SOLVED! The Rescue of an AGM Type Battery from a Low Charge State

MRRSM

Lifetime VIP Supporter
Wasn't certain where to Post this circumstance: (Tool Talk? Amazon Listings?) but since the problem DOES have a Technology Issue behind it... Here goes:

Last week, the Duralast Platinum AGM Battery in my Silverado took a a Helluva Hit after I accidentally left the Ignition Key in the”ON” Position all day long and completely forgot about the DTRLs making a constant drain on it, risking a power drop under 4 Volts DC.

My fear of it further dropping below to the Dreaded “Point of NO Return at 2 Volts DC" had to be avoided. Research indicated that Conventional AC to 2-10 Amp 12 Volt Battery Charging Units might damage the AGM Style Batteries. So I avoided hooking up the one I have on hand and ordered-received a North American (Six Cell Design) Deltran 'Battery Tender' Selectable 6-12 Volt Charger and Maintainer available on Amazon, specifically designed to avoid this Charging Problem:

https://www.amazon.com/Battery-Tender-Selectable-Lithium-Charge/dp/B07XMJDJX7/ref=sr_1_6?crid=3QGH1QMJBM0Y2&keywords=deltran+battery+tender+plus&qid=1581638025&sprefix=deltran+,aps,203&sr=8-6

DELTRANCHARGER1.jpg

After hooking it all up and leaving it on for around 6 Hours… (Red Positive to Red Positive and Black Ground to the Alternator Bracket) the *Flashing* Green 12 Volts DC Selection Light and the Solid Amber Charging Indicator Light remained on in Combination indicating that this AGM Battery had managed to "Come back from the Dead" and was back up to around an 80% Charge.

The Instructions recommended leaving it on for a Full and Complete Charge while performing so at the rate of 1.25 Amperes Per Hour. This Unit employs a Micro-Processor Unit that will NOT allow the AGM Battery to Over-Charge. I’ll have to be much more careful from now on and remember to regularly use this “Trickle Charge” Unit when not driving the Truck on a regular basis. Leaving the Deltran Charger hooked up and running for extended periods is acceptable.
 
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Reprise

Lifetime VIP Supporter
I'll have a little good-natured fun at your expense (hopefully, you won't get too upset...)

To summarize your post...
- Your battery got to a low SoC
- You charged it (with the proper type of charger) quickly, and didn't leave it discharged long
- All is well now :laugh:


The *real* reason I replied... I'm not sure where you got the "4v" and "2v" measurements as far as avoiding damage. If your AGM battery ever got to 4v, I don't think you'd be able to recover it. And 2v would be worse, of course.

Here's a representative discharge curve / chart for AGM batteries (it does vary by ambient temperature, but we'll pretend that you're at 'optimal' 72F -- hey, you're in FL, right? LOL.)

As you probably know, AGM batteries can survive an 80% discharge rate without being permanently damaged (vs. about 50% for a 'traditional' lead-acid (FLA)). Note that this is a chart for a 12v AGM deep cycle, as opposed to a 'starting' battery, but the voltages are very, very close -- within 0.1v or so (else, I'd have gotten a more accurate chart, right?) :wink:

1581644934599.png

As we see here, the "80%" rule isn't a straight 12(v) * 0.2, giving 2.4 volts. Damage occurs LONG before that. Also, as a general rule of thumb, you don't want to be repeatedly getting into the 'orange' zone, in order to maintain the number of cycles the battery is rated for. You never want to get into the 'red' zone, if you can help it.

A better way of thinking about it (IMO) might be... "if the battery's SoC drops by 2v, it's a goner"
(you may be able to 'rescue' it around 10v or so SoC, but *some* damage will have occurred, shortening its life). 'Smart' chargers will flag a battery as 'bad' if they can't raise the SoC to a minimum value in a set period of time. Sometimes you can work around that (I've done it, but it takes time / patience, and it's a temporary band-aid - the damage is done).

