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Infinite parallel 16sXp good or bad ?

elvis_asaftei

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I have this battery setup that I use with 2 series of 200ah and 2 series of 280ah and allows me to add there any new number of 16s .
It is good or bad ?
advantage is that I can add at any time under power any number of new 16s packs .
I also noticed that cells are more probably to get better equilibrium because of mixed internal resistance in a 4 or more parallel row. You can notice 2,5mm2 equalization that will be used by more than one JK BMS Active for cell equalization.

Anyone can notice any disadvantages ?

FB0ED130-2E98-4D7C-A1CF-2C4260608174.jpeg
 
That's impressive... A bit of a nightmare, but impressive nonetheless. Took me lots of staring to get it to work out in my head.

Disadvantage: The more you have in parallel, the less likely you are to be able to balance current through each string.

At a minimum, your main terminals should be at opposite corners of the pack. As it stands, you have a bias for the smaller cells to handle more of the load than the bigger cells because that's where you've located your main terminals... and you have multiple "main" terminals.

Worth getting a clamp ammeter and checking the current values at these locations on both ends:

1625606133257.png
 
Another thing I notice is that some of the bus bars go from the top of the adjacent cell bus bar to the pad of the next one. The bus bars should be either on the bottom on both ends or on the top on both ends or they will not be sitting flush and will be prone to bad connections.
 
Balance issues aside, it really is interesting to see a pack designed for expansion.
 
I would echo that the 'max' in my mind is balance. Batrium mons are the heftiest balance that I'm aware of at 2a. My packs are 260ah and Batrium longmons can balance them in days. What's the max for Batrium mons? - they say up to 1000ah per cell - so maybe 700ah realistically.
 
That's impressive... A bit of a nightmare, but impressive nonetheless. Took me lots of staring to get it to work out in my head.

Disadvantage: The more you have in parallel, the less likely you are to be able to balance current through each string.

At a minimum, your main terminals should be at opposite corners of the pack. As it stands, you have a bias for the smaller cells to handle more of the load than the bigger cells because that's where you've located your main terminals... and you have multiple "main" terminals.

Worth getting a clamp ammeter and checking the current values at these locations on both ends:

View attachment 55270

Yes, i designed this type of setup because I had many new batteries to receive and wanted to be able to add new series without stopping any inverter.

I will definitely move and spread inverter connectors more evenly to reduce the AMPS on the spots you you noticed too.

Problem with 310Ah is that + / - terminals from battery are not centered on a cel half, as they are on 200ah cells. Please see that i was not able to use stock bus-bars because of that as i used on 200Ah battery
 
Another thing I notice is that some of the bus bars go from the top of the adjacent cell bus bar to the pad of the next one. The bus bars should be either on the bottom on both ends or on the top on both ends or they will not be sitting flush and will be prone to bad connections.

You can see that I used 3cm aluminum bus bars that are flexible and they do have connection on all surface, even so, it is the screw and nut that is transferring current too. Tested on high load with infrared camera and temperature is at 40C with 30C ambient temp after an hour, so tat should be ok ?

What other things do did you notice ?

Does anyone like the idea of 2,5mm2 yellow cable i used for balancing (all same length of same internal resistance - not that it can make a difference, but to be sure) and connected to WAGO connectors to be able to add up to 5 new JK Active BMS to the setup if this is needed (maybe to protect batteries from each inverter and go all through a separate BMS ) ?

Please post reply to this to see what is good and what is bad, I am new to this field and maybe that's why i think the setup differently than others.
 
I would echo that the 'max' in my mind is balance. Batrium mons are the heftiest balance that I'm aware of at 2a. My packs are 260ah and Batrium longmons can balance them in days. What's the max for Batrium mons? - they say up to 1000ah per cell - so maybe 700ah realistically.

Can you please help me understand what you mean ? I use JK Active BMS to balance and what i think is that using 4 or mroe cells in paralel, is actually balancing the internal resistance for that group and i ntoiced really well balanced cells even on laods or extremes because (one cell has 0.22, other 0.18, other 0.21, and in a pack all group of 4 is getting to a rounded value of 0.20 mOhms ... )

What do you think, is that right ?
 
