A CLASSIC PRODUCT ADDITION ???

[Barry Fields]

Barry, let's see your idea of a phone app and how it would show data

Can a person connect to the Classic or Hawkes with a android cellphone? I think yes.

Any data in the BBMT should be available over the modbus/canbus thru the Classic/Hawkes.

[Barry Fields]

I have updated the BBMT block diagram.

The purple wire to the classic AUX2 WBjr port could transmit both Bank voltage and current (alternately).
You would no longer need a Power cycle on that line.
This would not load up the MODBUS with "fast data".

The BBMT could generate the PWM signal.

This would provide:
12bit accuracy of PWM calculations (lithium)
Off loading PWM calculations to BBMT freeing up Charge Controller CPU time.
Remote battery buss sensing 12bit to the charge controller.
Allow the Charge Controller to occasionally check Controller to Battery buss excess voltage drop.

[Barry Fields]

Just trying to get a grip on rough timing issues.

Do the Classic or Hawkesbay continually respond to WBjr uart input or do they have to request it? If so how often?

How long would it take for a STM32F030 to check 9 ADC inputs (4 bank currents and bank voltage), add the 4 bank currents together, store that data in historical memory and output that data over uart?

What is a reasonable update time for SOC calculations in the Classic and Hawkesbay?

The MCU in the Classic max is 72 MHZ. The STM32F030 max is 48mhz. Is that a significant issue?

[ClassicCrazy]

Just trying to get a grip on rough timing issues.

Do the Classic or Hawkesbay continually respond to WBjr uart input or do they have to request it? If so how often?

How long would it take for a STM32F030 to check 9 ADC inputs (4 bank currents and bank voltage), add the 4 bank currents together, store that data in historical memory and output that data over uart?

What is a reasonable update time for SOC calculations in the Classic and Hawkesbay?

You could take a look at the code Graham wrote to see how he does it .
I was trying to find the timings in there but I am not good enough with code.
https://github.com/ClassicDIY/ClassicMQTT/blob/master/code/Python/support/classic_modbusdecoder.py
Larry

[boB]

The Classic updates SOC 10 times per second.  That is internally though.  The SOC is most likely pulled from the Classic much less frequently, like once or twice per second max.

Internally the SOC is measured in amp-seconds or amp-milliseconds.

For what you want to do, 48 MHz is probably just fine.  I tend to go with faster clock speeds these days.

boB

[Barry Fields]

Do the Classic or Hawkesbay continually respond to WBjr uart input or do they have to request it? If so how often?

I asking about the BATTvolts and BATTcurrent. How often and how long does it take?

[boB]

Do the Classic or Hawkesbay continually respond to WBjr uart input or do they have to request it? If so how often?

I asking about the BATTvolts and BATTcurrent. How often and how long does it take?

The WB Jr. is queried by the Classic or HB or Barcelona as often as it wants but maximum of 16 Hz I think.

Right now it is being sampled 10 times per second.   You only do things as fast as they are required otherwise it takes extra processor resources.

[Barry Fields]

The WB Jr. is queried by the Classic or HB or Barcelona as often as it wants but maximum of 16 Hz I think.

Right now it is being sampled 10 times per second.  You only do things as fast as they are required otherwise it takes extra processor resources.

I was under the impression that the WBjr ran async with no request required.

Attached is a block with what I think I know.

[Barry Fields]

Let us remember my goal here:

For the Classic line

   Eliminate the need to redesign the Classic line. It's not broke!
   Improve the current resolution (SOC calc & Float current)
   Add remote battery sense w/improved resolution (lifepo4 charging & setpoint/range discrimination)

for all MidNite charge controllers

   Add improved Charge Regimen (Float current confirmed Absorb time)
   Add parallel battery bank monitoring (battery bank health, Float current tracking, Current contribution/bank)
   Add sequential load management based on PWM
   Additional sense inputs (? batt box temp, ambient temp, h2o sense...?)

The BBMT would give a functional upgrade path without  unneeded additional MPPT and Charging abilities (major cost  portion of an additional charge controller)

[Barry Fields]

Even more stuff I do not know:

I understand the MPPT calculations need to be performed rapidly. I think I hear you saying that SOC and charging voltages are sampled @ 10/second. Battery voltages and currents move much slower than PV stuff.

If the Battery parameters were sampled @ 7 or 5 /second, would it reduce the accuracy enough to worry about? (it would free up MCU time)

just asking

[Barry Fields]

When the Classic stores and accesses EEPROM data, am I correct that is done thru DMA and not MODBUS?

Concerning the previous question, if the sample rate was 8/sec, then adding the last 8 samples and shifting the last 3 LSBs would give you the last 1second avg (approx).

[boB]

I notice you have the WB Jr AND your BBMT on the same line, Aux 2.

Aux 2 when being used for WB Jr is the only thing that will run.

You can see the data on the Aux 2 line being sent from the Classic and the WB Jr.'s response with an o-scope.

boB

[Barry Fields]

I notice you have the WB Jr AND your BBMT on the same line, Aux 2.

Me thinks you missed the big "OR" between WBjr and BBMT.

[Barry Fields]

point being,

The BBMT could send 12bit Battery current and voltage to the classic over MODBUS. (classic has 10bit accuracy)
The BBMT's Battery voltage would be remote sense (not available on the Classic)
The BBMT's EPROM could store individual Bank currents and float currents on Hourly & Daily basis. It could also compute weekly averages for 104 weeks to enable year over year comparisons.

[boB]

But the WB Jr. is 16 bit accuracy.  +/-  15 bits actually.

Modbus is a nice way of doing that communications.

You know, remote sense is nice when there is a lot of drop across that battery to CC cable but it isn't always necessary because as the battery gets full, the current goes way down during the absorb time.  That is, unless there are large loads on the battery at that time in which case you would not have been able to put out much bulk current before the voltage had risen to Absorb.

I would argue that a tenth or two of voltage inaccuracy isn't a big problem, even for most lithium.