Could you rate these 18650 cells for me?

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ryan380golf   10 µW

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Could you rate these 18650 cells for me?

Post by ryan380golf » Feb 24 2019 1:32pm

Brand: Panasonic
Model: NCR18650
Capacity: 2900mAh Rated
Voltage: 3.60V Nominal
Charging: 4.20V Maximum
1925mA Standard
— mA Maximum|
| Discharging: |2.50V Cutoff
580mA Standard
5400mA Maximum|
| Description: |Gray Cell Wrapper
White Insulator Ring
18650 Form Factor|

Hi guys,

I'd like to replace (3) SLA lead batteries rated at 12v 12ah, in series, 10s4p of these lithium 18650 cells. Do you think these will work for me? It's for an Eglide skateboard. I'm worried about the low discharge of these lithiums bought off of Ebay...

major   10 kW

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Re: Could you rate these 18650 cells for me?

Post by major » Feb 24 2019 5:17pm

I recently bought and tested some Panasonic NCR18650PF GA Cells, new. These were rated at 2900mAh, high drain hybrid, 10A and have a light green wrap and white washer. Attached are my curves.
Pana1thru8atVariousA.png
Pana1thru8atVariousA.png (38.78 KiB) Viewed 672 times
Pana1thru12at5A.png
Pana1thru12at5A.png (37.49 KiB) Viewed 672 times

ryan380golf   10 µW

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Re: Could you rate these 18650 cells for me?

Post by ryan380golf » Feb 24 2019 5:37pm

Thank you, but I'm not technical enough to understand your graph.

I think mine at 5400 or 5.4 amps max discharge per cell is about half the amps of the batts you tested. I'm just not sure if they would work in a skateboard / scooter application.

My thoughs are to build as a 10s5p.

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Sunder   100 MW

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Re: Could you rate these 18650 cells for me?

Post by Sunder » Feb 24 2019 8:18pm

ryan380golf wrote:
Feb 24 2019 1:32pm
Hi guys,

I'd like to replace (3) SLA lead batteries rated at 12v 12ah, in series, 10s4p of these lithium 18650 cells. Do you think these will work for me? It's for an Eglide skateboard. I'm worried about the low discharge of these lithiums bought off of Ebay...
Short answer, no. Long answer maybe.

There's a few facts that would have been helpful, so I googled/derived them.

Eglide: 800w Nominal, 1500w peak, 36V battery

800w/36v = 22.2A nominal
1500w/36v = 41.7A peak
Note - the manufacturer has quoted this as output, which is either odd, or wrong. If it's odd but right, then electrical power requirements will be 20-25% higher.

By your specifications, standard max discharge is 580mA standard * 4 (parallel) = 2.32A. So if you want a long life, you cannot use these.
By your specfications, peak discharge is 5400mA * 4 = 21.6A, so it could theoretically do it, but will be hot as hell, and you won't get much life out of it.

But, I think either your source is wrong, or you've not copied it correctly. Every stat you've got there is right except discharge:

https://voltaplex.com/panasonic-ncr-186 ... y-ncr18650

If my link is right over yours, then standard discharge is 12 * 4 = 48A, which means even peak output of the motor will not threaten these batteries.

If you've already bought them from eBay and you don't think you'll get a refund, then may as well give it a try, but watch the temps. If they get too hot, stop it, before you set something on fire. If you can get a refund, you should test, or get tested these cells. There's a few ways you can do it, but let me know before I take the time going into a fairly deep technical subject you may not be interested in.
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ryan380golf   10 µW

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Re: Could you rate these 18650 cells for me?

Post by ryan380golf » Feb 24 2019 9:42pm

Thanks so much for taking a look at these.

Perhaps they are this battery. https://voltaplex.com/panasonic-f-18650 ... -ncr18650f
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ryan380golf   10 µW

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Re: Could you rate these 18650 cells for me?

Post by ryan380golf » Feb 24 2019 9:52pm

https://secondlifestorage.com/t-Panason ... ifications

This is where I pulled my info... It's was used in a medical device of some kind. I have enough cells to make a 10s5p.
Last edited by ryan380golf on Feb 24 2019 11:43pm, edited 1 time in total.

major   10 kW

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Re: Could you rate these 18650 cells for me?