Anyway... I hope this helps a bit.

W/ regard to float / trickle charging... you can pretty much leave a FLA / AGM battery on one indefinitely (and is recommended, for long-term storage). That's what the Deltran 'Battery Tender' brand has made its rep on, of course. But they're not the only game in town, any more.

Here's a Wikipedia article on the charging standard, which is pretty much universally used in today's "intelligent" three-stage chargers:


Finally, for our members with 12v FLA batteries... the 'damage' cutoff for those is about 50%... here's a representative chart for those:

1581647582743.png
 

littleblazer

Gold Supporter
I'll have a little good-natured fun at your expense (hopefully, you won't get too upset...)

To summarize your post...
- Your battery got to a low SoC
- You charged it (with the proper type of charger) quickly, and didn't leave it discharged long
- All is well now :laugh:


The *real* reason I replied... I'm not sure where you got the "4v" and "2v" measurements as far as avoiding damage. If your AGM battery ever got to 4v, I don't think you'd be able to recover it. And 2v would be worse, of course.

Here's a representative discharge curve / chart for AGM batteries (it does vary by ambient temperature, but we'll pretend that you're at 'optimal' 72F -- hey, you're in FL, right? LOL.)

As you probably know, AGM batteries can survive an 80% discharge rate without being permanently damaged (vs. about 50% for a 'traditional' lead-acid (FLA)). Note that this is a chart for a 12v AGM deep cycle, as opposed to a 'starting' battery, but the voltages are very, very close -- within 0.1v or so (else, I'd have gotten a more accurate chart, right?) :wink:

View attachment 93150

As we see here, the "80%" rule isn't a straight 12(v) * 0.2, giving 2.4 volts. Damage occurs LONG before that. Also, as a general rule of thumb, you don't want to be repeatedly getting into the 'orange' zone, in order to maintain the number of cycles the battery is rated for. You never want to get into the 'red' zone, if you can help it.

A better way of thinking about it (IMO) might be... "if the battery's SoC drops by 2v, it's a goner"
(you may be able to 'rescue' it around 10v or so SoC, but *some* damage will have occurred, shortening its life). 'Smart' chargers will flag a battery as 'bad' if they can't raise the SoC to a minimum value in a set period of time. Sometimes you can work around that (I've done it, but it takes time / patience, and it's a temporary band-aid - the damage is done).

Anyway... I hope this helps a bit.

W/ regard to float / trickle charging... you can pretty much leave a FLA / AGM battery on one indefinitely (and is recommended, for long-term storage). That's what the Deltran 'Battery Tender' brand has made its rep on, of course. But they're not the only game in town, any more.

Here's a Wikipedia article on the charging standard, which is pretty much universally used in today's "intelligent" three-stage chargers:


Finally, for our members with 12v FLA batteries... the 'damage' cutoff for those is about 50%... here's a representative chart for those:

View attachment 93151
So I drained my Optima to around 6.8 volts measured with a multimeter a few times... I won't say it is as good as it was but it's still working in the TB...
 

Beacon

Silver Supporter
Hindsight. would have been interesting if you had put a volt meter on the battery before charging.
 

Reprise

Lifetime VIP Supporter
So I drained my Optima to around 6.8 volts measured with a multimeter a few times... I won't say it is as good as it was but it's still working in the TB...
Red / yellow / blue? Just curious. Guessing Red (starting).
Yep... you can recover it with the right charger & some luck (?), but it'll have less capacity, less service life, or both.
Incidentally, Optima makes a really trick charger ('digital 1200'), optimized for their own batteries, of course.

