New 14s battery pack, US18650VTC6 vs NCR18650GA

Batteries, Chargers, and Battery Management Systems.
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Jan-Erik-86   10 W

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New 14s battery pack, US18650VTC6 vs NCR18650GA

Post by Jan-Erik-86 » Sep 16 2019 11:30am

I've abandoned my first thought on simply adding some high power cells to my old pack, and have decided on making a new pack.

I have a DD hub motor with a shunt modded KT controller which pulls up to ~50A from the battery, but my load is normal in the range of 600-1000W. I mainly use the bike for commuting 16km each way, but do not have many hills on the way. My average power usage is around ~12Ah.
I ride it in the winter time as well, so cold temp performance is also important. I plan to stay in the 20-80% SoC range, but want a bit extra capacity for longer trips and expected capacity drop over time.

I have space for up to 9p14s and have been looking around a lot for which cells to use, and i think i've come down to 2 main options (or maybe 3).
The cells i'm mainly considering are either Sanyo GA or Sony VTC6. Now these are two completely different cells, but with the seemingly low price on the VTC6 I think it might actually be a very good option. I first thought the LG HG2 would be the best option, but that have dropped down to the "maybe option 3" on the list due to it's price vs capacity, power handling and cycle life.

From what i can see, this is how the two cells compare:

US18650VTC6: 9p14s / 126 cells + 5x vruzend kits = €649
Capacity: 27Ah, 60% Min. of Initial capacity at 500 cycles (from specs/graph with 4A charge, 15A discharge). (looks much better with the 7,5A discharge graph)
Max cont. current: 135A (270A)
Weight: 5,86Kg
Std. charge: ~22-27A (?)
Warm sag: 58,8V -> ~56,7V @ 45A ~25c
Cold sag: 58,8V -> ~45,5V @ 90A -10c

NCR18650GA: 8p14s / 112 cells + 4x vruzend kits = €614
Capacity: 27,2Ah, ~65% of Initial capacity at 500 cycles (from specs/graph with 1,65A charge, 6A discharge)
Max cont. current: 80A
Weight: 5,2Kg
Std. charge: 11,8A
Warm sag: 58,8V -> ~55,3V @ 40A ~25c
Cold sag: 58,8V -> ~46,9V @ 32A -10c

Now maybe i've overlooked something important here, but from what i can see the VTC6 will be slightly heavier and slightly more expensive, but other then that it will handle way higher both charge and discharge current, it sags less (significantly less in cold temp), and the capacity drop with cycle life does not appear to be an issue compared to the GA cell - at least not from the graph in specs.

On the other side I know the GA have been proven to be a very long lasting cells even when used at a high DoD and up to 3C discharge, and even though the specs don't claim it they appears to "settle down" after dropping to ~80% capacity. I don't know if any similar tests have been made on the VTC6?
However the GA do sag a bit under higher load, and i expect the sag to increase with the cycles even though the capacity drop settles, and i'm getting close-ish to the max current load.

Hopefully you guys can point me in the right direction here. I'm open for any feedback and recommendation, and just because i've been looking at these two cells does not mean you can't convince me to choose something else if it's a better option. :)

Hillhater   100 GW

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Re: New 14s battery pack, US18650VTC6 vs NCR18650GA

Post by Hillhater » Sep 17 2019 9:25pm

I have packs of GA cells 10s, 4P, and have no problems or complaints.
..But, i do not run much more than 2C, and i am not a daily user/ charger , so no experience with cycle life etc.
However , i have seen comments on this forum from other GA users who have reported poor cycle life with heavy use.
So, i would suggest you do more research here before deciding .
PS.. i dont know your location (not that it matters anyway). But you may be interested in this source for cells..
viewtopic.php?f=31&t=61608
A very honest and recommended supplier of good cells.
PPS... those 29E cells are very popular and often recomended on this forum ?
This forum owes its existence to Justin of ebikes.ca

Jan-Erik-86   10 W

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Re: New 14s battery pack, US18650VTC6 vs NCR18650GA

Post by Jan-Erik-86 » Sep 18 2019 7:02am

Thank you very much for the reply. :)

I have a friend with the GA cells on his bike that also have a peek pull of around 50A. He have no problems after a few years usage, and only a few volts sag in the summer time, but i don't think he rides in the winter time when it's cold though, and he also have a 9p or 10p pack.

