No wonder the ‘big boys’ are so damn expensive!

“where did you get it tested? Did you try going to a proper battery dealer?“
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On one occasion my mechanic tested it, and on another I had O’Reilly’s test it. It should be stated the battery before it went out was at least 4 years old.
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“but it only gets used every several years ...”
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Yes, but when I use it I want to make sure my results mean something. I don’t want a false sense of security.
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“are you sure the battery is the problem?”
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Yes, because the next battery lasts me another 4+ years.
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“the gold standard:”
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Thank you, this is what I am looking for and at under $300 it’s not a bad price. I was expecting more than double that ($600). Having a good, reliable battery test is imperative alongside a good scan tool.

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“Carbon pile. It's the only tester that comes close to duplicating real world loads.”

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Thank you again.  So how come the electronic ones don’t duplicate real word loads?  Some of them cost $140.

This tester (Foxwell BT705) can’t do what the Mactools one does?
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https://the-gadgeteer.com/2022/12/04/foxwell-bt705-car-battery-tester-review-stay-current-on-your-battery-health/

Because to simulate a real world load, you would need to draw about 4,000 W from the battery (briefly). There is physically no possibly way to dissipate that much energy in a hand-held unit.

Inexpensive testers will draw small amounts of current, and use that measurement to extrapolate (guess) how that battery might react to a real load (the starter. 100's of amps). Except, the assumption that the battery reacts the same way is wrong. There are dynamic effects you cannot predict. Batteries are chemical devices, and chemistry is not an exact science. The exact construction, and formulations used from battery to battery varies greatly. The condition of the lead plates inside varies. There are simply too many variables, and this is why they often get it wrong.
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That being said ... for the price of a reliable tester, you can buy several new batteries.

So then all these digital meters (even the $150-$300 ones) that measure Voltage, CCA, and especially state of charge or SOC (%) and state of health or SOH (%), along with resistance (Ohm) - we should take those numbers/results with a grain of salt?

I would, and it sounds like your experiences suggest the same

Have you witnessed one of those Carbon pile testers in use? I know you said you get your battery tested at the battery place. I will watch some videos to see how to use them since I am interested to buy. They seem straightforward to use but I imagine you would want to set the load correctly so as not to damage the battery.
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Is there anything else from your experience I should know about those testers so I don’t damage my battery or myself?
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The Autozone does not use that carbon load tester, disappointingly. They have their own “special” electronic tester (definitely more expensive than the ones most use at home). But it seems to report the same metrics as the cheaper ones, so accuracy is in question.

Yes I did watch and it was explained to me (a long time ago). The battery needs to sustain a certain current for a certain period of time, without dropping below a certain voltage, but I can’t remember the specifics. I’m sure the tester comes with instructions or they can be found on the web.

I will look for some videos. Some of these digital testers also monitor the voltage while the engine is at idle as well as when you increase the RPMs, plus with headlights on and off, and they also look at the cranking time. I don’t know if all digital testers do that but the pricier ones do. But we can say these additional tests are done with actual loads - wouldn’t those digital testers be valid in that case?

Thanks for the help. I just purchased the MacTools 500 A Carbon Pile Load Tester. In the states here, it was $230.

good deal. Let us know how it turns out.

I also bought an electronic tester made by a reputable company Autel. Definitely not cheap but also not super expensive. It has no screen and pairs with my smartphone or Autel full-system scan tool tablet which I already have. I just have to download the app.
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Anyways, I want to see the side by side comparisons between the two over time. It will be an interesting exercise to say the least.

Cool. I'm interested to hear what you find out.

I will post the results here as I get them. It will be nice to directly compare the Autel electronic tester with the “gold standard” Carbon Pile Tester and see how far off it is.

I've used these , and let me tell you, they don't work. They are, again, an approximation, and often a poor one at that.

I'm sure they're not very precise but I've certainly found bad batteries with that kind of inexpensive load tester over the years. Back in the day we used a hydrometer to directly check specific gravity of the acid in the cells but you can't use that on a sealed battery.

if the toaster style tester says your battery is no good, then it's probably no good. But if it says it's good, I find that too often it's a false positive.
There are still vented batteries (eg deep cycle ones), but a hydrometer will only tell you the state of charge, not health. Most of the time a volt meter is good enough.

Value of a hydrometer is finding cells where one or more are weak (or dead) and the others holding a charge.

Exactly. It's only reason I have one.

The article mentions:
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“Some manufacturers emphasize that their batteries should not be load tested, but instead tested for conductivity. They claim that load testing can damage the battery. Therefore, always check the service information for a given battery before performing a load test.”
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What if I can’t find that information for my vehicles?

interesting, but I've never had an issue load testing batteries. They must be talking about some very specific situation.

And after all ... the battery is "load tested" every time you start the car.