allen-goldstein avatar image
allen-goldstein asked

2 MPPT 75/10s. Battery connected in parallel. Both need manual restart of charger when 1 goes to 0 W

I think Victron needs to change the firmware.

This is a new install. 2 75/10 in parallel with the battery. Load outputs are disconneted. No other Victron devices present and the 2 MPPTs are 4 inches apart.

At low load and full battery SOC one of the Mppts will go to 0 W (not always the same one). Now when I add load such as turning on my freezer. The MPPT will remain at 0 W even though the battery is discharging.

The only way to get it working is to disable charging on BOTH MPPTs, Then re enable the one at 0W first.

But then, if I shut off the freezer. Both MPPTs will go into absorption mode even though the battery is 100% SOC.

After a while one or the other MPPT will go to 0W and the cycle begins again where it will never output power until both are disabled and re-enabled.

MPPT SmartSolarmppt state
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Alexandra avatar image Alexandra ♦ commented ·

@Allen Goldstein

Try changing your tail current or rebulk offset under expert mode.

What batteries do you have?

Bulk and absorption are the same target voltage, one just draws more current that the other.

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allen-goldstein avatar image allen-goldstein commented ·

I have 2 4D agm batteries 220 AH each.

The focus of this thread should be on the need for a manual disable and re enable. Not the fact that after reenable the charger goes into absorption. Manual operation should not be needed.

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Alexandra avatar image Alexandra ♦ allen-goldstein commented ·

So you are running the loads off the battery

If the mppt thinks the battery is fully charged, it will not produce anymore (otherwise the battery could be overcharged)

So you need to change the rebulk offset, so that the mppt will begin bulk production sooner.

Did you use an agm profile then alter charged voltages?

I did not focus on the absorption, I suggested the re bulk option fix first, gave an explanation for the absorption.

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