classic 150 questions and suggestions

[Barry Fields]

   My hope here is that some incognito MidNite Engineer would take the time to read this Epistle. My goal is to better inform myself and other Forum readers of information not included in the manual for the MidNite 150. It is also, through my questions, rationale and suggestions, to help MidNite make a better "mousetrap".  I fully realize that this may take you more than 15 minutes.  I want to thank you in advance for any efforts you might take on my behalf.

[Vic]

Hi Barry, Welcome to the Forum.

Short of time now,  but did skim your doc.

You may want to look at the Knowledge Base for some additional info, mostly Classic-related:
http://www.midniteftp.com/support/kb/faq.php?cid=1

With FLA batts,  you might want to AVOID Al bussbars ...

Later,  Vic

[Vic]

...  a few additional thoughts,  as breakfast, here, cooks:

Four parallel strings of LA batteries are generally not a good idea.
FLAs have needs for attention, and with 96 cells (!!), to tend,  water, SG check, etc,  as well as battery balance issues,  this can lead to less, than needed attention.  If you really need that much batt Capacity,  one or two strings of larger batts is generally a better idea.

Also (IMO) AIMS has not had a stellar record of reliability,  support, and parts availability.  Please carefully check all specs,  especially,  what is the Standby power (Tare) losses with the inverter running,  but delivering no power to loads,  and so on.

EDIT:  6 kW,  is a large inverter,  forget all of your loads,  but more inverter power is not always better.

Usually,  one would do a Power Budget,   which includes how much power needs to be provided, vs when it is needed<.

Also,  if this is your first battery power system, it may be difficult for you to design it to meet your real needs.

Later, just sayin'  ...   Vic

[ClassicCrazy]

[1]  I presume the Absorb and Float set points are Battery Bank Temperature compensated values.TRUE?
[2]  When the unit is in Absorb or Float, what voltage drop initiates Absorb(mppt) or Float(mppt) and a what voltage does the unit return to Absorb or Float?
[3]  When the unit is in Absorb and a primary load drops the Bank voltage significantly, is the Absorb timer paused?
   If TRUE, what are the parameters for pausing and restarting the timer?   If FALSE, should it be?
[4]  During ABSORB (constant voltage) or FLOAT(constant voltage)  what are the reasonable expectation of the +/- voltage ranges delivered to the Battery Bank?

You set your absorb and float voltage, you set the temp compensation value. The absorb and float setpoints will adjust up or down automatically according to the battery temperature sensor . Example - batteries get colder , the absorb and float values go up.

If in Absorb the voltage absorb timer starts , if voltage drops below Absorb setpoint, it will
start again at the remaining absorb time once it rises again to absorb voltage.
If in Float and it drops below float setpoint it will go to Float Mppt . It will stay at float setpoint until next day no matter what the battery voltage is - so if battery dropped below float but then raises up it will go back to float.

During Float and absorb - power will always go to loads. You can use Aux settings to turn on and or control loads to use extra power above absorb or float  . example - if in absorb or float  you can have aux turn on a ssr relay to send just the extra power to something like a water heater .

Larry

[ClassicCrazy]

regarding your aux questions -
Take a look at some of the videos I made of how I use classic aux 2 waste not to pwm ssr for water heater.
I made a few videos of how I got this going or updates.
Here is one
https://youtu.be/Non3H88UzPs

Larry

[Barry Fields]

Hi Barry, Welcome to the Forum.

Short of time now,  but did skim your doc.

You may want to look at the Knowledge Base for some additional info, mostly Classic-related:
http://www.midniteftp.com/support/kb/faq.php?cid=1

Barry - I was unable to find any of the voltage tolerance levels that I seek' questions 2,4,7,9,10,11,12 &13. Are you aware of any specific posts that might answer these questions?

With FLA batts,  you might want to AVOID Al bussbars ...

Barry - My buss bars are 1ft from the batteries. The #4 copper connections from each Bank String are made with anti-corrosion compound. In 1 1/2 years of operation there is no evidence of corrosion, most likely due to the H2 detector properly venting the Battery Box.
Later,  Vic

[Barry Fields]

...  a few additional thoughts,  as breakfast, here, cooks:

Four parallel strings of LA batteries are generally not a good idea.

