I was wondering what you guys could teach me about AGM batteries in equipment. It seems like I'm seeing more of them. A couple of examples, T880 trucks and recently a Bell haul truck. In the T880 it must be because they are in the cab under the passenger seat. Safer, can't spill, won't gas, though they do have vent hoses that hook to the battery and go out the floor. Someone said that you have to charge them with a special charger, one that is for AGM batteries. It seems like when they go died that they can be hard to charge back up. What is special about an AGM battery charger? In my experience it is easier to kill them and cost alot more to replace AGM batteries. Is there a special way you should charge them? Why are they in equipment more? In my opinion the best battery ever made is a DEKA group 31 with threaded top post.
I’m having similar questions on a smaller scale. How does a vehicle with original lead acid battery charge the AGM properly at higher required voltage?
A dumb, constant-current charger will chronically over-charge an ATM. They require the constant voltage 14.4-15v. So, a digital controlled charger is needed. Some vehicle alternators don’t work so well With AGMs. AGMs don’t handle abuse or deep cycling very well. They don’t gas, so they work good in the cab. They can be shipped by airplane, so that’s nice when I have to ship batteries to the bush.
I'm not sure the bank will be impressed if you try and charge their ATM...
I've wondered the same thing. I charged the AGM in my F150 with an old 6 amp charger with no ill effects. It's all I had after the battery went dead when I was in the hospital. I just changed that battery because it was getting a little weak and the cold and snow was coming. Being 10 years old I can't complain. I had a deep cycle RV battery explode and spray battery acid all over. If I keep the 5th wheel, I'll put in an AGM.
AGM vs Flooded Lead Acid video AGM (Absorbent Glass Mat) Flooded Lead-Acid Construction Sealed with fiberglass mats absorbing the electrolyte Vented with liquid electrolyte, which can be topped up with distilled water Maintenance Maintenance-free Requires regular checks and additions of distilled water Vibration Resistance High Low, more susceptible to damage from shock Spill-Proof Yes, can be mounted in various positions (except inverted) No, must be kept upright to prevent spills Recharge Rate Up to 30% faster Slower Cost Higher initial cost Lower initial cost Lifespan Typically 4-7 years or more Typically 3-5 years Deep Cycling Can handle deeper discharges (up to 80%) better Lower deep cycle ability (around 50%) Safety Safer, sealed design minimizes gassing and risk of spills Vents produce hydrogen gas
I like AGM and have used for years in Truck/Boat with no issues. Haven't tried my equipment yet but might do it next time. The issue is I'm using Odyssey and Lifeline Bats which are on the higher end side, not like Duracell, Interstate and such. They last years longer then LA
Seems to me, very unscientific, the AGMs are more sensitive to freezing damage that flooded lead acid. Which, goes against the inherent nature of AGM’s. I can rescue a cold, discharged, old fashioned battery where the AGMs just don’t bounce back. But, IDK? Swapping those passenger side, under-seat batteries on a K-Dub sucks. And the voltage drop from the batteries to the starter is well above SAE spec. On a brand new rig. And PACCAR installs an inaccessible battery cable quick connection under the cab. Which then corrodes. Molded connections, and not enough extra rope to make a repair. But, a complete cable assembly is unbelievably expensive and prohibitively unavailable. No way to even access with the air reservoirs, transmission, exhaust system in the way. Best you can do is patch and cobble.
A better battery when running a mass of emergency/rotating light systems.
Heavy on the cobbler-peach by chance?
Where do you see that with analysis?
A decade of maintenance expense tracking with a fleet of 80 power units. And my NAPA Pro-link account. About 1/3 of the fleet uses AGM batts, but they account for the majority (60%) of battery replacements. It’s not scientific by any stretch, just a casual observation with many variables. IMO, the Mexican made Clarios red tops are junk. The Missouri EnerSys ODYSSEY are decent, but over-priced. The Deka AGM from Pennsylvania is my favorite and 1/2 cost of a ODYSSEY.
Thanks I'm in a area where lowest temps are maybe -10F and they don't stay that way for long. Your area probably gets colder My LA boat Bats would last 3 years on average. The lifeline and Odyssey weight more and last on average 7 years. My watercraft last 9 years and reg LA last 2 yrs. Truck is at 3 yrs for LA and 6 for AGM Odyssey. Going to do a real test this time. Had 2021 Ram diesel and just bought Odyssey Bats because cold weather was having issues. Installed then removed because I bought a 2025 Ram diesel so swapped Bats and traded. Have Bats in the barn and keep them topped off. Hope they last, otherwise and lot of wasted money
Not having to top them up is a big bonus of AGM's. I've had LA batteries last 7-13 years in machines I don't use regularly but 10 years for the AGM in my daily driver that has gone dead a few times from sitting a couple month's is impressive. It wasn't completely dead but the cranking speed was a little slower so I changed it before it got in the -20'sC. My truck also has auto start/stop which I think tests a battery more. I didn't mind paying the extra $$ for a new AGM.
