This story started very interestingly and then went absolutely nowhere. I suggest next time you spice it up with things like events and conclusions.
Force of habit.
This is very bad advice.
Back in the old days, when cars had generators, a quick and dirty method for testing the generator was to disconnect the battery. If the car continued to run, the generator was probably ok. If the car died, the generator was probably toasted.
Back in the 1970s or so, you could probably still do that same test for an alternator. You might fry the radio if it was turned on, but nothing else in the car’s electrical system would likely be damaged by disconnecting the battery.
Modern cars rely on the battery to do a lot of the bulk filtering and voltage regulation. If you disconnect the battery, the alternator’s output is, as the name implies, alternating. Without the battery to smooth out the output, the alternator’s output is going to swing wildly. Not that big of a deal for a 1970’s era car with its fairly simple electrical system, but it’s going to be VERY BAD news for a modern car and all of it’s computer controlled gizmos. You can damage the engine computer, the instrument panel, safety systems like ABS and airbag controllers, all kinds of things.
Do not disconnect the battery on a modern car that is running. Very bad things can happen.
Yep. Once the engine is running, the battery sorta acts like a big capacitor. So while it’s true all of the electrical energy comes from the alternator (again, once the engine is running), the battery provides short-term voltage stability.
Ehh, only if you plan on powering things with the engine off for extended periods of time, or using things that draw significant power w/ the engine off. This won’t be true for 99% of people. Even then, I would probably look for another way to power these things vs. using the car’s battery.
There is a good reason car manufacturer’s do not use deep cycle batteries in their vehicles…
My opinion (and my previous dealings with Jiffy Lube) is they are trying to sell you something you don’t need. If your battery is truly failing after a year take it to where you purchased it and repeat (or show paperwork) with Jiffy Lube’s “recommendations”. They will test it according to their standards.
Problem with taking it to the parts store and doing the test where the carry out a machine and hook it up still in the car you will probably get the same results as Jiffy Lube if they were telling the truth. The correct way to test a battery is to remove the battery and hook it up to a machine that does a “load test” and other various tests. This will usually last from a 1/2 hour to several.
As far as the numbers? If it is the CCA and going into summer I wouldn’t be concerned. If it is still under warranty I would get it checked ASAP, unless it is "free replacement, they will prorate the warranty based on the warranty period. The longer you wait, the less warranty pay back.
I had my battery replaced by AAA in February. It was dead, didn’t start. They came to my house, did the work (which included removing and replacing the windshield wiper assembly) and charged me $30 more than what I would have paid to buy a battery at AutoZone.
So, yes, they did.
@nearwildheaven don’t let people change your mind about using Jiffy Lube to get your oil changed. I’ve been having mine changed by Valvoline for years with no problems. Just because you can do it cheaper at home doesn’t mean you should/could/would. But do know they will upsell you, just like Valvoline does. You’re right to say no and confirm!
My son has his done at the stealership. If he didn’t, it would never get changed
A modern car has several electrical circuits - starting, lighting, accessories, etc. They are all 12V DC circuits, and the car’s battery is the voltage source for all of them. They do NOT run off the alternator. The alternator’s only job is to supply power to the battery. That power is AC and has to be regulated and turned into DC via the regulator/rectifier. There is no electrical system in the car that will work with the battery removed, whether the car is running or not. Because the battery is continuously conditioned and charged while the car is running, it does not normally need to be a deep-cycle battery. If you plan to add additional loads to the circuit far beyond what the accessory circuit was designed to handle, or intended to run for lengthy periods with the car turned off (and thus not being charged), adding a deep-cycle battery is a good idea. Just wanted to point that out since I’m seeing several posts that erroneously describe how a car’s electrical system works.
Well, this is somewhat debatable.
During starting, 100% of the car’s electrical demand comes from the battery.
Once the car is running, the alternator supplies 100% of the average demand. The battery may supply current durning peak loads (like, using a winch), but if the alternator can’t supply the required average load, the car will eventually stall.
The battery is only used to load balance and to filter the voltage variations from the alternator (which has somewhat crude voltage regulation).
You can say the alternator supplies 100% of the power to the battery that the battery needs to supply to the car, but it is incorrect to state otherwise. All of the voltage/current required by all of the car’s systems is supplied by the battery. Voltage conversion and regulation from the alternator is handled by the regulator/rectifier, not the battery.
Not from an electrical engineering standpoint.
Draw the circuit, tell me what component is supplying the current.
An alternator puts out AC. That’s why they call it an alternator. A typical alternator has three sets of windings in it, which go through a rectifier set. This converts the output into something that kinda looks like 3 sine waves added together with the negative parts flipped to be positive. It’s a very messy waveform and it isn’t anything close to flat DC.
The battery provides a lot of the voltage regulation (there’s a regulator in the alternator as well that adjusts the field current in the alternator) and the battery also does all of the bulk filtering, basically smoothing out that messy sine wave (ish) waveform into smooth flat DC.
So at times when the alternator output is high, the current is flowing from the alternator and into the battery and also into the rest of the car’s electrical system. When the alternator’s output is at a lower part of its cycle, the battery is supplying all of the current to the car’s electrical system. This repeats over and over multiple times per second.
So no, the alternator is NOT supplying 100% of the power to the car. ON AVERAGE, the alternator supplies enough power to both power the car and to charge the battery, but at any given instant, the battery might be supplying power to the car or the alternator might be supplying power to the car. It all depends on where the alternator is on its alternating cycle.
My old (actually antique) VW Beetle has a generator. This puts out DC. When the engine is running, the generator supplies all of the power to the car. Which, since it’s a Beetle and I can literally draw a diagram the entire electrical system from memory (it’s pretty simple), it’s not much.
Sorry, but you are incorrect.
The alternator must supply 100% of the current necessary to run the car, or it will eventually stop running.
It will eventually stop running why? Because the battery dies.
Read what I wrote again. On average, the alternator supplies enough current to both run the car and charge the battery. At any given instant though, either the alternator or the battery might be supplying the current. It all depends on where the alternator is on its cycle.
ETA: Unless you are being nitpicky. Technically, all of the current in the car ultimately comes from the alternator. It’s just that some of it gets stored in the battery before being used.
Re using a deep-cycle battery (as suggested previously in the thread), this is not usually a good idea. For a given physical size, deep-cycle batteries generally will not provide CCA equivalent to a standard battery. They are specifically designed to provide lower current for a longer period of times. Probably won’t make much difference in a temperate climate, but it will make cold starts up north an iffy thing.
Bingo!
And, this is the ‘Dope. Of course I’m being nitpicky!
If you want to be really nitpicky, it all comes from the sun.
Energy from the sun was used to grow the plants, and the dinosaurs ate the plants, then the plants and dinosaurs became oil, part of which became gasoline…
So technically my cars are all solar powered!
I didn’t ask for “absolutely everything that’s happened up till now.”
The nearest (drive-through) oil-change place is Valvoline, but it was a Pennzoil shop before that. The shop is quick cheap, and reliable. But one time in the previous iteration the manager was going over the post-oil change checklist and he came to the tires. ‘Tires, 50 psi…’ I said, ‘What? Did you say 50 psi? It should be 30.’ He looked at what he’d just read, and then had my tires deflated to the proper pressure. I appreciated that someone would go through the checklist every time. The new iteration doesn’t do that. Anyway, there’s a NAPA-adjacent shop that does a good job. They’re more expensive than a drive-through oil change shop, but they’re thorough.