Of course, it's definitely the safest, and it is also very cheap. As I already told you in another topic, powertrading is not doing their business properly (you are probably going to lose your money and your batteries if you buy from them), and their batteries are more expensive after shipping and VAT.
New Panasonic Cell ncr18650bd 3200mah
- Thread starter savaoaknyc
- Start date
district9prawn
1 kW
riba2233 said:
Nothing spreads faster than misinformation
Riba have you got a discharge graph of your BE cells?
cwah
100 MW
riba2233 said:
I'm paying with Paypal, so I'm protected in case it's fake cells or if I don't receive goods. I can potentially pay more VAT than I should. For me, the worse would be to receive fake cells.
cwah said:
I was also protected by paypal, but trust me, it was really really hard to get my money back, it's not worth it. It's also more expensive to buy from powertrading then nkon, so why would you do it?
district9prawn said:Nothing spreads faster than misinformation
Riba have you got a discharge graph of your BE cells?
Unfortunately
I don't have it yet, but I can record one if 5 A is enough (that's the limit of my tester, imax b8+)I can however do comparison between 25r, be, pf, and 29E once I receive PF. I can't get a hand on BD unfortunately... However, I trust lygte and dampfakkus, so if you are interested in some graphs, you can check them already!
cwah
100 MW
NCR18650BE cost 5.95 euro. Compared to power trading at 3.8usd, it's about double price even including shipping cost.
They have a really good offer for NCR18650PF, so the only good deal they have now are for these NCR18650PF if they are authentic ones.
They have a really good offer for NCR18650PF, so the only good deal they have now are for these NCR18650PF if they are authentic ones.
Paypal protection is no good if you receive the wrong cells, fake cells or fewer than you paid for, as Paypal's only resolution is that you return the good by a tracked service for a refund, which to China is likely to be cost prohibitive.
cwah said:
Are you sure? So, let's do some maths.
You have to order 200 cells, so let's do maths for 200 cells.
You have 200 cells, so 200*3.8. You also have shipping, which is about 370$. That's 1130$ for now. Now, you pay tax on that price, so 1130*1.2 (20% in uk). You also have some tnt's fee, which is about 100$, so we are on 1456$. And that's 1210€, or 6.05€ per cell. And you will probably get a decent discount at nkon for that quantity, and you are 100% sure that you'll get original cells, and you wont have trouble with customs and you'll have cells in less that 5 days.
Or if you want even lower price, buy lg mh1 at nkon, and ask for volume discount. They are also 3.2 ah 10A cell.
cwah
100 MW
Let me show you my math:
- I get 200 cells at 3.8USD + 164USD shipping cost = 924 usd. With customs if seller is not an a*** (like BMSBattery or leafbike), I only usually only pay 80USD customs for that sort of weight. which makes the total of 1000USD or 5USD/cell.
- If I manage to get someone to buy with me in the uk and get 400 cells at 3.8USD + 200 shipping = 1720USD. Let say I have 130USD customs = 1850USD or 4.62usd / cell.
In any case, way cheaper than Nkon.
How much volume discount can they do? If it's 3.15euro like the ncr18650pf that would make me buy from them
ps: LG MH1 is LiNiMnCoO2 chemistry, which is famous for having very poor calendar life, so I'm most likely not going to buy these cells
- I get 200 cells at 3.8USD + 164USD shipping cost = 924 usd. With customs if seller is not an a*** (like BMSBattery or leafbike), I only usually only pay 80USD customs for that sort of weight. which makes the total of 1000USD or 5USD/cell.
- If I manage to get someone to buy with me in the uk and get 400 cells at 3.8USD + 200 shipping = 1720USD. Let say I have 130USD customs = 1850USD or 4.62usd / cell.
In any case, way cheaper than Nkon.
How much volume discount can they do? If it's 3.15euro like the ncr18650pf that would make me buy from them
ps: LG MH1 is LiNiMnCoO2 chemistry, which is famous for having very poor calendar life, so I'm most likely not going to buy these cells
I think that your math is false, because you can't cheat customs. TNT has warehouse in Liege in Belgium, and first stop is Belgian customs, where they confiscated my batteries. But ok, it's up to you. And are you sure about shipping cost? It was much more expensive for me.
Send NKON a mail and ask them for discount. My friend got a really nice offer on samsung 25r's, way below their price on internet.
LG is probably NCA, but I'm really not sure because there isn't any reliable source on that information.
