VFX2812 Limiting Charging Current?

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feudalkaos
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VFX2812 Limiting Charging Current?

Post by feudalkaos » Fri Feb 14, 2020 7:24 am

I have a VFX2812 connected to a 400Ah LiFePO4 bank at 12V. I have configured charging as such:
Absorb Voltage: 14.0 Time: 0.1
Float Voltage: 12.0 Time: 0.0
Re-Float Voltage: 11.0

My bank is around 50% charged and at about 13.5V right now. I set the charger to Auto so it went into Bulk charging mode as expected. For some reason it is limiting the output current much lower than it is capable. It is configured to limit AC current to 14A for charging (the maximum) and my current AC input voltage is 108V(this marina is a little low). That should mean that I have about 108A DC that could be given to the batteries if I am charging to 14V. For some reason I am only seeing 40A.

The ambient temperature is 72F so it is not likely a temperature problem and the temperature sensor has been disconnected from the inverter since the LiFePO4 cells do not need temperature compensation.

Any thoughts?

Thank you

Mike Curran
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Re: VFX2812 Limiting Charging Current?

Post by Mike Curran » Fri Feb 14, 2020 7:42 am

If your battery has a BMS then I'd suspect the problem lies there.

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feudalkaos
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Re: VFX2812 Limiting Charging Current?

Post by feudalkaos » Fri Feb 14, 2020 10:07 am

It does have a BMS however the BMS is not doing any current limiting.

Currently the BMS is allowing up to 350A for charging current.

raysun
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Re: VFX2812 Limiting Charging Current?

Post by raysun » Fri Feb 14, 2020 10:58 am

feudalkaos wrote:
Fri Feb 14, 2020 7:24 am
I have a VFX2812 connected to a 400Ah LiFePO4 bank at 12V. I have configured charging as such:
Absorb Voltage: 14.0 Time: 0.1
Float Voltage: 12.0 Time: 0.0
Re-Float Voltage: 11.0

My bank is around 50% charged and at about 13.5V right now. I set the charger to Auto so it went into Bulk charging mode as expected. For some reason it is limiting the output current much lower than it is capable. It is configured to limit AC current to 14A for charging (the maximum) and my current AC input voltage is 108V(this marina is a little low). That should mean that I have about 108A DC that could be given to the batteries if I am charging to 14V. For some reason I am only seeing 40A.

The ambient temperature is 72F so it is not likely a temperature problem and the temperature sensor has been disconnected from the inverter since the LiFePO4 cells do not need temperature compensation.

Any thoughts?

Thank you
There's two AC IN current limit settings, one for the overall AC IN to the inverter and the AC IN to the charger.

The inverter in bypass mode (using AC IN) prioritizes the the available current between loads and charging. If there is enough for both, the charger runs at its max current setting. If loads demand more, charging is scaled back. If loads demand more than AC IN can supply, then AC IN is dropped and battery power is drawn by the inverter.

What is the Shore power amperage?

EMCF
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Re: VFX2812 Limiting Charging Current?

Post by EMCF » Fri Feb 14, 2020 11:35 am

feudalkaos wrote:
Fri Feb 14, 2020 7:24 am
It is configured to limit AC current to 14A for charging (the maximum) and my current AC input voltage is 108V(this marina is a little low). That should mean that I have about 108A DC that could be given to the batteries if I am charging to 14V. For some reason I am only seeing 40A.

The ambient temperature is 72F so it is not likely a temperature problem and the temperature sensor has been disconnected from the inverter since the LiFePO4 cells do not need temperature compensation.

Any thoughts?

It's configured for an input AC current of 14AAC. Is it actually delivering that much?
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raysun
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Re: VFX2812 Limiting Charging Current?

Post by raysun » Fri Feb 14, 2020 11:49 am

Screenshot_20200214-094053_Chrome.jpg
Looking at the AC INPUT page on my inverter. There are two settings (three actually) that interoperate:

Grid Input AC Limit
Charger AC Limit
Input Type

Notice the Charger AC Limit is set to 14AAC
However, the Grid Input AC Limit is set to 5AAC

If there was zero house load, then the 5A AC IN would go to the charger (and no more, no matter the charger setting.) If there was a 3AAC house load, the charger would be restricted to 2AAC.

The Grid Input AC Limit should be set to the amperage of the Shore power circuit as indicated at the breaker.

(Or is you are marina bumming like me way back in the day, a shiny penny placed behind a blown fuse would set the shore power service to 92AAC. Should the wiring not handle that, there was always the outgoing tide for salvation.)

The Input type can switch between the two AC IN profiles,labeled "Grid" and "Gen"

feudalkaos
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Re: VFX2812 Limiting Charging Current?

Post by feudalkaos » Fri Feb 14, 2020 12:35 pm

my inverter is configured like this:

Grid Input AC Limit 30.0A
Gen Input AC Limit 30.0A
Charger AC Limit 14.0A

I have a 30.0A feeder into the inverter from a dock side shore power pedestal. I am seeing 108V from the pedestal which is having an impact but I am surprised at how much. I have not yet measured the actual current coming in on the AC side so that will be the next test.

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