Battery pack on Panasonic NCR18650B cell

I need 36V pack for my scooter project. I am waiting for 36V 360W hub to arrive next week. I am thinking on 10S5P pack out of these ICR18650D1 cells. It should be ok at 1-2C. Is my math correct regarding going 10S for 36V or do i still need to go 12S? These cells are 3.7V nominal and 4.35V hot, IR 0.08ohm.
Any BMS around for this kind of weird voltage?
Cheers

That is a typical laptop LiCo cell. So 1C is continuous discharge is ok, but pushing its limit. 2C should really be reserved for short burst.

The cell sags significantly at 1C and above. So it's better to have 11s or 12s to compensate for that.

http://www.candlepowerforums.com/vb/showthread.php?337641-Test-Review-of-LG-18650-D1-3000mAh-(Pink)

It's not going to easy to find a balance charger that supports 4.35V.

OK, i have decided to go with 3400 Panasonic NCR18650B. Can someone advice a reliable BMS for these cells? 37V nominal. I need one capable discharging up to 20A.
Thanks

agniusm said:

OK, i have decided to go with 3400 Panasonic NCR18650B. Can someone advice a reliable BMS for these cells? 37V nominal. I need one capable discharging up to 20A.
Thanks

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I would advice u to go with the PD version the 2.9ah it is way better at a higher discharge.

I don't really need higher discharge its a small project and i think it will be sufficient. I just need to figure out ways managing them. 5P - thats 17AH for these cells. so 17A constant would be OK with the with 34A bursts. The motor is 350W so that would be roughly 10A draw. I think i am well within reason.

agniusm said:

I don't really need higher discharge its a small project and i think it will be sufficient. I just need to figure out ways managing them. 5P - thats 17AH for these cells. so 17A constant would be OK with the with 34A bursts. The motor is 350W so that would be roughly 10A draw. I think i am well within reason.

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I'm in agreement with your assessment. Capacity is more important than discharge rate for your application. I wish I can recommend a BMS for you, but that's not possible. I have been looking for one for over a year now, nothing even come close.

So on my ebikes, I used either the Cycle Analyst or the controller to take care of LVC (pack's LVC, not cell's LVC) and maximum discharge rate. Since all cell groups in my battery pack have the same capacity (+/- 3%), they all reach LVC at about the same time. For charging, I use my home built charger that charges each cell group independently so the pack is always balanced.

Both wrong on this one. The 3.4 cell is bad even at 1c the 2.9 is far better and will probably shed less heat.

I don't know but my math tells me that 9 amps on 17AH pack is .6C constant.

I was looking for BMS for this pack i am about to build. As mentioned before it will be 10S5P pack. I came across this small BMS unit and was wandering if someone had used it or know anything about it. It looks like it is programmable which i like, the question stands which way? is it via some expensive interface or everything is included with it? I will know later when i get response from supplier. Here are some of the spec.:

Voltage:
Charging voltage - 42V

Current:
Maximal continuous charging current - 25A
Maximal continuous discharging current - 25A
Current consumption - ≤20μA

Overcharge Protection:
Over charge detection voltage - 4.2V~4.35V(Adjustable)
Over charge detection delay time - 0.5S~2S
Over charge release voltage - 4.0V~4.2V(Adjustable)

Over Discharge Protection:
Over discharge detection voltage - 2.3V~3.0V(Adjustable)
Over discharge detection delay time - 50~200mS
Over discharge release voltage - 2.3V~3.0V(Adjustable)

Over Current Protection:
Over current detection voltage - 0.1V~0.2V(Adjustable)
Over current detection current - Adjustable
Detection delay time - 5~20mS
Release condition - Cut load,automatically recover

Short Circuit Protection:
Detection condition - Exterior shot circuit
Detection delay time - 200~500uS
Release condition - Cut load,automatically recover

Balance/Equilibrium
Balance voltage for single cell - 4.20V±0.025V
Balance current for single cell - 42mA±5mA

Resistance:
Inner resistance - ≤20mΩ

Temperature:
Operating temperature range - -40~+85°C
Storage temperature range - -20~+125°C

Size (L*W*T) - 60mm*50mm*23mm

The size is really small.Here are some photos:



Let me know what you think.

I like it, at least on paper. I look forward to you sharing your testing of it.