Send NKON a mail and ask them for discount. My friend got a really nice offer on samsung 25r's, way below their price on internet.
LG is probably NCA, but I'm really not sure because there isn't any reliable source on that information.
cwah
100 MW
sent them an email for the mh1 and BE, let see what they say...
cwah
100 MW
I'm targeting 200... or more. So I need good price.
They can't answer me yet apparently and need to check with their supplier...
They can't answer me yet apparently and need to check with their supplier...
okashira
10 kW
I got my electronic DC load working and ran a quick test on one of my NKON PF's.
charged to 4.2V with 100mA cut-off, and waited 1 hour (to mirror HKJ's test method) (lygte)
Discharged to 2.799V, but I was having alot of contact resistance because I was using soldered magnets. Got about 2600mah.
I can also tell you a PF charged to ~3.75V will push about 152 Amps through a cheap chinese 18650 holder, two 16AWG 18" wires and two spring loaded copper grabbers, and of course, one Brymen BM867s. Shorted of course.
For 4 seconds.
On the bright side now I have two spring loaded copper grabbers with 16awg wire to bananna plugs that are now permanently attached to this 18650 holder. :lol:
charged to 4.2V with 100mA cut-off, and waited 1 hour (to mirror HKJ's test method) (lygte)
Discharged to 2.799V, but I was having alot of contact resistance because I was using soldered magnets. Got about 2600mah.
I can also tell you a PF charged to ~3.75V will push about 152 Amps through a cheap chinese 18650 holder, two 16AWG 18" wires and two spring loaded copper grabbers, and of course, one Brymen BM867s. Shorted of course.
For 4 seconds.
On the bright side now I have two spring loaded copper grabbers with 16awg wire to bananna plugs that are now permanently attached to this 18650 holder. :lol:
cwah
100 MW
So 2600mah at what discharge rate?
Few things to test for a good test:
- self discharge. To test that, put a batch of cells at high temps (40-60C) fully charged for few days and see if there is self discharge.
- Capacity loss after cycling. I tend to do 50 cycles to see what happen. Usually high discharge cells start with higher resistance before loosing capacity.
- Cell to cell consistency. Get 3-5 cells and discharge them at high rate all together and see sag under load and when they cut off.
- discharge at max C rate (3C) and see how cell warm up and capacity
If they pass all these tests, they are good cells to my eyes
Few things to test for a good test:
- self discharge. To test that, put a batch of cells at high temps (40-60C) fully charged for few days and see if there is self discharge.
- Capacity loss after cycling. I tend to do 50 cycles to see what happen. Usually high discharge cells start with higher resistance before loosing capacity.
- Cell to cell consistency. Get 3-5 cells and discharge them at high rate all together and see sag under load and when they cut off.
- discharge at max C rate (3C) and see how cell warm up and capacity
If they pass all these tests, they are good cells to my eyes
fellow
1 kW
riba2233 said:
This shows that we have two "idiot-proof" ebike cells to choose from that can be depleated to 0V without the noticable damage! The list:
1. Panasonic NCR18650BE Depleated by Riba's brother, saved by Riba
2. Panasonic NCR18650PF Depleated by Fellow's friend, saved by Fellow
okashira
10 kW
cwah said:So 2600mah at what discharge rate?
Few things to test for a good test:
- self discharge. To test that, put a batch of cells at high temps (40-60C) fully charged for few days and see if there is self discharge.
- Capacity loss after cycling. I tend to do 50 cycles to see what happen. Usually high discharge cells start with higher resistance before loosing capacity.
- Cell to cell consistency. Get 3-5 cells and discharge them at high rate all together and see sag under load and when they cut off.
- discharge at max C rate (3C) and see how cell warm up and capacity
If they pass all these tests, they are good cells to my eyes
3A... Here's the graph... note the voltage changes at 2800, 3000 and 4000 seconds, this was me messing with the connection to the battery
I will do another test when I get a better fixture setup. There was significant voltage drop across the connection to the battery
edit: oops, obviously capacity is right axis not left axis, not gonna fix
district9prawn
1 kW
okashira said:
Are you using separate leads for discharge and sensing cell voltage?
okashira
10 kW
district9prawn said:
Yes, however both leads contact together on one magnet which connected to the battery. It won't be easy to have two separate leads touch the cell at a different spot to eliminate contact resistance. Have to make something.
cwah
100 MW
okashira said:cwah said:So 2600mah at what discharge rate?
Few things to test for a good test:
- self discharge. To test that, put a batch of cells at high temps (40-60C) fully charged for few days and see if there is self discharge.
