100% discharge rate capacity

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goatman   100 kW

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Re: 100% discharge rate capacity

Post by goatman » Feb 05 2020 11:14pm

Ohbse wrote:
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.
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?

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Re: 100% discharge rate capacity

Post by Ohbse » Feb 05 2020 11:40pm

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.

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Re: 100% discharge rate capacity

Post by goatman » Feb 06 2020 12:03am

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%

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Re: 100% discharge rate capacity

Post by goatman » Feb 06 2020 12:23am

Ohbse wrote:
Feb 05 2020 11:40pm
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

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Re: 100% discharge rate capacity

Post by Ohbse » Feb 06 2020 12:36am

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

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Re: 100% discharge rate capacity

Post by goatman » Feb 06 2020 12:42am

Ohbse wrote:
Feb 06 2020 12:36am
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

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Re: 100% discharge rate capacity

Post by Ohbse » Feb 06 2020 12:54am

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.

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Re: 100% discharge rate capacity

Post by goatman » Feb 06 2020 1:02am

im not talking about how you use the battery, 4.09 to 3.8

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

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Re: 100% discharge rate capacity

Post by Ohbse » Feb 06 2020 1:31am

goatman wrote:
Feb 06 2020 1:02am
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.jpg
18650chargeDischarge-powercell-web.jpg (82.02 KiB) Viewed 847 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.

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Re: 100% discharge rate capacity

Post by john61ct » Feb 06 2020 1:50am

Yes, comparing how a battery works to an engine power curve is just inane.

There is no "way to use them like they were designed for".

You have your use case, choose the cells by balancing between your priorities

energy density vs power density
lower price vs consistency and better longevity

Then your **pack** design, for a given V/A

lower weight fewer P = higher C-rate, deeper discharge = shorter life

______
30Q was "not bad" years ago but now has a very bad reputation, random inconsistencies so some cells self discharge for no logical reason.

That review was saying they are bad, because **they do not** do what they are supposed to do.

So don't use it as an example to try to support a bass-ackwards opinion as to how battery technology works in general.

Start **listening** try to learn or you'll be making very expensive mistakes you could easily avoid.

Start by learning to google terms together with the

site:

and OR

keywords, using the dash, and quotes

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Re: 100% discharge rate capacity

Post by goatman » Feb 06 2020 2:01am

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

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Re: 100% discharge rate capacity

Post by goatman » Feb 06 2020 2:21am

hey john, hows it going

Start **listening** try to learn or you'll be making very expensive mistakes you could easily avoid.

I am listening but im a curious fellow I only wish Ohbse said he spent the rest of his trip at 3000 watts

3000w/76=39amps
12p/39a= 3ish amps per cell wich would have squashed the data that states 3amps kill a 30q

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

you don't have to follow along but I don't mind if you do

I hope I get called back to work soon lol

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Re: 100% discharge rate capacity

Post by Ohbse » Feb 06 2020 2:36am

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.

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Re: 100% discharge rate capacity

Post by goatman » Feb 06 2020 3:01am

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

that and I like to mess with john a little bit

have a good night

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Re: 100% discharge rate capacity

Post by madin88 » Feb 06 2020 11:41am

goatman wrote:
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
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 3:01am
I think it was pajda that cycled the 30q at 3amps and it was destroyed in 100 cycles.
In which regard it was "destroyed"?
  • reducded capacity
  • increased IR
  • too high self discharge (which would be killer factor 1 if assembled into a pack)

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Re: 100% discharge rate capacity

Post by goatman » Feb 06 2020 12:03pm

madin88 wrote:
Feb 06 2020 11:41am
goatman wrote:
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
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 3:01am
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)

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Re: 100% discharge rate capacity

Post by madin88 » Feb 06 2020 12:37pm

goatman wrote:
Feb 06 2020 12:03pm
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.

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Re: 100% discharge rate capacity

Post by goatman » Feb 06 2020 12:41pm

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%

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Re: 100% discharge rate capacity

Post by goatman » Feb 06 2020 12:41pm

let me find the 3a chart

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Re: 100% discharge rate capacity

Post by eMark » Feb 06 2020 12:54pm

deleted ... this thread is between goatman and ohbse ... my apology for intruding.
Last edited by eMark on Feb 06 2020 8:07pm, edited 3 times in total.

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Re: 100% discharge rate capacity

Post by goatman » Feb 06 2020 12:59pm

goatman wrote:
Feb 05 2020 9:53pm
goatman wrote:
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
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.

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Re: 100% discharge rate capacity

Post by goatman » Feb 06 2020 1:59pm

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%

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Re: 100% discharge rate capacity

Post by goatman » Feb 06 2020 3:34pm

this is what im picturing

Image

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Re: 100% discharge rate capacity

Post by Ohbse » Feb 06 2020 4:59pm

No, again, your graph is meaningless. The % figures you reference have ZERO bearing on how this works.

Forget you ever read the table with those figures as they have literally nothing to do with calculating lifespan, efficiency, power etc.

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Re: 100% discharge rate capacity

Post by goatman » Feb 06 2020 5:59pm

hi ohbse, you keep whacking me with a stick but im not quite done exploring this yet, my brain is weird and if I don't satisfy my curiousity itll bug me.

do you mind if I ask what amps you charge your pack with?

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