Sun Xtender AGM Battery - Bad Experience

I'm curious if anyone else has had experience with the Sun Xtender line of AGM batteries.
In 2012 I purchased 4 (PVX-1040T) to use in a 48v solar system using Morningstar's MPPT Charge controllers. The system was small at that time and never was drained below 60% charge. About 2 months after the warranty expired, two of the batteries would no longer take full charge and about a month later failed to hold a charge under any load.
I contacted the manufacturer and they gave me no explanation for the issue and offered no help in testing or determining the failure.
In late 2013 I expanded my system and added 8 new AGM batteries, Being a glutton for punishment, I purchased them again from Sun Xtender.

Again, around 2 months after the 12 month warranty 2 more of the 8 batteries failed, They no longer will charge correctly or maintain voltage with even a minimal current load (5-10 amps).
I contacted the company again, same results as before. About 2 months farther down the road, 2 more of them failed.
I purchased an expensive charger/re-conditioner for AGM batteries, that specifically listed the brand and model of the battery, as being compatible.
The batteries are still unusable .

Comments

  • BB.BB. Super Moderators, Administrators Posts: 32,235 admin
    I am really sorry to hear about your problems with the Sun Xtenders...

    Lead acid batteries are usually toast once they "go bad"... So, my questions would be along the lines of what was the charging voltage you measured at the battery bank?

    How do you know the State of Charge of the batteries (good quality DMM measuring resting voltage/Battery Monitor/etc.)?

    Have you been keeping track of each battery's voltage in the series strings? Are batteries going bad because of "open" or "shorted" cells? Do you see warning signs (hot battery/hot battery caps from over charging/hot catalysts, swelling, etc.)? Do the batteries sit for days/weeks at less than full charge (lead acid batteries sitting at less that ~75% state of charge without cycling tend to sulfate over days/weeks/months). Are the batteries kept in a hot/cold/high vibration environment? Have the batteries ever "vented"?

    Many batteries go bad becasue of mistakes by the user or problems with the charger/application (not blaming you--Just trying to figure out what is happening). On occasion, charge controllers have been known to have problems too.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • KRLUTHERKRLUTHER Registered Users Posts: 2
    Thanks for your response and questions.
    Currently I'm using Morningstar's TriStar MPPT-60 controller, It logs the values of the battery bank overall, And at regular intervals I use a Sencore DVM to measure each individual battery. Both during charging and during load usage.
    Since this is my primary source of power the battery bank has never been left idle, other than a few days a year when I am gone. At that time the receive charge/float from the solar array without any draining loads.
    I'm not sure how to know if the battery is shorted or open cells. Being that they are AGM I can not do "Specific Gravity" testing. Also this type of battery has no visible venting to observe.
    The batteries will show fully charged, and may remain that way for a day, however when placed under a 100 watt test load they drop to 4-6 volts almost instantly and do not recover above 10 volts after 10 seconds of load.
    One of the batteries will show fully charged, but begins loosing voltage slowly when disconnected, over about a 10 hour idle time, it drops below 10 volts.

    The TriStar units have remote battery temperature monitoring and have never recorded excessive heat. Also the batteries show no external signs of heat, leakage or anything I can visualize.
    The building that houses them is well ventilated and is not exposed to any movement or vibration.
    The interconnects to the batteries use copper lugs soldered to #2 stranded copper wire.

    Note: I have several Alpha Cell brand AGM batteries that have been in service now for over 8 years, They are just recently becoming weaker and not holding up to a moderate current draw. (By Moderate, I mean about 4 amps of load, they run down in about 2 hours.) these batteries are 85AH rated.

    The Sun Xtender batteries I'm using are rated for 108 AH, and are separated from the Alpha bank using latching relays, and they use a secondary MPPT-60 for their charge control.
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    KRLUTHER wrote: »
    "at regular intervals I use a Sencore DVM to measure each individual battery. Both during charging and during load usage". (But not at rest)
    The batteries will show fully charged, and may remain that way for a day,

    How do they show you that they are "fully charged"? What is the design voltage of your batteries and how many are wired in parallel strings? Were good new batteries wired up with older batteries that were no longer working properly?
    Here's a good read on batteries: "Most batteries don't die - they are murdered". http://www.solarsolutionssa.co.za/?battery-faq,93

  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    here is some info I got a few years back from a company that tests AGM installations for industrial apps..
    IEEE Std.1188 VRLA TESTING RECOMMENDATIONS:
    An acceptance test of the battery capacity should be made at the manufacturer’s factory or upon initial installation, as determined by the user. The test should meet a specific discharge rate and duration relating to the manufacturer’s rating or to the purchase specification’s requirements.

    Batteries may have less than rated capacity when delivered. Unless 100% capacity upon delivery is specified, initial capacity can be in the range of 90 to 95% of rated capacity. This will rise to rated capacity after several charge-discharge cycles or after a period of float operation. These acceptance criteria should be based on a time adjusted calculation, running the full published rate.

    An acceptance test should also establish the baseline capacity for trending purpose. If the time adjustment method will be used for future performance tests, then the above time-adjusted calculation can be used for the baseline. If the rate adjustment method will be used for future testing, then an additional capacity calculation should be performed to establish the baseline.

    Batteries should undergo additional performance tests periodically. When establishing the interval between tests, factors such as design life and operating temperatures should be considered. It is recommended that the performance test interval should not be greater than 25% of the expected service life or two years, whichever is less. The expected service life may be significantly less than the warranty period. The recommended interval assumes that an on-site acceptance test was performed with acceptable results. Acceptable results are defined as the capacity of each cell exceeding 90%, and the capacity of all cells are within 10% of the average cell performance. For batteries that were not acceptance tested on site or had unacceptable results, the first performance test should be given within one year of installation.

    Capacity testing may also be warranted within the recommended interval where internal ohmic values have changed significantly between readings and or significant physical changes have occurred to the cells.

    Annual performance tests of battery capacity should be made on any battery that shows signs of degradation or has reached 85% of the service life expected for the application. Degradation is indicated when the battery capacity drops more than 10% from its capacity on the previous performance test or is below 90% of the manufacturer’s rating

    AND wrt to using a Megger to test
    No, it's special ground meter that can put up to 1,000 volts through cell.
    If there is a leak then the meter will display numeric value showing a direct short.
    If there is no leak then it will show infiniti.

    It's made by Megger (insulation break down meter).
    It can be used on electric motors or anything that needs to be checked to ensure there is no ground path.

    hth
     
    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,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • BB.BB. Super Moderators, Administrators Posts: 32,235 admin
    KRLUTHER wrote: »
    Note: I have several Alpha Cell brand AGM batteries that have been in service now for over 8 years, They are just recently becoming weaker and not holding up to a moderate current draw. (By Moderate, I mean about 4 amps of load, they run down in about 2 hours.) these batteries are 85AH rated.

    Note: 4 amps * 2 hours = 8 AH of stored (useful) energy.

    Those batteries are "end of useful life" by the standard definition--A battery has "failed" if it loses ~20-40% of its capacity. Your batteries have (patiently) lost around 90% of their capacity.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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