LIFEPo4 cells, 21700 3000mah, recommendations?

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zeccato   100 W

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LIFEPo4 cells, 21700 3000mah, recommendations?

Post by zeccato » Mar 14 2020 3:38am

I'm looking at these cells:
https://m.made-in-china.com/company-lithiumionbattery/
LIFEPo4 cells 21700 3000mah (68g.),
to make a package from 48v 27Ah, and that would be about 10 kg.
to go lighter than the bigger (26650 85g.).
(cells of 18650 with 2,500-3000mah I can't find LIFEPo4).
recommendations? other brands?

I am happy with my 8 year old LIFEPo4 25ah battery (no brand bought in China), which still works well at 75-80% Ah.

I have to decide between LIFEPo4 cells 21700 3000mah, or normal li-ion cells 21700 5000mah.
I don't have a big weight problem, I want a duration minimum 7 years.
Last edited by zeccato on Mar 15 2020 1:57am, edited 1 time in total.
Full susp. folding 20 swxh r. (2011),. 02 2020 MacT8. batt. 48v. 25A Life (2012), and 48 7,5A a123 (2018?). Controller programmable EB3 12 FET. Charger Balancer 14s: TP1430C. Gophert CPS-6011 60V 11A. Mercury (rarely). Buzzer. https://www.google.com/url?sa=t&source= ... 6dXxc9-lNW

john61ct   100 GW

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Re: LIFEPo4 cells, lighter with 21700 3000mah, recommendations?

Post by john61ct » Mar 14 2020 9:31am

For assured longevity need to use A123 ANR26650M1B, or at least the older ANR26650M1A

Full River, K2, Hixon, Queen battery, VariCore / Liitokala, Goldencell / Heter / ENERpower

are other brands I've come across, but in dozens of threads, thousands of posts have yet to see anyone comment that any of them are even decent quality, for either short-term power output nor build quality / longevity.

Headway, maybe?

Mr. Ping has a good rep for built packs, but I don't know what cells he uses.

john61ct   100 GW

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Re: LIFEPo4 cells, lighter with 21700 3000mah, recommendations?

Post by john61ct » Mar 14 2020 9:35am

I would not buy from a random source like that no matter what, but IMO the higher the energy density rating from an unknown company, the more likely they are lying scammers.

But if you do take a chance, please do accurate capacity benchmarking, and keep us updated how they do over the years.

Packs made from A123 cells can last for decades, depending on how they're treated of course.

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zeccato   100 W

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Re: LIFEPo4 cells, 21700 3000mah, recommendations?

Post by zeccato » Mar 15 2020 1:56am

Tanks,
I calculated that the 18650 1800mah to make 27ah have about the same weight.
So the 3000mah are no longer light.

p.s I have A123 26650 2500mah 16s 3p for the city, but for a big 27ah package I would like something lighter.

To do about 27ah:
144 cells 21700 3000mah 68g) = 9792kg,
176 cells 26650 2500mah 85g.) = 14960kg,
about 5kg difference is remarkable for my folding bike.
Full susp. folding 20 swxh r. (2011),. 02 2020 MacT8. batt. 48v. 25A Life (2012), and 48 7,5A a123 (2018?). Controller programmable EB3 12 FET. Charger Balancer 14s: TP1430C. Gophert CPS-6011 60V 11A. Mercury (rarely). Buzzer. https://www.google.com/url?sa=t&source= ... 6dXxc9-lNW

john61ct   100 GW

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Re: LIFEPo4 cells, 21700 3000mah, recommendations?

Post by john61ct » Mar 15 2020 7:18am

The problem is, you are accepting numbers from marketing materials that are likely bogus.

Reducing weight with **quality** cells - I assume longevity is important to you?

means reducing either voltage or Ah range, if you stick to LFP.

Otherwise go to the much higher density LI chemistries like NCA / NMC etc

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zeccato   100 W

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Re: LIFEPo4 cells, 21700 3000mah, recommendations?

Post by zeccato » Mar 15 2020 9:04am

john61ct wrote:
Mar 15 2020 7:18am
The problem is, you are accepting numbers from marketing materials that are likely bogus.

Reducing weight with **quality** cells - I assume longevity is important to you?

means reducing either voltage or Ah range, if you stick to LFP.

Otherwise go to the much higher density LI chemistries like NCA / NMC etc
I had calculated other brands 26650 that weighed about 85-87g.,
while the a123 weighs 76g.

(18650 LFP) (42g) 1800mah 16s 27ah = 240 cells = 10080 kg
(26650) (76g) A123 2500mah 16s 27,5ah = 176 cells = 13376 kg.
(Nkon).

my first 8-year-old battery is about 14kg, I would like max 10kg.
Full susp. folding 20 swxh r. (2011),. 02 2020 MacT8. batt. 48v. 25A Life (2012), and 48 7,5A a123 (2018?). Controller programmable EB3 12 FET. Charger Balancer 14s: TP1430C. Gophert CPS-6011 60V 11A. Mercury (rarely). Buzzer. https://www.google.com/url?sa=t&source= ... 6dXxc9-lNW

john61ct   100 GW

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Re: LIFEPo4 cells, 21700 3000mah, recommendations?

Post by john61ct » Mar 15 2020 9:40am

zeccato wrote:
john61ct wrote:
Mar 15 2020 7:18am
The problem is, you are accepting numbers from marketing materials that are likely bogus.

Reducing weight with **quality** cells - I assume longevity is important to you?

means reducing either voltage or Ah range, if you stick to LFP.

Otherwise go to the much higher density LI chemistries like NCA / NMC etc
I had calculated other brands 26650 that weighed about 85-87g,
while the a123 weighs 76g
What you are trying to get at is "specific energy" and the unit is Wh/kg

Again, other than A123 I think you need to buy first and measure the actual cells, not believe the manufacturer.
zeccato wrote:my first 8-year-old battery is about 14kg, I would like max 10kg.
Then you will need to accept much smaller Ah capacity

or give up the much longer lifespan of LFP in order to get the much higher density of the other chemistries.



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zeccato   100 W

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Re: LIFEPo4 cells, 21700 3000mah, recommendations?

Post by zeccato » Mar 15 2020 9:59am

thanks for the clarification, I'll think about it, for now I'm not buying anything, because I'm undecided on the best choice to make.
Full susp. folding 20 swxh r. (2011),. 02 2020 MacT8. batt. 48v. 25A Life (2012), and 48 7,5A a123 (2018?). Controller programmable EB3 12 FET. Charger Balancer 14s: TP1430C. Gophert CPS-6011 60V 11A. Mercury (rarely). Buzzer. https://www.google.com/url?sa=t&source= ... 6dXxc9-lNW

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