48 v 35.2ah li-ion battery pack

I bought 64 Sanyo 18650 -2200mah cells, in the form of 16 factory welded 4 packs each 8800mah series wired. I thought this would simplify connecting 16 balance wires from my BMS to each of the 16-4packs. Now I'm concerned that my 48 v BMS is factory set to handle one wire to each cell of 2200mah, and not one wire to each 4pack of 8800mah masquerading as one cell. My uncharged pack reads 57.92 v. My BMS schematic indicates one wire to each of the 16 cells; which are actually 16-4packs. Is this a potential problem "thermal runaway" or just nothing to really worry about. This is my first ebike battery, so I want to get the format down pat with you experts, before I start to solder my balance wires.

Humberto said:

I bought 64 Sanyo 18650 -2200mah cells, in the form of 16 factory welded 4 packs each 8800mah series wired. I thought this would simplify connecting 16 balance wires from my BMS to each of the 16-4packs. Now I'm concerned that my 48 v BMS is factory set to handle one wire to each cell of 2200mah, and not one wire to each 4pack of 8800mah masquerading as one cell. My uncharged pack reads 57.92 v. My BMS schematic indicates one wire to each of the 16 cells; which are actually 16-4packs. Is this a potential problem "thermal runaway" or just nothing to really worry about. This is my first ebike battery, so I want to get the format down pat with you experts, before I start to solder my balance wires.

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Cells in parallel act as one.
No problem with your BMS handling 4 cells as one.

Actually your pack is only 48V 8.8AH
My concern:
How many amps is your BMS capable ?
Can your cells supply the demand ? ( C rating )
If you expect 35 Amps that is a rating of 4C minimum.

you do not understand how the BMS works. can you post a picture or tell us where you bot it and we can tell you how much current would flow at max through the sense wires.

the biggest risk is that the wires can short and burn up on something metallic in the battery case. or that the charging lead will short out as has happened already to cause a fire.

Your title is wrong if you have them wired in series your pack is 8.8AH there fore 48v 8.8ah.
Then, you have wrong cell count because 48V system is 14 cells in series unless you have LiFePO4 cells which you don't! Coming further the BMS you have will probably not do and you will need to go with something Dnmun is working on, Bestech BMS.
I can almost say for sure that you are underpowered. You are lucky if they can supply 1C discharge which is 8.8 amps most. if it was 35ah pack it would change the game, but your pack should consist of 15 cells in parallel and the 14 cells in series or 15P14S - 210 cells total for max of 1.5kW output power.
Too little info you have on your hands to start building a battery which will lead you to some cash loss.
I have build 36V system out of Panasonic cells, i have used 10 in series and 5 in parallel for a total of 17AH for 15A max draw with 24A spikes. You could look it up in battery section "battery pack on Panasonic NCR18650B"
Hope it will be of some use.
AG

I need to clarify my posting. My four Sanyo 4 packs, consist of 16 cells each per battery bank and are factory rated as 35.2 ah per 16 cells. I have 4 banks, of 4 packs; 16 cells in each bank or 64 cells in a series that read 61v. uncharged. So please don't tell me I do not have 35.2ah. I bought a $50.00 mother board on Ebay that has 16 balance wires and is factory described as a BMS/PCB/PCM 48 v. (51.2 v) lifepo4 battery pack (16 cells with 50+/-10A limit with balance function. The schematic clearly spells out that the application is for 16 cells with a discharge current of 30A. My battery pack does not have 16 cells, It has16 four packs and I'm not convinced that I should balance wire them as if they were 16 single cells. Can anyone hear me now?.

Each of your groups has 3.7V and 8.8Ah. You have 16 groups like this. If you put these in series, you will have roughly 60V nominal with 8.8Ah capacity. If you want 35.2Ah, that means you have to configure 4 groups (16 cells) in parallel, which leaves you with only 4 such clusters in series = 15V pack which is too little for ebike. Next, your BMS is for LiFePO4 packs which have totally different voltage to your Li-Ion cells, hence you can't use it. I say you are screwed.

This my BMS.

This my BMS.

