is very strict compared to most regular users.

Dropping about 10% from 2100mAh actual storage down to 1900mAh over the first year or two over 300 cycles, would be a pretty decent performance for these propulsion chemistries even treated gently

meaning lower C-rates and especially lower avg DoD%, maybe also lowering charge rate and stop-charging point, storing cool and discharged a bit as well, etc.

"when a cell can deliver 100% of its capacity" usually means going way too high on avg DoD (energy capacity)

You seem to mean operating at a very high C-rate (power capacity).


"operate the cell the way its designed to operate" again does not mean maxing out power capacity. The continuous maximum rate will murder the batt, pack needs replacing very frequently.

Even the peak rate, might not shorten lifespan much if just say 10sec out of a gentle hour, but for 5min out of every hour definitely will.

I am tired of repeating this over and over.

"if its operating at 100% the chemical reaction is behaving like a clean burn, not creating deposits inside the cell"

Is completely ignorant of how the chemistry works, like you are trying to invent some kind of alternative reality here, please stop that.


"I want to know why 3 amps kills a 30q"

Because they don't consistently have the quality required to maintain that C-rate **and** have good longevity, you need to buy a cell better suited for that use case.

"I know 1 amp doesn't but I think at 1amp its running 97%. I think from 10amps down to 3amps it goes from 100% to 93?% and then from 3amps to 0.6amps it goes from 93% to 100%"

I have no idea what you think you mean there, please attach proper units and terminology to those numbers, otherwise just random gobbledygook noise without meaning.

heres a 30q at 1amp

john61ct   1.21 GW

1.21 GW
Posts: 3756
Joined: Dec 18 2018 2:06pm

Re: 100% discharge rate capacity

Post by john61ct » Feb 06 2020 10:14pm


goatman wrote:let me try to explain this way, when a 30q can deliver 100% of its capacity its working the way it was designed and the further from 100% it operates the quicker it degrades and resistance goes up.
No the complete opposite is true.

Please stop repeating such false statements.


john61ct   1.21 GW

1.21 GW
Posts: 3756
Joined: Dec 18 2018 2:06pm

Re: 100% discharge rate capacity

Post by john61ct » Feb 06 2020 10:22pm


goatman wrote:so I made another chart, the dashed line in the middle is 97%.
the peak at #1 is 10amps 100%
the peak at #2 is 0.6amps 100%
the valley at #3 is 3amps 95%

if you read the exchange of ohbse and me, I mention he operates at 97% 100% 97% at peak #1

when he cruises at 1200 watts that's 1.25amps or 98% of peak 2

Image

I was just talking about the 30q wolf pack at 20 amps/5 amps cell if my chart is right it would spend most of its life below 97% around 3 amps

5amps 97% 3amps 95% 1.8amps 97% 0.6amps 100%

there must be someone running a 30q luna wolf pack at 20 amps , no PAS that can kill this theory
Don't even bother drawing graphs from your imagination, wait until you have the gear and skills to publish ones created by **reality**.

There is no coherent theory being "explained" here. Not one that anyone can understand.

No one has any idea what your Y axis is there, do not use percentages but actual units of something that can be measured.

Just use proper terminology and units to tell us what you think you mean by those drawings.

We are not (yet) saying your statement is wrong.

We are saying you have not yet stated it in a way that is even comprehensible, the way you are trying to express your idea is like an infant babbling away pretending he knows how to hold a conversation.

But incredibly frustrating rather than cute.





Hillhater   100 GW

100 GW
Posts: 10678
Joined: Aug 03 2010 10:33pm
Location: Sydney ..(Hilly part !) .. Australia/ Down under !

Re: 100% discharge rate capacity

Post by Hillhater » Feb 06 2020 10:38pm

Even the thread title..... “100% discharge rate capacity” ....is a non sensible mish-mash of terminology.
It could mean ..”capacity at 100% discharge rate”..
...but the OP then goes on about cycle life instead ?
This forum owes its existence to Justin of ebikes.ca

goatman   10 kW

10 kW
Posts: 775
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: 100% discharge rate capacity

Post by goatman » Feb 06 2020 11:04pm

Hillhater wrote:
Feb 06 2020 10:38pm
Even the thread title..... “100% discharge rate capacity” ....is a non sensible mish-mash of terminology.
It could mean ..”capacity at 100% discharge rate”..
...but the OP then goes on about cycle life instead ?
im afraid john has has flooded this thread with so much frikn nonsense im surprised if anyone can follow along.

so yes its an odd title and I did clarify but whos going to find it with all this crap from john being injected here.

I was going to go and grab all the relevant info from the previous 2 pages and put it in a summary post


by goatman » Feb 05 2020 5:20pm

100% is just stupid, might lose thousands of cycles compared to that 60%.

I think I see the confusion I created

take a 40T at a 10 amp discharge rate it has 100% discharge capacity

im not saying discharge the battery of all its 100% capacity

im saying discharge the cell at 10 amps

if you want to start at 4.1v and end at 3.5v, good, but do it at 10amps

goatman   10 kW

10 kW
Posts: 775
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: 100% discharge rate capacity

Post by goatman » Feb 06 2020 11:07pm

john61ct wrote:
Feb 06 2020 10:22pm
goatman wrote:so I made another chart, the dashed line in the middle is 97%.
the peak at #1 is 10amps 100%
the peak at #2 is 0.6amps 100%
the valley at #3 is 3amps 95%

if you read the exchange of ohbse and me, I mention he operates at 97% 100% 97% at peak #1

when he cruises at 1200 watts that's 1.25amps or 98% of peak 2

Image

I was just talking about the 30q wolf pack at 20 amps/5 amps cell if my chart is right it would spend most of its life below 97% around 3 amps

5amps 97% 3amps 95% 1.8amps 97% 0.6amps 100%

there must be someone running a 30q luna wolf pack at 20 amps , no PAS that can kill this theory
Don't even bother drawing graphs from your imagination, wait until you have the gear and skills to publish ones created by **reality**.

