Great deal on Panasonic 18650's

[PhredDaKat]

Hi all, long time lurker here who finally signed up.

I wanted to share a good find on Battery Hookup. A new case of 108 Panasonic NCR1650A's. The cells are in 12 packs of 9 cells that were made for some medical equipment. New in unopened OEM boxes. $95 dollars! I plan on rebuilding a flat BionX battery pack and getting my new to me 100 dollar Dahon Mu on the road. Couldn't have done it without the awesome advice and knowledge I found here. Thanks!

https://batteryhookup.com/products/new-case-of-108-panasonic-ncr18650a-2900mah-cells

 

[calab]

Hi all, long time lurker here who finally signed up.

I wanted to share a good find on Battery Hookup. A new case of 108 Panasonic NCR1650A's. The cells are in 12 packs of 9 cells that were made for some medical equipment. New in unopened OEM boxes. $95 dollars! I plan on rebuilding a flat BionX battery pack and getting my new to me 100 dollar Dahon Mu on the road. Couldn't have done it without the awesome advice and knowledge I found here. Thanks!

https://batteryhookup.com/products/new-case-of-108-panasonic-ncr18650a-2900mah-cells

Yeah, BatteryHookup has some great deals on either side of the border, for shipment.

However, you must know what you are buying and have understanding of ebike battery safety, how they work, c-rates, have all within limites but that all comes in time, searching, Googling, ES'ing.
But, most importantly, DOING. We can dream all we want. Dont want to live life dreaming and not DOING!

 

[PhredDaKat]

Last time I rebuilt a battery pack was probably late 90's or early '00 and it was smallish power tool Ni-Cad sub c cells. For this project I've invested a lot of on my butt in front of the 'puter time learning everything I could suck in, almost an entire yellow legal pad of notes. I've gone through (sometimes 2 or 3 times) every lesson article In the Battery University website that seemed appropriate to the task. I only need 60 for my 10s-6p 36v pack so I plan on using the iffy cells I test first to practice on... some old lithium power tool packs!

 

[calab]

Yeah I remember reading that site, but I try to confirm what BattU was saying.
10s is 36v which is plenty good, 6p depends on the ah and discharge rate of each parallel and of course the quality of the 18650 ----> If is rejected QC 18650's from the big boys to put in flashlights or brand name 18650's
Panasonic gets my vote and my cash. :thumb:

As for your Panasonic 18650 NCR1650A, 3.1Ah 6.2A, is quite low, I like to have 8-10a for my amp discharge needs, like the PF, but I go with the 25R for low parallel groupings. 5a discharge is low power or lots and lots of parallels. I prefer a smaller battery myself. I also prefer to put less stress on the battery. Perhaps my next battery would be good for 100a discharge, but I only go for 50a. There are many ways to build a battery. I may opt to go uber high wh, like 36v 50ah, yet only use 25ah and the battery lasts longer. See how things work there.

At 10s6p, thats 18.3ah 36v is 658wh at 37.2A max, get a controller thats 30a and your GOLDEN.

Battery University
....
I only need 60 for my 10s-6p 36v pack so I plan on using the iffy cells I test first to practice on... some old lithium power tool packs!

 

[PhredDaKat]

With the proprietary aspect of the BionX system and my low bank account not allowing a new controller I'm trying to stay as exact to the original parts. I'll have the old pack on my work bench to refer to, even though it's a simple five by twelve straight rows of cells. and use the same temp sensor and BMS. I will have higher amp hours with the new cells, hopefully the picky BionX system is cool with it.

 

[calab]

With the proprietary aspect of the BionX system and my low bank account not allowing a new controller I'm trying to stay as exact to the original parts. I'll have the old pack on my work bench to refer to, even though it's a simple five by twelve straight rows of cells. and use the same temp sensor and BMS. I will have higher amp hours with the new cells, hopefully the picky BionX system is cool with it.

Understood
At 30a for your 6p, and 36v the cost of a cheap generic controller would be $20-30.
I believe you just hook up 5v to BionX hack, dont quote me on that, I dont even know where or how.

Have you checked out the fella making two packs of 1kwh each?