Humberto said:

I need to clarify my posting. My four Sanyo 4 packs, consist of 16 cells each per battery bank and are factory rated as 35.2 ah per 16 cells. I have 4 banks, of 4 packs; 16 cells in each bank or 64 cells in a series that read 61v. uncharged. So please don't tell me I do not have 35.2ah. I bought a $50.00 mother board on Ebay that has 16 balance wires and is factory described as a BMS/PCB/PCM 48 v. (51.2 v) lifepo4 battery pack (16 cells with 50+/-10A limit with balance function. The schematic clearly spells out that the application is for 16 cells with a discharge current of 30A. My battery pack does not have 16 cells, It has16 four packs and I'm not convinced that I should balance wire them as if they were 16 single cells. Can anyone hear me now?.

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No one will hear you unless you explain it properly. Few members trying to help you and and all of them are getting your explanation of your battery pack the same. Get some photos, upload hear so we can see.
I can give another shot at your explanation. So then you have 4 battery modules which are 16P4S? Each of your module should have 14.8 nominal voltage and 35.2AH when each cell is 2.2AH. In this case are those 4 modules already wired in series?
But then again you wrote that you bought 64 cells that just wont do 59.2V and 35.2AH unless you forgot to mention that you bought 4*64 cells.
That BMS as mentioned above is not suitable.

Humberto said:

I need to clarify my posting. My four Sanyo 4 packs, consist of 16 cells each per battery bank and are factory rated as 35.2 ah per 16 cells. I have 4 banks, of 4 packs; 16 cells in each bank or 64 cells in a series that read 61v. uncharged. So please don't tell me I do not have 35.2ah. I bought a $50.00 mother board on Ebay that has 16 balance wires and is factory described as a BMS/PCB/PCM 48 v. (51.2 v) lifepo4 battery pack (16 cells with 50+/-10A limit with balance function. The schematic clearly spells out that the application is for 16 cells with a discharge current of 30A. My battery pack does not have 16 cells, It has16 four packs and I'm not convinced that I should balance wire them as if they were 16 single cells. Can anyone hear me now?.

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a BMS for 51.2V is for a 16S lifepo4 pack, not lithium ion.

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Thank all of you for getting me on the right track, but I don't know which of you experts to believe. I strayed off of my original list of parts by taking advice from Youtube. Then I read the 18650 factory specs that said 16 cells; or four 4packs were 35.2AH. What configuration did they have in mind to make such a claim?. Can I salvage my project by adding 32 more cells; 8 more 4 packs and a new BMS that is Li-ion freindly?. If so how many AH will I get using your new configuration, and how many ballance wires will that include?. Doubleing my amount of cells is out of the question in terms of total weight and price. At that price I could buy a ready made Lifepo4 pack from China. How is anyone supposed to get the right facts when the experts don't all agree on a solution. I clearly understand the purpose of balance wires and the role they play in charging. I also have a 48v 5A charger. My 20" front wheel conversion kit is 850 watt.

My front wheel conversion kit included everything except a battery. Is it possible that what I thought was just the included controller also containes a BMS?. The controller has both charging cables and discharge cables with no mention of a BMS. It was too much information on Youtub that led me to buy a BMS.

miuan said:

Each of your groups has 3.7V and 8.8Ah. You have 16 groups like this. If you put these in series, you will have roughly 60V nominal with 8.8Ah capacity. If you want 35.2Ah, that means you have to configure 4 groups (16 cells) in parallel, which leaves you with only 4 such clusters in series = 15V pack which is too little for ebike. Next, your BMS is for LiFePO4 packs which have totally different voltage to your Li-Ion cells, hence you can't use it. I say you are screwed.

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Well, I agree all the way up to "you are screwed"

Maybe half-screwed. Sell the BMS to someone who is building a LiFePO4 pack and get the right one. Also, you have to re-think your configuration. A 30 Ahr 60V pack will be very large, if you really need one that big.

OK, maybe 3/4 screwed.

No bms is the controller. But it does have a low voltage cutoff. What voltage that is set for I have no idea. The lvc will shut off the discharge when voltage of the entire pack drops below whatever point it's set for. This may not prevent damage to the pack, since a single group of cells can overdischarge while the rest of the pack is high enough to prevent actuation of the lvc in the controller.

But, a properly set lvc is better than nothing.

I am still quite confused from reading the text exactly what you have. Your clarifying later post just confused me even more. Get some pictures or send us some specifications so we can better understand how many of what cells you have in each pack. I understand from your first post that your packs are each 4 cells. And that you have 16 packs.

But if your packs have 4 cells in series, you have 2200 mha of about 16 volts in each pack.

If your 4 cells are paralelled, then you have 8800 mha of about 3.7v in each pack.

