question

Phillip Gutowski avatar image
Phillip Gutowski asked

MPPTs will not switch to bulk mode when connected to Smart Shunt via VE.Smart Network

(3) SmartSolar MPPT controllers receive voltage data from a SmartShunt via a VE.Smart Network. When the controllers are all on the network and receiving battery voltage data, they stay in float and never switch to bulk. When they are off the VE.Smart network, they work as expected and switch in and out of bulk separately, but the voltage rises on the charging bus and causes them to leave bulk early. Two of the MPPT controllers are being used as DCDC converters and are fed a constant ~53 volts.

  • The batteries are (3) 12v Kilovault 100AH LiFePO4 in parallel.
  • SmartShunt voltage sense wire is on the positive terminal of the middle battery
  • MPPTs have been tested with a custom battery profile
    • Float: 13.4
    • Absorb: 14.1
    • Re-bulk: 0.1
  • MPPTs have also been tested with the "Smart Lithium" profile with the same results.
  • Firmware version on the MPPTs: v1.61
  • Firmware version on the SmartShunt: v4.14

Note how the 12v battery voltage is being shared with the MPPTs in this screenshot and is well below the re-bulk voltage of 13.3v. The batteries discharged from 100% SOC to this state in about 4 days. The voltage has been well below the re-bulk voltage for many hours if not days.

screenshot.jpeg

MPPT ControllersSmartShuntVE.Smart Network
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Alexandra avatar image
Alexandra answered ·

@Phillip Gutowski

It is best in your use case to leave the smart network out if it. Leave the mppts to relybon their iwn charge algorithm.

In many install scenarios, the network is unreliable or gets interference and this can cause issues.

To answer your other question, rebulk is rebulk, so the network should not be stopping that, it is more likely it is not receiving data so not doing anything since and that is why they are unactive.

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Phillip Gutowski avatar image Phillip Gutowski commented ·

Thanks @Alexandra. Just to confirm, you think it could be a network issue even though the MPPTs are clearly displaying the battery voltage data they are receiving from the SmartShunt?

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Alexandra avatar image Alexandra ♦ Phillip Gutowski commented ·

There is a strong possibility. Do you have voltage drop over your cables etc?

And it is more interference issues that not receiving any data.

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