Hi
If you are going to make your own BMS be aware that BMS problems have killed more batteries than they have saved
If you are going to make your own BMS be aware that BMS problems have killed more batteries than they have saved
The 18650 - 13s10p Project - 48V x 34Ah
The 18650 - 14s10p Project - 48V x 34Ah
This is to chronicle a project to construct a 1.6 kWh module from 18650 cells. The configuration is 13s10p (edit: upgraded to 14s10p) using 130 (140) "Grade A" Panasonic NCR18650B (edit: unprotected) li-ion cells. These cells are nominally rated at 3.4 Ah and guaranteed to 3.25 Ah.
The first order of 100 cells (at US$3.28 each - $272/kWh) was received from Shanghai today and I have started testing individual cells, and plan to test all cells. Shipment was by air and arrived in 4 days. Shipment adds another $1 to the price, and with transaction costs amounts to $1.24 a cell. I was told it is not possible to ship via sea, and must be by air.
It has been observed that cells purchased from some suppliers in China have contained some fake mislabeled re-cycled cells or fake low-quality low-capacity Chinese cells. I plan to test for capacity, weight, impedance, and thermal behaviour during charging.
Photo of shipment - each cell has an individual white paper box with a safe handling warning, and a pair of these boxes are inside a green box with the same warning. These boxes were not from the original manufacturer (Panasonic / Sanyo). Each cell had a sticker that covered the manufacturer's label that says NCR18650B without giving the capacity. The sticker says "18650 3400 mAh 3.7V". There are also lot numbers on the cell's wrapping and probably on the steel casing, which may give a clue to the origins of the cell.
This is to chronicle a project to construct a 1.6 kWh module from 18650 cells. The configuration is 13s10p (edit: upgraded to 14s10p) using 130 (140) "Grade A" Panasonic NCR18650B (edit: unprotected) li-ion cells. These cells are nominally rated at 3.4 Ah and guaranteed to 3.25 Ah.
The first order of 100 cells (at US$3.28 each - $272/kWh) was received from Shanghai today and I have started testing individual cells, and plan to test all cells. Shipment was by air and arrived in 4 days. Shipment adds another $1 to the price, and with transaction costs amounts to $1.24 a cell. I was told it is not possible to ship via sea, and must be by air.
It has been observed that cells purchased from some suppliers in China have contained some fake mislabeled re-cycled cells or fake low-quality low-capacity Chinese cells. I plan to test for capacity, weight, impedance, and thermal behaviour during charging.
Photo of shipment - each cell has an individual white paper box with a safe handling warning, and a pair of these boxes are inside a green box with the same warning. These boxes were not from the original manufacturer (Panasonic / Sanyo). Each cell had a sticker that covered the manufacturer's label that says NCR18650B without giving the capacity. The sticker says "18650 3400 mAh 3.7V". There are also lot numbers on the cell's wrapping and probably on the steel casing, which may give a clue to the origins of the cell.
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