Weird things are happening with my car - what might be wrong?

Factual Questions
21

The “float” or smart chargers are great, they will pay for themselves and help maximize the service life of a battery. Maybe double in some instances. I use to mess around with old cars, clean and tight cables and connection are very important, even a paper thin tiny bit of corrosion, almost invisible, is enough to interfere with charging.

Something to do with small amounts of resistance in a high current, low voltage circuit having an outsize effect. Sometimes you’ll hear people say “The ground cables look good”. Yeah, unless you’re super man, with x-ray vision, there is nothing gained by looking at them.

This is sort of why I mentioned the battery charger routine above, after needing a jump start. The alternator is not intended to fully charge a battery, it takes a long time. When you hear about “desulfators” that’s kind of a marketing term. Any battery charger is a “desulfator” by definition, the paste that forms on the plates as it is discharged is converted back into solution during charging, but a battery that remains in a discharged condition, some of the paste becomes resistant, forms hard crystals, and is said to be “sulfated”. It represents a permanent loss of capacity. Just keep them topped off, and a battery will usually last a lot longer. I live in the northern climes, hot weather or high temperatures (and vibration) is actually what kills them. 10 to 12 years is doing pretty well.

There are only a limited number of charge/discharge cycles available, but keeping the battery topped off as with a smart charger or float device means it will keep its performance and service life.

Another thing that is overlooked, if you have 10 vehicles - depending on where you live, a battery that isn’t fully charged, the electrolyte will freeze in cold weather and destroy the battery. Maybe not right away, but it is going to have problems, maybe even catastrophic.

22

Thank you for advice. I appreciate it. Im in Santa Barbara and it freezes very rarely. Hardly ever in fact.
When you say “the alternator is not intended to fully charge a battery, it takes a long time”…what do you mean.? My understanding is that 10 minutes or so of driving should get you “topped up” of course depending on how discharged the battery is. Usually works on a car not starting but still having lights etc working. Really discharged I think I would want to drive for a half an hour or more?
Do you recommend smart chargers left on all cars if possible? I purchased a little solar charger for my 2000 Toyota Tundra, which was having low battery voltage after sitting for a month or so, the little panel really seemed to help. Also nice not to have cords running about.
Ive been driving the truck weekly now, and Im not having any problems. (solar panel got stolen tho…grrrr)
I used the NOCO “repair cycle” on it, where the charger uses high voltage, “high frequency” pulses to knock the crystals back into solution, or so they say.
The truck “seems” to be starting better, but…I am driving it alot more, so really cant tell about the NOCO claims.

23

If you have a deeply discharged battery, the alternator will charge it, but it will charge it quickly. The charge doesn’t get a chance to propagate to the interior of the plates, so it’s not an ideal charge.

A lead-acid battery works by having two plates, one made of lead and the other made of lead oxide, with a mixture of water and sulfuric acid in between as an electrolyte. As the battery discharges, both plates become lead sulfate, and the sulfuric acid becomes water. When you charge it, the chemical reaction reverses.

If you charge it too quickly, the lead sulfate can form permanent crystals on the plates, which permanently reduces the capacity of the battery.

If the battery is deeply discharged, and you have the time (i.e. you’re not stranded beside the road and need to get home), you want to use a slow charger of some sort. Even if it’s a fairly dumb slow charger, slow charging it will prevent crystals from forming and will give a more even charge into the center of the plates. Using the alternator to charge the battery definitely is not the way to go. But if you are stranded beside the road, a quick jump and the alternator will get you home. It’s just not very kind to your battery.

Absolutely. Lead-acid batteries tend to chemically self-destruct if they get too far discharged. If your vehicle drains to the point of having a low battery warning after a month (fairly typical on a modern car) then repeatedly draining it to that point will eventually kill the battery.

It doesn’t take much to top off a battery, so while that solar panel may not seem like much, that type of charger is usually enough to prevent battery damage.

Most of the claims that I have seen about the effectiveness of pulse charging to break up the sulfate crystals is advertising bullshit from the companies that make the chargers. It sounds good in theory, but I personally would like to see some independent tests that verify whether or not the technology does what it says it does. If anyone has a link to an independent test, I’d like to see it.

