Batteries not BULK charging to set voltage 29.8V

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JeffinthePeace
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Posts: 102
Joined: Mon Oct 01, 2018 8:20 pm
My RE system: VFX3524 Inverter/Charger.
2 x FM80 Charge Controllers.
12 Trina PV panels: 365W, 48.0Voc, 9.3A Imp.
Total 4380W PV.
Midnight Sun Combiner Boxes.
Mate (Original) and Hub4.
TriMetric 2020 Battery Monitor.
1065 Ah Yuasa 85T-21 FLA 24V battery bank (10 yrs old).
10kW 120/240VAC Kubota/Stamford diesel generator.
PSX-240 Auto Transformer for generator charging.
No Utility Grid available.
Location: Peace Country, British Columbia

Batteries not BULK charging to set voltage 29.8V

Post by JeffinthePeace » Fri Dec 14, 2018 7:06 am

Hi -
My batteries do not seem to be bulk charging to the set voltage of 29.8V, before the amperage starts dropping.
I have 80 Amps of charging capacity thru a VFX3524.
The batteries will start charging at close to 80 Amps, but after few hours the amperage starts slowly dropping, to 70 and slowly down from there. And the batteries are only at 28.6V!!
In my mind, the charging amperage should stay as high as possible until the Absorb setpoint of 29.8V is reached.
The generator I am charging with is a 14kW genset so lots of power.
The battery bank is 24V 1065Amp-Hour bank.
Any ideas??

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Kurt Lundquist
Alpha Energy Engineering
Posts: 1447
Joined: Tue May 31, 2011 7:23 am
My RE system: VFX3524, Mate3, 200Ah 24V AGM Battery Bank
Location: Arlington, WA

Re: Batteries not BULK charging to set voltage 29.8V

Post by Kurt Lundquist » Fri Dec 14, 2018 7:35 am

Hi Jeff,

Do you have a battery temperature sensor installed on the VFX?

Does the Mate show Absorb when the current starts to drop off or is it still in bulk mode?

Is the AC input set to 60 Amps?

-Kurt
Kurt Lundquist
Renewable Energy Project Engineer
http://alphaenergy.us/

JeffinthePeace
Forum Guru
Posts: 102
Joined: Mon Oct 01, 2018 8:20 pm
My RE system: VFX3524 Inverter/Charger.
2 x FM80 Charge Controllers.
12 Trina PV panels: 365W, 48.0Voc, 9.3A Imp.
Total 4380W PV.
Midnight Sun Combiner Boxes.
Mate (Original) and Hub4.
TriMetric 2020 Battery Monitor.
1065 Ah Yuasa 85T-21 FLA 24V battery bank (10 yrs old).
10kW 120/240VAC Kubota/Stamford diesel generator.
PSX-240 Auto Transformer for generator charging.
No Utility Grid available.
Location: Peace Country, British Columbia

Re: Batteries not BULK charging to set voltage 29.8V

Post by JeffinthePeace » Fri Dec 14, 2018 7:48 am

Hi Kurt -

I do have a Remote Temperature Sensor, yes.
(The batteries do get quite warm and are gassing, that is for sure.)

I cannot tell on the Mate what Mode it is charging in. I donÔÇÖt know if itÔÇÖs in Bulk or Absorb. ItÔÇÖs a older Mate or Mate 2.
How can I tell?

In the menu:
ADV/FX/GEN
The setting ÔÇÿac2/genÔÇÖ input limit is set to 48.0 aac.
Should this be set to 60 Amps??

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Kurt Lundquist
Alpha Energy Engineering
Posts: 1447
Joined: Tue May 31, 2011 7:23 am
My RE system: VFX3524, Mate3, 200Ah 24V AGM Battery Bank
Location: Arlington, WA

Re: Batteries not BULK charging to set voltage 29.8V

Post by Kurt Lundquist » Fri Dec 14, 2018 1:12 pm

Hi Jeff,

On the Mate go to STATUS > DC > METER. Press down to see battery actual, then down again to see battery temp compensated. If the battery temp compensated shows 29.8V then the temperature is the reason why the battery charge current is dropping off before you see the battery actual voltage hit your Absorb target. Keep pressing down until you see Absorb Time Remaining. If that clock is counting down the system is in Absorb.

