Parallel Bank Monitor

[boB]

Barry, the Pi SBCs run off of their micro-SD cards pretty much.

SOME have this EMCC (right term ?)  memory that aren't so failure prone as the micro SD card on the Pi board itself.  That is better.

These Pi boards run a form of Linux and so they are nice to work with and update.

They already have a MCU that works well but with that speed and power just don't have the peripherals we would all like, as well.

boB

[ClassicCrazy]

Barry, the Pi SBCs run off of their micro-SD cards pretty much.

SOME have this EMCC (right term ?)  memory that aren't so failure prone as the micro SD card on the Pi board itself.  That is better.

These Pi boards run a form of Linux and so they are nice to work with and update.

They already have a MCU that works well but with that speed and power just don't have the peripherals we would all like, as well.

boB

The Pi4 and the newly announced and soon available Pi5 can boot and run from an attached hard drive.
Here are some details on the new Raspberry Pi 5
https://youtu.be/nBtOEmUqASQ?si=BcJjlBaYszekWaVV

Larry

[Barry Fields]

Good video. Hope there is not a test later.

[Barry Fields]

Does the 150 receive charge/discharge  as positive/negative values or are they biased positive?

Does the 150 MCU have spare input ports SPI or UART?

[boB]

Does the 150 receive charge/discharge  as positive/negative values or are they biased positive?

Does the 150 MCU have spare input ports SPI or UART?

Classic microprocessor pins are all used up I think.

There are 4 UART connections but all used for RS-232 and Arc fault communications.

It's kind of an older ARM processor.  LPC2366

boB

[Barry Fields]

Does the 150 receive charge/discharge  as positive/negative values or are they biased positive?

purple wire on aux2 always a positive voltage?
I'm missing something here. Does the circuitry on the WizBang receive it's power thru the purple wire?
It's obviously more complicated than I first thought.

[boB]

Here in the US, we tend to call discharging "negative" and charging as "positive"...

I think that SMA, for instance, is backwards of that.

The WB Jr. purple wire is power (~ +15V) for around 90 milliseconds, then data and then back to power again until the next 1/10 of a second.

Negative for that of course is battery negative itself. 

That line can actually do A/D and D/A over a very limited range but we don't use that at the moment.
Pretty cool, huh ?

Oh, so I guess that data does use a 5th UART but just for receiving one the Classic.
That part just happened to work out.   

 

boB

[Barry Fields]

Nice. I love creative solutions to problem solving.

[Barry Fields]

Here in the US, we tend to call discharging "negative" and charging as "positive"..

We here in Tennessee actually consider ourselves part of the US. Maybe you should have said "Here in the present". Just an old timer's thought.

The WB Jr. purple wire is power (~ +15V) for around 90 milliseconds, then data and then back to power again until the next 1/10 of a second.

Tell me where I am going wrong.
This implies a sampling  rate of 10 times a second. How much accuracy would be lost if the sampling rate was 5 times a second. The battery currents probably do not change rapidly.

Would a lower sampling rate free up enough data time for a "Whiz bang Sr" to monitor 4 separate battery bank shunts?

[boB]

"How much accuracy would be lost if the sampling rate was 5 times a second."

A/D is 16 bits maximum.  Five per second won't make it any better.

10 times per second is better for more accurate Amp-Hour calculation.

Now, we could go much faster and get less accuracy but 16 bits is the max resolution which we use.

Offset is re-calibrated between every sample, too.


"We here in Tennessee actually consider ourselves part of the US"

Yes, Tennessee is included in the US.  I should have said US and north America.

boB

[Barry Fields]

A/D is 16 bits maximum.  Five per second won't make it any better.

10 times per second is better for more accurate Amp-Hour calculation.

I guess I'm asking how much does battery current change from 1/5th of a second to the next.

Yes, Tennessee is included in the US.  I should have said US and north America.

Except for that time in the 1860's

[boB]

I guess I'm asking how much does battery current change from 1/5th of a second to the next.


Battery current can change 120 times per second in north America.  8.33 milliseconds due to full wave rectified 60 Hz ripple.

That is why these A/D inputs have some R-C averaging but not real slow.

Faster is more accurate.

boB

[Barry Fields]

I guess I'm asking how much does battery current change from 1/5th of a second to the next.


Battery current can change 120 times per second in north America.  8.33 milliseconds due to full wave rectified 60 Hz ripple.

That is why these A/D inputs have some R-C averaging but not real slow.

Faster is more accurate.

boB

I am going for the dumb questions of the day.

Where is the ripple coming from?

Why not improve RC filtering rather than ADCing the ups and downs of the ripple. should be minimal effect on accuracy.

How absolutely accurate bank current is required compared to added functionality?

Barry

[boB]

Ripple comes from the inverter AC current.  There is always some 120Hz ripple reflected to the battery side due to limited energy storage in the inverter itself and the fact that AC current drops to zero at zero crossings.

The RC has been done for years and we aren't thinking about fixing what isn't broken at the moment.

Maybe some day we will look at this again though.

boB

[Barry Fields]

Every system is different. I have attached the schematic (reverse engineered by me) for the power board of the AIMS inverters (48v 6000w 220v split phase) I use. One on continuously and the other for opportunity loads.

On the left you will note 9.9 Kilofarads per unit attached across the battery buss. I'm thinking I do not have much AC ripple.
Just an FYI