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Bms for 16s
#11
You need 80 mons if you dont plan to connect each pack together. but thats very small packs per longmon... 1 longmon can easily handle 100Ah pack but you need to rewire. Neither less you need to rewire to use a longmon on it since they should not be used with shared wiring

Shared wiring is when 2 mons share the same wire to one battery
+ for one mon and negative for the other...

Dont forget that with the batrium you need the shunt and a breaker with trip function as well for it to become a complete bms. Advantage is that it can talk to some victron gear.
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#12
>Ok so now I’m a little confused. Each pack has 16 cells making up 64v I was planning on paralleling the whole pack 
I see.  When you wrote 16s5p...   this implied to me that you were planning to parallel the16 cells of each battery.   Instead, it sounds like you plan to have 5 batteries of 16s1p in parallel.   

 Again, @Daromer had it right then as 5 batteries of 16s1p is  5 x 16 = 80 longmons.   At 1 longmon per cell, Batrium is way more powerful than you need - but that's not a bad thing functionally, just very expensive -  https://www.batrium.com/collections/cell...ngmon-100x  :)

@DavidPoz did a custom chevy batttery bank in 14s1p * 5? (several) 'batteries in parallel'.   Each 14s1p had it's own (cheaper) BMS + circuit breaker and they paralleled to an overall bus.  He used the phone / android BMS path.   If you go to 15:26 on this youtube you can see the end result on his phone - https://youtu.be/XGLs9-nIOjw - followed by a recap showing the gang of circuit breakers and overall + / - If you look this at this youtube and a little earlier youtubes you can see the overall details of design.  It might be inspiring for your situation.
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#13
I have paralleled my LiFepo4 packs to so that i dont had to have several 100s of longmons. But you need to think ahead when doing it.
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#14
Again, @Daromer had it right then as 5 batteries of 16s1p is 5 x 16 = 80 longmons. At 1 longmon per cell, Batrium is way more powerful than you need - but that's not a bad thing functionally, just very expensive - https://www.batrium.com/collections/cell...ngmon-100x Smile

@DavidPoz did a custom chevy batttery bank in 14s1p * 5? (several) 'batteries in parallel'. Each 14s1p had it's own (cheaper) BMS + circuit breaker and they paralleled to an overall bus. He used the phone / android BMS path. If you go to 15:26 on this youtube you can see the end result on his phone - https://youtu.be/XGLs9-nIOjw - followed by a recap showing the gang of circuit breakers and overall + / - If you look this at this youtube and a little earlier youtubes you can see the overall details of design. It might be inspiring for your situation.


O.K so I think yes . I guess that is a major lack of understanding on my part. I thought my 16s with 5 battery packs paralleled together made it a 16s5p.

I believe you are saying for it to be a 16s5p I’d have to parallel each individual cell in each pack to the other 4 packs ?

The idea was to parallel the whole packs , I.e go from the positive terminal of the pack to the positive of the next pack etc and same with the negative

So I guess doing it my way will need 80 longmons , and the other way only 16 but what really screws my mind is that I thought the longmon balanced each individual cell to the right voltage and what I don’t get is if you have say 1 cell from each pack in parallel with 1 cell from each of the other packs how I appreciate the voltage stays the same across the 5 cells and it balances that but how would you know if one of the cells was at a higher voltage than the others or am I overthinking this ?

Thanks for the link to the video. I’ll take a look at that tomorrow.
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#15
Excellent questions - so I did some drawings to try to help the discussion Smile

Here's a couple of drawings illustrating 16s5p (16 longmons) vs  16s1p * 5  (80 longmons):




>I believe you are saying for it to be a 16s5p I’d have to parallel each individual cell in each pack to the other 4 packs ?
Yes.   The top drawing above.  This is 16 longmons and cost effective (save $1000) if using Batrium.


>The idea was to parallel the whole packs , I.e go from the positive terminal of the pack to the positive of the next pack etc and same with the negative
This is 16s1p (1 battery) with 5 of these in parallel.    This is 80 longmons.    The 2nd from the top drawing above.

>".....and the other way only 16 but what really screws my mind is that I thought the longmon balanced each individual cell to the right voltage and what I don’t get is if you have say 1 cell from each pack in parallel with 1 cell from each of the other packs how I appreciate the voltage stays the same across the 5 cells and it balances that but how would you know if one of the cells was at a higher voltage than the others or am I overthinking this ?

When cells are in parallel (e.g. via the sense leads) they will all have the same voltage all the time - they keep each other the same.   So 1 longmon will lower the voltage of the 5 cell(s) in parallel at the same time.    A single longmon is very powerful compared to other BMSs - and can easily handle 5 of your cells in parallel.  16 longmons - 1 for each group of 5 cells with parallel sense leads - are controlled by the Watchmon supervisor...  to keep all 16 groups of 5 cells in balance.

*The next question is... won't the sense leads *burn up* under load?.   The load current will not flow thru the sense leads.     The load will flow thru the battery cell to cell serialization connections within each battery and the external parallel battery wires (e.g. the heavy red/black on the drawings).   

The sense leads will keep each group of 5 cells in almost exact unison of voltage...  all the time...  and so the current flow is small.  The only time you could get a spike of current thru the sense leads would be the 1st time you hook up the cells together...   so you want the 5 batteries to be near the same voltage before you connect parallel sense leads.   After that - they will never be out of sync again Smile
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#16
You have 5p16s if you dont interconnect. 16s5p if you interconnect them all Wink
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Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 100kWh LiFePo4 | 20kWh 14s 18650 |  66*260W Poly | ABB S3 and S5 Trip breakers
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#17
That’s brill. Very clearly explained . A picture really is worth a 1000 words Smile

That’s totally sorted out my misunderstanding. O.k so I can see that the batrium is probably overkill but I’ll still probably go that way.

I’m not sure how easy it would be to rewire the packs to 16s5p. I certainly don’t think they will dismantle easily ...

I’m ok with spending a bit more on the longmons , it’s not like I have any other hobbies Smile my wife might be a bit annoyed though If she finds out Smile
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#18
I would not go 80 longmons for 20Ah cells.. Its better just to rewire it properly if you ask me.
NOTE! My links supplied in this message may be affiliated with Ebay and by clicking on them you agree on the terms.
YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 100kWh LiFePo4 | 20kWh 14s 18650 |  66*260W Poly | ABB S3 and S5 Trip breakers
Upcoming: 14S 18650~30kWh
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#19
You know....   hooking up 80 longmons is 80 x 2 = 60 wires between longmons and the cells.  Plus you need to hookup the daisy-chain for the 80 longmons to the supervisor.   Not sure its any more work to parallel the individual cells out to 16 longmons and you can save $1000.      The key thing I find helpful is to identify the cells and their + / - (s) and then work up a diagram (pencil + paper is fine) and then wiring should be straight-forward.  

I found this BMW i3 Battery Module 'closeup' youtube - https://youtu.be/w61o8vPF9AY    I couldn't find an i8 youtubes but maybe its similar? / pull of the top and you can see the cells and trace the wiring harness and then use the sense lead wiring harness to branch/extend out + and - as needed.    Or use a volt-meter to measure the sense lead wiring harness to find 0 -> 4v,  -> 8v, -> 12v ...  etc.
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#20
O.K yes I am here to learn so I’ll follow your advice and start studying how to re-wire them .

I’ll go ahead and order the watchmon 4 and 16 longmons so I’m ready . Thanks for pointing me in the right direction. I’m sure I’ll be back for more advice soon Smile
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