How you connecting the tabs, MOT with control pcb or dx.com tab wedler?


I made a mistake.
NCR is
Continuous Discharge Rating: 6.2A
I thought that was max
See how easy it is to mess up :lol:
6px6.2a=37.2a continuous
Probably have to hit the Lyte website to find max amps, which is a good number to find out.
https://lygte-info.dk/review/batteries2012/NCR18650A%20protected%20%28Green%29%20UK.html
look at the charts, should suit your low power needs.
I think you just break down each parallel groups amps.
36.2a/6p=6a per "P"
6a/10s is 0.6a per cell.

So what I was looking at was the 0.5a line on the charts. looking at the 1a per cell line, means a system of 36.2a x 2 = 72a continuous with 36v.
0.5a x 2 = 1a. So that correlates the meaning of the other lines, 1.25a, 1.50amps etc etc etc.

Hopefully I am not spitting garbage.

 

[PhredDaKat]

I have two homemade spot welders that I'm going to try. A MOT based one and a capacitor powered one (both designs I found on Instructibles.com) the timer control I got from a friend, I don't know much about it. When I tear apart the old power tool packs I want to rebuild I plan on using the old cells for fine tuning and seeing which works best.

The new Panasonic cells are 2900mah, should give me 17.4AH, much better than the original 9.6.

 

[electric_nz]

For what it’s worth, I bought a large box of unused old stock laptop packs with NCR18650A and built a 14s5p pack out of them. Hammered them daily with a 95%-25% cycle at 52A (more than 10A per cell) during cold and heat, leaving them fully charged each night for the morning commute. The datasheet shows a 3C discharge curve so it’s still mostly within spec.

After about 100-150 cycles they still capacity tested within a few percent of new and same for internal resistance. A top quality cell!

 

[PhredDaKat]

For what it’s worth, I bought a large box of unused old stock laptop packs with NCR18650A and built a 14s5p pack out of them. Hammered them daily with a 95%-25% cycle at 52A (more than 10A per cell) during cold and heat, leaving them fully charged each night for the morning commute. The datasheet shows a 3C discharge curve so it’s still mostly within spec.

After about 100-150 cycles they still capacity tested within a few percent of new and same for internal resistance. A top quality cell!

That is good news, thanks. These packs were designed for some medical equipment and never used, 7/20 is manuf. date. I was hoping that they would be good cells because of the medical app, plus the Panasonic brand. I've spent a lot of time looking on the interwebs for a good price for my cells. This was the best I found that was quality and US shipping. I can't wait to get started!

 

[electric_nz]

Electric nz,
Can you tell us please how you went about capacity testing and testing the internal resistance of the individual cells within the pack...in particular without taking the pack apart?

Thank you.

I disassembled my 14s5p pack after that, as it was a soldered job and I had an option come up for some properly welded 21700 packs with lower internal resistance (less sag)

I compared a spare unused cell with a couple of the used cells on a xtar tester for a laugh and was fairly surprised to see how well they had held up.

 

[calab]

I'd bet you mean 10a per parallel grouping, which for 5p means 50a total. In 10s, these numbers would represent 0.5a per every cell in the battery, assuming even resistances across the board.

The key with low amp discharge cells, like laptop batteries are, to use more parallel groupings to reduce the stress of battery cycling.
Mose ebikes use 20-30 on up in amps you have to use more parallel groupings, for a series first parallel second which was how I built all my batteries.

I find charging to 40.80v from 42v top charge helped me out but I couldnt confirm.

For what it’s worth, I bought a large box of unused old stock laptop packs with NCR18650A and built a 14s5p pack out of them. Hammered them daily with a 95%-25% cycle at 52A (more than 10A per cell) during cold and heat, leaving them fully charged each night for the morning commute. The datasheet shows a 3C discharge curve so it’s still mostly within spec.

After about 100-150 cycles they still capacity tested within a few percent of new and same for internal resistance. A top quality cell!

 

[john61ct]

Yes, parallel count multiplies Ah capacity (range), amps current rate

thus also multiplies power output per same C-rate per cell.

Series count determines system voltage into the controller.