I agree with you on the PACCAR deal. Nice truck to drive but a real pain to work on their batteries and cable system. All special components, nothing off the shelf, and all expensive. No just crimping a new end on in the field.
It seems like my little experience is that they take longer to bring back when they are dead. Not sure if they last longer or not yet. Part of the problem may be that I know how lead acids act and AGMs act different and so I just need to learn how they act better.
In my business we have a large fleet of F150s with the AGMs from the factory and we're replacing them very often. Not sure if it stems from poor charging, extreme temperature fluctuations, or parasitic drain. It's not brand related either...the ones from the factory lasted no longer than the NAPA Legends that we replace them with. We usually see around 2 years lifespan. I love AGMs and have had great success in the past. My old Bronco using the winch would fry a lead acid battery quickly but the Deka AGM seemed indestructible. So I'm certainly not anti-AGM. But there must be some situation that they thrive in and some situations that they perform poorly in. I think sitting out in the elements in extreme temperature fluctuations without getting a charge often enough may be one of those situations where they don't seem to last. There's probably some real nerdy battery folks out there somewhere on the www that could shed more light on the subject.
I got 10 years out of the AGM in my 2015 F150 and it wasn't completely bad. I changed it for winter because it wasn't cranking over quite as fast. I put an OEM back in because I was impressed with the original. It had even gone dead a couple times when I was in the hospital but charged it up and it was fine.
The US military has been using AGMs across it's fleet since the early 2000's. Some of the main reasons cited from switching from sealed lead acid battery (SLAB) to AGM were lower maintenance, less off-gassing, and less spillage during "operational use". That means that battery acid doesn't go everywhere when the battery gets hit by a bullet or shrapnel or when the vehicle gets flipped over by IEDs. Are they better than SLABs? I feel like they are but like said above, they have their downsides. Personally, I think most batteries die from either crappy manufacturing designs/standards to cut costs or from poorly regulated charging profiles. The next wave of batteries being introduced in the military are li-ion batts so vehicles will have much longer ability to work off the batt without idling the engines. I can only imagine what a military 6T Li-ion will cost....
You knwo wgat really seems to help (Im calling out all the farmers and lazy/cheap owners here) Battery hold downs if thw poor thinks are bouncing around like a rabbit one redbull they arnt going to last. They need to be held good. When stuff shows up to me they get either fixed or atleast a nice 1 inch strap around to hold them. Seems every machine i touch for the first time has them gone
True Dat. Who has time to keep a battery compartment properly maintained? AmIright? So many of them. All wanting attention.
I don't have alot of experience with AGM's yet but it seems like some of them last a long time and some of them don't. I wish I know what made the difference. At this point I think alot of it is using them wrong. The lead acid batteries that last the longest for me, are the ones that I use every day. Batteries want to be used but not abused.
Batteries only start a vehicle and act as a backup bank if alternator can't keep up for a minute or two. What boils out or damages a lot of batteries is a poor connection to battery from alternator. If alternator senses low voltage it will overcharge and slowly kill battery. That is a nice looking battery box compared to many that I have seen. Simon C
Is that a 12v system? Sure looks like a hard way to wire up a 4 bank.
Yes, it’s a 24 model year Kenworth. Yeah, it sure gets busy with all those group 31’s, then add in the extra up-fitter cables. Shame on the mess.
Nah, I ain't judging on a sturdy and functional hookup. Almost everything I touch is yellow or green iron with a disconnect so the batteries themselves are fairly clean on cables. Yours just looked busy to me. And I'm just not used to 12V systems on work trucks. Is that the new way going forward?
It’s been that way forever. The ATA and the TMC standardized the group 31 as the de facto truck battery. We’ve ran out of frame rail and are putting them under the passenger seat on vocational rigs. .
My 1965 tractor with a Perkins diesel gets long life from batteries and I only use it occasionally. It has the original generator in it. I had to replace a bearing a long time ago but I think because it charges at a low rate it saves batteries. I had 1 battery go 12 years and it was a reconditioned battery. I'd top up the fluid occassionally often with rain water or melted snow. Now I keep some distilled water around.
