But the sad part is most car batteries that are made now don't have easily openable caps, so you cant check the specific gravity without either prying up the plate holding the caps, or drilling the centers out of the holes in the plate while using a shop vac to catch the plastic drillings.
Very true. I think I've mentioned here in the past that I restore/regenerate automotive batteries as a little sideline. Most modern batteries do not have easily removable caps and some are impossible to remove at all without destroying the battery case.
Another thing worth noting is that newer batteries use less lead in their plates than the older ones did. That didn't happen overnight, but has been an ongoing decrease in quality. That's just yet another example of how manufacturing integrity has gone down the tubes in so many things.
Lastly, I'll share a little tip with you that will save you a lot of money over the years if you use it. I have informal arrangements with auto parts stores that allow me to test their trade in batteries, looking for good candidates for my restoration process. I'm not going to get into a lengthy explanation of what I test for or how I do the regeneration, but I will share the best secret:
A lot of the batteries the auto parts stores take in are perfectly good and do not need restoration. By "a lot" I mean probably between 10 and 20%. Perfectly good. Another 25% or so aren't "perfect" but still have a lot of usable life in them, ready to install in another vehicle. Some of the auto store techs might be a little crooked and try to sell the customer a battery he doesn't need (especially if they're on commission), but more often it happens because the tech doesn't remove the battery terminals before doing the test and reads current through the old terminals which are corroded and dirty.
If you buy an inexpensive battery testing device, you can check these things for yourself. There are several things I test for, but the single most important one is the cold cranking amps left in any given battery. It's also good to test the resistance (less is better) and the voltage.
Start checking your batteries now, as we are getting into the colder months when they are likely to fail.
Best
Doc