With 14kW of gen you should be able to put AC input amps up to 60A from the 48A default. This will help make sure the battery charger doesn't slow down if your AC load exceeds 28A.

-Kurt
Kurt Lundquist
Renewable Energy Project Engineer
http://alphaenergy.us/

JeffinthePeace
Forum Guru
Posts: 102
Joined: Mon Oct 01, 2018 8:20 pm
My RE system: VFX3524 Inverter/Charger.
2 x FM80 Charge Controllers.
12 Trina PV panels: 365W, 48.0Voc, 9.3A Imp.
Total 4380W PV.
Midnight Sun Combiner Boxes.
Mate (Original) and Hub4.
TriMetric 2020 Battery Monitor.
1065 Ah Yuasa 85T-21 FLA 24V battery bank (10 yrs old).
10kW 120/240VAC Kubota/Stamford diesel generator.
PSX-240 Auto Transformer for generator charging.
No Utility Grid available.
Location: Peace Country, British Columbia

Re: Batteries not BULK charging to set voltage 29.8V

Post by JeffinthePeace » Sun Dec 16, 2018 8:43 pm

Hi again -

About the battery voltages, I found them displayed in the Mate under STATUS/FX/BATT.

I am currently charging with the generator, a few hours into it:
Battery Actual = 28.2 vdc
Battery Temp Compensated = 28.4 vdc
(On my TriMetric = 28.0 vdc)

Absorb Time Remaining has NOT started counting down yet, so this leads me to believe it is still in Bulk Chatge mode.

On the TriMetric it shows 70 amps charging. But I think it should still be putting a full 80 amps into the batteries!

We are not using much power in the house (a few lights) so we are not robbing the inverter of charging amps. Besides, with a 14kW genset and our Gen Input Linit set to 60.0 aac now (up from the default 48.0 aac), there is no shortage of input power.

So I still have this mystery as to why the charging amperage starts dropping way before we get to the Absorb set-point of 29.8V.

Any ideas?? We need every amp possible going into the batteties!! With a battery bank of 1065 amp-hours but only charging at 70 amps (and dropping) I fear we are really under-charging our batteries :/

User avatar
Kurt Lundquist
Alpha Energy Engineering
Posts: 1447
Joined: Tue May 31, 2011 7:23 am
My RE system: VFX3524, Mate3, 200Ah 24V AGM Battery Bank
Location: Arlington, WA

Re: Batteries not BULK charging to set voltage 29.8V

Post by Kurt Lundquist » Mon Dec 17, 2018 7:12 am

Hi Jeff,

Is the inverter set to 20 amps AC for charing?

Is your generator 120V or is it 120/240?

Are you using the PSX-240 transformer to step down generator voltage or to step up inverter voltage?

What is the AC input voltage when you notice the charge start to slow down?

-Kurt
Kurt Lundquist
Renewable Energy Project Engineer
http://alphaenergy.us/

blackswan555
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My RE system: Other peoples, VFX "E" versions, FLA`s, Generators.
Location: Ibiza Spain,

Re: Batteries not BULK charging to set voltage 29.8V

Post by blackswan555 » Mon Dec 17, 2018 7:46 am

What are your SGs doing ?
Tim
ps, Kurt, What is the VA output in charge mode, is it just doing V vs A and a bit of temp derating ?
My comments are based on my experience and research, They are not endorsed or checked by Outback.I am an independent British electrician living in Spain, So please take this into account when reading /acting on my post`s.

