7.2AH battery charge question

I have a panasonic 7.2AH battery I purchased from digikey a year or two ago for an electronics project i was working on. I took it out this week and noticed the charge was at 12.5v or so.. so I used my trickle 1A charger I've always used to get it back to 12.7v, it gets up there but 20 mins later without using the battery it goes back to 12.5v, and I tried several times.. has its lost its capacity allready? i know its a lead acid battery but is it deep cycle? is this behaviour normal?

Comments

  • mike95490mike95490 Solar Expert Posts: 8,489 ✭✭✭✭✭
    Re: 7.2AH battery charge question

    1A may be too much for that battery, and cause it to vent. You may be seeing "Surface Charge" effect, with the voltage going back to a stable state. Try about 300mA charge for a hour - see if the voltage starts to creep up.
    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 ,

  • System2System2 Posts: 6,290 admin
    Re: 7.2AH battery charge question

    there's no voltage regulator that allows me to send 300ma on it, its a plug and play device I got for 10$ but thanks for the answer, does that mean this battery is no longer good now? since the vents openned?
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: 7.2AH battery charge question

    it may hay lost some capacity due to non-use and just stored, but don't count it out yet as 12.5v isn't terrible either. use it and see what happens.
  • KamalaKamala Solar Expert Posts: 452 ✭✭
    Re: 7.2AH battery charge question

    What battery type? Flooded, sealed, AGM, gel?
  • System2System2 Posts: 6,290 admin
    Re: 7.2AH battery charge question

    this is the one

    http://www.parts-express.com/pe/showdetl.cfm?partnumber=140-465

    says sealed lead acid in the specs
  • mike95490mike95490 Solar Expert Posts: 8,489 ✭✭✭✭✭
    Re: 7.2AH battery charge question

    The spec chart at your link shows it's a VRLA battery.
    Needs a constant voltage charge of 13.7V float usage, or 14.5V cyclic usage
    Expected trickle/float life of 3-5 years, cyclic will be less.

    See what voltage your charger is giving it, try 2 or 3 days at 13.7V, or 1 day at 14.5V
    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 ,

  • System2System2 Posts: 6,290 admin
    Re: 7.2AH battery charge question

    i measured the output voltage of the charger and its 16.83V, that is the only output it gives, I cannot change it
  • mike95490mike95490 Solar Expert Posts: 8,489 ✭✭✭✭✭
    Re: 7.2AH battery charge question

    Connect the charger to the battery, and measure there, what is that?
    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 ,

  • System2System2 Posts: 6,290 admin
    Re: 7.2AH battery charge question

    i measured 15.28 volts
  • RCinFLARCinFLA Solar Expert Posts: 1,280 ✭✭✭
    Re: 7.2AH battery charge question

    The charger voltage probably changes under load. Check the voltage on the battery terminals with the charger connected. Let it set on charge and check voltage periodically. If it gets over 14.6 vdc take it off charger.

    Depending on your charger it may automatically drop back to 13.8 v. If not, don't let it set at >14.5 for more then five hours.

    If it is 15.3 vdc as soon as you connect charger the battery is probably bad. It has very high internal resistance that will not support a load.
  • System2System2 Posts: 6,290 admin
    Re: 7.2AH battery charge question

    there's 2 LEDs on the charger block, one says "POWER" the other "CHARGING", the power is on when i plug it in and the CHARGING led goes off about 30 seconds after the battery is connected to the charger.. when it used to work right it would say CHARGING for an hour or more and would hold the 12.7 charge for days or weeks.. now after 30 seconds the CHARGING Light goes off and the volts go back to 12.5 or so without using the battery
  • KamalaKamala Solar Expert Posts: 452 ✭✭
    Re: 7.2AH battery charge question

    Found this link at Panasonic

    http://www.panasonic.com/industrial/battery/oem/chem/seal/

    While shopping for AGM batteries I was confused by the term VRLA (Valve Regulated Lead Acid.) I have come to the conclusion that all AGM batteries are VRLA. But, probably, not all VRLA are AGM. The Panasonic site states the the battery in question can be "used in any position." This leads me to believe that this is an AGM battery. The purpose of VR in an AGM is to keep the case from deforming, cracking (exploding?) under overcharge conditions by venting 2 parts hydrogen and 1 part oxygen, meaning loss of electrolyte (water). (My East Penn 8AGC2s will vent @ 2PSI and I will never allow that to happen.) In a flooded battery, the electrolyte is easily replaced by adding distilled H2O to the individual cells of the battery. In a VRLA the cells are not accessible and the electrolyte cannot be replaced. It is gone forever.

    Charging an AGM or VRLA at nearly 17 volts will damage it. I think this is what has happened in your case. If you get a proper charger (search for Battery Minder of Battery Tender) you may be able to get some more life out of your battery. If you continue to charge it at 16.8 it will die soon.

    Sorry.

    [with other posts ahead] Keep V <15

    Craig
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