AGM Auto Batteries

[Briar Lee]

Anout thirty years ago my best friend Johnny’s father Freddie was waxing profane at the short lifespan of a couple of tires on his Allis Chalmers tractor. Freddie claimed that tractor tires made after Pearl Harbor of synthetic rubber weren’t as good as the old kind, The tires had dry rotted and they just weren’t that old, and he’d bought them over at Stockton not all that long ago.

My friend Johnny said Daddy, didn’t you tell me you bought those before the Stockton Allis Chalmer’s dealer closed during the Korean War and you could have got them at half price?

Freddie said that was another reason he was mad, he’d paid full price and should have waited.

I felt like old Freddie today about our Suburban battery. It discharged too fast if we leave our Garmin plugged in, but Thursday evening the dad blasted battery died and left my wife stranded at the office, which did not make her very happy, and our 29 year old son and I rescued her and jumped the Suburban and I tasked him with replacing it on Friday. I reminded him it wasn’t that long since he’d replaced it at nearly $200.

As it turned out the battery was replaced August 2018, far past the three year warranty.

And he paid $247 for the best AGM battery the parts shop sold.

I read up on AGM (glass mat) batteries and it should definitely be an improvement, but my 30 year old battery chargers at the farm don’t have AGM switches, but our newer ones here are AGM capable.

What Is an AGM Battery? AGM vs Standard Batteries | Interstate Batteries

Lots of new cars sport AGM batteries. But what are they? Here’s the big deal.

www.interstatebatteries.com

The new AGM battery is supposed to be better in every way better is measured.

Anybody else have an AGM battery?

 

[captpat]

AGM batteries have quite a following in the RV and boating worlds where batteries can be subjected to long periods of discharging at a low rate (think trolling motor). They have a different charge profile so old battery chargers may do some damage and shorten their life. OTOH if treated properly AGM batteries will last longer than an equivalent lead acid battery, in my RV it's about 8 years vs 5. However, they do cost more, ~$500 for an AGM vs. $200 for lead acid (again for a 6V 220 AH RV battery). Some high-end RV builders are moving to Li-Ion batteries, on some the upgrade cost is ~$90,000,

 

[HawkeyeLinus]

Got along fine years ago with quality Die Hards and last many years use Interstates which have been fine in extreme cold and so forth. Batteries are going to go, AGM isn’t a thing with me, but don’t know much them, I just replace when they inevitably need to be. Make sure there wasn’t something other than the battery causing it to discharge.

 

[Buffalo]

Over the course of about the last ten years, I've noticed that most auto manufacturers are selling vehicles with AGM batteries in them. I believe this has a lot to do with the technology in vehicles today. Modern vehicles have many more electronic components in them that, even with the key off, are still drawing power from the system. Regular lead acid batteries don't handle this well, due to the design of the lead plates being suspend in an acid bath. AGM batteries or absorbed glass mat batteries handle this better, due to the greater surface area afforded by sandwiching thin lead plates between fiberglass mats of electrolyte solution. AGM batteries provide greater electrical potential than standard batteries do.

Companies like Interstate claim that AGM batteries provide three times as many vehicle starts than the standard lead (60k vs 20k). When you factor that in, AGM batteries are actually more economical than standard batteries, even with their higher initial cost.

The biggest thing with AGM batteries is to not let them fully discharge (due to their design, discharged AGMs are more susceptible to sulfation), don't overcharge them (the thin plates can deteriorate this way) and to not charge them with a non-AGM charger.

My vehicles all have AGM batteries in them, save for the motorcycles, which I've switched to Lithium Ion batteries and my old ford Tractor, which still has a lead acid battery in it. When the batteries in my two zero turns finally kick the bucket, I'll swap them for Lithium. The Lithium batteries are much better and setting for long periods without discharging, but you are paying a premium for that technology. For vehicles, lithium ion batteries are just not cost effective enough, yet, for me to make that shift.

 

[Jbrewer2002]

Just replaced my motocraft led acid battery yeasterday with another one. The last one lasted 8 years. I can’t complain or have reason to switch.

 

[troutface]

I was going into winter and elk hunting season with a five year old battery. Not a wise decision. It was only about a $50 difference to go with an AGM battery and as far I can see there are no other downsides. Supposed to handle the vibration of being offroad better.

