classic 150 questions and suggestions

[boB]

The waste not PWM is set to a 0.1 V  resolution which gives that function the 1.0 volt width.  The Classic's natural resolution is 0.1V and that is why it went that way.

I suppose it could have used a slower average for say, 0.5V width but would have taken more time to engineer.

Samples at 5 kHz and so that is why the output PWM is at 500 Hz for the 1V width.

boB

[Barry Fields]

The waste not PWM is set to a 0.1 V  resolution which gives that function the 1.0 volt width.  The Classic's natural resolution is 0.1V and that is why it went that way.

I suppose it could have used a slower average for say, 0.5V width but would have taken more time to engineer.

Samples at 5 kHz and so that is why the output PWM is at 500 Hz for the 1V width.

boB

My hope was that a width of .4v would yield 0% 25% 50% 75% 100% PWM.

As I have no external drivers (wind/hydro) a 1volt width would either never reach 100% or it would interfere with the Absorb cycle.

Below is my dream. (@ 74 I still dream)

[ClassicCrazy]

Barry - are you reading the range of absorb and  float voltages that Deka recommends ?
My understanding of those ranges was that you used the lower of the range when the batteries were new, and then increased the voltages as the batteries aged. Or maybe due to the stress the batteries are under if they get too cold , hot , or are being deeply cycled compared to less deep .
If you have flooded lead acid and took specific gravity readings and SG wasn't what it should be , the you would increase the voltage setpoint which compensated for the condition of the battery.

Larry

[Barry Fields]

Larry,
Yes. No mention of age/condition.

[ClassicCrazy]

https://batteryuniversity.com/article/bu-403-charging-lead-acid
Larry

[boB]

Barry, thank you for the charge stage pic.  That is good.

Classic update software forging ahead.  From 1.0V to 0.4V width and your percentage PWM references would be great to add.  I don't know of any other requests for this feature change  BUT  I can certainly see the thinner width V  as being an advantage for lithium battery chemistries as well.

Can't guarantee this will be added on the next round but I will definitely put a bit of thought thought into it in case there might be a quick and easier way.

i.e.  We'll put this one on the list for sure      I like it !


 
boB

[Barry Fields]

Barry, thank you for the charge stage pic.  That is good.

Classic update software forging ahead.  From 1.0V to 0.4V width and your percentage PWM references would be great to add.  I don't know of any other requests for this feature change  BUT  I can certainly see the thinner width V  as being an advantage for lithium battery chemistries as well.

Can't guarantee this will be added on the next round but I will definitely put a bit of thought thought into it in case there might be a quick and easier way.

i.e.  We'll put this one on the list for sure      I like it !


 
boB

boB,
Thank you for your response. You may not know how good it makes me feel to be validated by someone as competent as yourself. (says aw shucks and kicks dirt with foot)
Given the improvement discussed, I would love to acquire a Classic 150. Please keep me apprised as to progress.

If I could be so bold as to make some observations, without being overly negative or critical.
When I first addressed my questions to MidNite Product Support, I was told that they were not allowed to bother the Engineering Group and that the Classic 150 was approaching End Of Life.

Product Support not being allowed to bother Engineering left me (be polite Barry) bemused. That is something that should be handled by someone with a higher paygrade .

I am not a Marketing genius but I fear you take the chance of leaving behind a significant portion of your loyal customer base.  Not everyone is going to follow MidNite to the Hawkes Bay unit for a varity of reasons.
It appears to me that the Classic 150 is a pretty rock solid unit that should be allowed to live. If I could make some further suggestions.

It seems that you are depending on ONE onboard firmware revision level  to be "all things to all people".  You may be running out of MCU capabilities to give you the flexibility you need.  I am not a software/firmware designer so I won't pretend to say exactly what might be done.
If you could "offload" your battery algorithims to a memory stick on the USB port, you could free the up the onboard MCU for other stuff.  A customer could install appropriate memory stick (for example) one for Lead acid or one for Lithium or one for the next generation of battery chemistry yet to be discovered. This would likely free up some flexibility in dealing with the tighter voltage tolerances 12v lead acid and Lithium systems.
I would also add a third timer to the AUX1 waste not high that would start at the end of delay. Delay could be set to say 5 minutes as a restart delay for compressors. The new timer could be used as minimum run timer (maybe up to an hour). and the hold time would remain as a "bounce out" delay.

I believe these suggestions could significantly extend the life and flexibility of the Classic 150. It wants to live.
Thanks again.
Barry

[Barry Fields]

I hope my previous post was taken as positive and constructive as it was intended.  I hope I did not step on anyones toes, but I can only be forthright in my assesments.  I am pleased that VIC and Larry have not yet critiqued that post.

I realize that I have given you much to mull over and am certainly not asking for weekly updates. If I could add a couple of more observations that you may have already thought of.

Product Support has confirmed that after a firmware update the customer has to re-enter their parameters (absorb v, absorb time, Float v, etc).  If those parameters could also be off-loaded to the memory stick it could make the update process a little more user friendly.

I have also seen requests on the Forum for a voltage resolution of better than .1volts. I do not know if that is a hardware or a firmware restriction. If it is a firmware restriction, off-loading MCU tasks could enable improvement.  If it is a hardware restriction, never mind.  You should want any Classic 150 improvements to be downwards compatible with your installed base.

Just a final note. I have never understood companies that say: "We have a really good product that many people are happy with, let's stop making it".  Just saying.

