What voltage new AGM batteries show?

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I discovered that the batteries aren't maint-free recently, and um so nearly 3 yrs, not too bad, the warning lite on the 12v panel flashing etc, buy a load of new maint free ones, AGM type from Lifeline. Fitted them - but the warning lite still flashes dammit. Port eng batt actually fine, no warning. But one of these, yet to be fitted only showed 11.7 out of the box. Is it knakd, just need charging or wot? Ok another shows 12.4. Any ideas pls...
 
I reckon at 11.7 it'll never be too good even if you charge it.

Not at all happy about 12.4 either. Not a great deal over half charge.

been sitting around for far too long.

see what others say.
 
are there any ID numbers on the battery casings ? You should be able to track the date of manufacture with Lifeline.

The Lifeline Tech manual suggests a self discharge rate of 1 to 3% per month, so it looks as is the low value one might have been stored for quite a long time, or it is faulty - which is unlikely, given their QA.

They set pretty stringent storage conditions (defining both duration and temperature) for their batts:

"While in storage, batteries should be boost charged every 90 days or when the open circuit voltage (OCV) drops to 12.5 volts for a 12 volt battery (6.25 volts for a 6 volt battery). This OCV corresponds to approximately 75% state of charge. Boost charge batteries using a constant voltage charger set at 14.4 to 15.0 volts for a 12 volt battery (7.2 to 7.5 volts for a 6 volt battery).
The boost charge should be applied until the charging current falls below 0.5 percent of the battery’s 20 hour rated capacity (0.5 amps for a 100 Ah battery). "

They also suggest that their batteries only reach approved performance levels after a number of cycles (15 is the number they quote) so you may find that performance improves as the battery is used.

There is a conditioning process which is suggested if a battery has been stored for an extended time in a partial or low state of charge. They suggest 8 hours at 15.6v for a 12v batt at ambient 25degs C.

If the batts have been stored for a long time without boost charging, then a Deep Discharge Recovery is suggested.
"WARNING: This procedure should only be done in a well ventilated area because a significant amount of hydrogen gases may be released from the battery.

1. Stabilize the battery at 68-86°F (20-30°C) for at least 24 hours prior to testing.
2. Charge at a constant current of 5% of rated (20 hour) capacity until the voltage reaches 15.6 volts (7.8 volts for a 6 volt battery), then continue charging at this rate for an additional 4 hours. Note that the charging voltage may get as high as 18.0 volts (9.0 volts for a 6 volt battery), so the power supply must be capable of outputting this level to maintain constant current. This constant current charge may take 16 to 20 hours.
CAUTION: If the battery becomes hot (above 130°F/55°C) during this charge, stop the current and allow the battery to cool to room temperature before continuing the charge.
3. Perform a capacity test as described in Section 5.7.
4. If the capacity is less than 80% of the battery’s rating, steps 2-3 may be repeated up to 2 times. Be sure to start the constant current charge with a fully discharged battery.


They seem to have covered every aspect of maintenance in their manual manual click here
 
We have 4off Lifeline 210Ah AGM's.
During the delivery trip we had problems with the charging taking too long so we contacted Lifeline and they put us in touch with their Spanish agent who was great. They felt the reason was there was a build up on the plates from spending too much time sat around before they were fitted to the boat. There is a date stamp on the side of the battery where you can check.
After the agent consulted the technical guys at the factory I was advised to equalise them although it's not normally recommended for AGM's. We have a Xantrex Link 1000 battery controller, this was set to lead acid instead of AGM (return to AGM after equalise) and the batteries were then eqalised. Whatever this done seemed to work as on a test after we used around 250Ah of the total 840Ah and then recharged. The batteries went onto float charge after 3 hours so not bad really.
The technical guys are really good and the support was excellent so its well worth at least an email. Whan fully charged we have around 13.7 to 14v available.
I hope that helps.
 
Re: update

[ QUOTE ]
I motored for about three hours...and the batteries perked up. Set the charger for AGM, and they're up to 12.9V at full charge, all sorted it seems.

[/ QUOTE ]12.9V on load, on charge or open circuit?
 
Re: update

[ QUOTE ]
12.8+ on load, the charger runs them up over 14v. Manual quotes 12.82v OC or higher for 100% charged. Seems they ok?

[/ QUOTE ]12.8 on load sounds good. 12.75 is near to 100% for FLA, don't know about Lifelines, my Lifeline is a very small one and is a bit lower. If you have an AGM setting and you seem to be getting a full charge then I think you're right....no problem /forums/images/graemlins/smile.gif
 
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