6v lead acid battery

electrokid

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.

Estragon

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.

mike95490

Loosing 2v in a couple days indicates a cell inside has gone bad.   A 6V battery has three, 2V cells internally, wired in series.

electrokid

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.

electrokid

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.

Estragon

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.