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I have tested my alternator with a Schmacher battery charger that requires that the car needs to rev to 2200 rpms for 2+ minutes to test the alternator charging capacity. What that tells me is that you need to be driving your car at speeds that will allow the alternator to charge the battery. If you drive around town at low speeds and start and stop this may not be enough to charge the battery sufficiently. Anyway getting the alternator tested is a good place to start. Your local RI Auto Zone parts store can do this test without taking it to a repair shop
This is an excellent point, even with wife and buddy's mom's cars. Batteries are good per load tests post dying. Cars are regularly driven. HOW, were they regularly driven, in suburbia which is mostly stop and go? Probably....(although my garage queen typically months in the garage) Just saying so many variables it's good to level set.
You should do a voltage drop test. This can be accomplished two ways with a multimeter. Measure the voltage between the alternator charge post and the positive terminal on the battery with the car running. This reading should be very near zero. If it isn't there is a problem with the charge wire from the alternator to the battery (corrosion, loose or broken connection, etc). You can also determine this by comparing voltage readings from the alternator charge post and the positive battery terminal with the car running. I diagnosed a Silverado this way that has been to several shops and had had several new batteries over the course of a few months. It was losing 2 volts through an 8 inch charge wire between the alternator and battery.
You should do a voltage drop test. This can be accomplished two ways with a multimeter. Measure the voltage between the alternator charge post and the positive terminal on the battery with the car running. This reading should be very near zero. If it isn't there is a problem with the charge wire from the alternator to the battery (corrosion, loose or broken connection, etc). You can also determine this by comparing voltage readings from the alternator charge post and the positive battery terminal with the car running. I diagnosed a Silverado this way that has been to several shops and had had several new batteries over the course of a few months. It was losing 2 volts through an 8 inch charge wire between the alternator and battery.
Interesting, especially given that nowadays, many batteries are remotely located, such as in a trunk under the passenger's feet in a SUV. Where is the computer measuring the voltage? On a BMW, it's at the terminal in the trunk because there's an IBS sensor placed there. It would seem that GM doesn't do that in the case of your Silverado. Maybe in some other models they do?
I happened to look when I replaced the bulbs on my wife's GM pre state inspection (backup was burned out). Also at the time after 341 miles the I/M was still INC, but it changed 2 days later fortunately
p.s. while I was dealing with the bulbs, since a cargo light was out, I decided to try LEDs that were 10 for $7.19. One thing led to another and now the cargo plus 3 rows are all LEDs. Would love to now do the LS430....(I mean 1 watt instead of 5 watts, and 3X the brightness)
p.p.s. since the alternator is inconvenient to get to on our cars, what if, at the positive terminal, the voltage is say 14.25V. Maybe that's an easier way to verify things are good. Or it may be 13.8V. Something well over 12.x volts.
If yer only doing 100miles per month, that's not enough to keep the battery charged.
Modern cars have a LOT of electronics and will flatten a battery unless they get run at a half decent speed.
Short runs around town will kill a battery quite quickly, and every time you flatten it completely, you do damage to the battery.
Facelift LSs are worse unless you disable the SmartKey system.
It sounds to me like you either need to fit a solar changer if it is parked outside, or else plug it into a battery tender when it's in the garage.
Since Covid has meant I now work 100% from home I am no longer driving 300+ miles per week, so I am having to plug mine in when not driving it.
Since I started doing that, no more problems. :-)
My laptop crashed, so I am behind and will read all your replies as I get a chance. Thanks very much,
I had just remembered something that happened with my previous car, a Buick. The battery died several times for no apparent reason. Finally one day I walked into the garage and heard something running in the car even thought the car was, of course, turned off. I drove it to the dealers and a friend gave me a ride home, He could hear the thing also, but since it was after hours, by the time the service people looked at the car, the battery was dead and the noise was gone.
