Parallel Bank Monitor

[Barry Fields]

I have several steps in solving problems.
1) Admit a problem exists.
2) How significant is the problem.
3) Solutions   Ignore it - Fix it when it occurs - Predict it's occurrence - Prevent it from occurring

THE PROBLEM
In systems with multiple parallel battery banks, one failing bank can drag down the other banks. It would be best to be able to identify a failing bank before it becomes a larger problem.

A PREDICTIVE APPROACH
By monitoring and comparing currents in and out of each individual bank, a failing bank could be identified for further assessment and corrective action.

A POSSIBLE SOLUTION
Attached is a rough suggestion for a device to do this PREDICTIVE MONITORING. I would suggest the following:
1) Set an alarm should any bank current deviate by more than 5% (best guess). The alarm would suggest further diagnosis of the problem and corrective action.
2) It should be a stand alone unit. That is, not dependent on external processing but have the ability to communicate with a MidNite charge controller/software if desired.
3) A 12 volt version might be unnecessary or look much different. (marketing decision)

NOTE
It is not my intention to cover all the possible diagnostic/corrective actions in this post. They might include: loose connections, an undercharged cell, water levels, battery age, voltage readings, SG readings if possible etc.

Any and all comments or suggestions would be appreciated.

EDIT
Sorry it was late at night.
In the upper left of the display - 00.00 is real time bank voltage
All amps are real time for short term issues.
All KWH and Efficiency data are cumulative and re settable.

[boB]

I love the idea !

Just costs money of course...   Have a display that shows relative  running average of Amp-Hours between the battery strings and monitor it.

The reporting of some threshold for failure of one of those strings would be handy.

I could see several shunts, each with their own Whizbang Junior feeding a cow milking looking device to handle the data.

boB

[Barry Fields]

I love the idea !


I could see several shunts, each with their own Whizbang Junior feeding a cow milking looking device to handle the data.

boB

I just added this edit

EDIT
Sorry it was late at night.
In the upper left of the display - 00.00 is real time bank voltage
All amps are real time (for short term issues).
All KWH and Efficiency data are cumulative and re settable (for medium/long term trending).

You may consider that it should work with a variety of shunts to broaden the marketing base.
In my case I do not have a MidNite controller or a WizBang. I presently use a 100a 75mv shunt on one of 4 banks for data. My design has a max buss draw of 300A (75A per bank). For me I would choose 4ea 200A shunts.
Should be flexible.

Thanks for the encouragement

[Barry Fields]

Something else I do not know:

Do any of the existing Lithium battery management systems do this kind of Inter-Bank monitoring?
If so, what price bracket are they in?

Also, no insult intended but I prefer to deal in KWH as opposed to Amp Hours. All my loads are rated in and use watts, not Amp Hours. Just saying.

[boB]

All of these lithium battery banks are expensive but usually have communications for when stacking them in parallel for larger systems.

kW-hours can be done easily through software.   Most of the lithium battery banks also have communications that show either current and voltage and maybe even kW-Hours as well so that should be easy to connect up to an external computer of raspberry pi or something like that.

boB

[ClassicCrazy]

Something else I do not know:

Do any of the existing Lithium battery management systems do this kind of Inter-Bank monitoring?
If so, what price bracket are they in?

Also, no insult intended but I prefer to deal in KWH as opposed to Amp Hours. All my loads are rated in and use watts, not Amp Hours. Just saying.

I guess you could get Peacefair PZEM-017 monitors for each battery bank. They send data out on rs485  but what I did was use a Tasmota ESP32 ( or esp8266 works too I think) and that will make the data to Mqtt data . Either way if you get the data into something running Node Red like on a raspberry pi you can have it do whatever you would like.
https://www.aliexpress.us/item/2251832727645285.html?pdp_npi=3%40dis%21USD%21US%20%2412.80%21US%20%2410.11%21%21%21%21%21%402101ddb816975873218516645d00e2%2165948002171%21sh07%21US%21721645136&spm=a2g0o.store_pc_promotion.promotePruductList_2006910302101.10&gatewayAdapt=glo2usa
You can get them with whatever size shunt you want.
I made a video on how I hooked it up to esp running Tasmota and I also have two more videos getting the data to a raspberry pi and grafana .
https://youtu.be/TbLLrlZ3deI?si=e2_rljoi_hEgME_t
The PZEM-017 has been a bit flakey now and then on me but that might be because I have it on direct dc water heater so it cuts the power off to zero every night. The PZEM-016 ac version and PZEM-004t have been very stable using them for over a year.