I was doing alittle training on batteries, and I found out why you should use a special battery charger on AGM batteries. AGM battery chargers use a different algorithm than conventional chargers. Similar to what TPPL batteries use.
I put new batterys in the f750 thismoring the old ones where from 2011. Keep in mind the truck they where in probably only see 2 or 3000 miles a year but still
What brand batteries were they?
Yes, flooded cells should use over 15v during final charging profiles to prevent stratification (the heavy sulphur ions in the battery acid sink) by causing a small bit of excess of electrolysis bubble generation to 'stir' the electrolyte and keep a constant specific gravity across the face of the plates. This is why you also need to add distilled water back to a flooded cell battery as you're off-gassing a small bit of water to fully charge the batts and prevent sulfaltion from the stratified electrolyte. Thin plate pure lead (TPPL) and absorbed glass matt (AGM) constructions don't have a free liquid that can stratify so a lower voltage like 14.4-14.8v is used to prevent excess electrolysis. Once you turn the electrolyte's water into excess oxygen-hydrogen gas that leaves the battery (through the gas valve), you're essentially drying out the cells. No ability to add water back to TPPL and AGMs. So the problem with tossing TPPL or AGMs in an old style engine charging circuit is that those old alternators/generators don't control the voltage very well and you're generally drying out those high $$ batts when the charging voltage gets above 14.8v. And don't forget that what you're reading with a DVM, or worse on your old-school analog gage, is the average voltage. There's ac ripple on that charging dc that can easily be above 15v (and worse if you have failing diodes in the regulator) that is causing the same electrolysis of the electrolyte. Here's a decent video showing ripple: If you're not verifying the charging profile of your engine's alternator to a tee, it's a gamble if AGM/TPPLs will last any longer than an old school flooded cell as you could be slowly drying them out. And if you decide to use flooded cells on a charging system designed for lower voltage AGM/TPPL, you could cause an early death because stratification can occur. So many variables impact battery life. Vibration, temp, cycling, charging profiles, mechanical design, etc. That's why there's such an argument on whether AGM are better than flooded cell as very rarely does anyone truly perform a valid experiment relative to their situation.
That is a good explanation on charging AGM and TPPL batteries. How do they hold up to deep cycling and running them done and leaving them dead for a while?
Deep cycling is relative to the type of battery. Deep cycling a standard or 'starting' flooded cell I think means only discharging to 50% whereas deep cycling an AGM means discharging to 20%. This means deep cycling can mean two different things in that deep cycling a flooded cell is okay as long as it's within limits of a flooded cell 'deep cycling' definition...if that makes sense. But to understand why there's a difference in deeply discharging between the two battery designs, you need to know that when you discharge a lead-acid battery (TPPL or AGM or Flooded Cell), you're converting metallic lead on the negative anode and lead dioxide on the positive anode to lead sulfate by consuming the sulfuric acid. In a flooded cell, the lead sulfate can flake off if too much is built up (too much discharge) and fall to the bottom of the battery. Once the flake layer gets too high on the bottom of the battery and touches the plates, it creates an internal short. This is why sometimes you can recover an old school flooded cell by dumping out the electrolyte, rinsing out the sediment, and then refilling it with fresh electrolyte. Of course the battery won't be perfect but it can be usable again. Don't forget that every time you dump out the lead sulfate, you're reducing the batteries capacity. Since the TPPL and AGM designs keep the lead sulfate in place, you can discharge them deeper and not worry about the flaking of the lead sulfate. Even if discharged to zero volts, there still a chance to recover some capacity of an AGM or TPPL, simply because of the mechanical design. This is another reason why the military uses them as military vehicles sitting in a motor pool are notorious for draining the batts to zero. A typical flooded cell would be dead-dead if drained to zero as all the lead sulfate would be mud at the bottom. And if you're wondering how flooded cell deep-cycle batts are different, well, in simple terms they just trade off max starting amps for long term durability. Starting batteries have a lot of thin plates to provide that high yet short burst of electricity. Deep cycle flooded cell batteries have thicker but less number of plates that can produce a small but steady current for longer periods. When you deep cycle a flooded cell deep cycle, you're still producing the lead sulfate but the plates are thicker so there's more lead if the lead sulfate flakes off. And deep cycle batts generally have a deeper sediment area so the sulfate can be deeper before it shorts out plates. So really, since the chemistry is the same for all lead-acid batteries, it's just the mechanical design of the battery that really influences how much discharge or deep cycling it can handle. But to answer your question about draining an AGM battery to zero is very risky. The sulfation is pretty deadly and even if you were able to recover an AGM after zero volts, it won't be near the full capacity it was when new. Sometimes a recovered battery will work for your application...but I wouldn't trust it long term.
