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Re: Which cell for long lasting battery

Posted: Jun 13 2019 8:03am
by john61ct
Wow good stuff
Pajda wrote: If you insist on longer cycle life (500 full cycles should be enough for most applications)
In most of my use cases there is no "enough", daily cycling or dozens per month anyway, usually just replace at EoL defined as 70-75% SoH, so longer the better

So which batteries do you recommend for the below in LI chemistries, not counting LTO or LFP?

Cost per Ah **per year** is the Most Important factor

Must be readily available, consistent supply

Next is per-cell Ah capacity, higher is better, building and maintaining large banks, so fewer cells is a huge advantage

power density is irrelevant, bank sized to keep discharge rates below 0.2C most of the time, never over 0.5C

charging usually at 0.2C, sometimes 0.5C when fast is required


_______
It seems you don't test for usage patterns other than 100% DoD, but just FYI

LVC is 3.2V (low current remember), and

charge termination is CC-only, end V set so SoC is kept well under 95% of that reached by stopping at 4.1V at 0.3C

In effect translates to keeping cycling between about 10% & 90% of the SoC defined by maker specs,

but only where range is critical, otherwise I try to stop discharge at between 50-70% DoD





or faster charging like 0.5C then take only LGs. Sanyo GA suffers with steep initial capacity loss and the most important problem is its huge DCIR rise. VC7 is very expensive and inferior to both LGs.

in best price category: Samsung 29E, Panasonic PF, LG M29, Sony NC1 I would recommend 29E as the best chioce. Panasonic PF is slightly worse under almost all cycle life test. PF is only better in fast charging (like 0.7-1C). I do not already have data for M29 and NC1 because I started with their cycle life tests only few days ago.




Re: Which cell for long lasting battery

Posted: Jun 13 2019 9:36am
by Pajda
john61ct wrote:
Jun 13 2019 8:03am
Wow good stuff
Pajda wrote: If you insist on longer cycle life (500 full cycles should be enough for most applications)
In most of my use cases there is no "enough", daily cycling or dozens per month anyway, usually just replace at EoL defined as 70-75% SoH, so longer the better
I give you an example a hard data from my measurement. Tesla Model S 85 cell is after 500 cycles (the same settings: 0.5C-1C 100% DoD) at 81% of its nominal capacity and after 1000 cycles at 71%. This is much worse result than almost all above mentioned cells. Do we heard about any significant Tesla batterygate? My laboratory cycle life tests are excellent for direct comparison of the modern state-of-the-art cell technology under different working conditions but they are far from the real traction application use.

Re: Which cell for long lasting battery

Posted: Jun 13 2019 4:25pm
by Dak77
Pajda wrote:
Jun 13 2019 6:56am
Dak77 wrote:
Jun 12 2019 9:54pm
Is HG2 in that 1000cycle club?
Sure it is. But HG2 also has its own issues. The problem with HG2 is that it loses capacity very quickly during the first 50 cycles (ca 8-10% of nominal capacity). Between 50-100 cycles the capacity drop start with stabilization and after ca 150 cycle there is only minor capacity loss (86% of nominal capacity at 1C discharge 100% DoD after 1000 cycles). The good thing is that HG2 behave practically the same even under 3C continuous discharge (82% capacity drop at 3C discharge 100% DoD after 1000 cycles). For example LG MH1, MJ1 and M36 dies very quickly at 3C discharge torture.

So this is the reason why many users prefers Samsung 30Q or Sony VTC6 before LG HG2. Because for flashlight, powertools and many other applications the 50-100 cycles is the whole life. I am charging my cordless drill no more than 10 times per year. So it is useless that LG HG2 in cycle life totally outperforms both above mentioned cells after ca 400 cycles, when particularly 30Q dies.
That's music to my ears. I was already leaning towards the HG2 for my next project and now I'm sold.

