Author Topic: Classic display shows 0% for hours before "low battery"  (Read 342 times)

auroralm

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Classic display shows 0% for hours before "low battery"
« on: February 17, 2020, 10:31:42 PM »
I have a Classic 150, four 320 watt panels and two 640 lithium batteries, with another battery and two more panels about to go online.

In the past, when the display shows around 25% charge left in my batteries, I'd get a low battery warning on my inverter, and power would shut off not too much later.  Suddenly the Classic is showing levels of 1% or even 0% but I continue to have power for hours before the low battery warning comes on.  I'm brain injured and dyslexic, and for me, the % number is the easiest way for me to track the state of the batteries. I recently moved to the mountains of Puerto Rico, where constant weather changes make input unpredictable, so I really need accurate information.  Can you tell me why it might have suddenly changed its behavior and what to do about it?

Also, and this has always been true, sometimes it doesn't show the % at all and I can't figure out what setting I have to change so it will.

Finally, I recently had a circuit rewired, and changed from a DC fridge that was a nightmare to get any service on, to an AC fridge that I was told would only draw 1.5 amps.
 
Is there an easy way to tell from the Classic itself how much power the fridge is actually drawing?

Thanks,
Aurora
Finca La Lluvia
Maricao, Puerto Rico 
 

ClassicCrazy

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Re: Classic display shows 0% for hours before "low battery"
« Reply #1 on: February 17, 2020, 10:46:42 PM »
First I am assuming you have a whizbang installed with a shunt on your system ? Because the SOC wont really work without those.
Do you use the Local Status app to monitor your Classic ? If so you look at first Status Screen and the System Amps shows everything going into and out of the battery.
At night you will only be taking out so if you know when the refrigerator starts up you will be able to see that extra power draw on the system amps.
If you have an Android tablet or phone get Grahams Classic Monitoring app because it has good graphical displays of the SOC and all the other voltages, amps , and temperatures of the Classic and shows better than the Local App power consumption of devices because  you can toggle the screen between amps and watts .

It is hard to tell more about why your SOC changed without getting more info on how your system is set up. If you can take some screen shots of your local status app display or photos of your mngp screens that might help .
What battery voltage is your system ?

Larry
system one
Classic 150 , 5s4p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system two
Classic 150 ,5s 135 watt Kyocero , 16s Calb 100AH LiFePO4 , Outback VFX 3648 inverter
system three
Midnite KID MPPT 24 DC in to  12 volt AGM batterie

boB

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Re: Classic display shows 0% for hours before "low battery"
« Reply #2 on: February 17, 2020, 11:33:49 PM »
What Larry said, first of all...   And...

Lithium batteries don't usually have an "Absorb" cycle  and so I don't know how the Classic is set up for that part of your charge cycle.  The resetting to 100% works as sort of a calibration of the SOC%  part of things because the amp-hours in and amp-hours out aren't always the perfect way of know the state of charge over long periods of time.  This is because the charging efficiency is not perfectly known and even the true amp-hour capacity of the battery bank in most cases.  It can be higher or lower than the rating of the battery.

The Classic will reset to 100%  when the Classic goes from Absorb to Float, so that may be something worth thinking about ?

What you might try is this...   When you KNOW the batteries have gotten a full charge, force the Classic to 100% SOC to get it back on track.

There is a certain button pushing sequence that you can do on one of the MNGP's Whizbang Junior menus.  I don't remember off hand but will look.  Someone here may also know that sequence.  I think it is going into the WB Jr. SETUP menu or second status menu and holding down an arrow key while tapping the ENTER key ?  Will have to look.

I expect that it just needs to be reset to 100% when full once in a while unless something else is messed up,  We'll try for the simple fix first unless something wrong is obvious.

Also, you can kind of guestimate the current draw of your 120V AC load by noting the DC current draw when the refrigerator is on vs. when it is off.   If you have a 48V battery system, you should see something like 2 and 1/2 times the DC current of the refer on the WB Jr. because of the 120V/48V ratio.

BTW, I love Puerto Rico !   I spent a few days up in the mountains a couple years ago helping out with our products and Magnum inverters.  What a great time that was !



K7IQ

auroralm

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Re: Classic display shows 0% for hours before "low battery"
« Reply #3 on: February 18, 2020, 07:44:53 AM »
Thank you both.  So, reminder--I'm a brain injured newby and need everything spelled out. Exactly how do I "force the Classic to 100% SOC?"  Please come back to Puerto Rico! Now! :-) I'm going to need help setting up a second Classic and wind turbine.  Seriously, are there people you worked with here who might be able to help me?  I've found one person but he's not super available. Will post pics shortly.

ClassicCrazy

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Re: Classic display shows 0% for hours before "low battery"
« Reply #4 on: February 18, 2020, 10:43:06 AM »
Thank you both.  So, reminder--I'm a brain injured newby and need everything spelled out. Exactly how do I "force the Classic to 100% SOC?"  Please come back to Puerto Rico! Now! :-) I'm going to need help setting up a second Classic and wind turbine.  Seriously, are there people you worked with here who might be able to help me?  I've found one person but he's not super available. Will post pics shortly.

Do you use the Local Status app on the computer to monitor the Classic ? Or do you use the MNGP screen that is on the Classic ?
I would like to give  you the proper instructions depending on which you use .

Larry
system one
Classic 150 , 5s4p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system two
Classic 150 ,5s 135 watt Kyocero , 16s Calb 100AH LiFePO4 , Outback VFX 3648 inverter
system three
Midnite KID MPPT 24 DC in to  12 volt AGM batterie

Vic

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Re: Classic display shows 0% for hours before "low battery"
« Reply #5 on: February 18, 2020, 11:37:15 AM »
As boB mentioned,

To reset the Net  Ah to 0,  which should reset the SOC indication to 100% (with a  small exception):

Do this -  From the main Status page  on the Classic display,    push the small  round button on the left,  on the  display four times  --  this should take you to the WbJr Status page.   Press the Left square button.   This will take you to the page  on the display for WbJr Net Ah.    Hold down the left arrow  button,    while pressing   the Enter button.   This should reset the Net Ah to 0,  and return the SOC to 100%.      Only do this when you have a good reason to believe that the battery IS fully-charged.   Sometimes  you will need to hold down the left Arrow button AND hold down the Enter button for a few seconds,  for this reset to take place.  (as boB had mentioned).

Good luck,   Vic
« Last Edit: February 19, 2020, 11:20:39 AM by Vic »
Off Grid - Two systems -- 4 SW+ 5548s, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 3X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  Thanks MN for Great Products/Service/Support!

auroralm

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Re: Classic display shows 0% for hours before "low battery"
« Reply #6 on: February 22, 2020, 07:34:51 AM »
Thanks folks. I use the screen on the classic. Right now, getting to a full charge is a challenge. I'd probably have to unplug the fridge for a few days. But I'll figure out a way. Thanks, Vic for the blow by blow.