There is no coherent theory being "explained" here. Not one that anyone can understand.

No one has any idea what your Y axis is there, do not use percentages but actual units of something that can be measured.

Just use proper terminology and units to tell us what you think you mean by those drawings.

We are not (yet) saying your statement is wrong.

We are saying you have not yet stated it in a way that is even comprehensible, the way you are trying to express your idea is like an infant babbling away pretending he knows how to hold a conversation.

But incredibly frustrating rather than cute.
hey john why don't you piss off, all youre doing is filling this thread with a bunch of nonsense that no one can follow

goatman   10 kW

10 kW
Posts: 775
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: 100% discharge rate capacity

Post by goatman » Feb 06 2020 11:55pm

heres a summary from the previous 2 pages, im just pulling out quotes to try and clarify

im looking at batteries, why aren't people testing the life cycle of batteries at the cells 100% discharge rate capacity. isn't that when a cell is operating exactly the way its designed to?

goatman » Feb 05 2020 1:21am

a thread onwhy high c rates live less than low C rate, cant remember exact title, but e-s member jonescg stated

viewtopic.php?f=14&t=104529#p1527180

so if a cell is designed to work a certain way, why not operate them that way and test them that way and not the way theyre labelled.

example:

40t 35amp 4000mah, standard discharge capacity 0.2c@800mah is >4000mah
when 40t is discharged at 10amps it achieves 100% discharge rate capacity/3900mah
@35 amps its about 91.5% capacity
after 250 cycles at 35amps its at 2400mah or 60% of original capacity

heres another chart, I don't know how to bring it over

viewtopic.php?f=14&t=102682&start=50#p1504066

Ianhill » Feb 05 2020 6:36am

What are the noticeable effects of a degraded battery ? Capacity loss, increased IR off top off my head and both of these make that c rating drop with cycle life but this is never mentioned on the data sheet just a max rating from new not the average plot of the complete data set giving more of an idea of the range of the cell from new and degrade over time so it's easy to see where on the range your cells in hand would be.

Plus these cycle life test's are not repeatable in real world usage, an ebike battery or portable drill etc experience differing temperature extremes throughout the test aging them in a more extreme way than a controlled pack or indoor environment harsh cold is the worst on c rates and trying to pull amps at this point is not a good idea.

The life of a cell is a complex one and the discharge rate at the beginning creating x amount of heat will not be the same for the end of life and because they all have varying life styles owners permitting that can dramatically shorten their life to a 1/4 of its lifetime or worse so it safe to say that there's room for improvement on the way some handle cells discharge max when down the line that cell will become useless if spec'ed at its limit from day one.

goatman » Feb 05 2020 1:43pm

if im looking at pack design after I choose my volts I look at amps and ah if use 25 to 35 amps but spend most of my time around 25/30 amps, if a pick a cell that is 10amp 100% capacity I need 3p and the cell will be discharging around 97% to 100% capacity/efficiently but if I want around 20ah

30q is 3ah, 6p 18ah
40t is 4ah, 6p 24ah

if I run those packs at 6p/95% ill be degrading them a lot quicker than if I separated the packs into two separate 3p/100% packs and have them separated with a battery selector switch, run on pack A til its done and then switch to pack B. the temperatures ive been seeing for 100% is about 23 c to 60 c. if I keep the batteries between 23 and 40 it should be ok. two separate 3p packs wont get as hot in the middle as 1 6p pack

goatman » Feb 05 2020 3:59pm




LuboN wrote: ↑
Feb 05 2020 3:04pm
I am sorry to inform You that You got it totally wrong. Please read some battery life related threads to get the basics right first. by docware » Oct 15 2019 2:52am

The rate at which a battery or cell can be charged or discharged is limited by the rate at which the active chemicals in the cells can be transformed.
Forcing high currents through the battery results in incomplete transformation of the active chemicals reducing the battery’s effective charge capacity and it also causes unwanted, irreversible chemical reactions to occur because the chemical transformations cannot keep up with the current demands.
The unwanted chemical transformations consume some of the active chemicals causing the battery to lose capacity and thus age prematurely.

From the above we can expect that with each charge/discharge cycle the accumulated irreversible capacity loss will increase. Although this may be imperceptible, ultimately the capacity reduction will result in the cell being unable to store the energy required by the specification. In other words it reaches the end of its useful life and since the capacity loss is brought on by high current operation, we can expect that he cycle life of the cell will be shorter, the higher the current it carries.

A.jpgA.jpg (78.73 KiB) Viewed 692 timesThe capacity reduction at high discharge rates occurs because the transformation of the active chemicals cannot keep pace with the current drawn. The result is incomplete chemical reactions and an associated reduction in capacity. This may be accompanied by changes in the morphology of the electrode crystals such as cracking or crystal growth which adversely affect the internal impedance of the cell.

Ageing Accelerators
The previous paragraph indicated some of the basic ageing factors inherent in the battery chemistry. From this we can see that certain external environmental and usage factors, such as those following, can be considered as ageing accelerators.

High and very low temperatures
High energy throughput rate (Charge and discharge rates)
Mechanical stress or vibration which can give rise to open or short circuits or seal failures.

Operating Environment
In addition to the ageing accelerators noted above there are some less obvious environmental factors which can influence battery life.