In my personal experience, I used to have a fairly cheap slow charger that for some reason was extremely effective at bringing dead batteries back to life. It would take all night to charge them, but it almost always managed to revive the battery. Unfortunately, it died several years ago. My modern charger with its fancy shmancy anti-sulfate algorithms and what-not doesn’t seem to work as well, though it is more effective than the cheap simple chargers they used to make back in the day.

There is another issue called stratification, which might be an issue if you leave your car sitting for months on end (emphasis on the “might” part of that sentence). Water and sulfuric acid have different densities, and if a lead acid battery sits for too long, they will tend to separate and stratify (form layers). The different layers will cause small currents to flow, which will cause sulfation on the battery plates. Very large lead acid batteries, like those used for battery backup by phone systems or submarines (both of which might no longer use lead acid, I dunno), have stirring rods to mix up the electrolyte and prevent it from stratifying. But for car batteries, I have read conflicting information about whether or not the battery is large enough for stratification to be significant. Hence the “might”. If you are worried about it, drive your car around once every month or two to insure that the electrolyte stays mixed.

24

On most cars that I am familiar with (note - I am NOT a mechanic), this switch activates a solenoid that allows you to shift out of park. It does not usually prevent you from starting the car, it only prevents you from shifting out of park if your foot isn’t on the brake. There is usually a small button on the gear shift or nearby on the console that you can press to get out of park if the switch or the solenoid fails.

There is usually a different switch located on the shift lever that will prevent you from starting the car if it isn’t in park or neutral.

Your car may vary. I just personally haven’t seen a switch on the brake that prevents the car from starting. On manual vehicles, there is usually a switch on the clutch pedal that does it, but not on the brake.

25

I would expect that with a 2019 vehicle that the lights would automatically turn off after you turned the car off after a period time. So that shouldn’t be the cause of your battery drain.

26

Thank you! Very helpful. Nice concise summary! Getting straight answers on electrical issues can be a rabbit hole for many. Its often easier to “just get a new battery”. Many of our troubles involve folks either bumping the charging cord plug, or thinking they did a good job of hooking everything up etc etc. Human error. So 3 months later when the cars get taken out? Really dead. The english cars, expensive, are the worst, even with security off, they just drain like crazy. I think they need a massive cold start voltage to get going as well.
My first truck was an old used1964 Nissan 1200 one of the first, 60hp, teeny tiny thing. I got in in 1984 . Tough little truck though. Weird shifter on the steering column. It had a slot through the bumper and an indent to hand start it!! Found the crank in its spot behind the seat. Never tried it tho, it was quicker to push start. (early car learning curve)
When I push started it I could do so by walking it along, then sliding into the seat, pop the clutch. Learned a fair amount about electrical stuff tho…grrrr starter motor repair before the Internet!!

27

A jump start is an emergency thing, to get you off the side of the road. And a fast idle or driving the car a several minutes will get enough charge into the battery for it to start the car again. Good enough? Well it gets back to performance and especially service life.

However this does not mean it is fully topped off. It might be 50% or 75% or whatever. It is not particularly kind to the charging system. In cold weather, this becomes apparent, you can hear the engine & belts laboring under the strain - the alternator is much more difficult to turn. A battery can be permanently damaged by a complete discharge, not always, but it is possible. Then things like slip rings or rotor in the alternator, etc.

Given a choice, I would never accept nor give a jump start if a battery charger were available, for different reasons. But the idea generally is to keep the battery topped off. The problem as I see it, the 12 volt car battery was introduced in 1956, but in 2023 there are continuous parasitic loads placed on them.

If I had 10 cars and trucks to manage, most of them not in daily service or whatever, I would disconnect them at minimum. Maybe even remove them, high heat storage is to be avoided. Definitely connect them to a constant float charge.

But - disconnecting late model modern cars and trucks, especially high end cars - poses some potentially very serious issues that may require a trip to a dealer. If that’s the case you won’t have saved any money. Check the operator’s manual carefully for guidance, and follow any procedures listed when replacing or re-connecting carefully, too.

28

Update today: Twice, while out running errands, the engine sputtered a bit, but did turn over. The one unusual thing after the engine started? The mileage left in my gas tank didn’t register, except as dashes, for a few seconds.

I have scheduled a diagnostic check.

