This documentation is still very early and not complete nor well written.

Gouach Battery Framework

Eco-designed batteries

Weld-less contacts

Additional benefits of the Gouach approach

Manufacturing contacts

Pack assembly [WIP]

Fireproof casing

Connected batteries

Gouach Embedded Software

Monitoring interfaces

How to test cells ?

Internal Resistance principles

IR-V testing machines

IR-V tester feeding and outputs

Multi-channel cell cycling machines

Capacity grading and data output

How to grade cells

Cell combination criteria

IR testing cost estimations

EIS for 2nd Life

2nd Life cell testing process

Machines for 2ndLife and BatReseach

Cell testing equipment suppliers

Cell testing facility and safety

2nd Life battery packs collection

Lime B20 (s ou non ?)

Dott_Batch2 (B2)

Kruitbosch Bafang RP2

Kruitbosch Bafang RP3

Lime_Bdx_Batch1

Lime_Europe_Batch1

Lime_Paris_Batch1 (B1)

Momentum_not_confirmed

Battery pack reception tasks

Dott pack disassembly for 2nd Life

Salvaged cell inspection

Cell storage before testing

Tested cells storage SOC

Environmental footprint calculations

Frequently Asked Questions on the Infinite Battery

Gouach Battery Framework

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How to test cells ?

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2nd Life battery packs collection

Dott BD

Pack informations Pack photos Pack information BMS information Batch information 2nd Life information Process Ranking Statistics Cell counting spreadsheet Journal 06/02/23 - Cells from Elemoove reception, first PRETEST 08/02/23 - Chantal capacity statistics 10/02/23 - New cell capacity on Chantal 13/02/23 - Bad cell self-discharge 15/02/23 - PRETEST acceptance increase and TEST IMPEDANCE parameters 16/02/23 - Slow precharge for low voltage cells 02/03/23 - Reusable cells statistics on Mireille 29/03/23 - Speed improvement Todo

Pack informations

Pack photos

Add photos of the pack, closed and opened

Photo of battery sticker

Pack information

Fill ALL the above page informations when available

Spec sheet?

BMS information

Add photos of the BMS

MOSFET model:

MOSFET number:

BMS IC:

BMS schematic?

BMS protocol?

Batch information

Fill reception date, quantity, storage location… in the page information above

Add photos of packing, storage…

2nd Life information

Process

Ranking

Calculation sheet: https://docs.google.com/spreadsheets/d/1UKBXvYpqJI9ptoyBCIY99lIp26wOwSHP9paZGlLRGgs/edit#gid=0

90-91	C10R1	C10R2	C10R3	C10R4	C10R5
91-92	C9R1	C9R2	C9R3	C9R4	C9R5
92-93	C8R1	C8R2	C8R3	C8R4	C8R5
93-94	C7R1	C7R2	C7R3	C7R4	C7R5
94-95	C6R1	C6R2	C6R3	C6R4	C6R5
95-96	C5R1	C5R2	C5R3	C5R4	C5R5
96-97	C4R1	C4R2	C4R3	C4R4	C4R5
97-98	C3R1	C3R2	C3R3	C3R4	C3R5
98-99	C2R1	C2R2	C2R3	C2R4	C2R5
>99%	C1R1	C1R2	C1R3	C1R4	C1R5
SOH / IR 3.6V	22-25.5	25.5-26	26-26.5	26.5-27	27-28

Statistics

Cell counting spreadsheet

Link to statistics sheet for TESTED CELL COUNTING:

https://docs.google.com/spreadsheets/d/1JU5ei7JM9KxAfWVXTP5Lg1iH_0yy68mqY2E37xD9Gz8/edit#gid=0

Journal

06/02/23 - Cells from Elemoove reception, first PRETEST

We received cleaned up cells from Elemoove

Problems:

Some cells are cut on the periphery. Extremely dangerous

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0V, 0.3V, 0.4V on the punctured cells

2.24V 27mR on the cell crushed but not punctured

Most cells are badly cleaned up

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PRETEST program for B2 batch:

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Results on 85 cells:

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We put ~400 cells on Mireille

08/02/23 - Chantal capacity statistics

256 cells from SLOT1 were put on Chantal for a DC1_CHA mesurement

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1 cell at 3070

Need to cycle a few NEW BD cells on Chantal to get 100% SOH capacity DC1_CHA

Datasheet (no precision on @ what discharge current):

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Based on 3070:

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10/02/23 - New cell capacity on Chantal

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12% cells are between 2 and 2.2V

14.5% cells with a valid voltage are between 27 and 29mOhm

⇒ We could be less strict

We put 256 cells on Chantal. The 3 first cells are new BD cells from Nkon

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⇒ 3130mAh is the DC1_CHA capacity of new BD cells, it will be used as a reference for 100% SOH

See cap categories here: https://docs.google.com/spreadsheets/d/1UKBXvYpqJI9ptoyBCIY99lIp26wOwSHP9paZGlLRGgs/edit#gid=0

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13/02/23 - Bad cell self-discharge

One cell at 2.17V after Chantal:

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It is a bent cell:

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What happened when it went on Chantal?