A temperature gradient across the battery can increase the rate of battery ageing. From Arrhenius we know that, with a 10°C difference in temperature across the battery, some cells will age at twice the rate of others giving rise to unbalanced stresses on the cells resulting in premature failure. High pressure or cyclic pressure changes can cause mechanical failures of the cells.
High humidity can give rise to corrosion causing increased contact resistance at the battery terminals.

doesn't that chart state what im asking, if you run a battery at its most efficient rate of discharge it will last longer

wouldn't that mean discharging at as close to its 100% discharge rate capacity?

goatman » Feb 05 2020 4:01pm

download/file.php?id=260970

goatman » Feb 05 2020 5:32pm

hey john

stresses can be many things,
a cell operating at 100% shouldn't be too stressed if that's where it retains its capacity
a cell operating at 90% seems to get a little stressed out and starts to lose capacity

am I wrong by thinking if a cell is operating at its 100% discharge rate capacity that its operating the way its designed

the further away from 100% the cell operates at, the faster it degrades

Ohbse » Feb 05 2020 7:07pm

Splitting packs and switching between them is a design fail. End result will be higher degradation due to stress, lower performance due to sag and only half your battery mass contributing. Heat will be higher.

The rated discharge rate for any cell is the maximum that cell can output before it becomes too hot, too saggy, too short a lifespan. Running a cell below this maximum rating is obviously the best way to maximise lifespan.

goatman » Feb 05 2020 7:20pm

100% is just stupid, might lose thousands of cycles compared to that 60%.

I think I see the confusion I created

take a 40T at a 10 amp discharge rate it has 100% discharge capacity

im not saying discharge the battery of all its 100% capacity

im saying discharge the cell at 10 amps

if you want to start at 4.1v and end at 3.5v, good, but do it at 10amps

goatman » Feb 05 2020 8:32pm

52v luna wolf pack battery 14s4p

2 battery options lg mj1 and 30q

recommend if requesting 50amp bms use 30q

4p of 30q is max 12.5 amps/cell for 50 amps

a 30q has a 100% discharge rate at 10 amps

does luna know something

theres a lot of mixed reviews of the 30q

docware wrote: ↑
Nov 19 2019 10:27am
Some people on the Pedelec forum mentioned soldering as a root cause of the issue. Fortunately you read German :D ... wasn't sure if he was being a litte facetious (single cell), so brought up the subject of vaping (i'm not a smoker or drinker). You may have also noticed that when googling VTC6 (or HG2) vs 30Q some of the google comparisons are about vaping. Makes one wonder if as many of these 3000mAh 15-20A cells are sold to vapers as ebikers? Seems to be a tossup as to which cell is better whether for vaping or a DIY pack build ... but maybe these 3000mAh 15A-20A cells aren't the best cells for a 8P14S DIY ebiking build ?

"I use the Sony VTC6, as well as the Samsung 30Q. The VTC6 are slightly better cells. Their internal resistance is lower, and they have a bit less voltage sag. They also have about 4% more energy. But, overall, they’re very similar to the 30Q, and you’d probably not notice any difference.

For the ones you mentioned I would choose 30Q. I have had personal experience w/ VTC6 and LGHG2 degrading at a higher rate than 30Q."

Deciding which 3000mAh 15-20A cell to use for a sizeable DIY triangular bike pack usually comes down to cost (8P14S 112 cells). Currently at IMR in quanties of 100-199 ... VTC6 $4.85, HG2 $3.25, 30Q $3.85.

One might ask why Luna doesn't offer the VTC6 as an option in their 52V Wolf pack instead of 30Q or MJ1? Does it basically come down to the bottom line of cost savings even though VTC6 has a 20A rating to 30Qs 15A rating (so big deal).

Reminds me of the good ol' days when it was all about V8 horsepower between Chevy and Ford. Now it's about mAh capacity, amp rating and NCA vs NCM originating from Japan, South Korea and China. No longer America :(

Ohbse » Feb 05 2020 8:38pm




goatman wrote: ↑
Feb 05 2020 7:20pm
I think I see the confusion I created

take a 40T at a 10 amp discharge rate it has 100% discharge capacity

im not saying discharge the battery of all its 100% capacity

im saying discharge the cell at 10 amps

if you want to start at 4.1v and end at 3.5v, good, but do it at 10amps Running a cell to 100% of energy content will increase its rate of degradation.
Running a cell at 100% of its current/power output will increase its rate of degradation.

In your hypothetical use case, discharging from 4.1v and ending at 3.5v at 1amp will result in much longer service life, less heat, less stress, better performance.

Cell manufacturers test at the most the cell can do. It's obvious that running it at a lower output, it will live longer. It's 'worst case scenario'.

Ohbse » Feb 05 2020 8:41pm




goatman wrote: ↑
Feb 05 2020 8:32pm
52v luna wolf pack battery 14s4p

2 battery options lg mj1 and 30q

recommend if requesting 50amp bms use 30q

4p of 30q is max 12.5 amps/cell for 50 amps

a 30q has a 100% discharge rate at 10 amps

does luna know something

theres a lot of mixed reviews of the 30q
1. Luna definitely doesn't know much about building battery packs that last. They have time and time again sold packs destined for a very short, very stressed lifespan.
2. The 30q is rated at 15a as per Samsung, as quoted in your own post.
3. Cell testing is complex with lots of competing factors. Energy vs Power vs Lifespan, all at different temperatures and of course price. Obviously Luna doesn't make packs from VTC6 as they're substantially more expensive and for a while there, very difficult to obtain in quantities

goatman » Feb 05 2020 9:01pm

the 30q has a 100% discharge rate at 10 amps and 5amps 97% and 15 amps 97%

if you run it at 15amps 97% it loses 60% of its capacity after 250 cycles

if you run a 30q at 5amps97% will it lose 60% of its capacity

I guess I need to find someone that has life cycled a 30q,40t or 25r 250 times at 10 amps to see what its capacity will be

I might be able to find a 30q at 3 amps wich should be disastrous

john61ct » Feb 05 2020 9:05pm




goatman wrote:
I think I see the confusion I created

take a 40T at a 10 amp discharge rate it has 100% discharge capacity

im not saying discharge the battery of all its 100% capacity

im saying discharge the cell at 10 amps

if you want to start at 4.1v and end at 3.5v, good, but do it at 10ampsOK, I understand what you mean better now, but again, I'm afraid no the opposite is also true in this case too!

