Is a Johnson AGM starting battery fully charged at 12.68v???

[Naio]

Buying a new chassis battery, it took me forever to find somebody who actually had an AGM one in stock, as opposed to just claiming they did.

Got it yesterday. Johnson Control,
sold under the Duralast platinum label from AutoZone. Dated August of last year.

Not topped off when I got it. I idled the van for a while yesterday, ran out of time. Battery ended at 12.76 but I assumed that that was just because I didn't charge it long enough.

Today, hooked up a smart charger, and it reads as fully charged, although voltmeter said 12.68 before plugging in charger.

Not much luck finding specs online for this particular battery, and guys at AutoZone didn't even know what AGM was, so I can't ask them.

Is it possible that it really is fully charged at 12.68, or have I got a dud battery? It did start the van, although weather is warm.

Don't know what I would do without you guys.

[MEXICOWANDERER]

Regarding your new AGM battery....

• If your car never seems to have a low battery after sitting weeks and weeks
• You have accidentally left the headlights on drawing the battery down so the engine won't start
• Like to listen to the car radio with engine off
• Sometimes go where the temperature is near freezing overnight
• Hate the sight of corrosion on battery cables and on the new hole of your blouse sleeve...

You're gonna LOVE that new AGM battery. It may not say Deep Cycle but no matter, even car AGM batteries have better cyclability than standard RV car jar flooded Deep Cycle batteries. Eight or ten accidental drain downs until unable to start engine (then quickly recharge) the AGM will not adversely affect the battery. But like with deep cycle regular usage the battery must then be recharged 100% full.

Cars with alternators that finish charging in the thirteen volt range are OK with AGM. Why? Because underhood temperatures are far hotter than places where RV AGM batteries hang out. The charge until 100% full rule is strict only where the battery is cycled. And the car alternator certainly meets the 20% minimum amp hour recharge rate.

So - bottom line....

Happy battery

Ecstatic owner

[landyacht318]

Naio, you need not worry about alternator charging your Starting AGM, nor modify your vehicle's voltage regulation.

If you were to accidentally drain it dead I would recommend using a higher amperage plug in charger to get it back to full relatively quickly after a jumpstart, rather than assume the alternator will do it, because it will not, and the AGM left in the 85% charged range is not a happy AGM.

No lead acid battery is happy if less than fully charged so it should never be a question of 'should I charge it to full? ' Whether it is worth your effort is argueable. I'll skip that part of the procedure..

I modified my voltage regulation, because I deeply cycle mine and want maximum alternator contribution each time I drive for as long as i drive, and the whack job stock voltage regulator inside engine computer would prematurely drop to mid 13v range, and occassionally blast back upto 14.9v without rhyme or reason.

Most vehiclew will start with a higher sought voltage for a short eriod after engine starting, then drop to mid 13's. Most people do a quick check of voltage right after starting and assume that is the voltage always allowed/sought. Each vehicle will be different and no assumptions made about any specific vehicle with no data to back it up, or the tools to even collect it.

The drop to mid 13v range is Fine and dandy for a starting battery never discharged significantly, not great when the battery is drained deeply.

[Naio]

MEXICOWANDERER wrote:
...it takes under six seconds to say "Two medium coffees" Scrolling through the menu I timed Eduardo. Almost 30 seconds.

Yes! It is dang rude, this assumption that the customer's time is worthless.

Need a fuel filter...make model year sedan or convertible engine size automatic transmission type color ABS brakes air conditioning stereo GPS rear view camera HID lighting, fabric or leather.

When I was shopping for tires, many websites insisted I choose my engine size from the drop-down menu.

[MEXICOWANDERER]

The revealing psychology evident in ordering something at a fast food place is nothing short of scary. No cash register with numbers. The buttons have little images of burgers, fries and shakes icons.

The mindless automaton demands a cadence from the customer. Say anything out of cadence and the automaton loses it and demands a reboot.

Yesterday I went to a Mindless Golden Alphabet to get coffee with Eduardo while in the USA.

There stood a kiosk with pictures and prices. Push here select that. Normally it takes under six seconds to say "Two medium coffees" Scrolling through the menu I timed Eduardo. Almost 30 seconds. White liquid and sugar was added before it arrives. The McSnotrag cups featuring a hundred and fifty degree surface to grasp. So sorry out of recycled pleated insulation rings. "We Do It All For Us" Next trip we pack a thermos.

Need a fuel filter...make model year sedan or convertible engine size automatic transmission type color ABS brakes air conditioning stereo GPS rear view camera HID lighting, fabric or leather. Sorry out of stock.

Terminator IV "The Revolt Of The Wog Machine Worker" is inevitable. Look for it.

[Naio]

MEXICOWANDERER wrote:
MAKE AMERICA GREAT AGAIN

Starts off with mandatory schooling with periodic testing to make sure teachers have the ability to stuff knowledge into empty air heads. If the kid refuses to learn he joins the broom brigade.

