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Just some advise, two 100/30 mppt's, completely separate units, two separate panel arrangements, both mppt's battery cables connected to the same positive busbar but are reading different voltage, one reads 14.29v and is in absorption the other reads 14.14 and is still in bulk, both mppt's have the same settings, don't be concerned or is there something to adjust?
Rod.
They will never be 100% identical due to potentially different resistance in the wiring (cables, connections and fuses) and because one MPPT may be providing more current then the other, resulting in more or less voltage drop in the wiring. There will also be a very small amount of measurement variability between MPPT units, but this is minimal and well controlled.
~0.15V delta is a bit more than I would like to see, but nothing to loose sleep over.
Take a look what the voltage reading delta is at night when there is no current flow in the cables and voltage drop should be basically zero. If the reading is within say ~0.05V during that condition then the delta is related to voltage drop in the individual MPPT wiring during operation.
If you are concerned, you could;
- Review and potentially upgrade all your cabling/connections to minimize voltage drop and ensure that the cable type/size and length is identical for both MPPTs. Sometimes you may even just have a partially loose contact somewhere, such as at the MPPT screw terminals (so check all joints).
-If you have SmartSolar MPPTs, consider adding a SmartBattery Sense device https://www.victronenergy.com/accessories/smart-battery-sense or BMV-712 https://www.victronenergy.com/battery-monitors/bmv-712-smart which takes the voltage reading directly at the battery terminals and create a VE.Smart Network https://www.victronenergy.com/live/victronconnect:ve-smart-networking to send the more accurate voltage reading to the MPPTs.
Thanks for the detailed reply and information Mark much appreciated.
