You can test a battery if you go under the hood and connect up the right meter to measure the battery integrity but why can’t a modern car employ the technology easily? (Or maybe it does and I need a new car)
In: Engineering
So, mechanic here. Some (most?) trucks have a battery volt meter in the instrument cluster that reads the voltage at the battery (for simplicitys sake). Cars, not so much, but as stated theres a battery light in the cluster. Toyotas light up the abs and vsc light (if I’m not mistaken) when the alternator goes out and the car is running on battery power alone.
Disclaimer: its been an interesting weekend with the kiddos, so my memory may not serve me correctly. If anyone has any corrections please feel free to comment.
Mechanic here. The only thing your battery is really meant to do is START the car. Running electrical components and electronics while the car is running is not it’s main purpose. The generator (most people call this the alternator, it’s correctly called generator now buy the industry) keeps all those things working when the car is running. Ok so, testing a battery essentially tells you if it can hold enough charge to start the car after it’s been left off for some time. So your question, why doesn’t the car test the battery… Well they would theoretically involve determining if the battery can start the car… So, this would happen after you start the car? Or when you get in before you start it? Starting the car essentially is the test. If it starts, it’s good. So, do you want to know if it’s gonna start tomorrow morning? Well, testing it now won’t really tell you that. So you see, “testing” the battery is kinda pointless when it’s working. The reason we (mechanics) test your battery when the car won’t start is to make sure the problem is ACTUALLY the battery and not something else like parasitic drain, starter, wiring etc…
No answer for you but like question. I have a 2017 Jeep wrangler unlimited rubicon( can we use more words to describe the damn things?!?!) and the battery died Saturday. There was no light in the dash as others have mentioned, so not all newer cars have that. The only “indication” was a slightly off start sound Thursday afternoon. It wasn’t anything crazy, maybe a one second delay, but just enough delay that I thought that seemed odd. Since it started and got me home, I didn’t think much of it.
AAA came out to my house Saturday, jumped it and it started up. Then he hooked whatever up to it and said it was operating at about 20% so it didn’t have enough power to crank it. So I bought a new one from them (which is convenient). I didn’t leave anything on in it. AAA said anymore batteries last 3-4 years in newer cars because all the computer bits. That tracks because in my wranglers, I have had to replace the battery every 3 years due to them randomly dying, never have any warning either.
Car batteries don’t tend to have a long and drawn-out death. In general they work normally until one of the plates inside develops a crack, which massively limits the current the battery can develop and stops it from starting the engine.
Since there’s no practical way of detecting this it’s not worth checking.
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