The lower the actual C-rate, the more energy capacity you get per cycle.

And the longer the cell will last, until you get below 0.4C or so,

goatman » Feb 05 2020 9:19pm

I really should try to clarify what I mean by 100% discharge rate capacity

is when a cell can deliver 100% of its capacity

30q- 0.2c/0.6a and 10amps

40t- 0.2c/0.8a and 10amps

50e- 0.2c/0.98a

30q

by Pajda » Nov 21 2019 4:19pm

Here is another of my unwanted remarks 8)

I need to say something about this test https://www.e-cigarette-forum.com/threa ... g2.807131/ revealed by Mooch in 6/2017. I'm not afraid to say that if it wasn't published,the world will be a better place. This is unfortunatelly the example of information which makes more bad than good. There is not a problem in the results themselves. I made tests with similar settings and can confirm that the test results are correct with the Samsung 30Q as a clear winner. The problem is that this particular result leads to generalization that "Samsung 30Q must be then good in other settings as well". I am quite confident that Mooch is another victim of this seductive idea and so he just do not expect that there should be any problem with 30Q cycle life under another, particularly lower test settings. But he cannot be more wrong.

This level of capacity loss at 5C discharge rate should be clasiffied as excellent result. But the major problem is, that Samsung 30Q shows almost identical capacity loss under 3C and even under 1C continuous discharge rate. So at 3C continuous discharge rate its cycle life at 100% DoD is outperfored after just 100 cycles by M29, 29E6, E7 and even Panasonic PF performs significantly better than the Samung 30Q. At 1C discharge rate 100% DoD, the cycle life of 30Q is nothing but total disaster in comparison by almost all cells on the market. The same problem is with its DCIR rise, which is enormous with exponential course. Only narrow 70% or less SoC window helps 30Q to get at least usable results.

goatman   10 kW

10 kW
Posts: 775
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: 100% discharge rate capacity

Post by goatman » Feb 07 2020 12:18am

this is the summary with ohbse, he has a 30q pack with 30,000km on it

Ohbse » Feb 05 2020 10:48pm

Each time you clarify, it makes it significantly more confusing...

A 30q that is cycled at 1a output will last for longer than one that's cycled at 3amps which will last longer than one cycled at 10a etc. Both time spent discharging AND number of cycles over its life.

Put another way, a 30q that completes 250 cycles @ 10a discharge will lose MORE of its original capacity than one that is cycled 250 times @ 3a discharge.

Higher discharge power = shorter lifespan.

Deeper discharge = shorter lifespan.

I have cycle tested 30q vs hg2 and several others at all sorts of power levels. After extensive testing I bought 5000 30q's. I have one pack that has done ~30,000 km with less than 10% of its original capacity loss when tested. It does sag more under load, but not unacceptably and is now being retired from daily use anyway.

goatman wrote
At 1C discharge rate 100% DoD, the cycle life of 30Q is nothing but total disaster in comparison by almost all cells on the market.

I think 1c is 3amps?

this is great, you are the perfect person for me to ask a question.

you have a 30Q pack 30,000km on it, can you tell me how many p the pack is and what amps you normally use


Ohbse » Feb 05 2020 9:40pm

You're probably right - at 1c constant discharge (which yes, would be 3.0 amps) and 100% DoD cycle life will not be great. However in reality, it is impossible to actually do that regularly on an EV, or if you are - you have made a very, very bad battery pack for your requirements.

Pack in question is 20s12p - peak discharge was 180a or 15a per cell, however that is impossible to maintain for more than a few second in reality, because that's 13,000+ watts on a 50kg bike. 0-50km/h only takes about a little more than 2 seconds at that power level. Average discharge was about 1200wh in 60 minutes or an average of ~15a pack level discharge over my 60 minute journey. Other rides outside of commuting would be slightly more power than that.

The key to my longevity is that I charged to 4.09v/cell and discharged on average to ~3.8v on most cycles.

goatman » Feb 05 2020 10:03pm

so I think you said you discharge your pack at 15amps/cell 180amps

15amps is equivalent to running your pack at 97% of a cells capacity wich means the cell would be able to provide 97% of its ah@15a

youre not abusing the cells

your 12p
180a is 15a @12p 97%
120a is 10a@12p 100%
60a is 5a@12p 97%

goatman » Feb 05 2020 10:23pm




Ohbse wrote: ↑
Feb 05 2020 9:40pm
You're probably right - at 1c constant discharge (which yes, would be 3.0 amps) and 100% DoD cycle life will not be great. However in reality, it is impossible to actually do that regularly on an EV, or if you are - you have made a very, very bad battery pack for your requirements.

Pack in question is 20s12p - peak discharge was 180a or 15a per cell, however that is impossible to maintain for more than a few second in reality, because that's 13,000+ watts on a 50kg bike. 0-50km/h only takes about a little more than 2 seconds at that power level. Average discharge was about 1200wh in 60 minutes or an average of ~15a pack level discharge over my 60 minute journey. Other rides outside of commuting would be slightly more power than that.