User avatar
Kurt Lundquist
Alpha Energy Engineering
Posts: 1447
Joined: Tue May 31, 2011 7:23 am
My RE system: VFX3524, Mate3, 200Ah 24V AGM Battery Bank
Location: Arlington, WA

Re: Batteries not BULK charging to set voltage 29.8V

Post by Kurt Lundquist » Mon Dec 17, 2018 8:26 am

blackswan555 wrote:ps, Kurt, What is the VA output in charge mode, is it just doing V vs A and a bit of temp derating ?
Hi Tim,

You have a good point. The power conversion is current limited with 20 amps AC as the max input for battery charging. If we assume AC to DC conversion is ~85% efficient I could see charging amps dropping off when the batteries are ~26V or greater. If the generator AC voltage is low the problem would be even worse. Furthermore, battery charging creates a lot of heat in the inverter so the charging efficiency can drop over time depending on ambient conditions. All of these are logical reasons why Jeff isn't seeing 80 amps charging when the battery voltage is high.

If the generator is 240V a second VFX3524 inverter could be set up on leg 2 to increase battery charging. This would reduce generator wear and tear, save fuel, and Jeff would have an emergency spare/backup.

-Kurt
Kurt Lundquist
Renewable Energy Project Engineer
http://alphaenergy.us/

JeffinthePeace
Forum Guru
Posts: 102
Joined: Mon Oct 01, 2018 8:20 pm
My RE system: VFX3524 Inverter/Charger.
2 x FM80 Charge Controllers.
12 Trina PV panels: 365W, 48.0Voc, 9.3A Imp.
Total 4380W PV.
Midnight Sun Combiner Boxes.
Mate (Original) and Hub4.
TriMetric 2020 Battery Monitor.
1065 Ah Yuasa 85T-21 FLA 24V battery bank (10 yrs old).
10kW 120/240VAC Kubota/Stamford diesel generator.
PSX-240 Auto Transformer for generator charging.
No Utility Grid available.
Location: Peace Country, British Columbia

Re: Batteries not BULK charging to set voltage 29.8V

Post by JeffinthePeace » Sat Dec 22, 2018 5:03 pm

Hello Kurt and Tim -

Kurt:
i.The VFX3524 charger is indeed set to 20aac for charging, which is the max.
ii. The gen is a 120/240V.
iii. The AC input does come through a PSX240 transformer. I believe it is set up to step down the voltage but am not sure.
Is there a way to verify this?
iv. The AC is set to 120V, and is nice and steady on that setting.
Any feedback on these responses is appreciated!

Tim:
I charted a charge cycle - please see the attached image. I tracked battery voltage and temperature compensated battery voltage on the Mate, battery voltage on the Trimetric, and charging amperage on the Trimetric.
I took SG measurements hourly.
This was a 15 hour charge cycle.
Similarly, any input on these measurements is appreciated!

If i understand correctly, it is likely battery temperatures and other inefficiencies in the charge cycle that prevent getting a full 80amps through the cycle.
Then, if I understand correctly, the recommendation is to look at adding a second battery charger to the set-up.
I see the wisdom in adding another VFX3524 inverter, but wonder if I should consider looking at other after-market chargers like Xantrex, Iota or Noco? And adding two of those chargers?

Any feedback on this is really appreciated!
And I would like to add how much I appreciate the engagement on this forum! Thank you both so much!

Jeff
Attachments
A99B8691-3456-4507-85AB-63654194DDDE.jpeg
Charging Cycle

blackswan555
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Posts: 2637
Joined: Sat Aug 30, 2008 5:50 am
My RE system: Other peoples, VFX "E" versions, FLA`s, Generators.
Location: Ibiza Spain,

Re: Batteries not BULK charging to set voltage 29.8V

Post by blackswan555 » Sun Dec 23, 2018 6:05 am

First I explain the charging amps a little better
The AC is set to 120V, and is nice and steady on that setting.
Any feedback on these responses is appreciated!
That will be 120v X 20a giving 2400va,minus about 15% for losses, 320va, leaves 2040va divide that by your charge voltage to get charge amps
2040va @ 24v > 85 amps
2040va @ 26v > 78 amps
2040va @ 28v > 72 amps

Readings, They are strange (not what I would expect from a FLA bank anyway) I understand your bank is made up of 2 strings of 4 v cells ? (Please fill in your profile as fully as possible, It helps us to help you) I suspect there is something wrong there, Can you list the SGs and voltage of each cell please, Also when were they last EQd ?

