Time for new batteries

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hillside
hillside Registered Users Posts: 148 ✭✭
in Solar Beginners Corner #1
First off thanks again to Photowhit for help by posting a diagram for my series/parallel wiring last year. Saved a ton of grief!
So my 6V. golf cart batts are failing and am looking at options. They lasted all of 2&1/2 yrs.
A basic 940w system (4 panels) for backup power and washer/gas dryer.
Not used everyday, but if we get another hurricane it would be...
3000W Cotek pure sine inverter, with a SRNE MPPT C/C.
4-6V. 208AH batts and a 24 volt setup.

I like the Concorde Sun Xtenders AGM ,but shipping charge from NAWS for the 224AH is >$900.+ for 4.
For the 305AH it is, well, I stopped there as it is bigger and 27lbs. heavier. So, shipping matters!
Locally, I found the Deka 370AH lead acid batts. @ $270 ea. They are 6v.
Same place had Deka 12V AGMs @245AH, for $495.ea.
Price wise, it's close enough, but would it make sense to switch to 2- 12V AGMs for my 24V setup, or go with the lead acid batts. at a higher AH (370 vs 245), but with a shorter life span?
The only other factor is our warm climate, typically always 80* days, but 90* in summer, similar to South Florida, so the batteries, although in a concrete shaded walkway, stay warm. Thanks!

8- 235Watt panels, 2 strings in series/parallel, 4L16 Deka 6Volt, 370AH FLA. batteries, 3000W Cotek pure sine inverter, SRNE ML2440 40Amp Controller &  40 Amp Renogy controller, 24 Volt system.
5 stand alone PV arrays; 12V gate opener, 24V Dankoff rain water pumping system, 12V Shurflo rain water garden pumping, 12V bathroom LED lighting and fan.
4- 450 Watt panels with 4 L16 6 volt batts./ 2-Renogy Tracer 40 Amp controllers/ Xantrex 1800W PSW Inverter.
Honda EU3000W generator for backup.
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  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,044 ✭✭✭✭✭
    edited June 2019 #2
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    Does the size/shape of the battery make any difference? The 6 volt 370 Ah. batteries are probably L-16 type. Tall and pretty heavy (over 100 pounds). The 245 Ah. 12 volt batteries are probably a 4D or 8D type, low, long and wide. Also quite heavy.  The L-16's are probably a better fit, being taller , would have a smaller footprint for a given Ah. sized bank. 

    Why do you think the flooded batteries would have a shorter lifespan? AGM's are known for shorter lifespan, although poorly maintained flooded batteries will fail pretty darn fast when neglected.

    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,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

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  • Tecnodave
    Tecnodave Registered Users Posts: 437 ✭✭✭✭
    edited June 2019 #3
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    FLA with a shorter life than AGM???  I don't think you have the facts there,  AGM batteries do not have anywhere the lifespan of large format FLA batteries. My Rolls-Surette S-530 L-16's are 14 years old and still at full capacity, I've never heard of anyone getting that life from AGM batteries
    2 Classic 150, 2 Kid, 5 arrays 7.5 kw total  2ea.  2S6P Sharp NE-170/NE-165, 1ea. 12P Sanyo HIT 200,  2ea. 4/6P Sanyo HIT 200, MagnaSine MS4024AE, Exeltech XP-1100,  2 Banks L-16 battery, Rolls-Surette S-530 and Interstate Traction, Shunts with whizbangJr and Bogart Tri-Metric, iCharger i208B  dc-dc buck/boost converter with BMS for small form lithium 8S 16650 or LiFePO4,
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  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #4
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    Although checking FLA SGs and watering is a bit of a chore, I'd rather do it and have the extra confidence the info provides and the ability to take early remedial action as needed.  If I really needed the capabilities of AGM (eg some have higher charge/discharge rates, lower self-consumption, any orientation installation) I would use them, but otherwise would stick with flooded.

    My preference would be a single string (eg 4 x 6v L16s) if possible.  My L16s are still doing well (touches wood) after 5yrs.  Properly maintained, I hope to have some years left yet.
    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
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  • Thom
    Thom Solar Expert Posts: 196 ✭✭✭
    #5
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    If batteries only last 2.5 years you have a problem. Figure that out 
    Off grid since 1984. 430w of panel, 300w suresine , 4 gc batteries 12v system, Rogue mpt3024 charge controller , air breeze windmill, Mikita 2400w generator . Added 2@ 100w panel with a midnight brat 
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  • hillside
    hillside Registered Users Posts: 148 ✭✭
    #6
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    harbor, I thought AGMs had a longer life span because I've been reading the advertising!...that's why I came here for advice.
    And you're right in that the 370A  AGMs are tall and 121 lbs. Size is no problem; there's enough space for them.
    It's only recently that the choice of batteries here has improved. It only took Hurricane Maria to bring that about...
    I maintained the existing batteries carefully as they needed water almost monthly, but they're Interstate golf cart type. And someone here mentioned not to expect much life out of them.
    So, it looks like my 2 best choices are 6V FLA GC15 230AH  at $130. ea. or
    the L16 370AH also FLA...at $270. ea. And they're both in stock meaning no shipping charges.