29

A failing battery will often cause odd electrical issues. How old is the battery? They have a date on them.

30

The date was from 2020. The car has about 35,000 miles on it.

31

Yeah, since the car is vintage 2019 it would take effort for someone to install an older battery! Guess it’s just a habit to ask that. Failing wonky or loose terminals connections or something like that it does sound a bit like the battery is on the way out however. I would always recommend a nice thorough recharge and testing though before condemning it. It’s just a circle game for diagnosis - if a battery is dead or the car needs a jump start there is a reason for that, that may or may not include a bad battery part of the equation.

32

New battery is easiest fix, as others have said. I went through VERY similar symptoms for several weeks a few years ago with a newish vehicle (i.e., I wasn’t suspecting the battery was old enough to be bad). Had it in to the (proven to be only vaguely competent) dealership since it was still under warranty, who said charging system/battery were fine. But it continued. After jumping it, it would be fine for hours/days and then fail again.

Finally it happened, I had time, and was near enough to the dealership that I had it towed. This time, without having jumped it, the battery showed bad and they replaced it.

ObAnecdote: one of the times I was parked head-to-head with a car that two young guys in their 20s were about to get into. I had cables with me by then, asked if they could jump me; they said sure, “If you know how”. They’d never done it! Not putting them down: more than 40 years ago when I was their age, we were buying beaters and had to know how. I guess cars have gotten more reliable and so this is less of a problem. After all, I don’t remember how to adjust points (not that cars have them now) either, though back then I think I did. I haven’t changed a tire in decades, either. Still made me think/laugh.

33

A lot of new cars do have this safety feature. I have a manual transmission truck so I have the clutch switch. Also on my MC. I have to operate a variety of vehicles sometimes. Many newer ones with automatic transmissions have the depress brake to start system. Sometimes I am given a random fob and have to go start and move a vehicle. It can be a puzzle. Most still have actual keys. But a few of them require a brake application too. I also have to deal with some very unusual vehicles. Luckily they have instruction plates riveted to the relevant areas.

34

I just realized that I hadn’t updated this thread. I bought a new battery, and have had no further problems.

35

I’m thinking if you pulled into a shop for a quick test after driving a while, the battery would be charged even if compromised. What I found with a '85 Civic was that having left the lights on and discharging the battery too many times, the battery would not hold a charge more than a few hours. In those days with maintenace-possible batteries, you could see the cells (translucent battery case) and it was obvious some of the cells had only about 3/4 the proper amount of water/acid. Nothing fixed ths except a new battery. I should have checked sooner. Modern maintenance-free batteries will die the same way.

36

Automotive start batteries do not “like” deep discharges at all, they can be ruined by being discharged all the way down, even one time. Not a guaranteed thing but it is something to be avoided, running it down a handful of times and it is ready for recycling. Permanent damage is more likely with a dead battery the longer it is stored in this condition. It’s kind of a vicious circle because a defective battery can in turn damage the alternator, and when this happens any replacement battery may be damaged as well or fail prematurely. Batteries, parts, labor, alternators are getting expensive. So it pays to take care of the battery.

A quick and dirty test without special equipment is to note that while interior or dash lights, radio etc., may operate, this does not necessarily mean the battery is OK, these draw very little current. The battery may not have enough “oomph” to start the engine.

Turn the headlights on and see how they look. If they are nice and bright, the battery itself and the terminal and ground connections are likely OK. Then observe the headlight brightness while trying to start the engine (this is obviously easier at night, with the lights shining on a nearby garage wall). A battery and starting system in good condition, the headlights will only dim slightly momentarily. A failing battery, one that cannot supply current will show the headlights being “choked off” and immediately going out.

Modern cars somewhat constantly draw down battery charge, it’s only slight but it adds up. The sealed “maintenance free” battery is 100% charged when it measures 12.80 volts at 68F. This is the “resting” open circuit voltage, after the charging voltage or surface charge is removed, which skews measurement. Ordinarly leaving the headlights on for 10 minutes, and waiting an additional 10 minutes for the voltage to “bounce back” to the true voltage level will give good results.

If you’ve a car with a “phantom load” or parasitic drain they can be difficult to find. And a smart charger will happily float away while it drains down quite a lot.