Hindsight. would have been interesting if you had put a volt meter on the battery before charging.
I was going to mention this, but forgot. Thx for bringing it up.
With the charger I'm using these days, it shows (digital display) what the current voltage is when turned on, just before it starts charging. When finished, it shows the float voltage (which isn't constant, like you would think. Rather, it lets the battery 'bleed' down a little bit (.1v or so), then boosts the charge for a few seconds to bring it back up, rinse & repeat). So it short cycles, constantly.
 

littleblazer

Gold Supporter
Red / yellow / blue? Just curious. Guessing Red (starting).
Yep... you can recover it with the right charger & some luck (?), but it'll have less capacity, less service life, or both.
Incidentally, Optima makes a really trick charger ('digital 1200'), optimized for their own batteries, of course.



I was going to mention this, but forgot. Thx for bringing it up.
With the charger I'm using these days, it shows (digital display) what the current voltage is when turned on, just before it starts charging. When finished, it shows the float voltage (which isn't constant, like you would think. Rather, it lets the battery 'bleed' down a little bit (.1v or so), then boosts the charge for a few seconds to bring it back up, rinse & repeat). So it short cycles, constantly.
Red top. I used a regular plain old on off type charger the first time. The other two times I just jumped the truck and let it run. That was probably 4 years ago now and it's still kicking. If it sits for a month it'll usually just barely start but with it being cold that makes sense. Oh well lol.
 

Reprise

Lifetime VIP Supporter
You probably have one of the older Optimas, when they were still top-rated. Glad to hear that it's served you well. :thumbsup:

I *was* using WM's 'best' FLA line, called 'EverStart Maxx' (made by Johnson, so basically crap). The problem with them is that they discharge / sulfate really fast, if you don't use them just about every week. After exchanging the third one, I decided to go AGM (mfg: Deka / East Penn), and not from WM (my logic on the WM batteries was that I could get a replacement, even if I was out with the camper someplace). The Sierra has the last of the EverStarts.

I also got one of these, from Amazon. Has Bluetooth, so you can monitor the seldom-used battery via an app, and get the thing on a charger (or drive it) before it's too late. Put it on the Sierra, and the voltage reads a little low, per the device, vs. actual. Better 'low' than 'high', I suppose.
 

northcreek

Well-Known Member
At the expense of all who have posted (with all due respect), this subject gets way too much ink, Your battery is one of the longest lasting consumables that you will replace maybe 2 or 3 times at the most for $200 and at that you will have a 3 or 5 year free replacement.
Unless you are driving an ambulance...treat it like the lump of lead that it is...live it up :2thumbsup:
 
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HARDTRAILZ

Moderator
Last week I came out to truck and it was so dead the remote would not unlock and not even a click from it when I tried to start. Dead-Dead. Duracell AGM battery made by East Penn.

Put the ole 1960's battery charger on it for about an hour, came outside again, cranked the truck and it started right up and been fine since.

Wonder how low it was to not even recognize the remote unlock?

I think it is about 4 or 5 years old, so it may be replaced soon but it has been a damn good battery and never had issues with lights/stereo/winch n all the BS. I am pretty sure the drain was the aftermarket radio not shutting off. Happened a couple times with the cheap harness and opening doors before the truck is off. Its not an issue I ever worried about, but I guess I need to keep an I on it with the aging battery.
 

littleblazer

Gold Supporter
Mine was after the Johnson buy out but just before the brand totally went to crap. The one in the work truck used to get drained once a week, dad would forget to shut off the inverter. That one is now about toast but leaving the old school charger on it to psuedo desulfate it has extended the inevitable for now... been like that almost two years and is about 6 years old...
 

Mooseman

Moderator
Just before my trip to Long Island on Christmas day, my battery was completely dead. No locks and key was stuck in ignition. My fault, I forgot I left it on Aux power to keep the Android HU on while it was updating maps and stuff over Wifi and was left on all night. It's a new Kirkland from last summer (likely a Johnson Controls). I didn't want to just jump it and pump 140A into it from the alternator once it did start so I slapped on the 15A charger for an hour or so and she started right up. Been fine since and starts even in -25c.

Slower is always better. If I would have had the time, I would have used 2A over a longer period but I needed it fairly quick. I did bring a lithium jump pack with me just in case but was unneeded.
 