It's mainly the battery sag (especially in the winter time and after a few years) i was worried about and made me consider the VTC6 instead. While the GA have 15% higher rated Ah capacity then the VTC6, it appears that due to the sag difference the actual Wh difference at 5A load is only ~5%, and only ~2% at 10A. This is during warm conditions though, not sure how they compare in the cold.

Yes, the 29e is a popular cell and I'm sure it performs really well for the price, but with only 2.75A/8.25A cont./max discharge i don't think it will be well suited for my application?

I was hoping to order cells this week, so i will try to do some more research and see what i can find out, but would very much appreciate any feedback/thoughts/opinions others might have as well. :)

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Re: New 14s battery pack, US18650VTC6 vs NCR18650GA

Post by Joachim » Sep 18 2019 11:48am

wow big heavy battey for a e-bike :shock: why?
cells in the 3000+mah range age way faster after 60 till 100 cycles they already degrade.

8P 9P pack 40/50A max discharge you be fine with the Samsung 29E are the Panasonic PF cells.

Jan-Erik-86   10 W

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Re: New 14s battery pack, US18650VTC6 vs NCR18650GA

Post by Jan-Erik-86 » Sep 18 2019 12:58pm

The main reason for a large pack is that i want to buy a pack that will last for many years to come with 30Km daily commuting, and also have some extra capacity occasional longer trips (probably no longer then 60-70Km).

My understanding is the key factors to make this happen is to use no more then 80% of pack capacity (but less is better), charge with no more then 0.2c, and the lower discharge rate used the better.
With 80% capacity used, it appears the GA cells will last ~1000+ cycles and still hold ~80% of original capacity, so i guess for my usage i could be OK with a 6P GA pack as far as capacity goes - but my understanding is that a 30% larger pack, when used with the same charge/discharge current and Wh drained, will last significantly more then 30% longer and therefore be worth it in the long run?

Or am i making a way oversized pack here, simply fearing for how it might perform in 5+ years...?

john61ct   100 MW

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Re: New 14s battery pack, US18650VTC6 vs NCR18650GA

Post by john61ct » Sep 18 2019 1:50pm

Buying more Ah to reduce C-rate to make it last longer def has a point of diminished returns.

If something happens in six months more money wasted.

Maybe buy 2 packs, parallel for when you need the range, that way you have a backup.

Jan-Erik-86   10 W

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Re: New 14s battery pack, US18650VTC6 vs NCR18650GA

Post by Jan-Erik-86 » Sep 18 2019 1:57pm

I see, i guess you have a point there.
So in my case, where i will mainly use ~12Ah daily with ~50A max load and 5-6A charge current, would it be better, or at least acceptable, to simply go for a ~20Ah 6p14s GA pack, and just plug in an extra battery for when i'll go on longer trips?
If a pack like this can handle the load and not die off quickly, i'd rather do that i guess, as it's both cheaper and lighter.

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Re: New 14s battery pack, US18650VTC6 vs NCR18650GA

Post by john61ct » Sep 18 2019 2:06pm

Yes to all that, except seems like a consensus that GA is not the best value taking longevity into account.

If not VTC then PF?

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Re: New 14s battery pack, US18650VTC6 vs NCR18650GA

Post by 999zip999 » Sep 18 2019 3:02pm

I like that sony 35a cell.

cwah   10 GW

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Re: New 14s battery pack, US18650VTC6 vs NCR18650GA

Post by cwah » Sep 18 2019 5:42pm

Hello,

I've done some research on the best chemistry to use, and decided to stick to NCR chemistry. It appears it is the one that is ranked safest and best lifecycle: https://batterybro.com/blogs/18650-whol ... -explained

We can also see that in the cell datasheet. See for NCR18650PF after 500 cycles would still have around 2300mAH:
https://www.omnitron.cz/download/datash ... 8650PF.pdf

However, the Samsung which uses INR chemistry 35E after 500 cycles ends up with only 2010mAH capacity:
https://www.orbtronic.com/content/samsu ... 50-35e.pdf

I've also checked for the Sony VTC6, if you look at the data sheet, it goes down to 60% after 500 cycles. It doesn't mention which chemistry but my bet is that it's INR as well.

