Greetings,
I am a beginner, looking to learn from prior mistakes so I don't repeat them. Below is the tale of my first set of AGM batteries that I thought I had cared for properly, expected to last maybe 10 years, but are now degraded to only 5-10% of rated output after 9 years on almost continuous float charge.
Are these batteries done through natural causes (old age)?
Are they done because of no exercise?
Could the charger have abused them?
I want to plan a replacement purchase (considering eight SunXtender PVX-1080T) but now have concerns about getting the right batteries and charger/controller that will perform as expected. I would greatly appreciate some guidance and recommendation on batteries and charger/controller based on your experience with what has worked for you. Am willing to read more, study, do experiments, spend some more money, sweat--whatever it takes to learn and get it done right.
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APPLICATION
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PV Solar generation (design TBD) to charge battery bank that will power manually-activated (i.e. turn off main breaker, connect backfeed cable, etc.) 120v inverter to backfeed house main power panel from 120v/15A circuit in garage. Batteries to be located in ground-floor attached garage, with PV panels direct-mounted (approx. 67 deg angle) on second-story roof facing south in Fairfax, VA. Temperature in garage ranges from 40-85 deg F, but would likely get somewhat hotter without grid-powered AC cooling adjacent rooms on three sides. Would like to use AGM sealed batteries to avoid water maintenance and need for gas ventilation. Max connected load and system design ceiling limited to 15A (backfeed circuit), and initial implementation funding will buy much less than that, maybe half. Depth of discharge not to exceed 80% for maximum life of batteries. Load will be 120v house lights, 120v/9.7A Zoeller M53 sump pump that only runs during extreme rain, maybe a refrigerator.
Have 120v/50A circuit with NEMA outlet located on detached shed in back yard, to backfeed main house panel with propane generator (future purchase), but would like to reserve propane for emergency cooking and heating. And now I'm thinking I'd rather invest in more PV panels rather than buying a generator and having to change oil every 100 hrs anyway.
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INQUIRY SENT TO OPTIMA ABOUT POOR PERFORMANCE
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I purchased four Optima D31M 8052-161 batteries for standby inverter power in September 2003, less than 9 years ago. They have been maintained connected to a float charger inside residential, temperature controlled space. Before recent testing, depth of discharge (DOD) had never been over 50% and number of cycles is less than a dozen. Now I am planning on installing a photovoltaic solar charging system, so I have been testing these batteries for capacity output and they appear to be near end of life. This is very disappointing considering that, other than about 10 light duty cycles (some lights and TV for a couple of hours during power outages), they have been essentially maintained in float state in ideal storage space. I expected more from this product.
The nominal capacity of the bank is 75 Ah x 4 = 300 Amp hours
The four batteries in a parallel bank, produced the following measured output when run to 80% DOD (state determined by inverter):
Run 1: 59 hrs with 60w load = 3540 watt-hours / 119v = 29.74 Ah from the bank
Run 2: 84 hrs with 40w load = 3360 watt-hours / 119v = 28.23 Ah from the bank
Run 3: 40 hrs with 40w to 108w load, calculated total= 18.52 Ah from the bank
Battery voltage checks with load tester
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A B C D
Fully charged: 13.23 13.21 13.14 13.22
80% DOD, open: 10.79 10.78 10.80 10.78
80% DOD, loaded:6.88 7.66 6.06 7.82
In an attempt to "wake up" these batteries, I have run four cycles of slow discharge to 80% DOD using the following loads (1) a 120v 60 watt "fan" (CPAP machine) (2) a 120v 65 watt compact fluorescent load (3) a 120v 40 watt electric motor floor fan, and (4) combination of all above. The wake-up cycles produced no change in measured output capacity.
Test equipment details:
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OTC 3182 130 Amp Digital Battery Load tester
ProMariner ProTournament 100 10 Amp 3 stage battery charger
TrippLite PV1800HF DC to AC PWM sine wave Inverter
NO COMMERCIAL LINKS UNTIL 50 (REAL) POSTS PLEASE: DamonHD
New AIMS CBL01FT1/0 1/0 AWG 1 foot interconnect cables, with load connected pos and neg at opposite ends of the bank
The bottom line question:
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Does this sound like normal performance over time for your product? I had planned to build my PV array storage bank with D31M batteries, but now I have serious concerns about the quality and performance of this product over time.
Please advise.
Thanks,
Lee C
Fairfax, VA
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REPLY FROM OPTIMA
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Hello
Batteries will experience a reduction in capacity or run-time as the battery ages. The active paste
material in a lead-acid battery is a consumable item, similar to tread on a tire. Every time you
cycle/charge the battery some of the paste is used up. As the battery ages, less of the active paste is
available to charge and discharge, resulting in a reduced operating time.
Thank you,
XXXXX XXXXXX
Optima Customer Service
