4s16p x2 or 4s32p - Lifepo4 26650 cells also.... 2 bms? or 1 bms?

I'm curious, what is the best method to make my portable solar generator battery strictly using LifePo4 26650 (3300mah) cells?
I'd like to stick with 4s due to the 12v nature of my projects Except, 4s32p is too long of a pack for my case.
Here's my question...
Should I make TWO 4s16p packs and connect them parallel side by side?? this would make the pack fit....
AND
If I make Two 4s16p should I use two BMS boards (one for each?) or just use one bms?
Below is a photo of my cells how I want them in the box.
also I am open to any and all suggestions as well!
THANKS!!!
I'd like to stick with 4s due to the 12v nature of my projects Except, 4s32p is too long of a pack for my case.
Here's my question...
Should I make TWO 4s16p packs and connect them parallel side by side?? this would make the pack fit....
AND
If I make Two 4s16p should I use two BMS boards (one for each?) or just use one bms?
Below is a photo of my cells how I want them in the box.
also I am open to any and all suggestions as well!
THANKS!!!

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Second system 1890W 3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.
5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
Spring terminals ?
Soldered wires ?
Spot weld tabbing ?
How do you intent to dissipate heat from the middle cells in the pack ?
Mineral oil bath ?
mineral oil bath in flames ?
|| Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
|| VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A
solar: http://tinyurl.com/LMR-Solar
gen: http://tinyurl.com/LMR-Lister ,
The picture looks like two 4S16P, but if he flipped alternate rows he would have 32 P consisting of two rows of 16P.
I was just wondering if having two 4s16p with each their own BMS would be redundant versus one 4s32p and one BMS... Im still a little confused on this.
@Sween
With the layout topography is it necessary to have a gap between the cells as illustrated in the image or can they be grouped closer together? Having two rows of cells oriented the same way to create a cell block would be the simplest, as opposed to alternating, this way would be the easiest to create a bank. When I previously posted I was thinking this way, there would be no need to have two BMS's as the battery would be a 4S 32P.
Second system 1890W 3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.
5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
Second system 1890W 3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.
5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
32x90Ah Winston cells 2p16s (48V), MPP Solar PIP5048MS 5kW Inverter/80A MPPT controller/60A charger, 1900W of Solar Panels
modified BMS based on TI bq769x0 cell monitors.
Homemade overall system monitoring and power management https://github.com/simat/BatteryMonitor
IM open to any advice, as this is my first build besides a few 4s4p lifepo4 packs.
also Im still rather confused on how to combine the two 4s16p packs in parallel.... do I just connect negative to negative positive to positive on the end cells???
thanks so much everyone...
@karrak, very nice diagram Simon.
Second system 1890W 3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.
5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
Do you think bus bars are worth the effort vs Spot welding tabs?
Honestly I have a spot welder So, I was planning on using that.
32x90Ah Winston cells 2p16s (48V), MPP Solar PIP5048MS 5kW Inverter/80A MPPT controller/60A charger, 1900W of Solar Panels
modified BMS based on TI bq769x0 cell monitors.
Homemade overall system monitoring and power management https://github.com/simat/BatteryMonitor
32x90Ah Winston cells 2p16s (48V), MPP Solar PIP5048MS 5kW Inverter/80A MPPT controller/60A charger, 1900W of Solar Panels
modified BMS based on TI bq769x0 cell monitors.
Homemade overall system monitoring and power management https://github.com/simat/BatteryMonitor
32x90Ah Winston cells 2p16s (48V), MPP Solar PIP5048MS 5kW Inverter/80A MPPT controller/60A charger, 1900W of Solar Panels
modified BMS based on TI bq769x0 cell monitors.
Homemade overall system monitoring and power management https://github.com/simat/BatteryMonitor
^^^ This is the BMS I was going to use.... nothing fancy, over/under volt, short circuit, 30a
If I do decide to use the busbars is it possible to use steel or aluminum? nickle dosen't spot weld very nicely to copper Ive heard... thanks again everyone
Second system 1890W 3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.
5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
32x90Ah Winston cells 2p16s (48V), MPP Solar PIP5048MS 5kW Inverter/80A MPPT controller/60A charger, 1900W of Solar Panels
modified BMS based on TI bq769x0 cell monitors.
Homemade overall system monitoring and power management https://github.com/simat/BatteryMonitor
But I have one 4s16p pack assembled!!! (it's reading 13.07v, which at full cap. it should be 12.8v-13.2v (3.2v-3.3vx4)
I am going to order a new BMS that's rated for lifepo4 for li-on (with the Bluetooth module) (Thanks Simon)
Basically, I am going to build Two 4s16p packs, get them both to full charge (around 13.2v), then I am going to connect the two packs in parallel via 6 Gauge copper wire.
While I am waiting for parts for delivery, any further advice or discussion is totally welcomed...
like.... "What would you do differently"?
Thanks everyone!!!
However, even assembled as is , I would only need one BMS, as Mcgivor stated... because after connecting the two 16p packs the positive chain and negative chain combine forming 32p shared amperage across all cells. the BMS can then trickle charge each parallel positive bank (4 in total) (man are those balance wires small....) until even voltage is acquired across the 4 32p cells.
Correct me if I'm wrong though. Like I said, I am very new to manually assembling packs.
Second system 1890W 3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.
5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
I ordered this BMS. I like that it has serial output, full source code and schematic. All easy to understand.
Search ebay for "18v 5s 20a lipo li-ion charge discharge protection circuit balancing bms".
I am available for custom hardware/firmware development
Are you using LiPO cells or are the charge and discharge curves of your cells similar to LiPO? If not I hope the BMS is programmable so you can set the right parameters for you pack chemistry. I have used those kind of BMSs on electric bike packs where the pack might cost me several hundred dollars. For my stationary pack that would probably cost several thousand to replace I use a BMS that is fully programmable and offers pack quality reporting and bells and whistles. It is simply a risk management decision and I am risk adverse when it comes to losing at $3000 pack, so that is my feedback.
It contains an Arduino compatible processor with simple source code. Changing the program changes all of the chip (BQ76920) behavior. Max and min voltages, when to balance, etc.
I am available for custom hardware/firmware development