So if you'd like it to keep working for years... just do like Tesla, use NCR chemistry and don't trade up for a temporary increase of capacity and power. Probably good for Vape, not for ebike or anything using bigger battery
Help me find my stolen electric brompton: http://bit.ly/1a0vbBC and Bosch Sinus B3 http://bit.ly/1eV0WQz

cwah   10 GW

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Re: New 14s battery pack, US18650VTC6 vs NCR18650GA

Post by cwah » Sep 18 2019 6:12pm

I'm actually thinking to buy the NCR18650BD:
https://evwest.com/support/panasonic-nc ... asheet.pdf

The discharge curve after 500 cycle looks quite good from 3100mah to 2550mah? So still 80% capacity?
Help me find my stolen electric brompton: http://bit.ly/1a0vbBC and Bosch Sinus B3 http://bit.ly/1eV0WQz

Hillhater   100 GW

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Re: New 14s battery pack, US18650VTC6 vs NCR18650GA

Post by Hillhater » Sep 18 2019 6:43pm

Isnt the BD basicly the Tesla cell ?
This forum owes its existence to Justin of ebikes.ca

john61ct   100 MW

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Re: New 14s battery pack, US18650VTC6 vs NCR18650GA

Post by john61ct » Sep 18 2019 7:43pm

NCR is not a chemistry as such, likely mean LCO / LiCoO2 designed for high discharge rates and maximum power density, **definitely** not longevity. Or might be LiNiCoAlO2, a.k.a. NCA, pretty much ditto.

VTC6 is LiNiMnCoO2 aka NMC or INR.

You **cannot** base purchase decision on lab tests comparing longevity across different vendors.

Between lines from a single maker, maybe.

Same with generalizations from BU and other sites.

Longevity is not an attribute explicitly aimed for, the market cares about density and C-rates, and both of those may well sacrifice longevity.

Thus older formulations with great **user** reputation for longevity is a decent basis.

VTC4?
Panasonic PF?
Samsung 29E, 6 or 7?


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Re: New 14s battery pack, US18650VTC6 vs NCR18650GA

Post by Pajda » Sep 19 2019 2:27am

Hillhater wrote:
Sep 18 2019 6:43pm
Isnt the BD basicly the Tesla cell ?
Basically yes, I never tested BD to confirm it, but from info what i have the BD seems to be a twin of BE (BE is Tesla cell from original 85 battery) both with older NCA+C chemistry. The only difference is by my opinion that BE does have bottom vent and BD does not. Then we have BM cell which is an upgraded chemistry cell using NCA+C/Si and was used in newer versions of 85 battery. I make side-by-side comparison of both BM and Tesla cells under many loads and cycle life tests and i am quite sure that they have the same parameters.

Anyway all of the BD,BE,BM line is outdated and there are much better choices for DIYers.

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Re: New 14s battery pack, US18650VTC6 vs NCR18650GA

Post by cwah » Sep 19 2019 2:39am

Pajda wrote:
Sep 19 2019 2:27am
Hillhater wrote:
Sep 18 2019 6:43pm
Isnt the BD basicly the Tesla cell ?
Basically yes, I never tested BD to confirm it, but from info what i have the BD seems to be a twin of BE (BE is Tesla cell from original 85 battery) both with older NCA+C chemistry. The only difference is by my opinion that BE does have bottom vent and BD does not. Then we have BM cell which is an upgraded chemistry cell using NCA+C/Si and was used in newer versions of 85 battery. I make side-by-side comparison of both BM and Tesla cells under many loads and cycle life tests and i am quite sure that they have the same parameters.

Anyway all of the BD,BE,BM line is outdated and there are much better choices for DIYers.
What are the better ones which would make sense financially?
Help me find my stolen electric brompton: http://bit.ly/1a0vbBC and Bosch Sinus B3 http://bit.ly/1eV0WQz

Jan-Erik-86   10 W

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Re: New 14s battery pack, US18650VTC6 vs NCR18650GA

Post by Jan-Erik-86 » Sep 19 2019 3:07am

Thank you very much for all the replies and feedback guys!

Ok, so i guess for start, i should aim lower as far as capacity goes, and a bit over 20Ah sounds like a better size to aim for then.
Also, neither the GA or VTC6 is really a good choice for a long life then, if i understand good? Would the vt4, 29E, or PF last significantly longer then the GA?

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Re: New 14s battery pack, US18650VTC6 vs NCR18650GA

Post by docware » Sep 19 2019 3:28am

What temperatures can the battery experience during winter ? Can you keep the battery warm in thermal isolation during winter rides ?