    8- 235Watt panels, 2 strings in series/parallel, 4L16 Deka 6Volt, 370AH FLA. batteries, 3000W Cotek pure sine inverter, SRNE ML2440 40Amp Controller &  40 Amp Renogy controller, 24 Volt system.
    5 stand alone PV arrays; 12V gate opener, 24V Dankoff rain water pumping system, 12V Shurflo rain water garden pumping, 12V bathroom LED lighting and fan.
    4- 450 Watt panels with 4 L16 6 volt batts./ 2-Renogy Tracer 40 Amp controllers/ Xantrex 1800W PSW Inverter.
    Honda EU3000W generator for backup.
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  • Tecnodave
    Tecnodave Registered Users Posts: 437 ✭✭✭✭
    #7
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    The L-16 format had a sediment settling chamber twice as large as golf cart types, and raising sediment does contribute to fail mode, the tall skinny batteries have a distinct advantage in this area. I have two banks of L-16 in service, A purchased new set from Interstate , now 8 years old and the Rolls-Surette S-530's that I intercepted on the way to recycle 6 years ago, now 14 years old now and still at full capacity.  
    2 Classic 150, 2 Kid, 5 arrays 7.5 kw total  2ea.  2S6P Sharp NE-170/NE-165, 1ea. 12P Sanyo HIT 200,  2ea. 4/6P Sanyo HIT 200, MagnaSine MS4024AE, Exeltech XP-1100,  2 Banks L-16 battery, Rolls-Surette S-530 and Interstate Traction, Shunts with whizbangJr and Bogart Tri-Metric, iCharger i208B  dc-dc buck/boost converter with BMS for small form lithium 8S 16650 or LiFePO4,
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  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #8
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    2.5 years isn't terrible for GC batteries in hot conditions IMHO.  If they were using substantial water from day 1 though, I'd wonder if absorb voltage and/or time could have been dialled back a bit, and/or temperature compensated charging wasn't compensated properly.  If not used daily, just floating most days, and doing a full absorb cycle bi-weekly or so can also extend life. 
    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
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  • hillside
    hillside Registered Users Posts: 148 ✭✭
    #9
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    Estragon, regarding the golf cart batteries...only recently I upgraded to the MPPT C/C- before that I used a basic 30A PWM controller, but that was also with just 500 watts of panels. Could that have been an issue?
    I added the SRNE MPPT  controller when I added the new panels...
    Anyway, I'm leaning towards the bigger batteries, the L16 370AH...the better choice? :)
    8- 235Watt panels, 2 strings in series/parallel, 4L16 Deka 6Volt, 370AH FLA. batteries, 3000W Cotek pure sine inverter, SRNE ML2440 40Amp Controller &  40 Amp Renogy controller, 24 Volt system.
    5 stand alone PV arrays; 12V gate opener, 24V Dankoff rain water pumping system, 12V Shurflo rain water garden pumping, 12V bathroom LED lighting and fan.
    4- 450 Watt panels with 4 L16 6 volt batts./ 2-Renogy Tracer 40 Amp controllers/ Xantrex 1800W PSW Inverter.
    Honda EU3000W generator for backup.
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  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,044 ✭✭✭✭✭
    edited June 2019 #10
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    Batteries have a finite number of full charge cycles. This number can be extended with conservative depth of discharge. If they are heavily discharged on a regular basis they will defiantly live a shorter chronological life

    This is for gel batteries but still gives you an idea of how depth of discharge will affect the number of cycles in lead acid batteries.

    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,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

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  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #11
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    500w panels might produce 350ish watts in actual use, so ~15a, depending on panel voltages and wiring.  A bit low, but not terrible for a system not in daily use.  Like LH2 says, deep discharge (especially if left discharged for long) can make for shorter life.