The key to my longevity is that I charged to 4.09v/cell and discharged on average to ~3.8v on most cycles. I know you didn't agree with this statement I made previously


30q is 3ah, 6p 18ah
40t is 4ah, 6p 24ah

if I run those packs at 6p/95% ill be degrading them a lot quicker than if I separated the packs into two separate 3p/100% packs and have them separated with a battery selector switch, run on pack A til its done and then switch to pack B. the temperatures ive been seeing for 100% is about 23 c to 60 c. if I keep the batteries between 23 and 40 it should be ok. two separate 3p packs wont get as hot in the middle as 1 6p pack


6p of 30q at 30 amps would be 5amps or a little more or a little less so id be averaging 97% probably less and never at 100%
but if I ran 3p at 30/35amp max

35a is12a@ 3p 97%
30a is 10a@3p 100%
25a is 8a@ 3p 97%

its pretty much what you are running

goatman » Feb 05 2020 10:42pm




Ohbse wrote: ↑
Feb 05 2020 10:36pm
Where on earth are you getting these mysterious % figures?

Any cell will deliver less energy the higher the discharge current as more is lost as heat due to cell IR. To get '100%' of a cells capacity, you should be aiming to run it at the lowest possible level of discharge. There is no efficiency curve, cells do not work magically work better at higher levels of discharge.

Before some smartass points out IR varies with temperature curve, I'm aware of that - but it's not relevant for this discussion Samsung data sheet section 7.9 page 5

https://www.imrbatteries.com/content/samsung_30Q.pdf


Report this post
Quote





by Ohbse » Feb 05 2020 10:54pm

It's not relevant - measurement of mAh output is not the same as energy out. Higher discharges will output at a lower average voltage. The measured energy (wh) will be lower as discharge current increases due to losses.

Ohbse » Feb 05 2020 11:31pm




goatman wrote: ↑
Feb 05 2020 11:02pm
a cell is designed to work a certain way, if you putt around in a hot rod car at 900rpm, its going to start to run like crap and carbon will start to build up and eventually it will stall. samething with a battery if its running at 100% the matrix inside is working the way its supposed to.

if a 30q runs at 100% efficiency at 10 amps why isn't it be lifecycled at 10 amps Completely, absolutely 100% wrong. This is my point - your fundamental understanding is utterly incorrect.

The chart you're referencing is a relative measurement compared with a specific test scenario. It's purely to demonstrate that it's less efficient than 10a discharge at higher discharge rates like 15a and 20a. It is NOT saying that it's 100% efficient at a specific test point, it's only a comparison. It is MORE EFFICIENT AT LOWER DISCHARGES. Your own question should be a clue - why wouldn't they test at its optimum point to make it look better?


18650chargeDischarge-powercell-web.jpg18650chargeDischarge-powercell-web.jpg (82.02 KiB) Viewed 79 times
Here is a graph, discharging an 18650 at different currents. As you can see, the 10a discharge appears to have gone further along X, meaning higher mah of capacity - that's true. But also you can see this line is at a much lower average voltage, meaning that energy delivered (volts x ah in simple terms) is much lower. That loss is released as heat.

Every battery discharge graph looks like this. As discharge power increases, efficiency decreases.


goatman » Feb 06 2020 12:01am

ohbse

sometimes I need to be hit with a stick

I missed where you said 1200watts. 3.8x20p=76v

1200watts/76v= 15a
15a/12p=1.25amps per cell and you have 30000km on your pack

thank you very much


goatman wrote

I have been listening, I have been researching so now I have to go see if I can find out if 1.25a is 97%, 0.6a is 100%. if it is and I highly suspect it is, then Ohbse is still running at 97%

why does 3 amps kill a 30q

Ohbse » Feb 06 2020 12:36am

What are you talking about?

3a doesn't kill a 30q. The percentages you're referencing mean *NOTHING*

Read my previous post, look at the graph - what you're describing is utterly meaningless.

I spent my journey with WILDLY varying power from -13,000 watt to +4000 watt under regenerative braking, varying between those two points in less than a second. That's how you actually drive a motorcycle in traffic.

Synthetic cycle testing of a cell is good for a COMPARISON to another cell cycled under identical circumstances. You cannot and should not extrapolate your expected results from 100% discharge and then quick charge cycles as this is *impossible* to do in the real world.

goatman » Feb 06 2020 1:01am

Ohbse im pretty sure you are right, please don't be offended.

I think it was pajda that cycled the 30q at 3amps and it was destroyed in 100 cycles.

id keep typing but don't worry I really do appreciate your help and I believe you, im just doing some ocd thing here


goatman » Feb 06 2020 10:03am




madin88 wrote: ↑
Feb 06 2020 9:41am



goatman wrote: ↑
Feb 05 2020 3:32pm
hey john

stresses can be many things,
a cell operating at 100% shouldn't be too stressed if that's where it retains its capacity
a cell operating at 90% seems to get a little stressed out and starts to lose capacity

am I wrong by thinking if a cell is operating at its 100% discharge rate capacity that its operating the way its designed

the further away from 100% the cell operates at, the faster it degrades Sorry you are wrong.

As already meantioned several times by Ohbse, those "cell operating at ..% numbers" are not useful or meaningful for anything, in your case more the opposite, because 100% DOD will stress a cell more as 90 %DOD would.
The higher the charge and discharge current's, the lower the lifetime and the lower the usable Wh and Ah because energy get lost in heat due to internal resistance.



goatman wrote: ↑
Feb 06 2020 1:01am
I think it was pajda that cycled the 30q at 3amps and it was destroyed in 100 cycles. In which regard it was "destroyed"?

im not talking about DoD

im talking about when a cell can deliver 100% of its capacity, big difference. you can cycle your cells at 4.1v to 3.4v but operate the cell the way its designed to operate. 30q is 10amps.

if its operating at 100% the chemical reaction is behaving like a clean burn, not creating deposits inside the cell.

