Why AGM Car Batteries Are The Future

[Mwittke5857]

Not sure that this is truly an "apples and oranges" comment from @Mwittke5857, more likely just a misunderstanding, as I think @MarkS was trying to show. The lithium-ion batteries do still function at low temperatures, just at a lower capacity (as has been stated and is well known by those who have an interest).

Your comment about the batteries shutting down at low temps is probably jumping to a conclusion. At higher temps the battery shutting down is safety related, as they would not want a fire/explosion caused by the heat. Which reminds of another reason I personally would steer clear of lithium-ion in my vehicle.

You did mention motorcycle batteries and I believe (the last time I looked was a few years ago) those are generally LiFePo, which is different from what we generally think of as lithium-ion. I did have one of these in a motorcycle about 5 years ago and it worked great, until it got below a certain voltage and then it would no longer charge. That was probably due to an older charging system on an older motorcycle but it still left me stranded in the end.

I agree with you that for the most part, AGM is probably the correct choice. I do think the thread title is a little misleading since AGM has been widely available for decades. We all know OEMs are not using them much and that probably comes down to cost, though some BSs came with them in the pandemic years at least.

I had a LiFePo in my 2015 Dyna Low Rider, worked flawless for me up till the time I sold it in 19. Then again, my sled was probably newer

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[sajohnson]

Quote from the article:

"The legacy batteries that we were talking about above are called wet-cell batteries. And they’ve worked just fine for decades. However, newer vehicles with complex electrical systems and tech require much higher electrical demands making Absorbed Glass Mat (AGM) batteries almost a necessity to keep them running properly."

Interestingly, the specs for the two OE Motorcraft batteries (lead-acid and AGM) are almost identical. That surprised me. I posted about that here on the forum a while back.

Many of the advantages of AGM batteries are N/A to automotive use -- can be mounted upside-down; can be installed in occupied spaces; can allegedly be shot with a rifle and keep working.

A useful feature for those that go off-road is the AGM's ability to withstand vibration better than flooded lead-acid batteries.

I'm not clear on how, "...complex electrical systems and tech require [present] much higher electrical demands..." I'm not saying they don't, but complexity does not necessarily = a greater load. The displays are mentioned as well -- they take very little power, and none with the ignition off. Of course, when the engine is running any increased load is a non-issue, and when the BS is off, there should be very little current draw. I haven't measured the current when off, but the battery only loses about 0.01V per day when parked. And again, the specs on the two OE batteries are close to identical. IIRC, the reserve capacity was identical, so whatever the draw is, the AGM would not perform better.

All that said, I did a quick Google search a while back and it appeared that the OE lead-acid and AGM were very close in price. If that is actually the case, might as well go for the AGM.

 

[Meanderthal]

I had a LiFePo in my 2015 Dyna Low Rider, worked flawless for me up till the time I sold it in 19. Then again, my sled was probably newer

Mine worked fine for me, until I was in a ADV class and had to shut down and start up many times per hour as we performed different training procedures. At the time, I thought that I had a failed alternator, as taking it for a long ride did not solve the issue and it only got worse until it would no longer even run. Hooking it up to admittedly low tech (no tech?) chargers did nothing either. It was only after hauling it home and hooking it up to a Battery Tender did it recharge and then worked again. I however decided it wasn't worth that sort of issue reoccurring in the wild and went back to a more traditional battery. It was a better solution for that motorcycle and potentially for how I would use it (i.e. camping in the CO mountains was a multiple times per year occurrence).

 

[Mark S.]

I think MarkS is referring to known issues EVs like Tesla’s could experience with loss of battery capacity in cold areas

Correct.

using Tesla as an example to justify a claim against performance drop is not applicable to a Bronco Sport use of a 12V lithium-ion battery and in fact there will be some performance drop with extreme temperatures for all lithium-ion batteries.