Thanks for that write-up!
Exide from the local truck parts place.
Thicker plates placed further apart is also why it's better to get a starting battery with less CCA for the same size of battery. They're usually better built and handle vibration better. I've had great success with reconditioned batteries (10-12 years) and the guy that owned the shop said too many people think it's best to get the highest CCA rating for specific battery type. A little less CCA means less plates further apart and more importantly longer life.
That passenger seat in T880 SUCKKKKS! hard and like 2ft off the floor so a head smasher.
Thank you for both of those post. They are informative and well written. Also good video on the first one.
I agree but this is also one of those "Yes, but..." statements. I started buying lower cca batteries a few years ago too when I was told the same thing. Everything I own is 24v diesel so at least I try to match a high cca battery to my 'larger' engines. For instance, the trucks with a Cummins 8.3L I'll go with two 750-800 cca but for the Cummins NHC-250 (14L), I'll go with a pair of 1000cca for that little bit extra crank. Does it really matter for me in central Texas (today will be a high of 80F)? Probably not but it's what I do. But after doing a lot of my own research (for my own particular job/career right now), I don't think all manufacturers are really using thicker plates that are truly more mechanically robust for lower cca batteries. I think some are just not using as many plates of the same thickness to achieve the lower cca. Here's why I think it's a mixed bag out there: At Walmart, you can buy the EverStart Group 65 850 cca and 150 min reserve for $140 or the 650 cca with 140 min reserve for $110. Each weighs 47.4lbs so at least here I believe the plates are thicker for the 650 cca. A reduction of 200 cca but the same weight implies the same amount of lead so the plates are probably thicker by 31% in the 650 cca. And now look at Catepillar Group 31 batts which I'm sure are very commonly used by everyone here. There are three types: General duty, Heavy Duty, and AGM (see the attached brochure). For heavy duty, let's compare two similar group 31's with the only difference being cca and reserve. You can see the 1000cca battery is actually a pound lighter than the 825cca even though it has 21% more cranking power. This means the 825cca has less plates and they must be thicker, about 26% thicker than the 1000cca. The rule of 'lower cca = thicker plates' holds true here like the Walmart batteries. But when you look at Cat's General Duty batteries, I think they're trying to hose us. For these the 1000 cca is 58lbs while the 760 cca is 52.5lbs. From my calculations, there really is no thickness change in the plates between the 1000cca vs 760cca. The 760cca is just a weaker battery. Here the rule breaks down. If you want to get into the brute batts, the AGMS, here you can see a much more robust battery. The 800 cca is a full 6lb heavier than the 925 cca and has higher reserve than anything else. So, on the outside, it looks like the AGM is by far a better battery for anyone to stick in their vehicles. But wait, remember the discussion about charging profiles where AGMs need to charge at lower voltage than flooded cells? Even in the Cat brochure it says to charge their AGMs at a lower voltage: Alternator and charger instructions: for 12-volt AGM Batteries charge to 14.4 volts but no more than 14.6 volts at 68° F (20° C) . If you don't, you're just frying your $$$ Cat AGM. So bottom line: A lower CCA battery that weighs as much or more than a higher CCA batt in the same brand and family probably has thicker plates. If it weighs much less, it's probably just a cheaper battery. And if you toss in an AGM into the system, make sure you're charging it correctly or it may be a waste of effort.
Thanks- I appreciate the compliment. For my current job position, I had to do a lot of research on batteries in heavy duty equipment and I learned it's not really that complicated once you understand the basics. So hopefully after explaining the basics of what I know, everyone here too can be better informed when they drop their hard earned cash on a new set of batteries. Just paying it forward to the group...
Good information for us not knowing. The 14 year old exides got replaced with Cat battetys. We put cat batterys in everything if they have one that fits. We seem to get the longest life from them.
I think the Cat Heavy Duty's are better built than the General Duty ones. A Cat heavy duty group 65 is 46 pounds while the general duty is 41 pounds so a lot lighter with a lot less lead. But what kinda sucks is the dang Walmart brand group 65 is 47.4 pounds! This is why I have trouble recommending a specific brand anymore...so many variables like anchored bottoms, through cell connections, etc. really come into play. I've always wanted to cut open a bunch of batteries and make a video of the internals like folks due with oil filters. But man what a messy, nasty thing to cut open batteries!