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Surprisingly its impedance is OK!

Je pense que lors du PRETEST elle était > 2.2V, et que le temps de la passer sur Chantal elle est passée en dessous à cause d'une autodécharge élevée, sûrement due à une autodécharge forte à cause de micro court-circuits internes vu qu'elle est tordue

Check bent cell. Self-discharge? What happens if I precharge slowly? It was a 2.17

Up the PRETEST limit to 28mOhm. Bad cells will be discarded after voltage equalization on Chantal

Take the cells down to 2.0V?

If so, change program on Chantal to precharge at low current until at least 2.5V. Add a timetout?

Je pense qu'il faut qu'on ajoute une première étape de précharge lente jusqu'à peut-être 3V ou +, avec un timeout. Comme ça si une cellule monte pas en tension (court-circuits) elle s'arrête

Put again the cells from SLOTs 5 and 7 in the machine

15/02/23 - PRETEST acceptance increase and TEST IMPEDANCE parameters

More PRETEST stats:

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About 52% “good” cells (2.0~4.2V, 27~29mOhm), 48% “bad” cells (others)

14% 0~2.0V

11% 2.0~2.2V (0~29mOhm)

5% >29mOhm

16% 27~29mOhm (>2.2V)

The 2.0~2.2V and 27~29mOhm (11% and 16%) cells went again through Mireille with the new parameters (take cells down to 2.0V and up to 28mOhm):

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⇒ We regain 77% of the previously discarded cells 2.0V~2.2V and 27~29 (11% and 16%)

⇒ 0.52 + 0.77 * (0.11 + 0.16) = 73% “good” cells instead of 52%

Impedance of 3x new BD cells:

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Is the measurement repeatable?

4x the same 3 cells:

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⇒ Voltage measurement is VERY accurate

3.6081: 23.8, 23.6, 23.0, 22.7

3.6105: 24.1, 23.7, 23.7, 23.6

3.6098: 24.4, 24.2, 24.4, 24.0

It looks like the measurement current “wakes up” the cell a bit, because the impedance value decreases at each measurement

Test Impedance parameters selection

Results from IMPEDANCE_TEST on voltage equalized cells?

Test IR on voltage-equalized cells :

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New cells are 23~24mOhm

Almost none (< 0.1%) of the tested cells from Dott were in this category

0.7% <24mOhm

3% 24~25mOhm

25% 25~26mOhm

55% 26~27mOhm

14% 27~28mOhm (there will be more in this category since we now also take the 27~28mOhm cells during PRETEST)

0.2% >28mOhm (there will be more here too)

Proposition:

R1	< 25
R2	25~26
R3	26~26.5
R4	26.5~27
R5	27~28

Test with cells from C5:

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⇒ Not well distributed

New proposition:

R1	22~25.5
R2	25.5~26
R3	26~26.5
R4	26.5~27
R5	27~28

New try with the same cells:

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⇒ Good !

Here are the final resistance categories:

Rx	Range	Distribution (approx)
R1	22~25.5	33%
R2	25.5~26	35%
R3	26~26.5	22%
R4	26.5~27	9%
R5	27~28	1%

Program name: B2_TEST_IMPEDANCE

16/02/23 - Slow precharge for low voltage cells

Précharge lente 300 mA :

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Ici la cellule se restabilisait peut-être vers 2.7V, donc elle est repassé à 3V en 3min30. A voir combien de temps si on part de 2V vraiment.

Programme pour mieux descendre vers les 2V :

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Relancé sur 3-8 (BD)

02/03/23 - Reusable cells statistics on Mireille

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73.6% reusable cells. Estimation was spot on

29/03/23 - Speed improvement

We modified the program to improve the speed at the last step.

We were doing a CC charge 1.5 A up to 3.71 V

New program (v3): CC charge 3.0A up to 3.72 V. Should end up at the same voltage

Todo

Calib Chantal?

Lime B20 (s ou non ?)

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Content

Pack informations

Pack information

BMS information

Batch information

2nd Life information

Cell counting spreadsheet

06/02/23 - Cells from Elemoove reception, first PRETEST

08/02/23 - Chantal capacity statistics

10/02/23 - New cell capacity on Chantal

13/02/23 - Bad cell self-discharge

15/02/23 - PRETEST acceptance increase and TEST IMPEDANCE parameters

16/02/23 - Slow precharge for low voltage cells

02/03/23 - Reusable cells statistics on Mireille

29/03/23 - Speed improvement