Jan-Erik-86   10 W

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Re: New 14s battery pack, US18650VTC6 vs NCR18650GA

Post by Jan-Erik-86 » Sep 19 2019 5:16am

Winters can be cold here in Norway, but I doubt i'll be riding in much colder then -10c.
I'm able to park the bike indoors both at home and work for now, so the "starting temp" for most rides are not going to be much colder then around +5c. It's a 30 min ride each way, but i guess while in use they won't be much affected by the cold?
I sometimes need to park it outside though, so i think we can say that a worst case would be -10c.

The battery will be mounted in a metal case, together with the controller (i know, not recommended, but i've monitored the temp for a few months and it stays cold even at high load for a longer time), so it will be somewhat insulated in that way. I guess i could also add some thermal insulation around the battery pack itself if this is recommended.

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Re: New 14s battery pack, US18650VTC6 vs NCR18650GA

Post by docware » Sep 19 2019 6:00am

You maybe have read that EV cars have thermal management to keep cells at optimal temperature.
To ensure battery long life you need to do the same. Starting temperature 5°C is too low. Ideal working temperature is 20 – 30°C. Running battery bellow 10°C means faster degradation of the cells.

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Re: New 14s battery pack, US18650VTC6 vs NCR18650GA

Post by john61ct » Sep 19 2019 6:06am

design removable packs, bring those inside

Jan-Erik-86   10 W

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Re: New 14s battery pack, US18650VTC6 vs NCR18650GA

Post by Jan-Erik-86 » Sep 19 2019 6:34am

A won't go for a removable battery solution because i want a none-removable, sealed, an hidden system.
I understand they will degrade faster in the cold, but i don't have too many options when it comes to this and will just have to accept the extra wear. Will a lower internal resistance cell like the VTC also suffer as much degradation in the cold as a high energy cell? Both with regards to charge and discharge (though i can probably lower the charge rate a bit in the winter time if needed).

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Re: New 14s battery pack, US18650VTC6 vs NCR18650GA

Post by flippy » Sep 19 2019 7:01am

john61ct wrote:
Sep 18 2019 1:50pm
Buying more Ah to reduce C-rate to make it last longer def has a point of diminished returns.
If something happens in six months more money wasted.
Maybe buy 2 packs, parallel for when you need the range, that way you have a backup.
not really, if you have the capacity you can drop the top voltage down to 4V for example and get thousands of charges.
Lithium beats liquid dinosaurs.

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Re: New 14s battery pack, US18650VTC6 vs NCR18650GA

Post by docware » Sep 19 2019 7:04am

Jan-Erik-86 wrote:
Sep 19 2019 6:34am
A won't go for a removable battery solution because i want a none-removable, sealed, an hidden system.
I understand they will degrade faster in the cold, but i don't have too many options when it comes to this and will just have to accept the extra wear. Will a lower internal resistance cell like the VTC also suffer as much degradation in the cold as a high energy cell? Both with regards to charge and discharge (though i can probably lower the charge rate a bit in the winter time if needed).
Another solution could be to resign to shorter battery life and use cheaper but here recommended Samsung 29E cells. Charging at low temperatures is however issue.

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Re: New 14s battery pack, US18650VTC6 vs NCR18650GA

Post by john61ct » Sep 19 2019 7:06am

flippy wrote:
john61ct wrote:
Sep 18 2019 1:50pm
Buying more Ah to reduce C-rate to make it last longer def has a point of diminished returns.
If something happens in six months more money wasted.
Maybe buy 2 packs, parallel for when you need the range, that way you have a backup.
not really, if you have the capacity you can drop the top voltage down to 4V for example and get thousands of charges.
Yes, that I just assume, 4.05V is my top anyway.

Reducing DoD draw point, and lowering C-rates are each a separate "coddling for longevity" factor

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Re: New 14s battery pack, US18650VTC6 vs NCR18650GA

Post by john61ct » Sep 19 2019 7:13am


Jan-Erik-86 wrote:won't go for a removable battery solution because i want a none-removable, sealed, an hidden system.
The **only** alternatives are an active pre-heating system, or moving to some other, much less energy-dense chemistry.

At cold enough temps, not a question of "reduced longevity", but discharge in effect just stops, and charging means the pack is instantly rendered useless, unrecoverable scrap.

Insulation will help a bit at marginal temps for a short rest time, but well below freezing for hours outdoors, only with active pre-heating.


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