    A pwm controller can charge just about as well as mppt, provided panel/string voltage is well matched.  A very basic model may not adjust charging voltage (absorb and float) for battery temp though, which can be a problem if bank temp varies much from 25°C.
    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
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  • hillside
    hillside Registered Users Posts: 148 ✭✭
    #12
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    We've never let the current set of batteries get over discharged. The system only does part time work and goes several days at a time w/o use, and the inverter is turned off.
    Currently the batteries have gone into the "fair" range in SG, showing between 1.250 and 1.225. Still serviceable for what we use them for but as I said, I'm favoring the 370AH FLA batteries. Just looking to get better service and will probably use the system more to defray cost of electricity here. Thanks for the help.
    8- 235Watt panels, 2 strings in series/parallel, 4L16 Deka 6Volt, 370AH FLA. batteries, 3000W Cotek pure sine inverter, SRNE ML2440 40Amp Controller &  40 Amp Renogy controller, 24 Volt system.
    5 stand alone PV arrays; 12V gate opener, 24V Dankoff rain water pumping system, 12V Shurflo rain water garden pumping, 12V bathroom LED lighting and fan.
    4- 450 Watt panels with 4 L16 6 volt batts./ 2-Renogy Tracer 40 Amp controllers/ Xantrex 1800W PSW Inverter.
    Honda EU3000W generator for backup.
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  • MichaelK
    MichaelK Registered Users Posts: 234 ✭✭✭
    #13
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    I think the details are important here.  Are these two 250W 60-cell panels that are putting out 29-30VDC.  Were these wired into the PWM controller in series or parallel?  If The ambient daytime temperatures are very high, it may be that the panels were never putting out high enough voltage to properly charge a 24V battery bank.  Can you tell us what the actually the CHARGING voltage was when the panels were in noon time sun?  I have a set of four Trojan T105's that still have SG in the range of 1.27 to 1.28 after 5 years.  They were lightly cycled though, powering little more then lights and a TV in the time they were in use.  Now that you have a MPPT controller, what are the charging setting adjusted to?  How are the four panels now wired?  Are they still in parallel, or are they in series?  I have to agree that something has not been optimized that your batteries are only lasting about 2.5 years.
    System 1) 15 Renogy 300w + 4 250W Astronergy panels,  Midnight 200 CC, 8 Trojan L16 bat., Schneider XW6848 NA inverter, AC-Delco 6000w gen.
    System 2) 8 YingLi 250W panels, Midnight 200CC, three 8V Rolls batteries, Schneider Conext 4024 inverter (workshop)
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  • hillside
    hillside Registered Users Posts: 148 ✭✭
    #14
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    I haven't checked noon time charging voltage in some time but will so so tomorrow. I can't find the record of it-(usually keep up on that stuff)
    I have 4 235 watt panels wired series/parallel like Photowhit posted in this diagram:  https://forum.solar-electric.com/discussion/comment/390900#Comment_390900
    The batteries are Interstate Powerfast 208AH golf cart--not sure of their reputation...

    8- 235Watt panels, 2 strings in series/parallel, 4L16 Deka 6Volt, 370AH FLA. batteries, 3000W Cotek pure sine inverter, SRNE ML2440 40Amp Controller &  40 Amp Renogy controller, 24 Volt system.
    5 stand alone PV arrays; 12V gate opener, 24V Dankoff rain water pumping system, 12V Shurflo rain water garden pumping, 12V bathroom LED lighting and fan.
    4- 450 Watt panels with 4 L16 6 volt batts./ 2-Renogy Tracer 40 Amp controllers/ Xantrex 1800W PSW Inverter.
    Honda EU3000W generator for backup.
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  • hillside
    hillside Registered Users Posts: 148 ✭✭
    #15
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    today at 11;30AM, before it clouded up, I read 52.5 volts from the panels at the charge controller. That's consistent with past readings.
    8- 235Watt panels, 2 strings in series/parallel, 4L16 Deka 6Volt, 370AH FLA. batteries, 3000W Cotek pure sine inverter, SRNE ML2440 40Amp Controller &  40 Amp Renogy controller, 24 Volt system.
    5 stand alone PV arrays; 12V gate opener, 24V Dankoff rain water pumping system, 12V Shurflo rain water garden pumping, 12V bathroom LED lighting and fan.
    4- 450 Watt panels with 4 L16 6 volt batts./ 2-Renogy Tracer 40 Amp controllers/ Xantrex 1800W PSW Inverter.
    Honda EU3000W generator for backup.
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  • hillside
    hillside Registered Users Posts: 148 ✭✭
    #16
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    And all are 60 cell panels.
    8- 235Watt panels, 2 strings in series/parallel, 4L16 Deka 6Volt, 370AH FLA. batteries, 3000W Cotek pure sine inverter, SRNE ML2440 40Amp Controller &  40 Amp Renogy controller, 24 Volt system.
    5 stand alone PV arrays; 12V gate opener, 24V Dankoff rain water pumping system, 12V Shurflo rain water garden pumping, 12V bathroom LED lighting and fan.
    4- 450 Watt panels with 4 L16 6 volt batts./ 2-Renogy Tracer 40 Amp controllers/ Xantrex 1800W PSW Inverter.
    Honda EU3000W generator for backup.
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