I made no claims regarding the relative benefits of lithium-ion vs traditional battery technologies. Indeed, I didn't even bring up Teslas with respect to this discussion. The only reason I chimed in to begin with was to get clarification from @Mwittke5857 regarding his claim that Teslas do not experience loss of battery performance in cold weather. I have no idea how or whether the fact that Tesla batteries do indeed experience a performance drop in cold weather applies to lithium-ion battery use in a Bronco Sport.

I have nothing against new battery tech. In fact, I've been using a pair of Lithium Iron Phosphate (LiFePO4) batteries in my airplane for a couple of years now with great success. I replaced a single flooded lead acid battery with a pair of LiFePO4 batteries. When connected in parallel, these two batteries essentially doubled my cranking power, increased available amp/hours (in the event of alternator failure) by almost 75%, provide a third independent power source (two batteries and the alternator) for redundancy, and decreased the aircraft's empty weight by over ten pounds.

 

[Mark S.]

Mine worked fine for me, until I was in a ADV class and had to shut down and start up many times per hour as we performed different training procedures. At the time, I thought that I had a failed alternator, as taking it for a long ride did not solve the issue and it only got worse until it would no longer even run. Hooking it up to admittedly low tech (no tech?) chargers did nothing either. It was only after hauling it home and hooking it up to a Battery Tender did it recharge and then worked again. I however decided it wasn't worth that sort of issue reoccurring in the wild and went back to a more traditional battery. It was a better solution for that motorcycle and potentially for how I would use it (i.e. camping in the CO mountains was a multiple times per year occurrence).

Some of these batteries incorporate a battery management system that will not allow the battery to accept a charge when below a certain voltage. The batteries in my plane recharge within just a few minutes following engine start. I can watch the amperage go up to 50 or so immediately after the alternator comes on line. My batteries came with a warning not to attempt an engine start if battery voltage is lower than 13. The batteries will take whatever amperage is available from the alternator, and if the battery is too far discharged the rate may be high enough to represent a fire hazard.

There are specific chargers that change charging rate on the fly. The BMS will take a charge at a lower rate until the battery voltage is high enough to accept full charge rate.

 

[Dude]

Correct.


I made no claims regarding the relative benefits of lithium-ion vs traditional battery technologies. Indeed, I didn't even bring up Teslas with respect to this discussion. The only reason I chimed in to begin with was to get clarification from @Mwittke5857 regarding his claim that Teslas do not experience loss of battery performance in cold weather. I have no idea how or whether the fact that Tesla batteries do indeed experience a performance drop in cold weather applies to lithium-ion battery use in a Bronco Sport.

I have nothing against new battery tech. In fact, I've been using a pair of Lithium Iron Phosphate (LiFePO4) batteries in my airplane for a couple of years now with great success. I replaced a single flooded lead acid battery with a pair of LiFePO4 batteries. When connected in parallel, these two batteries essentially doubled my cranking power, increased available amp/hours (in the event of alternator failure) by almost 75%, provide a third independent power source (two batteries and the alternator) for redundancy, and decreased the aircraft's empty weight by over ten pounds.

Was not referring to any claim from you

 

[Dude]

Both the Antigravity and Dakota Lithium incorporate a BMS. The Antigravity comes in the H6/Group 48 size and an earlier post recommended the 40Ah model so I looked up its specs and chatted with the technical service rep at Antigravity about various topics.

These battery’s have a very specific temperature range they are spec’d to work with (See Post #6) and have built in protection mechanisms. Because I was most interested in the battery behavior under conditions that exceed its 140°F max operating temp spec I focused more of my questions there and posted about that in Post #6.

These batteries are also picky about the max alternator output voltage which I don’t believe the Antigravity spec is 100% compatible with the Bronco Sport since some owners reported seeing output voltage over 15V (alternator output).

I did not ask about the battery behavior below its low temp spec (Operational temp is listed at 23°F) because that was not of interest to me. That should be of interest to those living in cold to very cold climates.

For me the cost of the 12V lithium-ion battery and potential issues with operating temperature range and potential issues with the vehicles alternator output voltage indicates todays available lithium-ion 12V batteries are a non-starter (pun intended).

