Battery, again.
 

I have another dead batt. Last two AGM's (24F) died shortly after warranty.

Now I am going back to a std FLA.

Diehard Platinum 24F-RP 48mo warranty
or
Duralast Gold 24F 36mo warranty

Diehard is +$60

Thoughts, suggestions?

Single data point: I put a Duralast Gold 24F in the ES on 12/29/15 and it lasted 6.5 years (6/21) and 75k miles (I keep detailed service notes!).

The problem is that battery brands stay consistent, but underlying manufacturers and quality can shift frequently. Can’t say 100% it’s still the same battery as then. An option that HAS worked for me for 20+ years is getting Interstate Megatron Plus batteries at Firestone. I generally get six or seven years out of them (More for the bigger batteries in Euro cars, like H8 size).

As an aside, my dad has always bought AGM batteries for motorcycles and power equipment (quad) ever since they were available. In the last 10 to 12 years, the quality has dropped off dramatically and they last no longer than FLA batteries - no matter the brand. I don’t know what’s up with that but he/we are done with AGM batteries.

Going on 5 yrs with an Odyssey AGM. Best batteries made IMO

Going on eight years on a Deka Intimidator agm, group 34. It is part of a dual battery setup in my Tacoma, but Deka batteries have a good reputation.

... I just replace it every 3 years

Chip H.

Diehard is made by Odyssey.
This time around, used my Coscto card, Interstate 24F for $119 36mo warranty.
The Diehard Platinum AGM is 2x that price and also just 36mo.

Diehard Platinum RP (std FLA) is about $10 less than their AGM but comes with 48mo warranty.

I'll pop the caps and monitor water levels, see how long this Interstate lasts.

And btw, 27F is the std batt size for GX470, but things got too tight for my GX, 24F has plenty of crank amps.

I put the batt on my Minn Kota batt charger, will install tomorrow.

If you want to maximize battery life and save money, I highly recommend one of these, Dewalt 80a starter/charger/maintainer/desulfator.


I have brought back batteries that were otherwise trash - would not take a charge, cheap small desulfators would not recover, etc. Brought back two AGM motorcycle batteries, Interstate MTP that was dead from sitting six months (covid BS), a boat battery DieHard, same story. It really works.

Trick is to run the desulfate many times (it’s a 24 hour cycle). when I have a car in the garage for something, I’ll stick it on a good battery and run a cycle as preventative maintenance (that is how they say you are supposed to do it).

I got it 2nd hand off CL and it has paid for itself 10x over. If you only have one car, it may not make a lot of sense. But I have a couple, plus family cars I take care of, bikes, ope, a boat, etc. It really, really saves a lot of money.

The Minn Kota I have can do GEL, AGM, FLA, and has a desulphur cycle.
The dead batt I have is toast. The vehicle is driven daily too, Alt is a-ok.

The correct size is 27F. No problem with Costco Interstate batteries.

Just did a Costco interstate 27F last week….the real challenge is lifting that battery up and over the fender while standing on a stool…

27F is indeed the "correct" batt size for the 470. I use 24F because I have extra connectors and wiring around the area after I did swap to HID long ago. 24F works a-ok. Never had a start issue.

Costco IntState batts dont come with lift straps, at least not at my costco, so I just took the one from dead Diehard and used that one.
24F is a bit lighter than 27F. 24 fits in w/o struggle.

Will see how long this new batt goes.

In addition to high temperatures killing batteries prematurely, leaving cars sit and letting the battery drain down then recharge, dramatically shortens battery life, no matter what kind it is.

In order to understand how quick this happens on our heavily computerised cars I thought, I would run the test on my 2015 LS460 SWB AWD. I started with a quality Multimeter that has both DC and AC current(AMP) measuring capacity. You put the black lead into the common port, and the Red lead into the 10A port, may also be labelled just AC/DC A on some meter. Having Alligator clips on the end of the probes will make doing this a whole bunch easier.

I shut off the car, put the key FOB in the house in an RFID box, left the doors unlocked, and lifted the hood. My car does not have a hood open warning light so no hood open sensor that needs to be defeated. I disconnected the negative terminal on the battery, clipped the Red Lead to the battery terminal and the black lead to the Negative cable. I then opened and closed the drivers door. Reading popped to 4.8 amps with the interior lights coming on. Closed the drivers door, reading dropped to 2.7 amps and after about 30 seconds started to steadily drop. Within 90 seconds it was down to .7 amp and still dropping. Within three minutes it was reading between .03 and .04 amps, so 30 to 40 Miliamps.

