Help building a 14s7p 18650 battery

[SilverLine]

Hello forum....

I plan to build a new battery for my e-scooter, with hopefully less voltage sag than with the original battery.

The max battery Amp needed is about 50amps (the motor controller is 2 x 25 amp)

I have posted af picture of how i will build the battery, pretty standard and straight forward.

1. Is it enough to use 1pcs/layer nickel-metal strips 0.15mm 7mm for the seriel and parallel connections? , according to googeling they should handle about 10amp peak ?? And the way I make the connection, there should not be more than about 7amp over the strips, is that correct understodd ??

2. I have been out of the "battery DIY" game for some years now. Last time I build a battery was with Samsung Q30. Any recommendations around battery cells ?? 7 pcs in parallel shall deliver 50 amps (peak), and since its a e-scooter I want most possible capacity, but without pushing the cells to much, and hopefully with less voltage sag.


UPDATE : These strips are the one I plan to use, are they suitable ? : 1 meter nickel welding strip - 7mm*0.20mm or this : 1 meter nickel welding strip - 7mm*0.30mm

Hope for some help. Thank you ......

 

[pwd]

What are your size/space constraints for the battery? If you don't *have* to use 18650s - have you considered other cell formats or even 21700s?

 

[SilverLine]

What are your size/space constraints for the battery? If you don't *have* to use 18650s - have you considered other cell formats or even 21700s?

Unfortunately, no space for that. The e scooter deck, is same hight as a 18650 cell

 

[eMark]

Spec for each cell variant in an EM3ev 52V (14S7P) Rectangle Battery Pack

EM3ev 52V (14S7P) Hard Case Ebike Battery Pack | EM3ev

EM3ev 50V (AKA 52V, 14s7p) Rectangle Ebike Battery Pack uses top quality official Samsung and LG Chem cells. With safety features not found elsewhere.

em3ev.com

​

Cell Type	Capacity (Ah)	Capacity (Whrs)	Max Cont. Current	Max Burst Current	Weight
Standard – 22P	50.4V 14.7Ah	740Whrs	~29A	~44A	~5.5kg
High Energy – PF	50.4V 20Ah	1008Whrs	~40A	~55A	~5.7kg
High Energy – 33G	50.4V 21.7Ah	1094Whrs	~33A	~43A	~5.7kg
High Energy – LG MJ1	50.4V 23.8Ah	1200Whrs	~36A	~47A	~5.9kg
High Power – 25R	50.4V 17.2Ah	864Whrs	~40A	~55A	~5.5kg
High Power – 30Q	50.4V 20.7Ah	1041Whrs	~40A	~55A	~5.7kg
High Energy – Samsung 35E	50.4V 23.8Ah	1200Whrs	~36A	~47A	~5.9kg
High Energy – Panasonic GA	50.4V 23.8Ah	1200Whrs	~36A	~47A	~5.9kg

Cost U at least $500 for 100 brand name A-grade cells. May be further ahead to buy an EM3ev battery.
The peak maximum burst current is only for seconds (not even 1 minute) for prolonging battery cycle life.​

 

[SilverLine]

Spec for each cell variant in an EM3ev 52V (14S7P) Rectangle Battery Pack

EM3ev 52V (14S7P) Hard Case Ebike Battery Pack | EM3ev

EM3ev 50V (AKA 52V, 14s7p) Rectangle Ebike Battery Pack uses top quality official Samsung and LG Chem cells. With safety features not found elsewhere.

em3ev.com

​

Cell Type	Capacity (Ah)	Capacity (Whrs)	Max Cont. Current	Max Burst Current	Weight
Standard – 22P	50.4V 14.7Ah	740Whrs	~29A	~44A	~5.5kg
High Energy – PF	50.4V 20Ah	1008Whrs	~40A	~55A	~5.7kg
High Energy – 33G	50.4V 21.7Ah	1094Whrs	~33A	~43A	~5.7kg
High Energy – LG MJ1	50.4V 23.8Ah	1200Whrs	~36A	~47A	~5.9kg
High Power – 25R	50.4V 17.2Ah	864Whrs	~40A	~55A	~5.5kg
High Power – 30Q	50.4V 20.7Ah	1041Whrs	~40A	~55A	~5.7kg
High Energy – Samsung 35E	50.4V 23.8Ah	1200Whrs	~36A	~47A	~5.9kg
High Energy – Panasonic GA	50.4V 23.8Ah	1200Whrs	~36A	~47A	~5.9kg

Cost U at least $500 for 100 brand name A-grade cells. May be further ahead to buy an EM3ev battery.
The peak maximum burst current is only for seconds (not even 1 minute) for prolonging battery cycle life.​

What a nice chart.
The 50a is only acceleration max, it won't be constant at all. It's clearly to se now, when I accelerate the voltage drops about 4v, and goes back up, when reaching top speed