"Just give me what I ask for" has become my standard boilerplate opening statement in a parts store. It really is discouraging. I do not want them wasting a microsecond of my time trying to conjure by concentrating too hard.

I hate it when I ask for a specific part, like this battery, and they start in with the, 'What is your year make and model.'

Sometimes I have had to lie, look up a vehicle that uses a part I want as stock, and say that's what I have.

[MEXICOWANDERER]

MAKE AMERICA GREAT AGAIN

Starts off with mandatory schooling with periodic testing to make sure teachers have the ability to stuff knowledge into empty air heads. If the kid refuses to learn he joins the broom brigade.

"Just give me what I ask for" has become my standard boilerplate opening statement in a parts store. It really is discouraging. I do not want them wasting a microsecond of my time trying to conjure by concentrating too hard.

[Naio]

time2roll wrote:
Bosch AGM @ pep boys $150 group 65 Four year free replacement warranty. I believe prorated after that.

Oh, dang, I hate that I missed that! I got 3 years replacement, and no prorated after that. Who makes a Bosch AGM?

Voltage starts higher and drops over 15 to 30 minutes. Depends on engine (alternator) heat afaik.
Alternator charging is fine fine fine. Should last a decade or a bit more.

Ah, thanks 🙂

[Naio]

Argh, I have too many projects. You know what I really want? A cigarette plug for the output of my meanwell, that I can just plug into the dash to top off the battery when I feel like it. I don't suppose that is a actual possibility?

I do plan to put an Anderson on the dash when I get around to it. Had that on my old van for inverter and jump start. Any reason I can't use it for charging?

[time2roll]

Bosch AGM @ pep boys $150 group 65 Four year free replacement warranty. I believe prorated after that.

Voltage starts higher and drops over 15 to 30 minutes. Depends on engine (alternator) heat afaik.
Alternator charging is fine fine fine. Should last a decade or a bit more.

[Naio]

BFL13 wrote:
What is the alternator voltage now? It usually would go down some after the van gets going. Lots of people have AGM starting batteries and they seem to survive 🙂

I don't know. I am new to this van.

I am also not a car person. You say it goes down after the van gets going. Do you mean after the engine warms up, or when you are in gear versus idling or???

[BFL13]

What is the alternator voltage now? It usually would go down some after the van gets going. Lots of people have AGM starting batteries and they seem to survive 🙂

[Naio]

I got the AGM because I thought it would be easier on my brain to have chassis and house batteries be the same chemistry. But it wasn't till after I got it that I thought about how the voltage regulator might not be good for it .

[Naio]

2oldman:

First I tried a dealership .

Me: I need a group xx AGM.
Guy at dealership: AG what?
Me: AGM. Absorbed glass mat battery.
He: Absorbed gas...?
Me: Glass, like you drink a glass of water.
He: We really just deal in automotive batteries.
Me: It's an automotive battery. I'm trying to think what else you might know it by. Sometimes called a sealed battery?

This was a supervisor. Previously, sales rep guy had told me that the warranty was a secret.

After going around a bit, I asked, 'So you're saying that the only way that I would be allowed to know the warranty terms is if I buy a battery, have a problem, and then bring it in to you?'

He said, 'Yes'

I replied, 'Umm... Is there someone else I can talk to?' (That's code for 'Bless your little heart.')

That's when I got put on to the guy who didn't know what an AGM was. But at least he was nice and not a sexist *********. It took him some effort, but he ordered me a battery. And printed out a 7 page proration schedule, unasked!

But then, when the battery arrived from his distributor, it had a sticker on it that said the warranty didn't apply to this battery. He called me up and told me. (Honestly, I am laughing while I'm typing this.) So that's when I called AutoZone .

It's like keystone cops around here.

[Naio]

Mex, landy, etc.:

Oh gosh, so now I have to figure out how to adjust my voltage regulator on the van alternator? I was wondering about that. In the middle of the night.

It is good to give me very simple and straightforward directions. I was once upon a time a smart person, but now I have semi ok brain days and terrible brain days. This is why I keep trying to use my smart charger. It is more trustworthy than I. But it doesn't like sketchy situations.

[BFL13]

I got the idea of clamping on first then powering up, when doing it the other way around kept frying the inrush thermistor in my charger. Much discussion on here led to how it was easier on the charger to clamp on first.

Meanwells and other chargers may do better wrt that. The charger design I have was changed with different size thermistors and other mods, so now they can handle it all better and can survive not clamping on first episodes.

I is moot when the charger is a fixed installation such as a converter in an RV. It is when the charger is a portable with clamps that it could matter.

It is difficult to have the adjustable voltage charger in a fixed installation able to have its voltage set with the battery disconnected, unless there is a disconnect switch in the picture.

I beat that by marking some favourite voltages around the dial with the charger disconnected before installing it. Then I can dial it to the marks instead of using the voltmeter. The voltmeter then shows the progress of the recharge along with the ammeter showing when the AGM is full and it is time to drop the voltage to Float (using the mark for that voltage).