Reprise

Lifetime VIP Supporter
My fault, I forgot I left it on Aux power to keep the Android HU on while it was updating maps and stuff over Wifi and was left on all night.
I'll bet if you had hooked up the slow charger up to it while in Aux, you'd have been fine in the morning. We always think of those things in hindsight, tho.

Since it seems to always go where I do, I've taken to setting an alarm / timer on my phone when charging stuff, to check on it (like the underhood light that I always forget to turn off, drain, and then can't use until it charges up again.)
Now with the LED shop lights I hung up, I really don't need the underhood light, like I used to (just as well, b/c I misplaced the wall wart that charges it up.) :dunce:

Tried using one from another device, and it was a good thing I checked on it (see: 'timer', above), b/c it overcharged / heated up the battery (I can still smell the odor from the charging port). Could've set it (and the garage (!) on fire.🔥🧯👨‍🚒 Which brings to mind what happened to one of my musician friends a few years back, but that's a story for a different thread.

(on edit): @HARDTRAILZ : "Wonder how low it was to not even recognize the remote unlock? "

Not as low as you think. I left the liftgate up on my Voy for a couple of days (b/c I was using the spare tire winch), and because the CAN didn't go to sleep, it drained the battery (via the liftgate module still reporting 'open', most likely). Almost couldn't recover it (it was down to 9.x volts, per the charger). About two weeks later, I got tired of hearing the engine barely crank over as a result, decided I couldn't trust it in the future, and bought the AGM for it. Battery was just past the 36mo '100% replacement cost' period (still had pro-rata warranty, but wasn't going to futz with it for another 2yrs)
 
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Mooseman

Moderator
I'll bet if you had hooked up the slow charger up to it while in Aux, you'd have been fine in the morning. We always think of those things in hindsight, tho.
:Banghead:
 
OP
OP
MRRSM

MRRSM

Lifetime VIP Supporter
Left the Deltran Trickle Charger on all night. Just Checked the Battery with a DVOM and only get 4.9 Volts. Read some more over on this Site:


They suggested (3) Options for resuscitating a "Deeply Discharged AGM Battery". The one I'm considering doing looks a bit dangerous to try (but does makes sense) is to "Hook Up another Auto 12 VDC Battery in Parallel... AND also Hook up a Regular Battery Charger on Low Amperage for around 2 Hours". They mention feeling if the "Batteries Get Warm..." to shut things off immediately ...Hmmm.

Apparently, ALL Battery Chargers have a Safety Cut Off that prevents it working if the Dead (Flooded Lead Acid Batteries) Battery Voltage drops below 10.5 Volts. Autozone charged me an A&AL for this thing and its only around 8 Months Old... My Own Damned Fault.

On the brighter side... I was searching for the possibility of having one delivered right to my home if worse comes to worse. Lo and Behold... AAA DOES have an online Battery Ordering and Delivery Site.

Been a AAA Member since 1972 ...so if it comes down to cases, I might try them out. With their Member Discounts...it could turn out to be a wash rather than use any of the local stores. I have an Old FLA handy to give them to avoid a Core Charge, so I'd keep the AGM to fiddle around later on with if I decide to go that route.

 

Reprise

Lifetime VIP Supporter
They suggested (3) Options for resuscitating a "Deeply Discharged AGM Battery". The one I'm considering doing looks a bit dangerous to try (but does makes sense) is to "Hook Up another Auto 12 VDC Battery in Parallel... AND also Hook up a Regular Battery Charger on Low Amperage for around 2 Hours". They mention feeling if the "Batteries Get Warm..." to shut things off immediately ...Hmmm.
I've read about this in a couple of places (Optima and others). It's worth a try (but haven't done it myself.) What happens when you hook them up in parallel is that the charger 'reads' them as averaged together (not really, but you get the point), and sees sufficient voltage to bulk charge. Then, when they've been on for a couple of hours, the dead one will have enough juice to accept charge by itself. After you charge them for a couple of hours, take the charger off, wait 30min, and put a meter on the dead one. If it's at / above 10v, go ahead and charge it solo. If not, put them back in parallel and charge a little longer, until you can get at least 10v showing 'at rest'.