I want to know why 3 amps kills a 30q

I know 1 amp doesn't but I think at 1amp its running 97%. I think from 10amps down to 3amps it goes from 100% to 93?% and then from 3amps to 0.6amps it goes from 93% to 100%

heres a 30q at 1amp

download/file.php?id=265968
•reducded capacity
•increased IR
•too high self discharge (which would be killer factor 1 if assembled into a pack)

goatman   10 kW

10 kW
Posts: 775
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: 100% discharge rate capacity

Post by goatman » Feb 07 2020 12:25am

3rd summary

madin88 » Feb 06 2020 10:37am




goatman wrote: ↑
Feb 06 2020 10:03am
im talking about when a cell can deliver 100% of its capacity, big difference. you can cycle your cells at 4.1v to 3.4v but operate the cell the way its designed to operate. 30q is 10amps.

if its operating at 100% the chemical reaction is behaving like a clean burn, not creating deposits inside the cell.

I want to know why 3 amps kills a 30q

I know 1 amp doesn't but I think at 1amp its running 97%. I think from 10amps down to 3amps it goes from 100% to 93?% and then from 3amps to 0.6amps it goes from 93% to 100% Understood what you mean, but i think there is no such thing with a "clean burn", but i might be wrong and you found out something nobody knew yet before.

You said Pajda's cycle test of 30Q ended with a dead cell after 100cycles at just only 3A, but dead in which regard?
Because me and others also had troubles with 30Q dying eraly! In my case it was because of self discharge of a dozend or so cells from a larger pack which never was abused.

goatman » Feb 06 2020 10:41am

let me try to explain this way, when a 30q can deliver 100% of its capacity its working the way it was designed and the further from 100% it operates the quicker it degrades and resistance goes up.

Samsung 30q discharge

0.6amps is 100%
5amps is 97%
10amps is 100%
15amps is 97%
20amps is 95%

Samsung 30q charge condition

1.5amps is 100%
4amps is 98%

Samsung 30q temperature

discharge temperature
100% at 25c

charge temperature
0c is 80%
5c is 90%
25c is 100%
45c is 95%

goatman » Feb 06 2020 11:59am

so the above quote by pajda and 30q at 3amps

I made a comment about Luna wolf pack and I guess theyre getting bad reviews

why?

2 cell options- lg mj1 and 30q, if you want the 50 amp bms they recommend the 30q

does that mean the mj1 at 4p cant provide 12.5/cell

I don't know, im not looking at that cell

but

what happens if you operate a 30q wolf pack with a 20 amp controller

4p at 20 amps is 5amps per cell is 97% and will never go to 10amps or 100%

4p at 12 amps is 3 amps per cell or 95%

lets do this in watts

58.8x12= 705 watts at full charge is 3 amps per cell
lvc 44.8x12= 537 watts is 3amps per cell, 3.2v x 14s is the lvc of pack

does that mean if you operate the pack in between 705 watts and 537 watts its going to be operating most of its life at 95% causing premature failure?

the cell was lifecycled at 97% wich resulted in 1800mah or 60% of original capacity

20amps is 95%, is 3 amps also 95%

goatman » Feb 06 2020 5:49pm

so I made another chart, the dashed line in the middle is 97%.
the peak at #1 is 10amps 100%
the peak at #2 is 0.6amps 100%
the valley at #3 is 3amps 95%

if you read the exchange of ohbse and me, I mention he operates at 97% 100% 97% at peak #1

when he cruises at 1200 watts that's 1.25amps or 98% of peak 2

Image

I was just talking about the 30q wolf pack at 20 amps/5 amps cell if my chart is right it would spend most of its life below 97% around 3 amps

5amps 97% 3amps 95% 1.8amps 97% 0.6amps 100%

there must be someone running a 30q luna wolf pack at 20 amps , no PAS that can kill this theory

Hillhater   100 GW

100 GW
Posts: 10678
Joined: Aug 03 2010 10:33pm
Location: Sydney ..(Hilly part !) .. Australia/ Down under !

Re: 100% discharge rate capacity

Post by Hillhater » Feb 07 2020 1:47am

You Know... offering up a pile of regurgitated mess that has already been chewed over and spat out.... doesnt make it any more palatable the second time around !
This forum owes its existence to Justin of ebikes.ca

Ianhill   1 MW

1 MW
Posts: 1999
Joined: Sep 25 2015 5:55pm

Re: 100% discharge rate capacity

Post by Ianhill » Feb 07 2020 1:50am

Goatman are you electricgod playing a trick on John cuz surely No one can get it wrong this much.

My car has 200bhp I must use it all or I risk aging the system faster just crazy talk.

Look at humans we can sprint fast but after a few hundred metres shit goes south.
Same for the cell it has a max c rating does not mean it must be cycled at its max all the time to make a fitter person cells are not ufc fighters.

john61ct   1.21 GW

1.21 GW
Posts: 3756
Joined: Dec 18 2018 2:06pm

Re: 100% discharge rate capacity

Post by john61ct » Feb 07 2020 2:49am

Hey man sorry I might sound harsh but I am honestly trying to help.

It is very hard to correct all your misunderstandings when you can't explain what you mean.

And absolutely no one else is going to even try, they'll just completely ignore such long posts

Over 5000 words and you label that "a summary" wtf Image

The biggest problem holding you back from learning, is thinking you've got any grasp at all of the basics, while your inferences all seem to be the opposite of how batteries actually work.

Stop holding on to those myths, let them go, start over from scratch from the ground up

type one factoid at a time of what seems obviously clear and true to you and seek feedback on whether you got it right or not,

like building a good wall check your foundation first.

john61ct wrote:Don't even bother drawing graphs from your imagination, wait until you have the gear and skills to publish ones created by **reality**.

There is no coherent theory being "explained" here. Not one that anyone can understand.

No one has any idea what your Y axis is there, do not use percentages but actual units of something that can be measured.

Just use proper terminology and units to tell us what you think you mean by those drawings.

We are not (yet) saying your statement is wrong.

We are saying you have not yet stated it in a way that is even comprehensible, the way you are trying to express your idea is like an infant babbling away pretending he knows how to hold a conversation.

