Does all the OutBack systems/inverters carries out an over discharge battery bank protection?

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Ing. Alvarez
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Joined: Wed Jun 10, 2020 12:22 pm

Does all the OutBack systems/inverters carries out an over discharge battery bank protection?

Post by Ing. Alvarez »

Hi,
This is a general question and how OutBack solves it. Designing my system and looking at the big picture, Does all the OutBack systems/inverters carries out an over discharge battery bank protection? ...or need to consider it separately and together with designing the battery bank?
How the systems/inverters protects the batteries? Is it through a Voltage Sensitive Relay?
Is it true that VSR are not capable when drawing high amount of current?
Is it true that the surge that can occur when starting up some devices could trip the VSR, because drop voltage but not really low SOC?
Is it true that the protection that the inverters in general include is for protecting themselves for low voltage but not rely to protect the battery?

Thank you!
Cheers.
raysun
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My RE system: Flexpower Two: (2) FXR3048A, (2) FM80, MATE3s, FlexNetDC
SimpliPhi 48-3.8 (6 @ 48v)
Outback IBR3 battery enclosure
REC Alpha 440W panels - 2 arrays: each of 4 strings of 2 in series
Honda EU7000is gas fuel generator

Re: Does all the OutBack systems/inverters carries out an over discharge battery bank protection?

Post by raysun »

The Outback inverters all have Low Battery Cut Off (LBCO) settings. These set a battery voltage lower limit. If the battery drops below LBCO for 5 minutes, the Inverter shuts down. LBCO is principally to protect the Inverter from creating a distorted output waveform when supplied with too-low battery voltage.

LBCO is not really designed to protect the battery from over-discharge, though it can be used that way, after a fashion, by adjusting LBCO upward.

However, the relationship between battery voltage and state of charge is only valid with the battery completely at rest (open circuit.) Battery voltage will vary with change in load, so voltage readings on an active battery are a matter of interpolation and estimate.

It's much better to track battery state of charge (SoC) using a battery monitor that tracks charge flow into and out of the battery. These types of monitors can derive SoC with the battery under load. Outbacks FlexNET DC (FNDC) is such a monitor. It works in conjunction with the Mate3s to provide a functional battery monitoring solution including response to SoC events, if needed.
fcwlp
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My RE system: GS8048A, FM80 w/3,600W PV Fixed, FM80 w/2,700W on Zomeworks tracker, Mate3, 24 Trojan 2V L16 1100AH @ C20, Grid-Tied with Kohler 14RESA LPG Generator and MEP-803 Diesel if needed.

I install and maintain grid-tied and off-grid systems in my area and consult on solar system design/operation.
Location: 80 miles NE of Phoenix at 5500'

Re: Does all the OutBack systems/inverters carries out an over discharge battery bank protection?

Post by fcwlp »

raysun wrote: Wed Jun 10, 2020 1:37 pm he Outback inverters all have Low Battery Cut Off (LBCO) settings. These set a battery voltage lower limit. If the battery drops below LBCO for 5 minutes, the Inverter shuts down. LBCO is principally to protect the Inverter from creating a distorted output waveform when supplied with too-low battery voltage.
Raysun has an older inverter. The new VFXRs and Radians allow you to set the LBCO delay between 0.1 and 24.0 seconds with 6 seconds as the default.
raysun
Forum Emperor
Posts: 4624
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A, (2) FM80, MATE3s, FlexNetDC
SimpliPhi 48-3.8 (6 @ 48v)
Outback IBR3 battery enclosure
REC Alpha 440W panels - 2 arrays: each of 4 strings of 2 in series
Honda EU7000is gas fuel generator

Re: Does all the OutBack systems/inverters carries out an over discharge battery bank protection?

Post by raysun »

True that.
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