Lithium-ion batteries have lots of advantages but just on cost alone I could buy 2 or 3 AGM Batteries and I doubt the lifetime claim of a lithium-ion battery would be met under the harsh underhood summer time temps where I live.

Anyone thinking of switching to a lithium-ion 12v vehicle battery is encouraged by the battery manufacturer to do their own research to ensure compatibility with their intended usage.

 

[cprcubed]

some owners reported seeing output voltage over 15V (alternator output)

I'm one of them. I've had the recall done a few months ago, and with the current lower temperatures in Texas, I just saw the first foray into the 15V range after starting the BS over the last couple of days. It goes back into the high 14V range pretty quickly though. Cheers!

 

[Mwittke5857]

Just found an interesting article regarding EV (lithium-ion) batteries and "real world tests" vs "lab results"
https://fordauthority.com/2025/01/ev-batteries-last-longer-in-real-world-use-than-labs-study/

 

[Dude]

Just found an interesting article regarding EV (lithium-ion) batteries and "real world tests" vs "lab results"
https://fordauthority.com/2025/01/ev-batteries-last-longer-in-real-world-use-than-labs-study/

That does seem to be the case and I’ve been reading about that for several months now. It’s good news for anyone with an EV with super expensive battery packs.

I had wondered if the reason for longer lasting battery pack life may have to do with auxiliary methods used in many EVs to keep the lithium-ion battery pack in an acceptable temperature range and the charge/discharge algorithms employed to prevent damage to the battery packs.

A lithium-ion 12V battery in a Bronco Sport might not have auxiliary methods to keep the lithium-ion 12V battery in an acceptable temperature range but likely has a BMS to control proper charge/discharge cycles. An owner would need to verify specs for any 12V lithium-ion being considered for a Bronco Sport. See Poat #22.

 

[sajohnson]

That does seem to be the case and I’ve been reading about that for several months now. It’s good news for anyone with an EV with super expensive battery packs.

I had wondered if the reason for longer lasting battery pack life may have to do with auxiliary methods used in many EVs to keep the lithium-ion battery pack in an acceptable temperature range and the charge/discharge algorithms employed to prevent damage to the battery packs.

A lithium-ion 12V battery in a Bronco Sport would not have auxiliary methods to keep the lithium-ion 12V battery in an acceptable temperature range but has a BMS to control proper charge/discharge cycles.

Some 12V LFP batteries do have internal heaters, but IDK how effective they are. For one thing, the battery is not insulated, and the wattage must be relatively low so that the battery is not discharged too quickly.

 

[Mwittke5857]

I stand corrected, solid state batteries look like they may be the future. Still a way off, but if they are looking for a guineapig... Just sayin...
https://fordauthority.com/2025/01/ford-ev-partner-sk-on-announces-solid-state-battery-breakthrough/

 

[Dude]

I stand corrected, solid state batteries look like they may be the future. Still a way off, but if they are looking for a guineapig... Just sayin...
https://fordauthority.com/2025/01/ford-ev-partner-sk-on-announces-solid-state-battery-breakthrough/

Yep sure looks like these SS batteries could be the next big thing, sure am hoping for that!

 

[Mwittke5857]

Yep sure looks like these SS batteries could be the next big thing, sure am hoping for that!

I (think) this is how they got jump packs down to a size that fits in your hand.

 

[NMhunter]

I use a couple of LiFePo batteries for camping. They are perfect in the summer. But, they can't be charged below freezing, unless they are heated. I bought a heated one, and found out it could only be heated with a proprietary AC charger. One advantage of LiFePo batteries is that they can be discharged almost to zero without harm, while discharging a lead acid battery to near zero decreases its life quickly. The other big advantage is that they charge much faster.

For a vehicle applications, it would seem to be easy to warm it up in the engine compartment, and then start charging, as long as the BMS (Battery Management System) won't allow charging until the battery is above freezing. That would be a nice option on a Bronco Sport. LiFePo batteries also need to be charged at a higher voltage than AGMs or flooded. Without modifying the charging voltages, I'm not sure you'd get the full capacity of the battery.

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