But incredibly frustrating rather than cute.



goatman   10 kW

10 kW
Posts: 775
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: 100% discharge rate capacity

Post by goatman » Feb 07 2020 3:08am

yep, let this thread die and start a new one with a proper title that makes sense once I get some more info

User avatar
madin88   1 GW

1 GW
Posts: 3060
Joined: May 27 2013 2:02am
Location: Austria

Re: 100% discharge rate capacity

Post by madin88 » Feb 07 2020 7:51am

goatman wrote:
Feb 07 2020 12:25am
I want to know why 3 amps kills a 30q

let me try to explain this way, when a 30q can deliver 100% of its capacity its working the way it was designed and the further from 100% it operates the quicker it degrades and resistance goes up.

Samsung 30q discharge

0.6amps is 100%
5amps is 97%
10amps is 100%
15amps is 97%
20amps is 95%
From where do you have the info that 3A does "kill" a 30Q more quickly as 0,6A or 10A would?
Did you do cylce tests by your own and comparing capacity and IR after a given number, or do you have a source which proves that?
Non of the graphs or links you are referring to proves it yet.

If you have no proof then i would ask you to stop making those statements.

Ianhill   1 MW

1 MW
Posts: 1999
Joined: Sep 25 2015 5:55pm

Re: 100% discharge rate capacity

Post by Ianhill » Feb 07 2020 8:16am

For me I see it as the cell is trying to make the chemical reaction take place quick as possible to get the current delivered this is heat dependent then it's a case of managing that current without overheating that's where the internal foils resistance takes over, if either can't keep up then there's gonna be a life time shortening effect.

As for dendrites forming if you don't use the cells potential no that's not the case if you search dendrites you will find the aging process thats killing all liquid electrolyte based cells these have differing rates from chemistry to chemistry and not all cells act alike but there's a general trend to the ageing so thats the cycle life they state.

There's plating going on inside the cell providing the ions to move through the electrolyte and powering the circuit, over time this plating is where the tree like structure grow and penetrate the isolating boundary layer.

No cell gets to 0% health it's ability to deliever useful power would have come and gone along time before it gets anywhere near this range it's for landfill victims only.

john61ct   1.21 GW

1.21 GW
Posts: 3756
Joined: Dec 18 2018 2:06pm

Re: 100% discharge rate capacity

Post by john61ct » Feb 07 2020 10:07am

goatman wrote:yep, let this thread die and start a new one with a proper title that makes sense once I get some more info
I believe you can ask a mod to close it

eMark   100 W

100 W
Posts: 210
Joined: Nov 02 2019 11:53am

Re: 100% discharge rate capacity

Post by eMark » Feb 07 2020 11:38am

When you (goatman) start another thread it would be helpful if you reference what discharge rate in 30Q datasheet (3.7?) as beng "100% discharge rate capacity" ... https://datasheetspdf.com/parts/INR1865 ... ?id=951041 ...
3.7 Max. continuous discharge
15A at 25C, 60% at 250 cycles (Samsung rates 30Q 15A discharge to 60% of capacity)
Samsung datasheet also rates discharge at 10A ...
7.4 Rated discharge capacity
The rated discharge is the discharge capacity of the cell, which is measured with discharge current of 10A with 2.5V cut-off at 23C within 1hour after the rated charge.
Here's an independent 30Q data test including several discharge graphs ... https://lygte-info.dk/review/batteries2 ... %20UK.html
Rated discharge capacity (0.2C): 3000mAh
Rated discharge capacity (10A): 2700mAh
Cycle life: 300 cycles to 70% (4A charge and 15A discharge)
Cycle life: 250 cycles to 70% (4A charge and 22A discharge, pause at 70°C, resume at 50°C)
Here's one of those (independent test) 30Q data test discharge graphs (scroll down page to see all the discharge graphs) ...
Samsung INR18650-30Q 3000mAh (Pink)-CapacityTimeHours.png
Samsung INR18650-30Q 3000mAh (Pink)-CapacityTimeHours.png (25.37 KiB) Viewed 590 times
How Tests Were Done ... https://lygte-info.dk/info/Batteries2012Info%20UK.html ... on 18650 cells (not only 30Q)

goatman   10 kW

10 kW
Posts: 775
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: 100% discharge rate capacity

Post by goatman » Feb 07 2020 2:14pm

I apologise when im being compared to electric trump, that's probably pretty bad. im sorry my frustration got to me. my lack of knowledge has just confused everything.

lets try to look at this a little differently,
I think instead of using amps we can look at temperature

Discharge temperature
-20℃ -10℃ 0℃ 25℃ 60℃
60% 75% 80% 100% 95%

I think everyone would agree that you wouldn't want to run a cell at 60c or 0c without damaging it

goatman   10 kW

10 kW
Posts: 775
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: 100% discharge rate capacity

Post by goatman » Feb 07 2020 2:58pm

Ianhill wrote:
Feb 07 2020 1:50am
Goatman are you electricgod playing a trick on John cuz surely No one can get it wrong this much.

My car has 200bhp I must use it all or I risk aging the system faster just crazy talk.

Look at humans we can sprint fast but after a few hundred metres shit goes south.
Same for the cell it has a max c rating does not mean it must be cycled at its max all the time to make a fitter person cells are not ufc fighters.
yes you are right, I just confused everything. your first post. I think you might be able to understand me. I think 100% is when a battery is operating as efficiently as it can. like a motor when it is properly tuned, the further out of time the worse it runs and the faster it ages.
if your cars timing is off you start damaging the motor.

a 50e or other chemistries seem to have a straight line example 10amps 97% , 5amps 98.5%, 1amp 100% so the more p you add the better the pack gets

im just wondering if a 30q or 40t have a weird dip at 3amps/ 95%, it looked like ohbse spent most of his time riding in peak 1 or peak2 and not a lot of time at 3 amps

Ianhill   1 MW

1 MW
Posts: 1999
Joined: Sep 25 2015 5:55pm

Re: 100% discharge rate capacity

Post by Ianhill » Feb 07 2020 3:37pm

So your saying there's an efficiency to a cell if I'm getting it right and if I pull max current I'll get that full efficiency bit like a electric motor pulls large start up currents and then dies off further up the rev range but opposite way round and plus that is inductive effect completely different not related.

