Is my AGM dead???

[Mountainhwy4]

Hey y'all,

I've had the trailer sitting in the garage for most of this last year, so I've been neglecting the maintenance on it. I saw the battery get to a low charge at some point during the fall (around 11.7 or 11.8V if I remember correctly), and so I charged it up with one of those plug-in chargers. I just tried to take a look at the battery voltage and none of the indicator lights were on (usually either a green, yellow or red light will be on), so I whipped out the voltmeter and saw it was a paltry 3.32

Will I need to get a new battery? We aren't using the teardrop much these days, we're in the process of buying a house so it may be a bit before we go camping again. If I can just plug in the battery to charge it that would be nice at least.

[tony.latham]

Hey y'all,

I've had the trailer sitting in the garage for most of this last year, so I've been neglecting the maintenance on it. I saw the battery get to a low charge at some point during the fall (around 11.7 or 11.8V if I remember correctly), and so I charged it up with one of those plug-in chargers. I just tried to take a look at the battery voltage and none of the indicator lights were on (usually either a green, yellow or red light will be on), so I whipped out the voltmeter and saw it was a paltry 3.32

Will I need to get a new battery? We aren't using the teardrop much these days, we're in the process of buying a house so it may be a bit before we go camping again. If I can just plug in the battery to charge it that would be nice at least.

Extra dead. The rule of thumb is to never let them get below 12.0 volts.

Tony

[Squigie]

Below 12v is bad.
Below 9v usually means down for the count.
Below 6v, it is absolutely, completely toast.

[RJ Howell]

I'm a curious one.. I had a couple go low (and no read) and opened them up to find they had a wire had corroded (to the post). How old is the battery?
Was able to salvage one, just cause I wanted to see if I could, but never was much over 85% capable. Then other was beyond help.

Not saying it's worth attempting to repair, yet I am a curious one..

[Tom&Shelly]

I'm a curious one.. I had a couple go low (and no read) and opened them up to find they had a wire had corroded (to the post). How old is the battery?
Was able to salvage one, just cause I wanted to see if I could, but never was much over 85% capable. Then other was beyond help.

Not saying it's worth attempting to repair, yet I am a curious one..

Yes! I would scrape the terminals off real good and read the voltage again, just in case its corrosion fooling the meter. At this point you have nothing to lose, so I would put the battery back on the charger (again after scraping and sanding the terminals--the corrosion might even be microscopic) and see if it wouldn't rejuvinate.

If worst comes to worst, we got a credit with an auto parts store bringing in an old one. At least you might get a discount on a new battery or a "free" set of windshield wipers.

Tom

[working on it]

Hey y'all,

I've had the trailer sitting in the garage for most of this last year, so I've been neglecting the maintenance on it. I saw the battery get to a low charge at some point during the fall (around 11.7 or 11.8V if I remember correctly), and so I charged it up with one of those plug-in chargers. I just tried to take a look at the battery voltage and none of the indicator lights were on (usually either a green, yellow or red light will be on), so I whipped out the voltmeter and saw it was a paltry 3.32

Will I need to get a new battery? We aren't using the teardrop much these days, we're in the process of buying a house so it may be a bit before we go camping again. If I can just plug in the battery to charge it that would be nice at least.

What kind of "plug-in charger" are you using? I use a 1.25A Battery Tender for my BMW X5, an Amazon Basics Battery Charger 2A for both my Chevy and GMC pickups, an Autozone Duralast 1.5A charger for my HHR Panel, a Battery Minder Plus 1A for my AGM battery in my trailer, and a Black & Decker Bm3B 2A charger as a backup (or for the riding mower, and formerly used on my wife's Cobalt, while it was being worked on for 3 years). All these use high-frequency pulsating power to desulphate and maintain batteries, and can be considered "smart", as they can be left in place for months at a time. Mine are plugged-in immediately at home, after I arrive there, and they keep my batteries charged full-time. They've also prolonged their lifespans, as the average lifetime for the Flooded Lead-Acid batteries has been 11 years, and the AGM trailer battery is now 13+ years (after two occasions where it had to be totally reconditioned, back-from-dead, before I started using the trickle chargers on everything...except my wife's daily driver, because she never remembers to unplug it). These charger-maintainers are good to keep a battery up to snuff, even to keep one from freezing in cold weather (Texas cold, that is), but will not resurrect a battery from the dead.