Best regards
Barry

[boB]

Barry,  the 0.1V resolution is a hardware thing.  The only way to get better, say, 0.05 V resolution would be an averaging method going very slow from the 0.1 V input when it toggles between 2  0.1V points.   Not really all that easy to do at this point.

I really with that processor ADC had just ONE MORE bit !

Normally, updating the firmware does NOT over-write the Absorb voltage and other settings.

That may have been a thing during one of the older updates but I can't even remember when/if that happened ?   I think I know though what that is from.  Once in a while there would be some new registers and bits that needed to be initialized by the MNGP remote and THAT is probably where things had to get re-initialized.

The only way I know of to do a re-init from your saved numbers is from the local-app that connects via the Ethernet connection.  Not sure if you have used that or not but I seem to remember it being able to save and recall Classic settings ?

boB

[ClassicCrazy]

Yes you can use the Local App to save and restore the settings for the Classic.
Larry

[Barry Fields]

boB,
After this post I promise to go away for a while.

Let me outline the "niche" that the Classic line of controllers could continue to play in MidNite's future.  If I get anything wrong, please correct me.

Transitioning  to the Hawksbay unit would require the following:

[1] Any Classic 150/200/250 user with a 24 volt battery bank would have to revamp the battery bank to 48v AND purchase 48v inverters.

{2} Any Classic 150  user would have to upgrade their solar array AND PV breakers  to meet the minimum Hawksbay PV requirements.

Some of those users might opt for the Outback Flexmax 100 even though they would lose an AUX port.

I have no idea what the numbers are for Midnite's Classic installed base and what the permutations are.  I would suggest that Marketing do a survey to find that answer.  Only then could a rational migration path for existing customers be developed.

Hopefully that migration path is to MidNite products.

Again, my best assessment.
Regards
Barry

[FNG]

Just a summary of where we are

 Questions Answered
[1] The Absorb and Float set points are Battery Bank Temperature compensated values.TRUE {thanks Larry}
[3]  When the unit is in Absorb and a primary load drops the Bank voltage significantly, is the Absorb timer paused?TRUE -.3v (Thanks boB)

Un-answered questions
[3] If TRUE, what are the parameters for restarting the Absorb timer?
Absorb timer will reset under 3 condiutions, 1- At midnight if the clock is set 2- 2hrs after resting if clock is not set 3- when rebulk is triggered
[4]  During ABSORB (constant voltage) or FLOAT(constant voltage)  what are the reasonable expectation of the +/- voltage ranges delivered to the Battery Bank?, Usually what you will see is the voltage will hit the actual target then it can drift to -0.3v but will not over shoot. Essentially it trys to stay at target but it can be allowed to drift -0.3. boB is working on tightening this up now
[5]  Are Aux 1 and AUX 2 inactive during bulk and rebulk? it depends, Aux 1 and 2 have a lot of modes, If the mode is float for example yes it ignores the bulk but if its a simple diversion it triggers based on the voltage regardless
[6]  AUX 1 and AUX 2 setpoints automatically change from Absorb to Float settings.  TRUE? Depends, If it is something like Waste Not Hi yes, If its Diversion it runs n a single voltage independent of the target
[7]  In AUX 1 waste not high, what are the range of settings for Vhigh, Vlow, Delay and Hold? I would have to go look on this one
[11]  What are the range of settings for WIDTH and AUX 2 Vlow? I would have to go look
[12]  If WIDTH is set to 1v and AUX 2 Vlow is set to 0, Will 100% PWM be achieved ? (see question 4)
[13]  Would those settings interfere with the ABSORB TIMER? (see question 3)

Other Un-answered Questions
The rest of the questions apply to my peculiar system or are meant to prompt thought of a better mousetrap.  If I had the answers to the above, I could solve my own system applications.

[Barry Fields]

I do appreciate the time and effort you all have spent on this post. I hope it has been useful to many. Remember I do not yet own a Classic 150 but am looking forward to it. As I do not yet have a vested interest in MidNite, I can only hope I have helped generate an internal discussion of a "better mousetrap".
Best Regards
Barry

[Barry Fields]

[4]  During ABSORB (constant voltage) or FLOAT(constant voltage)  what are the reasonable expectation of the +/- voltage ranges delivered to the Battery Bank?, Usually what you will see is the voltage will hit the actual target then it can drift to -0.3v but will not over shoot. Essentially it trys to stay at target but it can be allowed to drift -0.3. boB is working on tightening this up now

If trying to harvest uncollected solar power using AUX2 PWM, some overshoot is needed to indicate that excess power is there to be collected. I would think that SETPOINT +/- .2 volts would do that for lead acid batteries. I would start the absorb timer @ SETPOINT -.2 volts and pause it at -.4 volts. These setting should be well within the tolerances for a 24v or 48v lead acid bank.

I do not know how one would do what I want to do with Lithium which is another reason I did not choose them.

SO, please DO NOT tighten the lead acid regulation specs.

Regards
Barry

[Barry Fields]

I really with that processor ADC had just ONE MORE bit !

Pretty sure you meant wish.
As I previously said, I am not a Hardware/firmware engineer but am always willing to ask a dumb question and learn something new.
Is it possible to assume the value of the Most Significant Digit of the ADC depending on battery bank voltage?
That would free up the Least Significant Digit for a resolution of .5volts.
Just asking.

Barry