Hello!
So my never-ending project car, (99 4.0), was received with the wrong battery class size, (26R in this case). The thing isn't in a drivable state so I figured I'd save a bit of coin in the near future by using it for all I could. Even after leaving it to charge, my tester is showing it's 4% healthy and a resistance over 25ohms even at 94% charge. It's time. Thing is, the stock battery size for this generation, (I think it was all 1998 - 2011s even), is a class 59 or optional 58R. But I can't find a single one with a CCA over 575. At with today's battery prices, that's just no good.

I live an area that gets below freezing in the winter and over 100 in the summer. So without regard to accessories or any of that stuff, I'm just looking for something that would have a good amount of CCA when needed. Hopefully 750ish at least. I've read a lot of threads on these forums with drivers looking to swap different classes and there seems to be a desire for 65. It's just so stinking big. I think I've settled on one: Class 34.

Advance doesn't list the 59 size in this chart, but 34 is super close.

Class:::Length:::Width:::Height
59 ::: 10.06" ::: 7.62" ::: 7.75"
34 ::: 10.25" ::: 6.812" ::: 7.75"

So I realize I'd have to secure that 3/4 quarter of an inch or so loss in width to prevent it from sliding around. But the length is already super tight. When I measure the inset of the battery tray, I don't even get 10". More like 9.5". I'm thinking I could take a Dremel or something and remove the tray's lip nearest the headlight, provided I secure the heck out of that thing from ever wanting to lunge forward.

My questions though, (finally rambling dude!): Are there any adverse effects to going to a different class? And besides the tray/bracket modding, are there such things as different size battery terminals I'd have to worry about? Again, for the current price of batteries, I just want to be sure I'm not going to regret the actual purchase, (forget time and effort wasted to make it fit).

Linking below to two I'm comparing now.
Class 59 Diehard AGM
Class 34 Diehard AGM

Any experience or insight is appreciated!

 

First thing is..............car batteries are ONLY there to start the engine, Alternator powers everything when engine is running, voltage flows TO the battery to keep it charged up when engine is running
i.e. battery voltage is 12.3v(old) to 12.9v(new) and alternators MINIMUM voltage is 13.5volts, so...................battery does nothing with working alternator and engine on, can even be removed after start up, i.e. racing vehicles often don't carry a battery

Yes, CCA is important especially on cold mornings
You can change battery sizes without having an issue as long as new battery has the CCA to crank engine for start up

Yes, battery terminals matter, of course, vehicles battery cables must be long enough, and have the right connectors, to connect to the CORRECT poles on the new battery

But the actual AMPS stored in the battery don't effect vehicle operation since battery is NOT USED when vehicle is running
So its strictly a startup/cranking issue

If it takes more than a few cranks/seconds to start an engine, then you have a engine issue not a battery issue

Car battery's last 5 to 6 years, that's just how chemical storage of voltage works, they can no long charge back up fully, most common failure is a self draining battery, plates inside short and drain the battery when it sits for a few hours
Car battery showing 12.3volts only has 50% of its original capacity, that happens at about 5 to 6 years old, and time to shop for battery sales, lol

 

Thanks Ron! And that's kind of what I'm thinking... I guess. 540+CCA should be enough to turn this engine over with ease. Otherwise, engineers would've went with a different size. But real world: that's day one of a battery's life. It seems since most were bought up by the big two, the performance you're getting 1, 2, or 3 years later is significantly less than the batteries you used to get, (not trying to get political). And with kids, this would never be a daily driver, (thus the only reason for AGM after reading on its stronger holding capabilities).

And with regards to the terminals, are these pretty standard (at least in the case of 59 vs the more popular sizes like 34, 65, and so on)?

 

There is "usual" on terminal placement on the same class of battery, and there are side terminals and top post terminals, there is no "standard" for car batteries, i.e. if its a 59 then its like this, doesn't always work
So know your current battery terminals(take pictures), before shopping for a new battery

Actually the newer batteries are lasting longer, some are getting 7 and 8 years with premium brands, I used cheaper brands because I figure I will have a electrical issue that kills the battery before I wear it out, lol
Doesn't always happen but I drive older vehicles so can happen

Bad batteries kill alternators and bad alternators kill batteries, which is why its not uncommon to have to replace both at about the same time


I also run 2 year life coolant, the green stuff, because I figure I will get a leak or another issue that requires draining the coolant, so will lose most of it anyway before the 2 years are up and I need to change it
Putting 5+ year coolant in my 1994 would be foolish, in my opinion

 

haha you need to switch your name to "Murphy" I'm usually the opposite. When I start tinkering, OCD or Type A or whatever takes over and next thing you know, I'm looking to do something the Egyptians or Romans would be proud of. Fast forward and guess how little progress I make?

And thank you for the info! I'm going to see if there might be an upcoming deals, (not likely and not worth waiting until Memorial Day), but your mention about longevity has me pretty optimistic!