Classic 150 Voltage Compensation

[glenn2387]

I have 3 Classis 150's and all 3 are behaving in the same manner. Each controller runs 1 PV Array charging the same 3 Lithium batteries (3 - 300 Amp Paralleled)  If I offset voltage when there's no sun / system is resting, it requires little to no offset but when charging the voltages all go higher that actual / true voltage by about .5 Volts causing the controllers to go into Absorb too soon. I'm verifying voltage with 2 other monitors and a Fluke Meter at the battery terminals on the Classics. If I set the offset voltage when the Controllers are charging, they all require an offset of -.5 V which when at rest are all reading the .5 too low but when charging they obviously read correct actual voltages. Is this behavior correct? See following examples / data:

Normal Target Voltages:
Rest 13.2
Absorb 14.2

Voltage Offset 0:
Resting Voltage 13.2V (Correct)
When charging voltage reads .5 High and will go into Absorb when batteries are actually only at 13.7

Voltage Offset -.5
Resting Voltage 12.7 (Actual voltage is 13.2)
When charging voltage reads correctly and goes into float at 14.2

All 3 Classics are new and are behaving the same way.  HELP?!?!

[FNG]

Sounds like voltage drop on wires/disconnects. When the classics are charging hard and you have the 0.5 volt variation measure the voltage at the classics terminals to see if they agree or are off by 0.5v

[australsolarier]

the midnite classic does not necessarily correspond with the shown voltage as compared what the real voltage is. even after adjusting the Vbat voltage.
the wire resistance should not really affect the midnite classic voltage, only the voltage at the battery terminals.
battery sense wires would really be a great thing.