Larry

[Barry Fields]

Do you believe that a product like I described is worthy of MidNite development?

I can continue with questions and suggestions but understand I have only a year or two left on this planet. I would like to leave something behind but I do not want to write memos to someone else's wastebasket.

Just trying to be realistic.

Larry

Thanks for your input. I learn something new from most of your posts. Would a rasberryPI take inputs directly from multiple shunts and process them for display?

[ClassicCrazy]

Do you believe that a product like I described is worthy of MidNite development?

I can continue with questions and suggestions but understand I have only a year or two left on this planet. I would like to leave something behind but I do not want to write memos to someone else's wastebasket.

Just trying to be realistic.

Larry

Thanks for your input. I learn something new from most of your posts. Would a rasberryPI take inputs directly from multiple shunts and process them for display?

I thought you were trying to develop something for yourself Barry. No I don't think what I suggested would work for Midnite stuff. Most people can already get or have the Whizbang which does about all anyone would need to do for lead acid batteries. With the price of lithium batteries as low as they are now I doubt too many people these days are buying lead acid. Most every new lithium comes with a bms that provides all the data on it's cells, charging, discharging, soc, etc and many you can change the setpoints.  Most of those batteries can also communicate with inverters/charge controllers to provide info or control.
Larry

[boB]

Next part of software that should be included when using the WB Jr. for ending-amps is a schedule for doing a timed Absorb once in a while.  Once a week or once every 2 weeks or whatever is wanted for that particular lead acid battery.

That, along with the Float/Re-Float scheme that Steve Higgins likes so much.  BTW, we used to work with Steve at Trace and at OutBack Power.  He's a good man !

But with  LiFePo4 batteries becoming so popular, most of this float charging will not be so common.

boB

[ClassicCrazy]

Next part of software that should be included when using the WB Jr. for ending-amps is a schedule for doing a timed Absorb once in a while.  Once a week or once every 2 weeks or whatever is wanted for that particular lead acid battery.

That, along with the Float/Re-Float scheme that Steve Higgins likes so much.  BTW, we used to work with Steve at Trace and at OutBack Power.  He's a good man !

But with  LiFePo4 batteries becoming so popular, most of this float charging will not be so common.

boB

What would be helpful with lithiums is if you could  set a small current for a certain amount of time. The bms in most of the present bms  have very small bypass current resistors so giving them the full charge. doesn't do much for balancing. But maybe pretty soon all the new batteries will have active balancers that can balance with 4 or 5 amps and that will solve that problem.
Larry

[Barry Fields]

Am I correct that a raspberry does not have ADC capabilities?

[boB]

Am I correct that a raspberry does not have ADC capabilities?

raspberry Pi ?

I don't think so.  But you can add one to them easily enough.

boB

[ClassicCrazy]

Am I correct that a raspberry does not have ADC capabilities?

Here is example of how to add adc chip to raspberry pi.
https://youtu.be/tn8sEqq0sJc?si=ImedxrQsiC3Z7yLd
https://learn.adafruit.com/reading-a-analog-in-and-controlling-audio-volume-with-the-raspberry-pi?view=all

Larry

[Wizbandit]

I designed a circuit board that adds 16 ADC channels to a Raspberry Pi model3. It has 16 ADC channels, I have 14 here in use on some AC current transformers and 4 monitor AC line voltages using a 12VAC transformer (wall wart) through a resistor divider network. I have 2 spare I might use for some DC inputs.

[Barry Fields]

I'll say it for ya. Bless his heart, he just don't know no better.


Does the Raspberry pi run the OS and program directly from the SD card as opposed to downloading to the processor?

The ADC additions I have viewed seem to convert an analog signal to parallel and then transmits that info to the PI in a serial format. The PI then converts that serial info back to parallel for computation.  If that is correct, it seems like that is the long way around Robin Hood's barn.

Would not an MCU with ADCs onboard make more sense?

If so, any recommendations or basic requirements for that MCU?