What you wrote in the first post, 4 cells series connected for 8800 mha is impossible.

Or..... Maybe you have 4 packs, each one is 16 cells in series? If so, you now need 4 bms's or you need to reconfigure to 4p.

How many ah you have depends on how you connect them.

In 1p you have 141 ah of 3.7v

in 4 series 16 paralell you have 35 ah of 16v

in , 16 series 4 parallel you have 8.8 ah of 60v.

If you have 4 paralelled cells in each pack, you can easily build an 8800 mha pack. 14 lipo cells in series would be "48v" 16 in series is 48v for lifepo4

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get some pictures dude, seriously.

don't buy more of them. using those laptop cells is seriously mistaken to begin with. there have recently been several nice batteries sold by people here for less money and you would have a better battery.

I have never been so misunderstood so it must be the internet here in NYC. I'm going to start over by desoldering 16 -four packs of 18650 cells. Each 4 pack has four 2200 mah cells welded together with battery tabs and factory specs of 8800mah for each 4pack. The total of these 16 -4packs is 64-18650 cells. Which part of 16 cells do you not understand, New Mexico?. These cell packs were advertised and sold on EBay as four 4 packs of 35.2ah per 16 cells. If this is false advertising show me how and where. What configuration of four 4packs of 16 cells produces 35.2ah?. According to the above experts my current configuration is only about 8ah. Assuming you experts know what your talking about I took apart my battery pack and I'm back to square one with $254.00 in the form of 16 four packs of 4 -18650 cells. How much of this is still not clear to you, in New Mexico?. What should my new configuration be for a 48 v. Battery pack. Keep in mind that I'm not going to buy another 16 packs of cells based on the above advise. I'm willing to live with a 15 or 20 ah battery pack.

Why should anyone help this guy? He's totally ignorant and he's audacious. The Ebay description cannot be any clearer, yet he can not understand it. Several people have already tried and now he's insulting them ("assuming you know what you're talking about"). I say ignore him, don't give him any more help.

Humberto said:

What should my new configuration be for a 48 v.

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Use Watt hours. Each cell is 2.2Ah and 3.7V. So each cell is 8.14Wh. 64 cells is 520.96Wh.
Theoretically 520.96Wh could provide 48V at 10.85Ah. At 2.2Ah per cell at 3.7V/c, that would be a 4.93P12.97S pack. Rounded off would be a 5P13S pack having a total of 65 cells.
Keeping the 4P welded cell groups, the closest 48V battery would be 4P13S for 8.8Ah at 48.1V, 423.28Wh and 52 cells.

Your attachment explains what you have. Each pack is 1s4p for 8.8ah per pack at 3.6V (nominal for the battery) with a .5C discharge. If you put the 16 packs in series, the AH rating doesn't change. It's still 8.8ah, just at a higher voltage of 57.6V nominal or 67.2V fully charged. You've got all kind of problems with a 48V controller. First, most 48V controllers won't support a voltage higher than 63V. Second, most controllers are at least 15-20A, and your pack with a .5C discharge rate means it will only be rated for 4.4A. It's quite clear to most people here that you are lost and don't have a clue what you are doing. I have no idea why you bought what you did, but if it was on the advice of a friend, he also is lost. Try and get your money back. Those Li-ion cells just won't cut it at all. And the BMS is the wrong one too. Buy a prebuilt pack. It will be cheaper and safer in the long run.

Its 35.2 watt hours, not ampere hours you d...h...
You are f%@ked anyway. Now you have a lot of battery for flash light.
Read the ad by letter and dont insult anyone here cause at the end u are a d!@&

You said, four 2.2 ah cells IN SERIES = 8.8 ah. That's not possible. In series it would still be 2.2 ah.

Then you "clarified" and made it sound like you have 4 packs, each one of 16 cells in series.

Now we understand exactly what you have. You have 4p packs, and you have 16 of them. You have enough to make a 14s 8.8 ah pack able to provide 4 amps of power at 48v, or a 16s 8.8 ah pack able to provide 4 amps of power at 55v.

And you have a completely useless to you bms, for the wrong chemistry battery. You need to run with no bms, or get a bms for cells that charge to 4.2v, not one for cells that charge to 3.65v.

Have fun and good luck, your 4 amps of power wont run much of an ebike. You need about 30 ah of that kind of low c rate cells. Then you could run a modest 15 amps bike. Your 4 amps discharge rate capable pack will run a 100w scooter, and that's about it.