Battery AHr Rating: How to Convert 1 AHr rating to 20 AHr rating

mnittlermnittler Posts: 59Solar Expert ✭✭✭
I have access to a used utility (C&D 4LCY7 SAN) battery bank that is currently being replaced after 8 years of service powering switchgear protective relays just because they are 8 years old. The SpGr looks pretty good, the individual cell voltages look good. The configuration consisted of 15 each 8VDC 212 AHr @1Hr rating, weight=310 lbs each. The batteries were originally wired in series for 120vdc.  I intend to pick and choose the 12 best batteries from the group of 15 each and make 2 banks of 48V for my solar system. I currently use 3 banks of 8 each 3 year old  Trojan T-105 6VDC batteries for 48V which will be replaced by the used battery banks.  How would the 212 AHr rating @ 1 Hr compare to the Trojan 225 AHr @ 20 Hr rating? Just looking at the 310 lbs for the C&D batteries vs 62 lbs for the T-105 Trojan tells me they should have more capacity. What is the calculation to convert 1 Ahr rating to 20Ahr rating. The C&D batteries are lead acid type. The used C&D batteries have probably only been cycled to low 12 times in the 8 years during a power outage and have also not been in a controlled environment. Another question is how many years should T-105's last not in a controlled environment in South Texas?

5.1kw Solar/GT SMA SunnyBoy 5000 String Inverter
5.4kw Solar/GT ABB/Aurora 300 MicroInverters
4.1kw Solar/GT Enphase 250 MicroInverters
3.0kw Solar/Hybrid Xantrex XW6048 Inverter
Xantrex XW60-150 MPPT Charge Controller with 3 strings T-105 Batteries (48VDC)
10.0kw Bergey Wind Turbine with 12kw GT PowerSync Wind Inverter
18kw Kohler Propane Generator
64 SqFt Solar Drain Back Water Heater

Comments

  • Marc KurthMarc Kurth Posts: 314Solar Expert ✭✭✭✭
    edited March 1 #2
    There is no universal conversion factor because different battery designs have different characteristics. With many common designs, the 1 hour rating of a NEW battery will generally be 50% to 70% of the 20 hr. rating, 

    If the 1 hr rating is the main published number, they were likely designed for UPS type duty with few, hard/fast discharges in lieu of a larger number of shallow discharge cycles expected with off grid systems.

    At 8 years, I would be very skeptical about how much real life is left.

    Put a fixed load on them and watch the time. You will have your answer.


    I always have more questions than answers. That's the nature of life.
  • BB.BB. Posts: 26,314Super Moderators admin
    Assuming they are good quality AGM batteries--Here is Concorde Lifeline battery curve the 20 hour rate is 100%. They graph out from 1h to 120h rates in comparison:

    https://www.solar-electric.com/lib/wind-sun/Concorde_Lifeline_tech_manual.pdf (see page 32).

    Their 1h rate seems to be ~63% of the 20h rate.
    • 212 AH (at 1h) * 1/0.63 ~ 337 AH (guess at 20h rate)
    If you go by weight (20 hours is relatively "mild" discharge:
    • 212 AH C&D * 6 volt Trojan * 1/8 volt C&D = 159 lb @ 6 volt battery
    • 225 AH (6v Trojan) * 159 lb C&D * 1/62 lb Trojan = 577 AH capacity based on weight compared to Trojan (normalized to 6 volt)
    Still a pretty wide range between the two methods.

    As Marc says--Doing a load test and see what happens is probably best. For example, Concord rates their batteries at end of life when they have less than 80% of rated capacity.