Post by major » Feb 24 2019 11:08pm

I was impressed with the NCR18650PF. Tested total of 32. All virtually the same. Manufacturer's spec sheet gives rating of 2750mAh, 2700 min. My charger was only getting cells to 4.05-4.10V which accounts for some slightly low Ah readings. I was able to fully discharge at 10 amps as per spec. At 12A, I thought cell was too hot and terminated early. That shows on the graph.

I'm able to find retail sources for these cells, new, at $2.50-4.00 US each. At prices like that, why screw around, especially if you're unable to test each cell?

Good luck,

major

Ref.

https://endless-sphere.com/forums/viewt ... f#p1444693

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Sunder   100 MW

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Re: Could you rate these 18650 cells for me?

Post by Sunder » Feb 24 2019 11:18pm

ryan380golf wrote:
Feb 24 2019 9:52pm
https://secondlifestorage.com/t-Panason ... ifications

This is where I pulled my info... It's was used in a medical device of some kind.
This looks like the official datasheet for your cells:

https://engineering.tamu.edu/media/4247 ... 650ncr.pdf

If you have a look at the bottom right graph, they discharge the battery at 2C (Discharged in 1/2 an hour), or 5.8A. Since you've got 4 in parallel, this 23.2A - marginally above the nominal rating of your bike.

I know you said you're not technical enough to read the graphs, but have a look at the far left of the graph. The cell which should be 4.2v, when placed under a 5.8A instantly drops to around 3.8v. That's a lot of stress on the battery, because of a concept called "internal resistance", which means that the battery is effectively "consuming" those 0.4v as heat, rather than sending it to the motor as motion.

Its down to guessing now, but I'm going to say it's *really* borderline. If you trip is a nice smooth flat road, and you're rarely at top speed, you should be fine. If there are hills, a lot of starts and stops, or you're constantly near top speed, I'd say these batteries are going to have a very short life.

Can you consider getting two packs and running them in parallel? Or at least change to a 10S6P arrangement?
eBike: Q100H on 16S with Phaserunner FOC Controller
eMotorscooter: Vectrix VX-1 Died... Electrified Ninja in Progress!
eCar: Mitsubishi Outlander PHEV... Warramty expired. Still not game!
eHouse: 6.2kw On-grid solar with battery backup coming soon!

After 5 builds, the best advice I can give, is start with high quality products. I prefer http://www.ebikes.ca

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Matador   10 kW

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Re: Could you rate these 18650 cells for me?

Post by Matador » Feb 24 2019 11:38pm

If it was me, i would not even bother trying it. 2C cell ar le going to live a month a best before dying for good. Get some 5C or more 18650 cells for an eboard. I can garantee you you ll be disapointed otherwises. Keep these cells for future batery banks, but dont put them in a EV

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Sunder   100 MW

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Re: Could you rate these 18650 cells for me?

Post by Sunder » Feb 24 2019 11:59pm

Matador wrote:
Feb 24 2019 11:38pm
If it was me, i would not even bother trying it. 2C cell ar le going to live a month a best before dying for good. Get some 5C or more 18650 cells for an eboard. I can garantee you you ll be disapointed otherwises. Keep these cells for future batery banks, but dont put them in a EV
To be frank, I would back this advice. I personally tend to over-engineer everything to make it last, but I'm aware that not everyone does that, and since you had already bought them, I thought it was worth a shot... It is a lot of effort to assemble a pack, not being sure if it will last or not.
eBike: Q100H on 16S with Phaserunner FOC Controller
eMotorscooter: Vectrix VX-1 Died... Electrified Ninja in Progress!
eCar: Mitsubishi Outlander PHEV... Warramty expired. Still not game!
eHouse: 6.2kw On-grid solar with battery backup coming soon!

After 5 builds, the best advice I can give, is start with high quality products. I prefer http://www.ebikes.ca

ryan380golf   10 µW

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Re: Could you rate these 18650 cells for me?

Post by ryan380golf » Feb 25 2019 12:31am

Yeah thanks guys. I think I'll just write this down as a cost for my battery education and use these for another project. I really appreciate all the help. I think you guys saved me from assembling, running a bms, etc,having a crappy non performing pack, or going down in flames... Will cut my loss now.

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