Biased battery manager

[GALAWA]

I have a WAECO battery manager which measures Amps charging and discharging from the service battery and computes/displays the state of discharge of said batteriy in Ampxhours.
To this effect net Amps are measured from a shunt on the - pole of the battery bank.
Unfortunately, the battery manager either underestimates the charging current or over estimates the discarging current: After a week it displays say 300 Amp x h discharge when the battery is actually fully charged and the MPTT in float mode.
I then reset the battery manager to zero discharge.... and a week later it displays again 300 Amp x h discharge when the battery is fully charged.
Could someone advise?

[smac999]

Are you sure the shunt is in the right place? There should be nothing between the shunt and battery neg post. Sounds like your solar might be in front of it.