    Put a 20 Hour load on the battery and see how long it lasts (and recharge immediately to prevent damage from sulfation).
    • 400 AH (guess) / 20 hour rate = 20 amp load for 20 hours to "dead"
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • westbranchwestbranch Posts: 4,738Solar Expert ✭✭✭✭
    Have you got some pics of the cells?  It is hard to search the C&D site without more info, also the group name or number would help.
    tks
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge, Hughes1100 Sat Modem
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • mike95490mike95490 Posts: 7,058Solar Expert ✭✭✭✭
    There is a reason the 8 year old batteries are being switched  out.  At 9 years they start failing.  Have fun with them for a year
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • littleharbor2littleharbor2 Posts: 424Solar Expert ✭✭✭✭
    C&D does have a large number of batteries and battery types. I would think any battery with a 1 hour rating on it would be for high rate discharge /UPS type duty and not necessarily suited to 20Ah rating,  daily cycle use.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 700 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.

  • westbranchwestbranch Posts: 4,738Solar Expert ✭✭✭✭
    Little Harbour2.... just checked out a few different batt. models and they ,C&D, list from 1 minute to 20 hrs on some and 1 min to 8 hrs on others so ???,  we just have to wait for more data on them...
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge, Hughes1100 Sat Modem
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • EstragonEstragon Posts: 888Registered Users ✭✭✭✭
    OP saying they were only discharged during a power outage suggests UPS type of battery.  Knowing the longer discharge rates would still be useful in a UPS application if you needed a longer guaranteed uptime for gear.  Remote telecom gear comes to mind.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • westbranchwestbranch Posts: 4,738Solar Expert ✭✭✭✭
    Ah Hemm.....well it is best when the new data is posted at the bottom of the discussion.... so we all know that there is new information!

    here is the data sheet for those batts.http://www.cdtechno.com/pdf/lit/12_324_0115.pdf


     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge, Hughes1100 Sat Modem
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • mnittlermnittler Posts: 59Solar Expert ✭✭✭
    edited March 4 #10
    Ok, so based on the information westbranch found (Which I appreciate greatly) the batteries are:

    C&D 4LCY7 SAN=Standard Case
    4CLY-420
    4CLY=Lead Calicium
    210 Ahr @ 1 hr
    315 AHr @ 3 hr
    366 Ahr @ 5 hr
    420 Ah @ 8Hr
    4 cells/unit, 7 plates/cell
    10.08" Long X 14.13" Wide X 22.75" H
    Weight 310 lbs
    The literature says for Telecommunications applications.

    I have no way to put a load test on the batteries until they are in my possession  since they are currently in use until the replacement batteries arrive.

    2 each of the C&D batteries have one cell that the plates are whiteish in color so I imagine those cells might be going bad but that still leaves 13 that appear to be good to choose from.
    Does anybody have any idea what the optimistic expected life of these type of communication batteries could be?
    The C&D batteries have been connected to a commercial C&D battery charger that was furnished with the system their entire life.

    What is the expected life of Trojan T-105 batteries (my first set that are currently 3 years old). If I purchase another set I will probably get Trojan L15's for the next set.
    The Trojan T-105's are connected to a Xantrex (Schneider) XW6048 and furnish power during power outages and switch to battery power for a residence from 11:00pm to 6:00am every night with a 1 amp (240watt) assist from the grid and have been holding up the entire night (Normally runs 78-82% state of charge in the mornings).

    Anyway would you chance trying the C&D batteries or stay with the 3 year old T-105's for now?


    5.1kw Solar/GT SMA SunnyBoy 5000 String Inverter
    5.4kw Solar/GT ABB/Aurora 300 MicroInverters
    4.1kw Solar/GT Enphase 250 MicroInverters
    3.0kw Solar/Hybrid Xantrex XW6048 Inverter
    Xantrex XW60-150 MPPT Charge Controller with 3 strings T-105 Batteries (48VDC)
    10.0kw Bergey Wind Turbine with 12kw GT PowerSync Wind Inverter
    18kw Kohler Propane Generator
    64 SqFt Solar Drain Back Water Heater

  • westbranchwestbranch Posts: 4,738Solar Expert ✭✭✭✭
    wet cells

    httpwwwcdtechnocomproductvlaasset4lcyjpg
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge, Hughes1100 Sat Modem
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
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