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Check out my LifePO4 build on YouTube


Current status: semi off grid  
Input: 4.5kw
Storage: 10.6kwh
Output: 5800w
No load consumption: 2w
Nominal voltage: 48v
Max charge current: 75A
Charge voltage:  <= 60v
Balance current: 1A
Battery life: 25 years


250w 24v panel x 18 (3 East, 9 North, 6 West)
200ah  Lifepo4  16S  
Latching relays + solid state relays
Arduino Mega
12" display
Inverter 1: Victron Phoenix 800VA
Inverter 2: MPP Solar PIP4048MS  
Fangpusun 150/70 charge controller X 2
Voltage range relay (40-61v)
100A hall sensors
Changeover switch
HRC fuses
KWH meter x2
Hot water Heat Pump


System: Arduino Mega
Voltage reading: solid state relay 2 pole optocoupler x 16
Balance method: dynamic  
Balance type: passive
Discharge method: resistor  
Balance current: 1000mA  
Data output: serial + Bluetooth
Display: 12"
Adjustable parameters: pack low voltage cutoff, pack high voltage cutoff, calibration (x3), lead, high voltage alarms, above average alarms, data frequency  
Code: available soon

Outlay: (USD)

Batteries  5280
Panels 2162
Rails 300
BMS 156
Charge controllers 340
Inverters 1350
Cable 170
Relays 61
Mega 12
Hall sensors 48
Fuses 66
Breakers 102
Kwh meters 24
Lugs etc 13
TOTAL = $10, 802 (ballpark)

Is there any possibility you have code or documentation on the inter webs anywhere?
I'm very interested in your approach on the bms side of things. I have been designing a circuit board, based on arduino, with similar methods, I just want everything in a complete package. I'm currently working on a way to recycle the excess voltage from the cells, rather than dump it to a resistor, I haven't even began writing the code yet, but I would love to look at yours.
Check out the separate category I started for the bms

Code coming soon
where is the project?
(04-04-2017, 08:17 PM)Swolrath Wrote: where is the project?

The link was buried in that mess of HTML...   Smile

I notice in your specks ..quote... "Battery life: 25 years " !! ... that's what I want ...

Please tell how this was determined ....
I think this is the schematic of what you are doing, I drew it a few weeks ago.

[Image: qezddb1.jpg]

And this is the general idea of how you can balance cells dynamically with minimal losses, with all the switches in the first position the cells are charged in parallel, when switched to the second position they discharge in series. The first circuit singles out the high or the low cell and the second one takes charge from it sends charge to it accordingly.

[Image: fyyftc1.jpg]

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