The specs says ≤20μA which is great, but it does not say where the power is drawn from? Is it across the whole pack or only from a few cells (creating a perpetual imbalance). Can you try to get this info from the manufacturer?

Another missing piece of info: Most (if not all) current BMSs will not do balancing when the difference in cell voltage is about 0.20V or greater. Most of the time, this difference is created by the BMS itself. Does this BMS suffers the same deficiency? In other words, can it balance when the difference is greater than 0.20V?

agniusm said:

I was looking for BMS for this pack i am about to build. As mentioned before it will be 10S5P pack. I came across this small BMS unit and was wandering if someone had used it or know anything about it. It looks like it is programmable which i like, the question stands which way? is it via some expensive interface or everything is included with it? I will know later when i get response from supplier. Here are some of the spec.:

Voltage:
Charging voltage - 42V

Current:
Maximal continuous charging current - 25A
Maximal continuous discharging current - 25A
Current consumption - ≤20μA

Overcharge Protection:
Over charge detection voltage - 4.2V~4.35V(Adjustable)
Over charge detection delay time - 0.5S~2S
Over charge release voltage - 4.0V~4.2V(Adjustable)

Over Discharge Protection:
Over discharge detection voltage - 2.3V~3.0V(Adjustable)
Over discharge detection delay time - 50~200mS
Over discharge release voltage - 2.3V~3.0V(Adjustable)

Over Current Protection:
Over current detection voltage - 0.1V~0.2V(Adjustable)
Over current detection current - Adjustable
Detection delay time - 5~20mS
Release condition - Cut load,automatically recover

Short Circuit Protection:
Detection condition - Exterior shot circuit
Detection delay time - 200~500uS
Release condition - Cut load,automatically recover

Balance/Equilibrium
Balance voltage for single cell - 4.20V±0.025V
Balance current for single cell - 42mA±5mA

Resistance:
Inner resistance - ≤20mΩ

Temperature:
Operating temperature range - -40~+85°C
Storage temperature range - -20~+125°C

Size (L*W*T) - 60mm*50mm*23mm

The size is really small.Here are some photos:

Let me know what you think.

Click to expand...

this looks like the BMS battery BMS PCM-L16S60-562(A) i have for 12S lifepo4. it looks like they have a third layer board in the middle which mine does not have but this one is smaller so i think they took the end of my board and cut it and stuffed it in the middle.

the thermal switch, shunts, and screws and pins and all the components are identical so it has to be from the same manufacturer. heat sink assembled and clamps the mosfets the same way. all identical.

you can put a switch in that thermal breaker lead and use that to turn off the BMS and that will turn off the battery. you can follow the trace to it from the top of #4 and if you look just inside that trace on the right you can see the trace from the top of #10 that drives the LVC/HVC signal through all the channels down to the gate drivers, which may be on that middle board.

i do wonder how they can reprogram the hysteresis but it would be preferable if it would balance around 4.15 but you could do that with the charger too.

on mine there are two of those 100 ohm surface mounts for the shunt resistor so (3.9/50=78mA) but for this one there is only the one 100 ohm shunt resistor so it is 42mA balancing current. but lipo is much closer in balance all the time so it really doesn't need much.

did you order some? can you identify the source?

I haven't ordered yet, was looking first if they could be rearranged for different HVC/LVC as you have mentioned i would like to keep them charged to 4.15V and discharged to 3.6V (need to confirm this LVC yet)?
The site i was looking up these is: http://www.bestekpower.com/37v10spcmbmspcbforli-ionli-polymerbatterypack/
You mean switch inline with thermoswitch?
They have one with I2C and HDQ interface but the again I2C adapter would cost some dough again unless its included. (Look at last BMS on the link above).
Those look different from the ones BMSbattery sells, up to 13S smart BMS.

yes put the switch inline with that white thermal switch. on mine i just cut the thermal switch out and used the two leads for my little dip switch instead and i can turn off the current for the gate drivers so it turns off the mosfets. this eliminates the precharge resistor stuff since you can make the connections while the battery is inactive, then turn it on after it is wired up.

i liked this one a lot and they used two of the 100 ohm shunt resistors in parallel so the shunt current is up to 84mA too.

