Author Topic: Voltage reading discrepancy  (Read 239 times)

openplanet

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Voltage reading discrepancy
« on: June 15, 2020, 12:30:47 AM »
Attached are two screen shots, each of the same place in LocalApp for my two Classics, named "Upper" and "Lower."  Note that for Upper, the battery voltage indicated on the dashboard is the same as that in Config/Tech/Offsets (and also the same as what my BMS reads.)  Now look at the screen shot for Lower. 
Can anyone explain why the dashboard reading doesn't reflect the corrected voltage as seen in Config/Tech/Offsets?

Thank you.
_____________________________________
The Sun is but a morning star.  --  H.D.Thoreau
https://www.youtube.com/watch?v=cIANk7zQ05w

Two 1.5 kW arrays --> two Classic 150s --> WbJr. --> four parallel 100 Ah/48 volt rack mount LiFePO4 --> Outback FXR3048 inverter.

boB

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Re: Voltage reading discrepancy
« Reply #1 on: June 15, 2020, 03:22:32 AM »

I'm not exactly sure.    But have you tried changing the offsets of the lower  to 0  instead of 0.3 ?

Does it then agree with the upper ?

These types of things are maybe why Greg at Trace only set voltage readings for 48V systems at a 0.4 volt resolution on
their SW inverter ?

Did you change the offset to 3 or was it like that when you got it ?

Or maybe I read you wrong and you need to change the upper to 3 and put the lower back to 0 ?

Do you have  Fluke meter ?   That's a good standard.
K7IQ

ClassicCrazy

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Re: Voltage reading discrepancy
« Reply #2 on: June 15, 2020, 01:14:55 PM »
Not sure if this is the case with this setting but some things in the Local App don't work correctly.
Try setting it via the MNGP and see if there is any difference.

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

openplanet

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Re: Voltage reading discrepancy
« Reply #3 on: June 15, 2020, 01:29:46 PM »
OK, I'll give that a try when I get home.
Odd thing is that the voltage reading in the dashboard dial is always .2 volts lower than the corrected voltage set in config/tech/offsets. 
_____________________________________
The Sun is but a morning star.  --  H.D.Thoreau
https://www.youtube.com/watch?v=cIANk7zQ05w

Two 1.5 kW arrays --> two Classic 150s --> WbJr. --> four parallel 100 Ah/48 volt rack mount LiFePO4 --> Outback FXR3048 inverter.

ClassicCrazy

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Re: Voltage reading discrepancy
« Reply #4 on: June 15, 2020, 11:57:32 PM »
Is this what you are seeing ?

LOCAL APP BUG
PV INPUT and BATTERY DIALS do not readout OFFSET VALUES, they read out exactly what is present at the blue terminals.
(You need to go to CONFIG / TECH and go down to the OFFSET OPTION to read the OFFSET VALUES)  What this means is if you set an OFFSET the dial will not show this offset voltage, it will remain displaying the "raw" Battery voltage.

from Midnite Knowlege base
http://www.midniteftp.com/support/kb/faq.php?cid=4

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

openplanet

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Re: Voltage reading discrepancy
« Reply #5 on: June 16, 2020, 10:22:54 PM »
Yes! That is exactly what I am seeing Larry.
Thank you!
_____________________________________
The Sun is but a morning star.  --  H.D.Thoreau
https://www.youtube.com/watch?v=cIANk7zQ05w

Two 1.5 kW arrays --> two Classic 150s --> WbJr. --> four parallel 100 Ah/48 volt rack mount LiFePO4 --> Outback FXR3048 inverter.

boB

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Re: Voltage reading discrepancy
« Reply #6 on: June 17, 2020, 04:54:45 AM »

Changing that offset is especially weird when the Classic is in Absorb or Float because since the Classic is trying to keep the voltage constant, the Classic's battery voltage meter does not change when you are adjusting it !

Another thing to add to the pile of knowledge.

Thank you Larry !!

K7IQ