Re: Which cell for long lasting battery

Posted: Jun 13 2019 5:55pm
by miro13car
in my book the best cells for ebike battery come from smashed /written off EV and hybrids - no doubt about it.
if you think about it,
how well those cells were researched and tested to be used in EV in laboratories before approved to pack production.
yes they are from smashed cars , of course the younger car the better.
yes most of such cells are pouches.
I use Chevy Volt to power my summer bike and Nissan Leaf to power my winter bike.

Re: Which cell for long lasting battery

Posted: Jun 14 2019 12:15am
by docware
Pajda wrote:
Jun 13 2019 9:36am

I give you an example a hard data from my measurement. Tesla Model S 85 cell is after 500 cycles (the same settings: 0.5C-1C 100% DoD) at 81% of its nominal capacity and after 1000 cycles at 71%. This is much worse result than almost all above mentioned cells. Do we heard about any significant Tesla batterygate? My laboratory cycle life tests are excellent for direct comparison of the modern state-of-the-art cell technology under different working conditions but they are far from the real traction application use.
Yes I agree, they are far away from the real traction application use.
Pajda, I respect your testing. But on the other hand I am more and more convinced that your testing conditions are too away from real life. Preceding that we are speaking about ebike world .

Nobody use 100 % DOD. Charging 0,5 C is quite high. In reality is charging rate usually about 0,2 - 0,25 C, never more than 0,3 C. Discharge 1C is also little bit high, properly designed pack can have cca 0,5 – 0,7 C discharge rate.

I have 5p10s Sanyo GA battery in my bike. Started using this pack in June 2017. Currently I have 4800 km on the odometer. DCIR of the cells is still sitting at cca 36 – 37 miliohm. Definitely don´t see any huge DCIR rise. New Sanyo GA cells are about 36 - 37 miliohm.

As we know, you are testing the cells also at different conditions, less strict, giving different results.

Re: Which cell for long lasting battery

Posted: Jun 14 2019 12:57am
by Dak77
docware wrote:
Jun 14 2019 12:15am
Pajda wrote:
Jun 13 2019 9:36am

I give you an example a hard data from my measurement. Tesla Model S 85 cell is after 500 cycles (the same settings: 0.5C-1C 100% DoD) at 81% of its nominal capacity and after 1000 cycles at 71%. This is much worse result than almost all above mentioned cells. Do we heard about any significant Tesla batterygate? My laboratory cycle life tests are excellent for direct comparison of the modern state-of-the-art cell technology under different working conditions but they are far from the real traction application use.
Yes I agree, they are far away from the real traction application use.
Pajda, I respect your testing. But on the other hand I am more and more convinced that your testing conditions are too away from real life. Preceding that we are speaking about ebike world .

Nobody use 100 % DOD. Charging 0,5 C is quite high. In reality is charging rate usually about 0,2 - 0,25 C, never more than 0,3 C. Discharge 1C is also little bit high, properly designed pack can have cca 0,5 – 0,7 C discharge rate.

I have 5p10s Sanyo GA battery in my bike. Started using this pack in June 2017. Currently I have 4800 km on the odometer. DCIR of the cells is still sitting at cca 36 – 37 miliohm. Definitely don´t see any huge DCIR rise. New Sanyo GA cells are about 36 - 37 miliohm.

As we know, you are testing the cells also at different conditions, less strict, giving different results.
What kind of amp loads are you hitting that GA pack with? Ball park figure

Re: Which cell for long lasting battery

Posted: Jun 14 2019 1:28am
by docware
Dak77 wrote:
Jun 14 2019 12:57am


What kind of amp loads are you hitting that GA pack with? Ball park figure
Amp load peaks are usually about 2,2 A per cell, very seldom 3 A.
Charging amps 0,8 A per cell for the first year, now cca 0,5 A.

Re: Which cell for long lasting battery

Posted: Jun 14 2019 1:35am
by Dak77
docware wrote:
Jun 14 2019 1:28am
Dak77 wrote:
Jun 14 2019 12:57am


What kind of amp loads are you hitting that GA pack with? Ball park figure
Amp load peaks are usually about 2,2 A, very seldom 3 A.
Charging amps 0,8 A for the first year, now cca 0,5 A.
:thumb: Gracias