20 mosfets can't be bad. gotta be 100A capable imo.

http://www.bestekpower.com/888v24spcmbmspcbforli-ionli-polymerbatterypack/PCM-D131.html

but now i know the source of the red pcb BMSs too. i always wondered who made them. so these guys must be good if they supply so many outlets. but like with all of alibaba stuff you gotta buy 1000 before they return your call.

Actually i got a quote from them with PI for this unit: http://www.bestekpower.com/37v10spcmbmspcbforli-ionli-polymerbatterypack/PCM-D114.html

It was 20USD plus shipping, 20 via DHL and 10 via HK post. That is the price i dont mind to pay and they were quick with response.

.

Nice on ya mate. I would probably be wrong person to test these sony cells and make some sort of judgement/post reviews as my background is far from electronics and all i learnt was here and on the net diy style. I can add up numbers, follow guides and that's about it
So my experience is mainly with LifePo4 stuff, A123 20AH to be exact. This time its LiCo which is considered dangerous and all but never the less i would like to build one battery using these lightweight cells. What would you suggest for LVC voltage to take it easy on cells, i mean not in a silly way but conservative LVC to keep them in good shape? Just to remind, these are Panasonic NCR18650B without built-in protection.
I have build 6 cell jig for testing/charging 18650 cells with BC168 balance charger.
Also, as my iCharger went kaput, is there a way to measure discharged capacity? I guess with timer?

So i have received email from Mr. Henry, BestTech power. He said that voltages are adjustable by them and not the customer. So on purchase you ask them to set them and they do it. Now back to the same question, what would be the best LVC for these Panasonic cells so i can order one as my cells coming in few days and i want to start the build.

Almost everything Panasonic claimed on their datasheets for 18650 cells are true. So I would use whatever LVC value they specify implicitly. Look at their discharge graphs and see where they stop.

SamTexas said:

Almost everything Panasonic claimed on their datasheets for 18650 cells are true. So I would use whatever LVC value they specify implicitly. Look at their discharge graphs and see where they stop.

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I have never seen a factory data sheet discharge graph that matched real testing.

I would do discharge tests to see where the cells start to go over the cliff.

As soon as the discharge voltage starts to drop fast under load is when the discharge should stop.

etriker said:

SamTexas said:

Almost everything Panasonic claimed on their datasheets for 18650 cells are true. So I would use whatever LVC value they specify implicitly. Look at their discharge graphs and see where they stop.

Click to expand...

I have never seen a factory data sheet discharge graph that matched real testing.

Click to expand...

I have never seen a Panasonic discharge graph that does NOT match my real testing.

I have never tested a cell that had the capacity claimed in the factory data sheet, ever.

I also find the discharge rates on a lot of factory data sheets will make the cells get way hotter than I like.

Does not matter much because I have the stuff to test them and like too.

I bought some A123 cells from a seller on eBay once that were bootleg.

Looked like the real thing but discharge tests showed different results than real A123 cells.

There are Panasonic bootleg cells out there too ?

If they are real they will be close to the factory specs but still maybe a little less ?

A bms will stop current at the set LVC while the cells are under load.

The larger the load the lower the LVC needs to be so that voltage sag does not shut you down ?

I would use lipo alarms on the pack and do some real world testing on the bike before ordering a BMS.

etriker said:

I have never tested a cell that had the capacity claimed in the factory data sheet, ever.

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Exactly when did you test a brand new Panasonic 18650 cell? Exactly which Panasonic cell was it?

SamTexas said:

etriker said:

I have never tested a cell that had the capacity claimed in the factory data sheet, ever.

Click to expand...

Exactly when did you test a brand new Panasonic 18650 cell? Exactly which Panasonic cell was it?

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I don't know that I have ever tested a brand new li ion cell of any kind.

Even the A123 M1 cells I bought new were from 2010.

Where would you find brand new ones except straight from Panasonic ?

I wish they would sell me for sure brand new Panasonic cells !

etriker said:

SamTexas said:

etriker said:

I have never tested a cell that had the capacity claimed in the factory data sheet, ever.

Click to expand...

Exactly when did you test a brand new Panasonic 18650 cell? Exactly which Panasonic cell was it?

Click to expand...

I don't know that I have ever tested a brand new cell of any kind.

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So how could you possibly make the above statement? You tested old recycled cells and you complained that they never meet the capacity claimed by the factory! End of discussion for me.