Proof of batterys discharge with better efficency when used closer to their C ratings would be the total Wh used on the discharge graph, but what we see is the complete opposite the more gentle the discharge curve the more Wh we can get from the cell in total and this is mainly that waste heat from high discharge being eliminated at lower c rates.

Even though the cell can run upto 30amps it will get warm that heat is waste energy that at low discharge does not occur.

To get a cell to run efficient it's different to a motor as it's a chemical reaction and at 0 degrees it slows to a stop and that's why we must not charge or discharge at that point it's not that there's no charge on the plates it's just frozen like a person in ice.

goatman   10 kW

10 kW
Posts: 775
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: 100% discharge rate capacity

Post by goatman » Feb 08 2020 9:01pm

Ianhill wrote:
Feb 07 2020 3:37pm
So your saying there's an efficiency to a cell if I'm getting it right and if I pull max current I'll get that full efficiency bit like a electric motor pulls large start up currents and then dies off further up the rev range but opposite way round and plus that is inductive effect completely different not related.

Proof of batterys discharge with better efficency when used closer to their C ratings would be the total Wh used on the discharge graph, but what we see is the complete opposite the more gentle the discharge curve the more Wh we can get from the cell in total and this is mainly that waste heat from high discharge being eliminated at lower c rates.

Even though the cell can run upto 30amps it will get warm that heat is waste energy that at low discharge does not occur.

To get a cell to run efficient it's different to a motor as it's a chemical reaction and at 0 degrees it slows to a stop and that's why we must not charge or discharge at that point it's not that there's no charge on the plates it's just frozen like a person in ice.
yes at 15 amps the cell gets hot 80c or 90%? for temperature at 60c its 95% and 15amps its 97%

im almost done gathering information but I think at 2c the 30q will have its best results or atleast the same results as when its tested at 1amp discharge. ES member SHUNT is doing some tests of the 30q at 2c and 3c.

in the li ion cell cycle aging post another member posted that they were working on a 30q 88s4p pack from a portable xray machine and the cells were dying.

I googled 30q xray machine and came up with a AccE gm85 portable xray machine, couldn't get much usable information about it except, it can travel 20km at 5.6km/h or 12.4m at 3.5mph. that's about 3.5 hours from a 4p 30q 12ah and if my math is right. the xray machine is operating at 1c/3amps, ill pm the member to see if that's the case.

john61ct   1.21 GW

1.21 GW
Posts: 3756
Joined: Dec 18 2018 2:06pm

Re: 100% discharge rate capacity

Post by john61ct » Feb 08 2020 11:15pm

So confusing, a "portable X-ray unit" traveling at a speed? Do you mean like it is self-propelled, the operator is driving an X-ray machine around in the streets?

80c 60c 2c 3c 1c ?

15A 1A 3A all measuring the same cells?

I'm sorry but it's just incomprehensible!

Gather all the data you like, but **please** use one standard set of units.

Forget amps, use C-rate, even if that means something like 2.35C

Or, if you can't manage that, **only** use amps per cell, and don't mention C-rate, stick to one consistent unit for current.

Either way, be sure to include if you mean peak (a few seconds) or continuous.

And don't forget °C or write "degrees" if you're talking temperature.

And then those percentages, of **what** ????

97% for example, which factor are you referring to, and based on what level of what units is the 100% you're comparing to?

goatman   10 kW

10 kW
Posts: 775
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: 100% discharge rate capacity

Post by goatman » Feb 09 2020 2:09am

ok I see the c and C confusion im causing and any time I use a % like 97% its the rate at which a cell can deliver its capacity, meaning it can only deliver 97% of its capacity but there are 2 different factors, temperature and amp. I can call it 97%t or 97%a

for example

a 30q at 10amps can continuously discharge 100%a but if its temperature reachs 60 Celsius it can only deliver 97%t, meaning it can only deliver 97% because its too hot

so the continuous 10amp rating of a 30q would be 100%a 97%t

my batteries are 25r4p and 40amp controller
when I ride my bike, throttle only, when im accelerating from a stop or going uphill my batteries operate from 2c to 4c but if im just cruising around at 32km/h im about 0.5c. I rarely spend anytime at 1c. my bikes battery is never hot but its nice and warm 25C to 30C. so I can ride at 10amp/4c burst for 10 sec 100%a 100%t or I ride up a slight grade at 2c 97%a 100%t and then back off and cruise at 0.5c 97%a 100%t. my batteries never spend time at 1c, I pass back and forth through it and my batteries spend most of their operating life at 97% to 100%

if you understand that then you will understand why I think a 30q being discharged at 6amps/2c will probably deliver a good lifecycle at 2c. at continuous 6amp/2c discharge it should stay within its 100%t but only 97%a

a 30q at 1 amp discharge after 300 cycles had 90% of its original capacity

a 30q at 1amp continuous discharge would be about 98%a 100%t just like a 30q at 2c

im still looking to see if a 30q at 1c continuous discharge would be 95%a 100%t

john61ct   1.21 GW

1.21 GW
Posts: 3756
Joined: Dec 18 2018 2:06pm

Re: 100% discharge rate capacity

Post by john61ct » Feb 09 2020 6:43am

Is this notation you are making up?

If so never mind.

If not please link to where you got it, hopefully explaining it more clearly and referring back to the way batteries work in reality.

Post Reply