Barry - Why?

FLAs have needs for attention, and with 96 cells (!!), to tend,  water, SG check, etc,  as well as battery balance issues,  this can lead to less, than needed attention.  If you really need that much batt Capacity,  one or two strings of larger batts is generally a better idea.

Barry - SLA's and AGM's would still need 96 cells without a way to check SG. Remember that some equalization occurs during ABSORB (per DEKA Batteries). SLA's and AGM's need about 1.5 volts less in ABSORB, therefore less equalization.

Also (IMO) AIMS has not had a stellar record of reliability,  support, and parts availability.  Please carefully check all specs,  especially,  what is the Standby power (Tare) losses with the inverter running,  but delivering no power to loads,  and so on.

Barry - Primary Inverter after 1 1/2 years of constant run (not stand-by) so far no problems.  80watt un loaded draw. Max load (everything on at once) = 6200 watts 104%overload.
Secondary Inverter is only on for opportunity loads. Max load = 5400watts


EDIT:  6 kW,  is a large inverter,  forget all of your loads,  but more inverter power is not always better.

Usually,  one would do a Power Budget,  which includes how much power needs to be provided, vs when it is needed<.

Barry - Done - Max Buss bar load @ 42volts and 88% Inverter efficiency = 311Amps  [buss bar rating 800A]
    Max load per Bank String = 78A  String wiring #4 copper (rated 85A @ 75 degrees)
Over the last 1 1/2 years, my average daily discharge was 1.2 KWH/string (10% of capacity). This fits well with my primary objective of running my Refridgerator, freezer, and waterpump for a minimum of 4-5 days.


Also,  if this is your first battery power system, it may be difficult for you to design it to meet your real needs.

Later, just sayin'  ...  Vic

[Barry Fields]

[1]  I presume the Absorb and Float set points are Battery Bank Temperature compensated values.TRUE?
[2]  When the unit is in Absorb or Float, what voltage drop initiates Absorb(mppt) or Float(mppt) and a what voltage does the unit return to Absorb or Float?
[3]  When the unit is in Absorb and a primary load drops the Bank voltage significantly, is the Absorb timer paused?
    If TRUE, what are the parameters for pausing and restarting the timer?    If FALSE, should it be?
[4]  During ABSORB (constant voltage) or FLOAT(constant voltage)  what are the reasonable expectation of the +/- voltage ranges delivered to the Battery Bank?

You set your absorb and float voltage, you set the temp compensation value. The absorb and float setpoints will adjust up or down automatically according to the battery temperature sensor . Example - batteries get colder , the absorb and float values go up.

Barry - Question 1 - Thank you.

If in Absorb the voltage absorb timer starts , if voltage drops below Absorb setpoint, it will
start again at the remaining absorb time once it rises again to absorb voltage.
If in Float and it drops below float setpoint it will go to Float Mppt . It will stay at float setpoint until next day no matter what the battery voltage is - so if battery dropped below float but then raises up it will go back to float.

Barry - Do we know at what voltage levels this occurs? (questions 2,3 and 4)


During Float and absorb - power will always go to loads. You can use Aux settings to turn on and or control loads to use extra power above absorb or float  . example - if in absorb or float  you can have aux turn on a ssr relay to send just the extra power to something like a water heater .

Barry - Kinda knew that but do we know the answers to questions 4,5 and 6 ?.

Larry

[Barry Fields]

regarding your aux questions -
Take a look at some of the videos I made of how I use classic aux 2 waste not to pwm ssr for water heater.
I made a few videos of how I got this going or updates.
Here is one
https://youtu.be/Non3H88UzPs

Barry - This was helpful. I was previously unaware of the capabilities of SSRs. Thank you.

Barry - Most of the rest of my questions deal with the following:

Can AUX1 waste not hi be be set with voltage levels that a "skimmer" circuit would not interfere with ABSORB and FLOAT performance yet still allow the "skimmer" to achieve 100% PWM?

