Charge controller not floating

Discussion about the FM100, FM80, and FM60 Charge Controllers

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mbryan
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Charge controller not floating

Post by mbryan »

Good day guys,

We have a single FlexMax 80 charge controller on a solar panel system. After absorbing the controller doesn't switch to float but a "Charged" status. I have checked all connections to batteries and all are tight and there is not a generator or other means of power input. Suggestions on how to make it float after absorb?
raysun
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Re: Charge controller not floating

Post by raysun »

The FM charge controllers, after completing Absorb, switch to a silent state (charged) until the battery voltage falls to the Float voltage, after which the controller wakes up, does an MPPT sweep, and enters Float.

What is the Float Voltage set in the FM80?

(On my system, it typically takes 20 - 40 minutes for the Float state.)

• Check that the battery voltage is reaching the Float voltage.

• Check that the FM80 is properly calibrated. Using a voltmeter, measure the battery terminal voltage and compare to the OUT voltage reading on the FM80 front panel.

• Check that the battery temperature isn't excessive.

• If all the above are normal, try the manual Force Float command. IIRC, its two screens deep in the Misc menu.
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SandyP
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Re: Charge controller not floating

Post by SandyP »

mbryan wrote: Wed Sep 29, 2021 11:49 am Good day guys,

We have a single FlexMax 80 charge controller on a solar panel system. After absorbing the controller doesn't switch to float but a "Charged" status. I have checked all connections to batteries and all are tight and there is not a generator or other means of power input. Suggestions on how to make it float after absorb?
Is this a new problem or has it just recently started happening?
What other equipment do you have in your system (ie inverter etc.) ?
Is there a load on the battery after the absorb stage finishes?
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mbryan
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Re: Charge controller not floating

Post by mbryan »

I tried to reset the controller and after doing it 2 days in a row it stopped for a few weeks. I just did it again today, charge controller said "Charged" and i saw the voltage was at 48v.

Float voltage is set to 54.4v.

The battery voltage just read as 50.18v and the controller has an output of 50.5v, it is actively charging. They do not seem to have excessive heat but I didn't notice for a few hours.

Is a forced float temporary? Will it cycle back to a normal cycle the next day?

The system is a few months old, it has happened a handful of times, 5 or 6.

We have a magnum 4k watt inverter, there is a small load on the system after the absorb state, likely about 480 watts +/- a few hundred watts.
raysun
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Posts: 5909
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01, (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: Charge controller not floating

Post by raysun »

What is the brand and model of the battery?

What is the full set of charging parameters programmed into the charge controller?
Absorb Voltage
Absorb Time
Absorb End Amps
Float Voltage
Current Limit
Re-bulk Voltage
Eq Voltage
Eq Time
Auto Eq Interval

Is a Remote Temperature Sensor being used?
mbryan
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Re: Charge controller not floating

Post by mbryan »

The inverter is a Magnum MS4448PAE.

The batteries are Trojan L16. 1 single bank of 8 batteries.

The charging parameters:
Absorb Voltage is 57.6
Absorb Time is 1 hour
Absorb End Amps is 0
Float Voltage is 54.4
Current Limit is 80 amp.
Re-bulk Voltage is 48
Eq Voltage is 62 volts
Eq Time is 1 hour
Auto Eq Interval is not turned on. I manually set to equalize.

There is not a temp sensor installed. The guy that put it in said it was unnecessary. Should I install the one from the inverter? Didn't seem to me it would make much difference as the current isn't traveling through the inverter to control the temp. When I have a generator for backup I will have it installed but at this point we are just using solar to charge.
raysun
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Posts: 5909
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01, (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: Charge controller not floating

Post by raysun »

mbryan wrote: Sun Oct 10, 2021 2:36 pm The inverter is a Magnum MS4448PAE.

The batteries are Trojan L16. 1 single bank of 8 batteries.

The charging parameters:
Absorb Voltage is 57.6
Absorb Time is 1 hour
Absorb End Amps is 0
Float Voltage is 54.4
Current Limit is 80 amp.
Re-bulk Voltage is 48
Eq Voltage is 62 volts
Eq Time is 1 hour
Auto Eq Interval is not turned on. I manually set to equalize.

There is not a temp sensor installed. The guy that put it in said it was unnecessary. Should I install the one from the inverter? Didn't seem to me it would make much difference as the current isn't traveling through the inverter to control the temp. When I have a generator for backup I will have it installed but at this point we are just using solar to charge.
The Outback Remote Temperature Sensor would be needed to allow the charge controller to perform temperature compensated charging. It's exclusion is not the cause of the no Float issue, but its better for battery health to have it installed.

Do you have a multimeter? When the Absorb cycle completes, and the charger controller status switches to "Charged", measure the battery voltage with the multimeter and compare to the "OUT" voltage on the front panel of the FM80. The two readings should be roughly equal.

Next, wait until the battery voltage drops below the Float voltage setting and make the same measurement.
mbryan
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Re: Charge controller not floating

Post by mbryan »

Good morning, Yesterday the charge controller floated and operated normally. Today is cloudy thus far, we will have to see if we hit the absorb phase.

When the absorb stage finished the batteries were reading 53.75 and the controller read 54.4, Later after the controller was no longer in the float state the batteries were 48.6 and the controller was reading 49.2 and then this morning the batteries were reading 45.9 and the controller was reading 46.4.

Is there a problem with it constantly being off by about 1/2 a volt?
raysun
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Posts: 5909
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01, (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: Charge controller not floating

Post by raysun »

mbryan wrote: Tue Oct 12, 2021 6:23 am Good morning, Yesterday the charge controller floated and operated normally. Today is cloudy thus far, we will have to see if we hit the absorb phase.

When the absorb stage finished the batteries were reading 53.75 and the controller read 54.4, Later after the controller was no longer in the float state the batteries were 48.6 and the controller was reading 49.2 and then this morning the batteries were reading 45.9 and the controller was reading 46.4.

Is there a problem with it constantly being off by about 1/2 a volt?
Yes, being off 0.5V is an issue. It will help to calibrate the charge controller to the battery voltage.

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mbryan
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Joined: Wed Sep 29, 2021 11:41 am

Re: Charge controller not floating

Post by mbryan »

I went into the "Advanced" menu and under vbatt calibration changed to -.5v. Is that what I was supposed to do? Currently the charger is reading 54.4v and the batteries are 54.2v.

Today is the first day we have had a full charge for the last week and after absorb if changed to float.
raysun
Forum Emperor
Posts: 5909
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01, (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: Charge controller not floating

Post by raysun »

mbryan wrote: Mon Oct 18, 2021 1:26 pm I went into the "Advanced" menu and under vbatt calibration changed to -.5v. Is that what I was supposed to do? Currently the charger is reading 54.4v and the batteries are 54.2v.

Today is the first day we have had a full charge for the last week and after absorb if changed to float.
The software voltage offset (VBATT) will adjust the internal voltmeter +/- 0.5V in 0.1V steps. If there is enough adjustment range, the OUT battery voltage on the charge controller's front panel display should equal the voltage measured at the charge controller Bat +/- terminals.

If VBATT adjustment is not sufficient, then the hardware calibration method should be used.
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