Extra charging, I would go with another vfx, it gives you a "spare" in event of master breakdown,


Tim
My comments are based on my experience and research, They are not endorsed or checked by Outback.I am an independent British electrician living in Spain, So please take this into account when reading /acting on my post`s.

JeffinthePeace
Forum Guru
Posts: 102
Joined: Mon Oct 01, 2018 8:20 pm
My RE system: VFX3524 Inverter/Charger.
2 x FM80 Charge Controllers.
12 Trina PV panels: 365W, 48.0Voc, 9.3A Imp.
Total 4380W PV.
Midnight Sun Combiner Boxes.
Mate (Original) and Hub4.
TriMetric 2020 Battery Monitor.
1065 Ah Yuasa 85T-21 FLA 24V battery bank (10 yrs old).
10kW 120/240VAC Kubota/Stamford diesel generator.
PSX-240 Auto Transformer for generator charging.
No Utility Grid available.
Location: Peace Country, British Columbia

Re: Batteries not BULK charging to set voltage 29.8V

Post by JeffinthePeace » Sun Dec 30, 2018 7:39 pm

Hi Tim, Kurt -

Tim, you had asked about my battery bank:
1065 Ah Yuasa 85T-21 FLA battery bank (10 yrs old).
ÔÇö> Batteries set up in 6 pre-fab boxes x 4V each = 24V system. (Eack 4V pre-fab box has 2 adjacent connected Negative terminals with vent cap on one side, and 2 adjacent connected Positive terminals with vent cap on the other side. Stored indoors, ventilated case.)
(Battery history, for context:
I used to have TWO 1065Ah sets as described above, total 2130 Ah, connected in parallel.
But, as I only have 80A of charge capacity with the VFX3524, and would be undercharging the entire 2130Ah bank, I have since disconnected one of the sets.)

I have just attempted charging my remaining 1065Ah bank at 20A AC ÔÇö result:
Achieved (reduced, ÔÇÿtrialÔÇÖ) Absorb setpoint voltage of 28.8V, and SG of 1.23.
Over 3 hours of Absorb time, voltage stayed at 28.8V and amperage dropped slowly to 45A. SG of 1.26.
I charged for another hour or so but amperage did not drop any more and SG did not rise any more.
During charge, battery temp went from 129units* (23C) to 132units* (28C).
This (partial) charge process to took 10 hours!

I then tried to equalize ÔÇö result:
Charge amperage back up at approx 75A, but voltage DROPPED over 4 hours...not rose...down to 27.6V.
SG did not rise above 1.26, but then readings got unreliable with the hydrometer I was using when electrolyte temps rose.
Battery temp rose to 117units* (41C). Literally boiling, gassing heavily.

Note: I am quoting only one SG value. I have checked SG values of all cells and they are all within 0.015 so far. Will continue checking/verifying this.

(These * battery temp units quoted above are from the Mate. Outback doesnÔÇÖt say what the temp units are but apparently falling unit values means rising temp, and vice versa. Counter-intuitive.)

So I do not seem to be able to charge or equalize these batteries properly any more.
I cannot get 29.6V into the battery on charge.
I cannot get a high enough voltage into the battery to equalize.
I cannot confirm getting get SGs above 1.26 (manufacturer claims full charge is in range of 1.265-1.275) but will try measuring again when electrolyte temperatures come down.

It is probably partly because of age (10 years) but the age likely just compounds problems from undercharging for so many years??
I am open to trying equalization again but fear I may be causing damage from high temps??
I would be willing to try anything. Any thoughts or ideas, gang??

