Battery Bank in Parallel

Discussion about the OutBack battery rack solutions
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headsavers
Forum Member
Posts: 8
Joined: Thu Jul 02, 2020 9:03 am
My RE system: Aquired

Just helping friend with aquired Outback components:
1- Inverter/Charger VFXR3648A

2-SOLAR CHARGER FLEX mAX 80

16-SLA BATTERY 12 VOLYS, 250AH

12-LG365Q1C-A5 365WATT SOLAR MODULES

Battery Bank in Parallel

Post by headsavers »

Have 2 battery banks composed of 8-12 volt 250AH SLA batteries connected series/parallel ( 16-total ). Can I connect the 2 battery banks ( 48-volt 500AH ) in parallel ( 48-volt 1000AH ) total capacity to 1-VFXR3649A Inverter ? Each battery bank is charged thru FlexMax 80 using solar array supplying 110 Volt at 20 Amps each.
raysun
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Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01, (2) FM80, MATE3s, FlexNetDC
6 SimpliPhi 3.8-48 (48v @ 75AH. 450AH total)
Outback IBR3 battery enclosure
REC Alpha 440W panels - 2 arrays: each of 4 strings of 2 in series
Honda EU7000is gas fuel generator

Re: Battery Bank in Parallel

Post by raysun »

Are all the battery monoblocks the same model, and the same age?
headsavers
Forum Member
Posts: 8
Joined: Thu Jul 02, 2020 9:03 am
My RE system: Aquired

Just helping friend with aquired Outback components:
1- Inverter/Charger VFXR3648A

2-SOLAR CHARGER FLEX mAX 80

16-SLA BATTERY 12 VOLYS, 250AH

12-LG365Q1C-A5 365WATT SOLAR MODULES

Re: Battery Bank in Parallel

Post by headsavers »

Yes, about 1 year old and are fully charged because I tried to charge 4 connected in series using a flexmax 80 CC from a solar array of 110 volt at 9.95 amps and it went directly to Absorb ( .2 Amps ) meaning won't take anymore charge. This I did to see if the batteries are good or not.
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SandyP
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Posts: 507
Joined: Tue Jun 21, 2011 4:44 am
My RE system: 8 x 190W 24V Suntech panels (4 strings of 2) July 2011
4 x 325W 24V Suntech panels (2 strings of 2) added Sept2018
Mate2
Outback FM60 MPPT (max output lowered to 55amps)
12 x 2V Hoppecke GEL 612 Ah C24 - 24V System (June 2011)
Outback VFX3024 Inverter/Charger
Victron BMV-602s
Honda 5.5kW Genset
Location: Victoria, Australia

Re: Battery Bank in Parallel

Post by SandyP »

headsavers wrote: Wed Jul 08, 2020 5:14 pm Have 2 battery banks composed of 8-12 volt 250AH SLA batteries connected series/parallel ( 16-total ). Can I connect the 2 battery banks ( 48-volt 500AH ) in parallel ( 48-volt 1000AH ) total capacity to 1-VFXR3649A Inverter ? Each battery bank is charged thru FlexMax 80 using solar array supplying 110 Volt at 20 Amps each.
Four parallel strings of batteries is not ideal. Make sure all the cabling is good and ALL the interconnectors are of equal length.
The VFXR will operate with the 1000Ah battery bank however the charging using the inverter will not be optimal.
Your solar panel array should give enough current to meet the charging requirements of the battery bank.
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provo
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Posts: 1093
Joined: Thu Jul 27, 2006 4:34 pm
My RE system: 16 Evergreen EC-120 (4 strings, total 1920W)
2 SimpliPhi 3.8-m-24V (150Ah each)
One FM80
One VFXR3524A
Hub 10
Mate3s
FNDC
Honda EU3000is generator
Location: Sierra foothills

Re: Battery Bank in Parallel

Post by provo »

SandyP wrote: Wed Jul 08, 2020 7:15 pm
Four parallel strings of batteries is not ideal. Make sure all the cabling is good and ALL the interconnectors are of equal length.
The VFXR will operate with the 1000Ah battery bank however the charging using the inverter will not be optimal.
Your solar panel array should give enough current to meet the charging requirements of the battery bank.
I'd say it's marginal. 4380W of panels at full rated power would give 91A at 48V. That's a 9% charge rate for a 1000Ah pack, and that's at a power level you'll rarely see. If you just lost (sold?) one string you'd have a pack that would be somewhat easier to keep balanced, and 91A into a 750Ah pack is a 12% charge rate.

Do you really need that much battery?
headsavers
Forum Member
Posts: 8
Joined: Thu Jul 02, 2020 9:03 am
My RE system: Aquired

Just helping friend with aquired Outback components:
1- Inverter/Charger VFXR3648A

2-SOLAR CHARGER FLEX mAX 80

16-SLA BATTERY 12 VOLYS, 250AH

12-LG365Q1C-A5 365WATT SOLAR MODULES

Re: Battery Bank in Parallel

Post by headsavers »

This setup is not mine, it was acquired by a friend and I am just helping him check the system so that he can sell the system or the components. I help people install grid tied home solar systems. Thanks for all your suggestions.

Romeo lampa
retired E.E.
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