Should AGM batteries gurgle during charging? Is voltage too high? UPDATE

belfert · August 12, 2009, 05:12:56 PM

I finally got my AGM batteries installed after sitting in my garage too long.

I have a Prosine 3000 inverter/charger 24 volt system. After I activated the charger on the Prosine I noticed the batteries were gurgling. Is this normal with AGM batteries? I also saw that the Prosine was putting out 28.8 volt at 30 amps. Isn't 28.8 volts a little high?

I want to make sure I don't hurt my new batteries so I killed the charger function for now.

dbenck · August 12, 2009, 05:39:43 PM

Have 4 AGM's on two 4024 Trace inverters..bulk charge is around 27.8 and float is around 26.5
I know they do warm up a bit when they are low, but have never listened to them on heavy charging.

David Benck
Somerset, WI

belfert · August 12, 2009, 07:54:53 PM

Anyone else have any experience with AGM batteries?

Hartley · August 12, 2009, 08:56:57 PM

I had several that started to make sounds and eventually start steaming
just before they went NUKE on me. I dragged the steamers outside and it took 2 days for them to cool down.. Shot too!

AGM's and GellCells apparently have a limited shelf life. Both get wierd as they age.
( They also can explode !!! )

I know that probably doesn't help...

luvrbus · August 12, 2009, 09:06:54 PM

Belfert, you need to charge 1 battery at a time then tie the batteries together and they won't gurgle.
This is from the Lifeline rep if you get AGM's hot enough to vent you will have trouble
good luck

boogiethecat · August 12, 2009, 11:03:39 PM

14.1 is the absolute max for an AGM 12 volt system, so it follows that if you're seeing more than 28.2 you're killing them. Often but not always chargers will have a setting for AGM that is different than for wet cells. Mostly they're the same but the higher voltage used in wet cell systems for equalizing is something you do NOT want to feed to an AGM. If you don't have an AGM setting available, maybe another charging system is something to consider.
No they shouldn't gurgle, and if heaven forbid steam is coming out, you're loosing irreplacable electrolyte and again, killing them. Their vent system is "emergency only" and should never open under normal circumstances.

Tony LEE · August 13, 2009, 03:34:30 AM

Isn't 28.8 volts a little high?

Depends on the temperature to a certain extent. Any reasonably high capacity charger (relative to the capacity of the battery) should really include temperature compensation.

Only the battery manufacturer can tell you what voltage and current is too high because not all AGMs are the same. Mine get charged to 28.8V on bulk and absorb and they are still quite happy after four years.

Does your charger have an equalise cycle? If so it should normally be disabled. Some AGMs can take a slight equalise cycle but it is normally much milder than for flooded cell lead acid.

belfert · August 13, 2009, 04:40:15 AM

Some answers:

My Prosine inverter will not automatically equalize batteries. It is a manual function.

The charge function only has options for Gel and Flooded batteries. No option for AGM batteries. I am using the flooded setting.

The charger defaults to 28.8 volts for bulk charge for flooded. It also does 28.8 volts bulk charge for gel, but the float voltage for gel is a little higher.

I am going to call the battery manufacturer today to see what they recommend.

belfert · August 13, 2009, 06:26:21 AM

I talked to the battery manufacturer and they seem to think 14.4/28.8 volts for bulk charging is a bit high.

I then talked to Xantrex and they said 14.4/28.8 volts is the industry standard for bulk/absorption charging. I did notice that Xantrex products with an AGM setting using 14.3/28.6 volts instead.

dbenck · August 13, 2009, 06:56:02 AM

Have you tried to charge using new values that are below 28 VDC ? Reset bulk thru float settings in the units menu.
Also as stated above..all should be charged individually first.

David Benck

belfert · August 13, 2009, 07:52:54 AM

Quote from: dbenck on August 13, 2009, 06:56:02 AM
Have you tried to charge using new values that are below 28 VDC ? Reset bulk thru float settings in the units menu.
Also as stated above..all should be charged individually first.

I talked to Xantrex and the charge voltage on the Prosine 3.0 cannot be changed according to them. I'll check the menus.

bevans6 · August 13, 2009, 08:06:46 AM

My experience with AGM batteries is that you can abuse them horribly and they keep on ticking... I use them in my race cars. They are designed so that they can be stored without maintentance for two years and retain 80% of their intitial charge. I use Oddyssey batteries, and they recommend 14.7 volts absorbtion charge level for a 12 volt nominal battery. They have low internal resistance so they can take a hefty charge rate, also.

http://www.odysseyfactory.com/chargers.html

There are little gas venting nipples/valves under the cover. if they are blown off, the battery is toast. I've never heard mine make a noise either. Other AGM batteries may be different. Oddyssey claims they have patents etc that make their batteries unique, I have no idea if that is marketing or engineering talking!

belfert · August 13, 2009, 08:35:14 PM

UPDATE: I got this issue fixed.

The battery manufacturer recommended setting the inverter to GEL even though some say to use flooded for AGM batteries. The inverted is supposed to use the same 28.8 volts in GEL or Flooded mode, but it seems to charge at about half a volt less in GEL mode. That half volt is enough to cause the batteries not to make any noise now.