NCR18650B

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PlanB
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NCR18650B

Post by PlanB » Wed, 12 Jun 2013, 19:32

I built a 48v 10Ah scooter pack out of 39 Panasonic NCR18650Bs (3.6v 3.4Ah) a few months ago, really consistent cell match. Sweet spot for discharge is 2C or less but they are down to $6 this month. I'm thinking 4000 would give me a 100S40P 40kwh(80%discharge)200kg EV pack for $24k. Packaging is a head scratcher but the price is half what it was last quarter.

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Richo
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Post by Richo » Wed, 12 Jun 2013, 20:32

There are cheaper non-Panasonic ones off ebay.
The cross over point seems to be about 5Ah before going to the next cell size up.
I think it was about 10 x 3.7V5Ah for $18 - same as a headway.
So I could have an ev with 5x the range but likely to be 1/4 of the life span.
Also the cheaper cells have worse discharge rates so I would either have to settle for lower power output or have to buy more.

The main thing that puts me off is they are still li-po's which are better at starting fires than LiFePO4. Image

Just break the pack down into sub sections or sub packs.
Then the sub packs get wired up like TS/SE cells.

The same size pack (48kWh) using headways would be about $28k.
So the short answer is NO but the long answer is YES.
Help prevent road rage - get outta my way!

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Post by Johny » Wed, 12 Jun 2013, 21:44

Richo wrote: There are cheaper non-Panasonic ones off ebay.
Right there my alarm bell starts ringing. Kind of similar sound to a fire bell.

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PlanB
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Post by PlanB » Wed, 12 Jun 2013, 22:14

I like the bolt each end on the headways but they are less than half the energy density of the LiPos. Word on the grapevine is Panasonic will have a 4Ah in the 18650 format later this year.

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Richo
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Post by Richo » Thu, 13 Jun 2013, 05:36

Ahh supposedly some of the ebay batteries start thier life here:

Image
So the short answer is NO but the long answer is YES.
Help prevent road rage - get outta my way!

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Richo
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Post by Richo » Thu, 13 Jun 2013, 06:46

I checked some battery manufacturer web sites and 18650's typically only go upto 3000mAh.
The highest being the NCR18650B PlanB lists at 3200mAh.
NOT 5000mAh as sold on e-bay.

Who would have thought - fake stuff on e-bay Image

So the short answer is NO but the long answer is YES.
Help prevent road rage - get outta my way!

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Post by cobber » Sat, 31 Aug 2013, 03:46

Panasonic manufactures 3 Li-Ion cells suitable for electric vehicles.
First and most popular is CGR1850CG which is 2.25 A/Hr weighing 45g and rated at 2C continious. Their latest cells are NCR18650A rated at 2.9 A/Hr and NCR18650NB rated at 3.2 A/Hr both weighing 50g. These cells are manafactured in Japan.
If your not buying genuine who knows what you will get.

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Adverse Effects
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Post by Adverse Effects » Sat, 31 Aug 2013, 06:23

cobber wrote: If your not buying genuine who knows what you will get.

the hard part is the fakes look so much like the genuine ones

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Post by cobber » Sat, 31 Aug 2013, 14:05

There is a supplier on Ebay they I have used before. They have made a couple of packs for me that went into high performance Ebike builds. Their cells were upto specs upon testing so I think they are genuine. They sell all major brands Panasonic, Sony, LG and Samsung power cells that are used in industrial applications such as power tools. They will also tab weld your packs together for no charge. If you want to buy BMS as well they can supply.
This supplier is SuPower.
http://www.ebay.com.au/itm/Panasonic-NC ... 337f4fe988

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Post by Tritium_James » Mon, 02 Sep 2013, 16:30

We've just designed and assembled a 5kWh solarcar battery pack for a client, and bought the NCR18650B cells from Master Instruments in Sydney. They did a great job with spot-welded PCB mount tabs on the cells. Pricing seemed good to me.

The cells are VERY consistent with capacity and internal resistance, much more so than the larger cells that we all typically see for EV projects...

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Post by Johny » Mon, 02 Sep 2013, 16:53

Good to know TJ. Site bookmarked.
http://www.master-instruments.com.au/

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Post by PlanB » Tue, 03 Sep 2013, 14:52

So TJ have you or MI come up with a modular packaging system for the NCR18650Bs? Bundles of 50 or so would be real nice, something like the Tesla brick.

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Post by Tritium_James » Tue, 03 Sep 2013, 15:42

I've done them as 'sheets' of cells on a large (700 x 180mm) PCB. For the solarcar, it's 11 cells in parallel for each group, and then 8 groups in series, per sheet. There's one of our BMS CMUs mounted on the sheet, with all cell sense wiring on the PCB.

There's five sheets in the pack, along with another PCB that holds the BMS master, DC/DC converter, 12V auxilliary cells (4 more NCR18650Bs), 12V fusing, and the pack ventilation fan.

There's one more 'power distribution' board with thick copper that has the three GX11 contactors, traction fuse, 3x MPPT fuses, and the DC/DC fuse, along with the HV and current shunt measurement connections.

I'm still not sure on the mechanical performance in the high-vibration environment of a solarcar (I'm a bit unhappy about the stiffness of the overall box) but all testing so far is looking good.

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