- Capacity loss after cycling. I tend to do 50 cycles to see what happen. Usually high discharge cells start with higher resistance before loosing capacity.
- Cell to cell consistency. Get 3-5 cells and discharge them at high rate all together and see sag under load and when they cut off.
- discharge at max C rate (3C) and see how cell warm up and capacity
If they pass all these tests, they are good cells to my eyes
3A... Here's the graph... note the voltage changes at 2800, 3000 and 4000 seconds, this was me messing with the connection to the battery
I will do another test when I get a better fixture setup. There was significant voltage drop across the connection to the battery
edit: oops, obviously capacity is right axis not left axis, not gonna fix
For proper test, you need to test at 10A(3C), not 3A (1C). As 1C is likely not to stress the cell.
I'm surprised to only see about 2600mah at 1C, is it because of resistance or fake cell?
okashira said:
Wonder that you can solder a magnet. When I tried like that, even with welding (at first), there was rather complete demagnetization. magnet options: putting e.g. a cleaned thin Ni-strip (as used for welding) or de'oxed Cu strip on the cell and Magnet on top; perhaps using glue for comfort; 2 strips and one huge magnet for 4point measurment .. ; or a sandwhich of magnet and strip ..
You could also measure the mV drop from magnet/holder-pin to cell etc, to actually see the magnitude of effect and if its critical. Though 4 point measurement will allow rather neutral resistance measurements (e.g. R-DC @ 10s square puls load @ 50%SoC), a voltage drop too large or too varying will be "unfair" in capacity readings as it hides part of full charge effectively. Thus the drop should be known, whatever mechanics.
Important is to note the temperature, at start at least, perhaps some value in between and at end too. some +-5 °C have huge influence on resistance / initial voltage drop / capacity. Would allow compensation later. Little data, whose negligence yet makes data questionable and hardly comparable. Estimated calibration is also an issue.
dampfakkus & lygte-info data would be worth much more if context would be known a little better. dampfakkus has rather inaccurate full charge stop condition which corresonds to some % in cap. A little sad for that huge database, huge effort put in ..
I'm rather interested in the NCR BD curves. The BD curve on dampfakkus is too far off from the curve on the first post's (chinese 4p-measured) curve here and from the Panasonic curve and from anything one could expect from such expensive cell. I suspect there is something wrong seriously with dampfakkus BD measurement, not just the above normal inaccuracies - odd cell, formation cycle needed, data confusion, ...
Panasonic NCR18650BD curves:
okashira
10 kW
cwah said:okashira said:cwah said:So 2600mah at what discharge rate?
Few things to test for a good test:
- self discharge. To test that, put a batch of cells at high temps (40-60C) fully charged for few days and see if there is self discharge.
- Capacity loss after cycling. I tend to do 50 cycles to see what happen. Usually high discharge cells start with higher resistance before loosing capacity.
- Cell to cell consistency. Get 3-5 cells and discharge them at high rate all together and see sag under load and when they cut off.
- discharge at max C rate (3C) and see how cell warm up and capacity
If they pass all these tests, they are good cells to my eyes
3A... Here's the graph... note the voltage changes at 2800, 3000 and 4000 seconds, this was me messing with the connection to the battery
I will do another test when I get a better fixture setup. There was significant voltage drop across the connection to the battery
edit: oops, obviously capacity is right axis not left axis, not gonna fix
For proper test, you need to test at 10A(3C), not 3A (1C). As 1C is likely not to stress the cell.
I'm surprised to only see about 2600mah at 1C, is it because of resistance or fake cell?
Please let me do a proper test with unused cells once I get my fixture sorted. I was hesitant to post the graph......
I have 4 cells sitting in the fridge that are untouched which will be tested more carefully.
x-speed said:
Like I said, please allow me to re-do the test with a proper fixture.
Also, I have BE's and BD's coming from fast-tech. I will do a direct comparison.
I agree with you, that dampfakkus has something wrong. They have alot of incorrect data in general. I much prefer HJK's tests.
On soldering magnets, that took some trial and error. I now have great results... I was even able to solder a very small thin magnet (8mm/1mm thick) with minor magnetization loss. I can solder sphere magnets (~7mm) with no noticeable loss. Ill post my process later, but as a hint: powerful flux, high temperature iron (Used ~775°F)
I definitely wont be using magnets for any future discharge testing, and compensation for contact resistance is not repeatable or reliable. I'll just make a fixture.
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