It does depend on brand. I think some better batteries have a thicker case top that would add weight. One of the 8D's I replaced in my track loader was considerably heavier. Even when I exchanged it for a reconditioned battery the guy agreed it was extra heavy and he handled a lot of batteries. Don't know what brand it was but must have been close to 150lbs. Major pain to take out with the backhoe attached. Had to remove the whole seat and support it bolts too to get it out and didn't have any kind of hoist to lift it. I've since cut slots in the back plate so I can loosen the bolts and slide the back plate up and off.
Cat sells a premium 8D battery that I have bought for Cat3412 generators, and they stopped the starter failures from the heavy current load required to start, about 150 LBS or more than I was willing to lift alone. Simon C
Great write up, LCA078. Thanks
Comical moment last week with some group 31 AGM’s in a new Western Star. We had not officially taken delivery of this unit, yet. But, the shipper had left the ignition key on, in the accessory position and the batt switch on. So, it’s sitting at the Port of Anchorage with frozen batteries, inconveniently blocking operations. Hey, your truck won’t start. Hey, ain’t my truck. You left the battery switch on. No, we didn’t, the cargo company left the switch on. Talk to them about it. Come get your truck. Dude, I can’t get on the Port. My top level security port clearance expired and I’m not sitting through your BS mandatory training BS and background check ever again. Somebody is removing the passenger seat and putting new batteries in this truck and it ain’t me. But, they showed me. They put some used, cheap group 31 cores in it to get it moved to the terminal. So, I still need to put new batteries in it.
Yeah, that'll get 'em jumping. Sometimes folks just have to realize 'oh crap- it really legally is my piece of equipment doing that!' Speaking of 8Ds, or 4Ds for that matter, any 'modern' piece of equipment still come with them as the standard battery? I know the marine folks still like them because they have massive reserve. But from my measurements, you can squeeze 3 group 24's or 34's in place of an 8d and get way more cca and have equivalent reserve. A couple 24s/34s can replace a 4D with similar results. Other than some additional cabling, I can't think of a reason to 'fork' around with those big ol' boxes of lead. Or is using an 8D for theft protection? lol!
Freightliner Alliance Group 31--950 cca, $91.99, last roughly 3.5 to 4 years being run everyday. All I care about is it cranks. *
Absolutely correct, cause once its running it's the alternator that keeps her going until the next start. Simon C
I know I've seen that battery before but I don't remember the Alliance brand. And then I remembered it looks suspiciously like the NAPA Commercial 950cca at twice the price: https://www.napaonline.com/en/p/BAT7236&store=801884
Well, heck. I was trying to find the specs to see if the Alliance or Napa brand was lighter or had less reserve capacity but when I searched on Alliance Group 31 950cca, I saw a dozen different brands with that exact same plastic case. Just a different sticker. I didn't look at specs but clearly it's by the same manufacturer: East Penn.
The real point is the price, it's the best price for 31's in my area, and lasts the same amount of time in a OTR. Les Schwab is $226 for same. There are Freightliner dealers everywhere 870 plus, I can't see a reason to buy anything else. I've used about eight different brands all lasting about 3.5 to 4 years. Zero reason to be spending twice the amount plus for same performance. Batteries are a consumable product in the cost of maintenance, some only slightly better or worse. Shock/shorted plates is the common killer in OTR. When underneath doing a service it's customary to reach up and run a hand over each battery looking for a a warm one or the smell of rotten eggs with one venting. If within 3 years old, replace all.
I just bought 2 group 31's last week for $99 (plus $28 core) from our local International dealer. Replaced two half size batteries from 2017 in our 'new' Hitachi EX100-1 Unusual to have an almost even price match to south of the border. They have them sitting there by the pallet load...good bang for the buck I figure!
Hmmm.....have I been overpaying? Sure looks like it.... But to be fair, it doesn't have the pop-up handle so the top is a bit different. I'm sure East Penn uses that case for a lot of their Group 31s. But until you cut it open and look inside, it's hard to say what it really is...
The handle is just a spec thing, handling selling point. I'm sure there are some internal differences but most of a batteries longevity goes to what it's installed in, is it secure, how many times has it been run down, has the charging system had issues. Years ago {about 20 now} I had Interstates on hand in the shop, I noticed when the truck showed up each month to replace there were several in the dead box that had same names. The delivery guy stated those brands were his best advertisement, {Napa, Les Schwab} were the main two. He did point out the average person was better off to buy a battery at Bi Mart for the simple fact they sell fresh batteries, the store turn over meant it hadn't sat on the shelf a year.
The problem with multiple batteries instead of one big one is there are more places for corrosion and bad connections. I think one big battery would be less money as well.