BTW, the above is also supposed to work for FLA batteries, as well.

Obviously, your battery is still under full warranty, if only 8mos old. You don't have to tell AAP the 'why' of what happened... if it failed to recharge, there's a good chance it'll fail a load test, too, meaning you can get a fresh one. I'd seriously think about going that route.
 
OP
OP
MRRSM

MRRSM

Lifetime VIP Supporter
Thanks Everyone for these Responses...

I've decided to throw my hat into the "Optima Digital 1200 Battery Charger" Ring. I figure since I've already dropped Two Bills + on the AutoZone Duralast Platinum Battery... I might as well try the Optima Charger since it can allegedly bring one back from Certain Death when drained down as low as 1.25 Volts DC. (We'll soon see...)

What the Hell... It's only Money...and what better way to "Jump Start The ❤" of this Thing ...than to order the Optima ...on Valentine's Day:

OPTIMA1200.jpg
 
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Mooseman

Moderator
I'd just chuck it and get a regular battery. Not worth the time, effort and expense compared to just getting a regular battery. They are consumables.
 

Sparky

Moderator
I just shoved my accidentally dead (read almost 0 volts) FLA on a 14V charger at work for a couple hours and it brought it back to life.

Never dealt with a dead AGM but I'd probably try the same if I did something to it.

By the time I did all this research and time and buying extra special chargers n crap... nah, just try something or by a new battey and be done with it.
 
OP
OP
MRRSM

MRRSM

Lifetime VIP Supporter
NP.... But my courage always rises in the face of these small technical challenges. So... I'm either going to be successful in playing Dr. AGM Frankenstein and the Battery takes 'The Lightning Bolt' from the Storm and continues to be useful... Or ....I'll have a Very Expensive and Flexible (AGM or FLA) New Battery Charger as well as the 4 Amp Trickle Charger Battery Maintainer on hand to keep me out of trouble with the Next One. In either case... I'll at least document here whether or not this can be done and tell the truth about what the outcome is ...one way... or another. :>)
 
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OP
OP
MRRSM

MRRSM

Lifetime VIP Supporter
The outcome of this expensive gamble was a complete success: (100% Recovery of AGM Storage Capacity)

It's ALIVE!

ITSALIVE.jpg

This worked after hooking up the Optima Digital 1200 Battery Charger to the AutoZone Platinum AGM 12 Volt Truck Battery and allowing it to function on the “Deep Charge” Setting for 24 Hours. Afterwards, my Truck started right up in 1.5 Seconds:

TESTOFOPTIMA1200CHARGER1.jpgTESTOFOPTIMA1200CHARGER2.jpgTESTOFOPTIMA1200CHARGER3.jpgTESTOFOPTIMA1200CHARGER4.jpgTESTOFOPTIMA1200CHARGER5.jpgTESTOFOPTIMA1200CHARGER6.jpg

I allowed the Engine to warm up for around 5 minutes; just long enough to confirm that the Alternator was charging nominally at around 14 Volts. Immediately after shut down, I hooked up the Deltran “Battery Tender”. Since I seldom drive this Truck… using that "Trickle Charge" Battery Maintainer will be my weekly routine from now on in order to prevent this problem from ever happening again.

Live and Learn… Problem Solved.

Visit this Link for more close up images showing the various features of this Optima Charger:

https://www.flickr.com/photos/126111508@N07/albums/72157713140253566

These (3) Optima Digital 1200 Battery Charger YouTube Owner Reviews are worth watching:

8VfH0K2JnqE
o4M3aTd_k5U
eNRTxod9qzI
 
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