Goes like this Mitch
Every battery that comes off the end of the line is subjected to better than a dozen tests
The BEST ones get diverted to be branded with the premium brand label.
From then on they get different labels for progressively cheaper brands as the quality declines.
Now the crunch comes with demand.
Because people are cheap & nasty, the demand for the premium brand is the lowest and the demand for the cheapest brand is the highest.
So when Walmart puts in an order for 1,000,000 grade -10 batteries the factory often will not have enough junk batteries to fill the order,
Thus they might get 400,000 -10 grade , 200,000 -9 grade , 100,000 -8 grade , 100,000 -7 grade etc etc till the order is filled using all of the lowest grade batteries available at the time .
I did QC for Simmsmetal down here who ran 6 battery factories so know exactly how it works
In a run of 10,000 batteries designed to be all +1 grade the bulk would come in at +1 to -5 , so the battery brands that get -10 batteries rarely got a full order of -10 grade batteries because we never had enough of them.
Thus you could luck in a -5 quality battery at a - 10 grade price but a +1 grade battery was always a + 1
as far as battery quality goes.. the shittest batteries on the market around here are good enough to last 3-5 years.. As an atomotive mechanic we have always told our customers (for 30+ years now) that if your battery is 5 years old and still work, good for you..
At the local lawn mower repair shop they tell thier customers 3 years..
Now I only use the cheapest batteries in my lawn mowers/snow blowers etc etc. and have had the same experience with every one of them. On the lawn mower I use daily to go around my property, it is started probably 25 to 30 times a day and the battery last about 5-6 years.. (it's a 2000 dy4000 craftsman, 22hp single banger). The starter needs to be replaced twice to each battery.
On my 1989 Yard machine briggs 18hp single banger, which is only used maybe 8 or 9 times a year mostly in the fall because I use it with a homemade leaf collector trailer for the fall leaes, so one in the spring then rest in the fall, the battery last 3 years, it has a .5 amp trickle charger and th battery is left hooked up all year round.
On my 1972 craftsman with a briggs opposed twin, the battery lasts forever.. (over 10 years old now), but it is on a quick disconnect, gets a full 1 amp charge the day before the tractor show here in town every year and is used maybe 3 or 4 times a year.
and on my john deere 400 it has a 10 year old car battery type 26 that fit my camaro starts every time, trickle charged at .5 amp used for snow plowing and spreading gravel, nice hydrolic machine that I rebuilt in 2009 from a barn find.
My 1979 camaro has a 10 year battery, it is started about 4x's a year and sits on a trickle charger..
Then there is my generator, with a 10+ year old 100ah deep cycle used for priming and starting it, it auto starts the gen ever 3 days and runs for 45 minutes automatically..
My 25 10ah deep cycle batteries o my 5KW solar array are discharged to about 50% and recharged to 100% at least once daily all year round, they also are walmarts cheapest 100ah deepcycle batteries they last at least 3 and 6 years tops.
Now, here's the difference between each of these batteries..
the lawn mower batteries have very thin, wide mesh matted lead platting, the car batteries have thicker lead plating on thinner mesh matting, the electrolite is identical in both.
The deep cycle batteries have much much thicker plates of lead on much thinner several layered fiber mesh, the electrolite is about 4x's more acidic then the car and mower batteries. They also put out much more toxic gas when overcharged then the mower and car batteries.
as far as how they are manufactured and graded, I never heard of simmsmetal, but at exide thats not how it is done. My cousin is a QC linesman supervisor for them, he said they get a pass or fail grade. If they pass they go on to different channels for labling for different companies, Walmart, pep boys, autozone, lowes, homedepot etc etc etc are all made on the same line and pass the same quality test.. then there are the "optima" style batteries which are made on a different line.. If they fail they get returned for recycling..
WHen I asked him about the grade of batteries 1-10 he smirked and said, who fed you that pile of malarky, batteries either pass or fail they are not graded..
