SIGforum
Oh, Great Knows-All Sigforum Members: Automotive Battery Question
December 25, 2025, 11:42 PM
nhracecraftOh, Great Knows-All Sigforum Members: Automotive Battery Question
quote:
Originally posted by trapper189:
quote:
The charging profile for an AGM Battery is supposed to change over time in order to maximize the life of the battery.
Same is true with regular wet cell and SLA batteries; the curve is different for AGM.
Three phases for smart chargers: bulk, absorption, and float. During the bulk phase, the charger throws as many amps as it’s capable of at the battery. IE, a 15 amp charger throws 15 amps at the battery. As this happens, the battery’s voltage rises until a preset limit. The limit is different for different batteries. Don’t quote me, but I believe 13.8v for gel, 14.4v for wet cell lead acid, and 14.7 for AGM. The batteries reach this preset limit at about 80% of fully charged. At this point, the absorption phase, the charger holds the voltage constant by reducing the amps it throws a the battery. Once the battery is fully charged, the charger goes into the float phase where it just keeps the battery charged and reduces the charging voltage, about 13.2v for a wet cell lead acid battery.
Cheap chargers let the voltage keep rising which cooks the acid and water releasing hydrogen and destroying the battery. There’s more, like temperature compensation, but I see eyes glassing over already.
We're getting off in the weeds here, but my main point was that programming the computer for the new battery affects how the vehicles charging system performs when charging the battery and resets the battery charging profile for a 'new' battery, not just the battery type. You had mentioned German cars, referencing VW and my info originates from Audi, which actually changes the battery charging profile based on the time in service for AGM Batteries.
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December 25, 2025, 11:53 PM
jimmy123xJohnson Controls makes Walmart batteries and interstate (and a few other brands). Walmart batteries, a lot of the maxx ones have the same specs as the equivalent Interstate but generally have a longer warranty.
December 26, 2025, 03:02 AM
armoredIs Costco a possibility for a new battery?
Last time a bought batteries it was from Costco.
They sold Interstate at that time.
December 26, 2025, 05:10 AM
NontypicalAnother vote for Walmart Everstart Maxx here.
December 26, 2025, 05:40 AM
trapper189quote:
Originally posted by jimmy123x:
Johnson Controls makes Walmart batteries and interstate (and a few other brands). Walmart batteries, a lot of the maxx ones have the same specs as the equivalent Interstate but generally have a longer warranty.
Johnson Controls sold its battery business to a private equity firm, Brookfield Business Partners, six years ago which then named their newly acquired business Clarios. Clarios owns Optima and Varta. The made in Germany labeled WalMart batteries were made by Varta. East Penn also makes batteries for WalMart.
December 26, 2025, 07:38 AM
sgalczynThe East Penn-DEKA AGM battery (Intimidator) has lasted 7+ years in my cars...................
"No matter where you go - there you are"
December 26, 2025, 08:44 AM
blueyeAnother Walmart fan here, easy peasy on the warranty if needed.
December 26, 2025, 10:00 AM
PHPaulNew Everstart Maxx being topped off as I type.
Only 500CCA available in the correct form-factor. I misread the label as a Type 24, but it's actually a type 51R.
Still, that's better than the 430CCA it came with and it lasted 11 years.
Be careful when following the masses. Sometimes the M is silent.
December 26, 2025, 10:39 AM
iron chefquote:
Originally posted by armored:
Is Costco a possibility for a new battery?
Last time a bought batteries it was from Costco.
They sold Interstate at that time.
Costco went to a pro-rated warranty, so if your battery dies in month 36 of its 36-month warranty, you will receive a credit for 1/36th of its purchase price.
Walmart EverStart warranties are full replacement. A dead battery in its last month of warranty time-frame will be replaced 100% w/ the equivalent model.
December 26, 2025, 11:50 AM
charlie12quote:
Originally posted by RogueJSK:
Walmart's Everstart batteries are some of the best bang for the buck in the battery world.
