You really need the charge specs for your specific battery but:
First you could try and charge the battery at 14.7 volts if your charger will let you, let that happen 2 days with no load on the battery. Bulk and absorb charge states should be around 14.7 volts then float 13.6ish once the battery is fully charged.
With no load if you set the bulk charge to say 14.7 and know full well the panel is clear in the sun, angled towards the sun even and that battery will not reach 14.7 but is hanging out in the 12s and low 13v range let it go that way to see if over time it can reach 14.7v. If it slowly creeps to 14.7 the battery is sulfated, if it hit 14.7 no problem battery is probably fine and charging voltage just had to be upped. If it never reaches 14.7 bad battery. Even the creeping situation ain't good but a day or two at 15.3v might save it (thats a standard equalize voltage and the only AGM I know that can't be equalized are Full River AGMs).
For prospective: Just had the same problem happen here. Got a new charge controller a month ago, hooked it up, said it was only putting in .5amps. Battery monitor said other controller was shoving in 17amps so shrugged and forgot about it. Yesterday morning batterys read 12.2 volts- the lowest I ever saw them since buying them last Dec. Turned out the new controller was broke and the other controller was failing. Another controller swapped in set to 15.3 volts for 240 minutes, the batteries struggled to reach 15.3 but finally did- damage was slight but with no loads held 12.9v at 4am.
If you have an AC battery charger with an AMP guage everything gets easier. This is a trick the owner of LifeLine batteries told me. Get your battery to 12.1v and make sure it stays there, want to be sure the battery needs a good charge. Hook up the charger and turn it on. Over the next 15 minutes watch the amp guage, a smart charger will ramp the amps DOWN when the charger thinks the battery is full. So you should have full amps to the battery at the start, if not badly sulfated or flat out bad batttery. If full amps draw down fast, sulfated battery. If full amps for entire 15 minutes, battery seems fine. Trick here is adjust the target time for battery size. This LifeLine test is for their AGM 12v and 6v 100+ah and has to be for 30 minutes for their batteries (warranty test purposes) but I've seen batteries fail time and again under 15 minutes. Evn one GRP24 that simple would not charge beyond 12.2v- flat out wouldn't even passed this test but it stayed at 12.2- never figured that one out..
I know, there's a lot here.. I started throwing money at solar in 2012 and in 2012 NONE of this would have made sense to me..you'll get there a piece of knowledge at a time.
First you could try and charge the battery at 14.7 volts if your charger will let you, let that happen 2 days with no load on the battery. Bulk and absorb charge states should be around 14.7 volts then float 13.6ish once the battery is fully charged.
With no load if you set the bulk charge to say 14.7 and know full well the panel is clear in the sun, angled towards the sun even and that battery will not reach 14.7 but is hanging out in the 12s and low 13v range let it go that way to see if over time it can reach 14.7v. If it slowly creeps to 14.7 the battery is sulfated, if it hit 14.7 no problem battery is probably fine and charging voltage just had to be upped. If it never reaches 14.7 bad battery. Even the creeping situation ain't good but a day or two at 15.3v might save it (thats a standard equalize voltage and the only AGM I know that can't be equalized are Full River AGMs).
For prospective: Just had the same problem happen here. Got a new charge controller a month ago, hooked it up, said it was only putting in .5amps. Battery monitor said other controller was shoving in 17amps so shrugged and forgot about it. Yesterday morning batterys read 12.2 volts- the lowest I ever saw them since buying them last Dec. Turned out the new controller was broke and the other controller was failing. Another controller swapped in set to 15.3 volts for 240 minutes, the batteries struggled to reach 15.3 but finally did- damage was slight but with no loads held 12.9v at 4am.
If you have an AC battery charger with an AMP guage everything gets easier. This is a trick the owner of LifeLine batteries told me. Get your battery to 12.1v and make sure it stays there, want to be sure the battery needs a good charge. Hook up the charger and turn it on. Over the next 15 minutes watch the amp guage, a smart charger will ramp the amps DOWN when the charger thinks the battery is full. So you should have full amps to the battery at the start, if not badly sulfated or flat out bad batttery. If full amps draw down fast, sulfated battery. If full amps for entire 15 minutes, battery seems fine. Trick here is adjust the target time for battery size. This LifeLine test is for their AGM 12v and 6v 100+ah and has to be for 30 minutes for their batteries (warranty test purposes) but I've seen batteries fail time and again under 15 minutes. Evn one GRP24 that simple would not charge beyond 12.2v- flat out wouldn't even passed this test but it stayed at 12.2- never figured that one out..
I know, there's a lot here.. I started throwing money at solar in 2012 and in 2012 NONE of this would have made sense to me..you'll get there a piece of knowledge at a time.