I had read that the FOB being too close would cause the vehicle to wake up so I went in the house and got the FOB. Even right beside the car, not change in .03-.04 AMPs being drawn. Used the FOB to open the trunk, reading popped up to 6 Amps. Closed the Truck with the auto close system using the button on the trunk lid, reading stayed at 5-6 AMPs. As soon as the trunk latched the AMPs dropped to 2.5 and then kept dropping following the same pattern above. I tried a number of different combinations and permutations, including putting the push button start in the run position without stepping on the brake so the car didn't start. Remember, your multimeter is limited to 10 AMPs, if you start the car, or turn on high draw things like Headlights, you will likely pop the fuse that protects the multimeter.

No matter what combinations I tried, the at rest reading dropped back to the 30 to 40 miliamp reading. The only thing I didn't do that I wish I had done, was lock the doors and see if the at rest reading increased with the security system active. Since I park in a secure garage and never lock the car, I didn't think about that till I had it all buttoned up again.

Since the car sits for long periods of time I have attached a NOCO harness to to the battery terminals to make hooking up the trickle charger much easier. This way I can just plug the trickle charger in without having to remove the clips and lift the battery cover each time to attach alligator clips. I have these quick connects on all my vehicles. Even at only 40 Miliamp, a battery will drop below starting voltage in about a month, if it is stored cold it will go flat faster than that. Remember, lead acid batteries do not like to be discharge down to 11 Volts and recharged. They are much happier and last far longer if kept above 12.3 volts and that means a trickle charger is a good idea if you don't drive your car for at least 30 minutes every 3 or 4 days.

Hope this information helps those of you suffering from batteries going flat or dying prematurely.

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Multimeters have a lot of different layouts, this is just for illustration.



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As a followup, Charged the battery to full, after an hour off the charger, read 12.73. July 2023 OEM Lexus battery. After sitting in the garage un-driven for 8 days, battery now reads 12.45. So the constant drain, even though very small, definitely draws down the battery over time. Battery went from 100% to 80% in 8 days. Still lots of juice to start the car. Left parked with no trickle charger, and assuming an even rate of drain the battery will be down to 50% in another 12 or so days.

At 12 Volts it is still enough to start the car but this is NOT what lead acid batteries like and will materially decrease its service life. If you aren't driving the car regularly your battery will last far longer if you put it on a .75 AMP to 2 AMP smart trickle charger like a Noco. The other option is to disconnect the negative battery during storage, but I find it a lot easier just to leave it on the trickle charger.


You can use the quick connect cable on the jump start terminals as well, they don't have to go on the battery itself. The reason I put them on mine was so I don't have to remove any of the under hood covers or the battery cover to hook up alligator clips each time I wanted to put the trickle charger on. On my LS you can't reach the battery terminals without opening the battery cover by the windshield.

Here is a picture of the LS460 Battery location. The panel with the Yellow sticker has to be removed at min to get alligator clips onto the battery.

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I've been down the path of monitoring idle current, nothing has changed for my GX.
I had other deep-cycle AGM's used for a 24v inverter, they were large, big enough to run my system (about 200watts) for 8hrs before needing to go back on Minn Kota. Over a period of about 3yrs those AGM's dried out. After they died I literally cut them open, little to no liquid inside, and the glass matts appeared to be dried up mush.

AGM's can indeed dry out, and when that happens they die and become scrap.

Side note, not sure what actual "24F" batt I got from Costco, it's the std FLA batt. The IntState label on the batt says "24F, 700CCA". But then I go look at 24's on IntState site and they say 560CCA. The Costco IntState batt does not ID it as an M-24F, it just says "24F". So perhaps some games they are playing with labels.

So, now I just check batt cell levels as summer ends, and monitor resting batt voltage on ocassion. Nothing more I can do beyond that.

If this Costco batt goes 36mo without issue, then it easily claims the value stake since it was just $119. If Ibuy two and that gets me 72mo, that's 2x longer for same price as one Diehard Platinum AGM.

i run walmart batteries since costco didn't have the size i needed last time... cheap and decent warranty... all the battery manufacturers have gone down...

Interesting experiment - and all functioning well. 50ma is the upper limit of acceptable draw once everything is asleep.

Another point - some cars will “fool” the simple tenders. I haven’t had the problem (mostly slightly older cars). My SIL has a BMW Z3 that sits a lot; had it since new. Great car. My brother has had battery issues w/it despite being on a trickle all the time. A tech told him to get a NOCO - the car would “outsmart” the simple chargers. He got the NOCO and no more issues.

2nd question - how why are these AGM batteries “drying out?” And can you do anything about it? Maybe that is what has been happening to my dad’s and our neighbor’s. I have two here I could cut open and check…