Barring any conflicting advise, I plan to continue trying to charge then equalize!

Signed,
Desperate :/

JeffinthePeace
Forum Guru
Posts: 102
Joined: Mon Oct 01, 2018 8:20 pm
My RE system: VFX3524 Inverter/Charger.
2 x FM80 Charge Controllers.
12 Trina PV panels: 365W, 48.0Voc, 9.3A Imp.
Total 4380W PV.
Midnight Sun Combiner Boxes.
Mate (Original) and Hub4.
TriMetric 2020 Battery Monitor.
1065 Ah Yuasa 85T-21 FLA 24V battery bank (10 yrs old).
10kW 120/240VAC Kubota/Stamford diesel generator.
PSX-240 Auto Transformer for generator charging.
No Utility Grid available.
Location: Peace Country, British Columbia

Re: Batteries not BULK charging to set voltage 29.8V

Post by JeffinthePeace » Mon Dec 31, 2018 9:23 am

Update:

I checked my SGs again this morning:
They are all consistently 1.255-1.260, so I donÔÇÖt believe I have any singular bad cells...maybe they are all bad.
Voltage is at 24.4, 4.06V per cell.
FYI my Trimetric shows I have used 230Amp-Hours since ÔÇÿchargeÔÇÖ.

I guess at this point I am looking for recommendations on how to recover these batteries!

J

blackswan555
Forum Emperor
Posts: 2637
Joined: Sat Aug 30, 2008 5:50 am
My RE system: Other peoples, VFX "E" versions, FLA`s, Generators.
Location: Ibiza Spain,

Re: Batteries not BULK charging to set voltage 29.8V

Post by blackswan555 » Mon Dec 31, 2018 10:40 am

Have a read of section 19,
http://rollsbattery.com/public/docs/use ... Manual.pdf
Corrective EQ, But as you say they are old,,,,,

But this sounds "about right"
I have just attempted charging my remaining 1065Ah bank at 20A AC ÔÇö result:
Achieved (reduced, ÔÇÿtrialÔÇÖ) Absorb setpoint voltage of 28.8V, and SG of 1.23.
Over 3 hours of Absorb time, voltage stayed at 28.8V and amperage dropped slowly to 45A. SG of 1.26.
I charged for another hour or so but amperage did not drop any more and SG did not rise any more.
During charge, battery temp went from 129units* (23C) to 132units* (28C).
This (partial) charge process to took 10 hours!
Tim
My comments are based on my experience and research, They are not endorsed or checked by Outback.I am an independent British electrician living in Spain, So please take this into account when reading /acting on my post`s.

JeffinthePeace
Forum Guru
Posts: 102
Joined: Mon Oct 01, 2018 8:20 pm
My RE system: VFX3524 Inverter/Charger.
2 x FM80 Charge Controllers.
12 Trina PV panels: 365W, 48.0Voc, 9.3A Imp.
Total 4380W PV.
Midnight Sun Combiner Boxes.
Mate (Original) and Hub4.
TriMetric 2020 Battery Monitor.
1065 Ah Yuasa 85T-21 FLA 24V battery bank (10 yrs old).
10kW 120/240VAC Kubota/Stamford diesel generator.
PSX-240 Auto Transformer for generator charging.
No Utility Grid available.
Location: Peace Country, British Columbia

Re: Batteries not BULK charging to set voltage 29.8V

Post by JeffinthePeace » Sat Jan 19, 2019 9:20 pm

Well I just wanted to follow up to say that I am having much more success with charging.
Doing a couple things different:
Keeping electrolyte levels in cells higher: more water, but not too much.
Improved battery storage box ventilation so I can keep the temperature down: avoid over-heating and excessive gassing.
Dropped the absorb voltage down to 28.8V, then working back up to 29.0V, then 29.2V and so forth.
Watching SGs closer.
And in general, giving the system a bit more care and attention.
Read, watch, and learn.
J

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