Battery pack on Panasonic NCR18650B cell

[agniusm]

I think you have to do maths for your self. Power isn't the only factor. It depends how much of it you need. Another factor is weight. The AHR32113M1Ultra-B cell going by the spec.sheet delivers 550W discharging, that would be 166A or 37C but the weight is big. 205g for 4.4Ah. To compare 20AH cell is 485g. I'm no expert and there are people here with a lot more experience than me so you should dig and try to avoid the ones who talk more than do, those with large post count and none posts on testing and building packs.
My cell of choice is prismatic A123 20Ah. It has good capacity for ebike, good power and acceptable weight for LiFePO4 chemistry aslo most safe. The down side is format and tabs. Format does not allow for battery arrangements and pouches are fragile. Tabs do not allow easy assembly of the pack cause of aluminium tab. There is a clamping method to join these cells in series and OSN provide one as well as i could supply mine but it adds to the cost.
So there, start your post, list what you want, what you are going to use and someone will help you out, even with the maths

 

[circuit]

Anyone considered NCR18650/A? These are bit lower in capacity, but are cheaper. Also Ri is lower, which may lower capacity difference.

Comparison table (some of these are my calculated values based on official datasheets):
NCR18650B
Capacity: 3400 mAh
Energy: 12.24 Wh
Ri: 67 mΩ
Capacity at 1C: 3300 mAh
Energy at 1C: 11.15 Wh
Price: 33 RMB
Energy/price ratio: 0.338 Wh/RMB
Energy/weight: 248 Wh/kg
Efficiency at 1C: 91.1 %

NCR18650A
Capacity: 3100 mAh
Energy: 11.16 Wh
Ri: 61 mΩ
Capacity at 1C: 3000 mAh
Energy at 1C: 10.251 Wh
Price: 27 RMB
Energy/price ratio: 0.380 Wh/RMB
Energy/weight: 228 Wh/kg
Efficiency at 1C: 91.9 %

NCR18650
Capacity: 2900 mAh
Energy: 10.44 Wh
Ri: 70 mΩ
Capacity at 1C: 2800 mAh
Energy at 1C: 9.5116 Wh
Price: 24 RMB
Energy/price ratio: 0.396 Wh/RMB
Energy/weight: 211 Wh/kg
Efficiency at 1C: 91.1 %

NCR18650PD
Capacity: 2900 mAh
Energy: 10.44 Wh
Ri: 35 mΩ
Capacity at 1C: 2750 mAh
Energy at 1C: 9.62 Wh
Price: 28.5 RMB
Energy/price ratio: 0.338 Wh/RMB
Energy/weight: 214 Wh/kg
Efficiency at 1C: 92.1%

NCR18650 vs. NCR18650B:
+17% energy per money
-15% energy per kg
might be a good money saving if 15% of weight is not a big issue.

NCR18650A vs. NCR18650B:
+12% energy per money
-8% energy per kg
also looks a good choice for EV application.

NCR18650PD.. at twice lower Ri, lower sag and heat, probably not worth it, as efficiency gain is barely noticeable?..

There is also NCR18650E model with high discharge capability, but capacity is only 2200mAh, so no way to reach energy density of these, even including Ri drop.

Also I've reviewed samsung ICR-18650-30A and those are really bad, compared to panasonic. Ri "≤100mΩ", capacity at -10°C only 50%, etc.

 

[jk1]

Does anyone know if the NCA chemistry of the NCR18650B has a self balancing ability or no need to run balance wires like the Sony Konion cells Dr Bass uses?

I.e can they be only balanced once when we are setting up the pack ?

 

[agniusm]

NCR18650B
Capacity: 3400 mAh
Energy: 12.24 Wh
Ri: 67 mΩ
Capacity at 1C: 3300 mAh
Energy at 1C: 11.15 Wh
Price: 33 RMB
Energy/price ratio: 0.338 Wh/RMB
Energy/weight: 248 Wh/kg
Efficiency at 1C: 91.1 %

NCR18650A
Capacity: 3100 mAh
Energy: 11.16 Wh
Ri: 61 mΩ
Capacity at 1C: 3000 mAh
Energy at 1C: 10.251 Wh
Price: 27 RMB
Energy/price ratio: 0.380 Wh/RMB
Energy/weight: 228 Wh/kg
Efficiency at 1C: 91.9 %

NCR18650
Capacity: 2900 mAh
Energy: 10.44 Wh
Ri: 70 mΩ
Capacity at 1C: 2800 mAh
Energy at 1C: 9.5116 Wh
Price: 24 RMB
Energy/price ratio: 0.396 Wh/RMB
Energy/weight: 211 Wh/kg
Efficiency at 1C: 91.1 %

NCR18650PD
Capacity: 2900 mAh
Energy: 10.44 Wh
Ri: 35 mΩ
Capacity at 1C: 2750 mAh
Energy at 1C: 9.62 Wh
Price: 28.5 RMB
Energy/price ratio: 0.338 Wh/RMB
Energy/weight: 214 Wh/kg
Efficiency at 1C: 92.1%

NCR18650 vs. NCR18650B:
+17% energy per money
-15% energy per kg
might be a good money saving if 15% of weight is not a big issue.

NCR18650A vs. NCR18650B:
+12% energy per money
-8% energy per kg
also looks a good choice for EV application.

NCR18650PD.. at twice lower Ri, lower sag and heat, probably not worth it, as efficiency gain is barely noticeable?..

There is also NCR18650E model with high discharge capability, but capacity is only 2200mAh, so no way to reach energy density of these, even including Ri drop.

Also I've reviewed samsung ICR-18650-30A and those are really bad, compared to panasonic. Ri "≤100mΩ", capacity at -10°C only 50%, etc.

