6v lead acid battery

electrokidelectrokid Posts: 3Registered Users
Hi all,
               I recently bought a lead acid battery (6v , 4.5Ah). The first time when I bought it it had a voltage of about 6.4v. while I charged it for the first time  ,it was not able to charge above 6v and this continued for all the subsequent charging. Moreover after the battery was removed from the charger and kept idle for few days, the battery lost about 2v within a week.
I used a simple 7.5 v battery charger to charge it( supplies a constant voltage at 500mA).
Please help me to find the fault with my battery/charger so that I can fix it.
Thanks in advance.

Comments

  • EstragonEstragon Posts: 2,839Registered Users ✭✭✭✭✭
    Is this a sealed type of battery, or flooded (with caps on top to access the acid inside)?

    If flooded, are the plates inside covered by liquid?

    If sealed, the should be a vent to allow gasses to escape if needed to prevent buildup of internal pressure. Is there any residue or discoloration near the vent?

    6.4v is about right for a "resting" voltage of a fully charged L.A. battery. 7.5v may be too high a charging voltage though, especially for many sealed types.
    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
  • mike95490mike95490 Posts: 7,902Solar Expert ✭✭✭✭
    Loosing 2v in a couple days indicates a cell inside has gone bad.   A 6V battery has three, 2V cells internally, wired in series.
    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

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  • electrokidelectrokid Posts: 3Registered Users
    Estragon said:
    Is this a sealed type of battery, or flooded (with caps on top to access the acid inside)?

    If flooded, are the plates inside covered by liquid?

    If sealed, the should be a vent to allow gasses to escape if needed to prevent buildup of internal pressure. Is there any residue or discoloration near the vent?

    6.4v is about right for a "resting" voltage of a fully charged L.A. battery. 7.5v may be too high a charging voltage though, especially for many sealed types.
    Thank you for your response.
    It is a sealed type battery.
    It is a vent type battery and it is normal (physically) from outside. On the side of the battery it has been mentioned as ' maintenance free lead acid battery '.(gel type).
    7.5 v is the charging voltage mentioned in the battery itself for a cyclic use.
  • electrokidelectrokid Posts: 3Registered Users
    mike95490 said:
    Loosing 2v in a couple days indicates a cell inside has gone bad.   A 6V battery has three, 2V cells internally, wired in series.
    Might be the reason. Each lead acid battery has each cell of about 2.2v.  so my battery has a total of 6.4v at full charge.
  • EstragonEstragon Posts: 2,839Registered Users ✭✭✭✭✭
    There probably isn't much more you can do. My guess is a manufacturing defect, so I'd return it - bought recently it's presumably under warranty.
    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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