Can AUX2 waste not hi be set so it minimally intereferes with ABSORB and Float performance?
If I had the numbers, I could answer these last 2 questions myself.



Larry

[ClassicCrazy]

[1]  I presume the Absorb and Float set points are Battery Bank Temperature compensated values.TRUE?
[2]  When the unit is in Absorb or Float, what voltage drop initiates Absorb(mppt) or Float(mppt) and a what voltage does the unit return to Absorb or Float?
[3]  When the unit is in Absorb and a primary load drops the Bank voltage significantly, is the Absorb timer paused?
    If TRUE, what are the parameters for pausing and restarting the timer?    If FALSE, should it be?
[4]  During ABSORB (constant voltage) or FLOAT(constant voltage)  what are the reasonable expectation of the +/- voltage ranges delivered to the Battery Bank?

You set your absorb and float voltage, you set the temp compensation value. The absorb and float setpoints will adjust up or down automatically according to the battery temperature sensor . Example - batteries get colder , the absorb and float values go up.

Barry - Question 1 - Thank you.

If in Absorb the voltage absorb timer starts , if voltage drops below Absorb setpoint, it will
start again at the remaining absorb time once it rises again to absorb voltage.
If in Float and it drops below float setpoint it will go to Float Mppt . It will stay at float setpoint until next day no matter what the battery voltage is - so if battery dropped below float but then raises up it will go back to float.

Barry - Do we know at what voltage levels this occurs? (questions 2,3 and 4)


During Float and absorb - power will always go to loads. You can use Aux settings to turn on and or control loads to use extra power above absorb or float  . example - if in absorb or float  you can have aux turn on a ssr relay to send just the extra power to something like a water heater .

Barry - Kinda knew that but do we know the answers to questions 4,5 and 6 ?.

Larry

Barry , for some reason I can't download or see your original question attachment.
Also as a side note - it would help if you answered outside the quotes since it would differentiate from original comment so we could see your reply easier. At least on my computer format.

So not knowing what your exact questions were - I think you asked when absorb timer or float starts - and that is when the Absorb voltage or Float voltage setpoints are reached.

I don't know what you mean by a skimmer circuit.
Using Waste Not or diversion pwm from Aux2 won't interfere with Absorb or Float performance since it only will use any excess power not needed to maintain Absorb or Float.

Larry

[Vic]

Classic Crazy Larry said,

"Barry , for some reason I can't download or see your original question attachment.
Also as a side note - it would help if you answered outside the quotes since it would differentiate from original comment so we could see your reply easier. At least on my computer format"

Larry,  I will try to attach Barry's Question file.   73   VicBarry Fields' Classic CC Questions.rtf

[Barry Fields]

Well, I was able to find ONE answer in the Hawks Bay manual. It states that the unit will enter Float(mppt) on a voltage drop of .3 v. I do not know if that also applies to the Classic 150.

If any of you reading this post feel that the information I have requested would also be of assistance to you, please make your voices known (peaceably and patriotically). I believe that my questions are reasonable and aimed at making more effective use of the Classic 150.

Thanks for ya'lls help.

[boB]

Yes, the -0.3V  is about the same as the Classic's.   

Both Absorb and Float are temperature compensated.

When the battery voltage drops back to bulk from Absorb, the timer will just stop counting.  It will suspend counting. Then, when the large load goes away or the sun comes back, the timer will continue counting from where it left off.    This is if it all happens during the same day.
If it is the next day, then the Absorb counter will start from scratch...  2 Hours or whatever it is set for.

boB

[Barry Fields]

Bob, Thank you for your response. You deserve a well thought out response. My cancer treatments leave me with just so much energy but I will get back to you. The Doctors say I have at least a couple of years left to aggravate people so I will persist in trying to leave something behind for others.
Thanks for your patience.

[boB]

Barry, I am sorry about your cancer and low energy level.

I have had 3 cancers within the last 20 years but nothing in the last 13 years or so (knock on wood)

I understand the problems of course but really commend you on your great attitude and motivation !

We can chat anytime you are ready.

boB