Can you please help me understand what you mean ? I use JK Active BMS to balance and what i think is that using 4 or mroe cells in paralel, is actually balancing the internal resistance for that group and i ntoiced really well balanced cells even on laods or extremes because (one cell has 0.22, other 0.18, other 0.21, and in a pack all group of 4 is getting to a rounded value of 0.20 mOhms ... )

What do you think, is that right ?
A balancer does not balance IR (internal resistance). IR is rather a characteristic of individual cells that tell you how much it will impede current flow - and is not 'balanceable' or 'changeable' in the short run.

A balancer attempts to make sure all the cells in series have the same voltage! Most balancers work by discharging a cell to lower it's voltage to match the others in different algorithms till they all have similar voltages within the parameters of the balancer. The larger the cell (or cells in parallel to make a larger and larger cell) the slower the balance will become because each 'cell' has so much power.

Lessor BMSs have small discharge currents and other BMSs have larger discharge currents. Batrium has up to 2a of current in it's longmon - e.g. 2a/cell in series. That's 2a * 3.7v (nominal) = 7.4w of discharge/cell in series. A lessor BMS might have 0.5a = 1.85w discharge capability.
 
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A balancer does not balance IR (internal resistance). IR is rather a characteristic of individual cells that tell you how much it will impede current flow - and is not 'balanceable' or 'changeable' in the short run.

A balancer attempts to make sure all the cells in series have the same voltage! Most balancers work by discharging a cell to lower it's voltage to match the others in different algorithms till they all have similar voltages within the parameters of the balancer. The larger the cell (or cells in parallel to make a larger and larger cell) the slower the balance will become because each 'cell' has so much power.

Lessor BMSs have small discharge currents and other BMSs have larger discharge currents. Batrium has up to 2a of current in it's longmon - e.g. 2a/cell in series. That's 2a * 3.7v (nominal) = 7.4w of discharge/cell in series. A lessor BMS might have 0.5a = 1.85w discharge capability.
I only use Active BMS and energy is moved from cell with highest vitals to the one with lowest using capacitors and no energy is lost …
 
I only use Active BMS and energy is moved from cell with highest vitals to the one with lowest using capacitors and no energy is lost …
There is energy lost - not as much as a passive balance, maybe 30% from what I read, but its still lost and more importantly and the key point I'm trying to make is that its a voltage equalization process / not an IR 'thing' :).

Also, the larger the cell, the longer it will take to balance - so there's a limit (depending on the balance current movement capabilities) on how large an individual cell in series can be and still be balanced in a timely manner.
 
There is energy lost - not as much as a passive balance, maybe 30% from what I read, but its still lost and more importantly and the key point I'm trying to make is that its a voltage equalization process / not an IR 'thing' :).

Also, the larger the cell, the longer it will take to balance - so there's a limit (depending on the balance current movement capabilities) on how large an individual cell in series can be and still be balanced in a timely manner.
Active balance with capacitors have less than 3% energy loss compared to 100% energy loss from passive equalizer with resistors. I have 5A equalizer that is not heating at all.
 
Active balance with capacitors have less than 3% energy loss compared to 100% energy loss from passive equalizer with resistors. I have 5A equalizer that is not heating at all.

Have you ever measured the current passing between the cells? They may say 5A, but it's rare that you get that.
 
It is dynamic , only goes up when cells are more unbalanced …

So, the answer is "no." You have no idea what they can really do in the real world. I have active 12V balancers on my 4S2P (48V) FLA that claim 6A. Even on dV > 0.5V in light or heavy current, I never saw more than 400mA of balancing current.

I have them because I got cheap used 12V FLA from golf carts, tested them 100% and have SoH from 75-95%, so I treat it as a 75% 48V battery and rely on the active balancers to keep thing from going sideways... BUT I would never expect the claimed 6A of balancing capability just as you should never expect 5A... unless you measure it. :)
 
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