 

[HawkeyeLinus]

Over the course of about the last ten years, I've noticed that most auto manufacturers are selling vehicles with AGM batteries in them. I believe this has a lot to do with the technology in vehicles today. Modern vehicles have many more electronic components in them that, even with the key off, are still drawing power from the system. Regular lead acid batteries don't handle this well, due to the design of the lead plates being suspend in an acid bath. AGM batteries or absorbed glass mat batteries handle this better, due to the greater surface area afforded by sandwiching thin lead plates between fiberglass mats of electrolyte solution. AGM batteries provide greater electrical potential than standard batteries do.

Companies like Interstate claim that AGM batteries provide three times as many vehicle starts than the standard lead (60k vs 20k). When you factor that in, AGM batteries are actually more economical than standard batteries, even with their higher initial cost.

The biggest thing with AGM batteries is to not let them fully discharge (due to their design, discharged AGMs are more susceptible to sulfation), don't overcharge them (the thin plates can deteriorate this way) and to not charge them with a non-AGM charger.

My vehicles all have AGM batteries in them, save for the motorcycles, which I've switched to Lithium Ion batteries and my old ford Tractor, which still has a lead acid battery in it. When the batteries in my two zero turns finally kick the bucket, I'll swap them for Lithium. The Lithium batteries are much better and setting for long periods without discharging, but you are paying a premium for that technology. For vehicles, lithium ion batteries are just not cost effective enough, yet, for me to make that shift.

Interestingly, the new Jeep Wrangler I picked up just a year ago comes with two batteries - a smaller one is to handle the the things running when the stop/start shuts it down - I hate that feature and always disable it when starting up, so I guess that battery will last awhile, lol, but in theory a good feature.

 

[Briar Lee]

Interestingly, the new Jeep Wrangler I picked up just a year ago comes with two batteries - a smaller one is to handle the the things running when the stop/start shuts it down - I hate that feature and always disable it when starting up, so I guess that battery will last awhile, lol, but in theory a good feature.

One of the undeniable advantages of the new fangled electric vehicles is they don’t have a gasoline or diesel engine that requires a battery to start.

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For battery electric vehicle (BEV) packs in particular, prices were $138/kWh on a volume-weighted average basis in 2022. At the cell level, average BEV prices were just $115/kWh. This indicates that on average, cells account for 83% of the total pack price.
——

A base level electric car with a mere 400 horsepower might only have a 50 kilowatt battery, which as prices keep falling means when it wears out it will cost $5,000 to replace. Double that for a 100 kilowatt battery that gives the electric ride nearly a thousand horsepower.

And while replacing a battery in an EV might sound expensive the actual electric motors should last a million miles, and the batteries that long as well. The average owner will trade it in long before that.

In 1974 as a sixteen year old kid working at a boat dock I drive a gas golf cart that would shut off every time I lifted the gas pedal and stopped. Even with carburetors a stop off, start on, feature worked fairly well on gasoline vehicles.


If a mechanic from 1923 came back from the grave, after he got over the initial shock of all the refinements, the actual vehicles we drive are still Otto cycle gas engines with a battery to start them. We really haven’t improved on the idea of a crankshaft being turned by pistons, only advanced and refined it.

I wonder what the vehicles of 2123 will look like?

 

[mikethompson]

One of the undeniable advantages of the new fangled electric vehicles is they don’t have a gasoline or diesel engine that requires a battery to start.

They still have a conventional battery to run various systems.

 

[Briar Lee]

They still have a conventional battery to run various systems.

I didn’t know that but it makes sense.

Let’s say the big battery fails.

The self driving system damned sure better not.

Nor should the power steering or brakes fail.

And the internet connections for the user’s phone should stay on so he can call for rescue.

When you think about, there might should be two small auxiliary batteries.

 

[macaroni]

I didn’t know that but it makes sense.

Let’s say the big battery fails.

The self driving system damned sure better not.

Nor should the power steering or brakes fail.

And the internet connections for the user’s phone should stay on so he can call for rescue.

When you think about, there might should be two small auxiliary batteries.

Wow--good point!