I typically get the Everstart Maxx.
There are only like 2-3 traditional lead-acid automotive battery manufacturers that supply nearly all the batteries in the US, with the ones at the automotive supply or big box stores generally being made by either Johnson Controls/Clarios or East Penn.
So if the specs are comparable and they came from the same factory, the price difference between different batteries from different places is just down to the brand/marketing/store markup. There can often be a $50+ difference between identical batteries that rolled off the same production line, just due to being sold at different stores with a different sticker on them. Go with whatever's cheapest with the specs you want.
I get mine from Walmart too. I just got one for my truck a couple weeks ago. Everstart Maxx
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December 26, 2025, 08:59 PM
mikeyspizzaWhat about the Duracell's from Sam's? I've bought 3 of them but in the past 3 years but don't have a track record to report yet other than they're still going.
December 27, 2025, 03:06 AM
trapper189The Sam’s Club Duracell AGM batteries have a 3 year replacement warranty while the WalMart AGM batteries have a 4 year replacement warranty. We spend several months 200+ miles from the nearest Sam’s Club but 20 miles from the nearest WalMart, so WalMart wins for me. The Sam’s Club batteries lasted just outside the warranty down here.
December 27, 2025, 07:01 PM
HRKYa know, WalMart has good batteries
December 27, 2025, 08:07 PM
sigarms229I own 3 vehicles. 2 of them currently have Walmart Everstart Maxx batteries in them. The only reason the 3rd doesn't is because I couldn't find a walmart with the size I needed in stock so that one got a Motorcraft Battery.
Sometimes, you gotta roll the hard six
December 28, 2025, 09:31 AM
gpbst3After doing my research I went with the Walmart battery. Like others said most batteries are relabeled. The main reason I went with Walmart is the warranty and locations. If the battery fails at 8pm on Sunday night I can drive 15 mins to Walmart and have new battery.
December 28, 2025, 10:24 AM
PHPaulquote:
Originally posted by HRK:
Ya know, WalMart has good batteries
Ya don't say!
I'll have to check that out.
Be careful when following the masses. Sometimes the M is silent.
December 28, 2025, 10:43 AM
cparktdI tried a few Walmart batteries over the last several years on my and family / friends vehicles.
NONE, not a single one, has lasted out the stated warrantee.
BUT... they sell multiple levels of them, good, better, best. Our local store virtually never has the top tier in stock in the size needed.
On the other hand, in ~55 years of buying Interstate top tier I have never had one fail before the warrantee is out.
I will say the Walmart warranty has always been honored.... if the battery is technically out by its MFG date, you will need your receipt.
YMMV!
Some people spread happiness wherever they go… some whenever they go. December 28, 2025, 11:40 AM
tatortoddquote:
Originally posted by cparktd:
I tried a few Walmart batteries over the last several years on my and family / friends vehicles.
NONE, not a single one, has lasted out the stated warrantee.
BUT... they sell multiple levels of them, good, better, best. Our local store virtually never has the top tier in stock in the size needed.
On the other hand, in ~55 years of buying Interstate top tier I have never had one fail before the warrantee is out.
Batteries that are 100% replacement (i.e. zero proration) warrantied 3 years and only last 30 to 35 months are my favorite kind!
My Frontier eats batteries between living in hot, humid Houston and Nissan's design. I've owned it 9.5 years and only bought 1 battery. Nissan did serial warranty replacements until 1 finally lasted past warranty. I bought an Interstate battery, and it didn't last until warranty so I got a new one for free. Interstate is smarter than Nissan and only replaces once.
Manufacturers make a northern version (i.e. excels in the cold) and a southern version (i.e. excels in the heat). The further north or south you live the more likely you are to kill the battery before the warranty. I drove my old Silverado from Houston to Alaska in Oct 2009, and by Jan 2010 my "southern" Interstate was deader than a hammer. In Alaska, my Silverado w/ "northern" Interstate batteries never made the warranty date.
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