Below 12v is bad.
Below 9v usually means down for the count.
Below 6v, it is absolutely, completely toast.

I have, however, resurrected my Optima Yellowtop AGM twice, Once from 7.3v, and the second time from 9.2v. I experimented on ways to do so, before I used the metodology outlined here (from this thread: https://www.tnttt.com/viewtopic.php?f=30&t=55957&start=30)

Here's what I found for conditioning AGM batteries on the Big RV forum.
This is the way I condition AGM batteries

3% A/H constant amperage (3 amps for a 100 amp hour battery)

Allow voltage to rise to no more than 15.2 volts. This will take time and you will see the voltage "spill" occasionally .2 or even .3 and re-climb. This is healthy.

You should monitor cell temperatures. A scanning IR reader is ideal for this. At the rate listed above cell temperatures should not rise more than 5 degrees F over ambient at 68F. But this is a total permitted rise not a sudden rise. And it applies to each individual cell.

I would love to see an amp hour meter used and limit the conditioning charge to 120% of regular amp hour capacity, regardless of the 3% - 15.2 Volt 5 degrees formula. No more than 120% regardless of other factorials. But you must start off with a battery that has been maintained at 14.4 volts for at least 48 hours.

1. Charge at 14.4 for 48 hours

2. Apply 3% amp hours constant current

3. Monitor cell temps and cease charging if cell gain is more than 5F @ 68F

4. Curtail charge at 15.2 Volts or 120% of A/H whichever comes first.

5. 7 Hours at 3 amps sounds about right for a 100 amp hour battery.

6. Make sure NONE of those cells gets too warm. This is critical.

This procedure (with some variations, necessary for my equiments' limitations) worked twice for me, using a combo of two chargers: a Schumacher XCS15 ("smart/automatic" charger/maintainer, 2-6-15A), and a Century wheel charger (fully manual,10-40-150A), but it was a prolonged effort.

I just bought a Solar/Clore Pro-Logix PL-2320 ("intelligent" battery charger/maintainer with "power supply mode", 2-10-20A) which would make battery resurrection much easier, as the "power supply mode" will maintain your settings as well as a fully manual charger (but with the added feature of providing clean power). And, if the battery has fallen below 10v, the Schumacher needed to be fooled with a secondary 12v (provided by a spare battery) so it would turn on, but the Pro-Logix has a special start button that turns it on with no battery power needed. It will be what I use from now on, if ever I need to bring a battery back to life.

i used the two on bottom;new charger on top right, oldest (fully manual) unit on top left is a backup

83944d1707510618-20-amp-stable-power-supply-diagnostics-my-chargers-2-9-2024[1].jpg (287.2 KiB) Viewed 1038 times

But, as Squigie's post above stated, your battery may not respond to the strategy outlined here, but also, what do you have to lose just trying it? Good Luck!

[Squigie]

I have, however, resurrected my Optima Yellowtop AGM twice, Once from 7.3v, and the second time from 9.2v. I experimented on ways to do so, before I used the metodology outlined here (from this thread: https://www.tnttt.com/viewtopic.php?f=30&t=55957&start=30)
(...)
But, as Squigie's post above stated, your battery may not respond to the strategy outlined here, but also, what do you have to lose just trying it? Good Luck!

I have managed to "resurrect" a few batteries that should have been dead for good. But the only true successes were with non-deep-cycle AGMs. The deep-cycles looked like they came back, but just couldn't push the amps. With any notable draw (even the 3 amps my furnace needed at startup), the voltage dropped and they couldn't produce the necessary juice.
Perhaps the Optima design has something about it that lends itself toward recovery more easily.