So from this looks like NCR18650B is most cost effective and most weight effective compared to the other ones. Then the question stands why buy cells that are more expensive, weigh more and in some variants have marginally lower Ri excluding PD cell? The PD looks good thou...on paper.

 

[circuit]

So from this looks like NCR18650B is most cost effective and most weight effective compared to the other ones. Then the question stands why buy cells that are more expensive, weigh more and in some variants have marginally lower Ri excluding PD cell? The PD looks good thou...on paper.

NCR18650B is least cost affective. Higher number = cheaper.

 

[emiyata]

I see only two applications I would go with this type of cell. It would have to be a light weight cargo bike with pedal assist (high Ah) for long distance hauling or a super light weight pedal assist bike (low Ah)that uses a smaller motor and both plan heavy amount of pedal assist . With the price reaching the level or exceeding the price of other high quality Ebike batteries, weight must be high priority. It will be very interesting to see how this battery performs in the ebike environment.

 

[tempusername]

my guess if you count in shipping price NCR18650 and A wh price should be almost equal, B being most dense product of course have price premium

 

[circuit]

I've found this cell: LG 18650 D1. It is onlo "3000mAh", but, compared to NCR18650, gives almost the same Wh at 5A load, and is 50% cheaper (23 RMB @ 1K).

 

[agniusm]

I got this spec sheet from Victpower on Panasonic NCR18650b cell. Does it means its made by Sanyo?

 

[circuit]

SANYO is Panasonic brand. I guess Pansonic purchased them some time ago.
But this datasheet is for other, older cell.

 

[migueralliart]

and how do you intend to charge to 4.35V per cell? You can do it in bulk with a trimmable charger but on a cell level?

 

[circuit]

and how do you intend to charge to 4.35V per cell? You can do it in bulk with a trimmable charger but on a cell level?

PLEASE.

Step one: set your charger at correct voltage.
Step two: use BMS.
Step three: ditch that BS term "bulk charge" and do things properly.

 

[agniusm]

He, he that "bulk charger" How about charger, RC charger and so on?
If this cell was 4.35V i would be laughing as 10S would be 43.5V which is .3V less than 12S lifepo4 at 3.65V which means it would meet 0.03V margin at 0.018V overcharge. This cell is 4.2V thou and 10S is 42V. LiFePO4 12S is as mentioned before 43.8V, and i should be able to find adjuster on the charger to down it a bit, if not, BMS should limit the charge but i am most certain that i will be able to reset the charger.

 

[Gab]

Does anyone know if the NCA chemistry of the NCR18650B has a self balancing ability or no need to run balance wires like the Sony Konion cells Dr Bass uses?

I.e can they be only balanced once when we are setting up the pack ?

 

[agniusm]

All lithium cells needs to be balanced in a pack, same goes for Sony Konion cells.

 

[999zip999]

I think all packs should have a set of balance wires BMS or not. Making so easy to check a string and balance if needed.

 

[Toby82]

Hi Guys,

I have been researching building a pack from the panasonic range of 18650 cells so this thread has been a good read. I have come across panasonic (claimed) NCRB cells with internal protection. See below links

http://www.orbtronic.com/protected-3400mah-18650-li-ion-battery-panasonic-ncr18650B-orbtronic.

http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=281004345565&refid=store&ssPageName=STORE:HTMLBUILDER:SIMPLEITEM#ht_8258wt_1219

This could negate the use of an external bms and wiring. Yes they are a fair bit more expensive but for my application this would clean up the battery build and all those annoying signal/balance wires.

Has anyone looked at this? Does anyone see issues with running these cells with internal protection in a 18s3p pack.

Cheers,

 

[circuit]

This could negate the use of an external bms and wiring..

No, it could not. It it a good additional layer of protection, but is not meant to replace the BMS. Some sort of additional safety layer is required when connecting cells in parallel, so here it is. But BMS is still essential.

 

[Toby82]

Thanks for the reply circuit.

Can you elaborate on this further as far as the additional protection required for paralleled cells?

I was under the understanding that the voltage of cells in parallel remains progressively the same throughout charge and discharge, and act like, and can be treated as one single cell.

Cheers,

 

[circuit]

Cells, typically, are designed to withstand external short or internal short without catastrophic consequences. However, if there are several cells in parallel and one shorts out internally, very high current will rush in from other cells and this will lead to chain reaction fire.
To prevent this, usually PTCs or well selected blow fuses are used on each cell.

 

[Toby82]

Thanks for the explanation.

So should we expect commercially available packs with high numbers of 18650 cells configured in both parallel/series (AllCell ect.) to use cells with PTC's fitted?

Has anyone opened up an AllCell or similar configured pack?

Cheers.

 

[circuit]

So should we expect commercially available packs with high numbers of 18650 cells configured in both parallel/series (AllCell ect.) to use cells with PTC's fitted?

Tesla does it this way.

But for ebike packs... Doubt it.

 

[agniusm]

Today received my BMS from BesTech Power. Quick service using FedEX for 10USD. So far so good. Here are some closeups:

Size reference:

The SMD component placement is wonky to my eye. there is few areas i'm concerned about, marked red:

 

[docnjoj]

Interesting Agnius. It looks hand soldered. I guess the proof is in the testing.
otherdoc

 

[Doctorbass]

All lithium cells needs to be balanced in a pack, same goes for Sony Konion cells.

Hey Agniusm, The konion just need to be perfectly balanced before to assemble in a pack ( all parallel them for couples of hours) and then they will rarely need to be rebalanced.

The first gen of Makita battery 5s2p wich worked for years did not have the balance connections and was using the Konion cells. The special LiMn spinel chemistry make the balancing by having the cahrge efficiency decrease as soon as the CV phase is began so they self equalize. :wink:

Doc