They had a devil of a time finding the thing, but it turned out the antenna motor (or something) was turning itself on, running the battery down and then was off when the battery was charged up. The fix was to disconnect it, since I never used it. It was shorting out or something that caused it to turn on.
If that's what's going on, I assume it will be the devil to find, and I may need to get some gizmo that keeps the battery charged or something, about which gizmos I know nothing. If anyone wants to recommend a simple, idiot proof gizmo, I would appreciate it.
I think a tender helps, but I'm not convinced they are a cure all--they go into green when the voltage is good. that's only V in v = ir. The older the battery is, the higher r is....
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If you want to do an $85 experiment? Get a new battery and see. Worst case it goes dead with a new battery, and now you're 100% sure it's not the battery. Again, my wife's car was dead, and after jumping, battery passed load test. Same as buddy's mom. So I have no explanation on that one...both cars driven....
I'm not sure what you're saying about a tender not being wonderful? Since I am thinking about that, maybe you could explain more about why not? Thanks.
I will ask the mechanic about the voltage drop test. They specialize in several cars including lexus, so I assume they know what they're doing, and have done good stuff in the past, but it can't hurt to ask. I already mentioned the alternator and hat maybe it is time to replace it even if it seems okay.
I have a nav system, not sure it is the one mentioned above, but I will read up.
I am inclined to think from some of the replies that the car needs to be driven much more than I am driving it. Sigh, And the solution is to hook it up to something that will keep the battery charged, Can anyone recommend a good, simple to use one? Do the comments in a couple of posts about problems with them, like their saying the battery is okay but the battery not being able to start the car apply to new batteries? Can they jump start the car?
https://www.thedrive.com/reviews/288...ickle-chargers
the top-rated charger (Battery Tender brand) should be a good one. All you need to do is follow simple instructions it comes with, typically just connect + terminal of charger to the + terminal of the battery and - terminal of the charger to the - terminal of the battery, and then plug in the charger into any household wall socket.
Interesting, especially given that nowadays, many batteries are remotely located, such as in a trunk under the passenger's feet in a SUV. Where is the computer measuring the voltage? On a BMW, it's at the terminal in the trunk because there's an IBS sensor placed there. It would seem that GM doesn't do that in the case of your Silverado. Maybe in some other models they do?
I happened to look when I replaced the bulbs on my wife's GM pre state inspection (backup was burned out). Also at the time after 341 miles the I/M was still INC, but it changed 2 days later fortunately
p.s. while I was dealing with the bulbs, since a cargo light was out, I decided to try LEDs that were 10 for $7.19. One thing led to another and now the cargo plus 3 rows are all LEDs. Would love to now do the LS430....(I mean 1 watt instead of 5 watts, and 3X the brightness)
p.p.s. since the alternator is inconvenient to get to on our cars, what if, at the positive terminal, the voltage is say 14.25V. Maybe that's an easier way to verify things are good. Or it may be 13.8V. Something well over 12.x volts.
Most vehicles read battery voltage at the ECM on the hot wire from the battery. The voltage drop test tests the wiring and connections themselves. It's a quick, easy test that most people can accomplish with just a multimeter. Voltage doesn't charge the battery or power the system, however. It's amperage that does that. Any shop worth it's salt has the equipment to test this and they should perform the test when dealing with any charging system issues. There are several diode sets in the rectifier assembly inside the alternator. As they burn out, amp output is reduced. It can reach a point where the alternator can no longer keep up with the demand placed on it. The car will still run fine but it will start having issues such as needing frequent battery replacement, glitchy electronics, headlights that rapidly fluctuate in intensity, etc.
As it happens, my brother (the original owner of the car) got an email from Lexus yesterday. Apparently some number of people are having their batteries go dead as they are driving less due to the coronavirus, and it suggested some remedies,
I hope my attempt to upload it worked. Anyway, I am wondering why driving it for 30 minutes at >= 40mph is as good as letting it sit in one's driveway running at 0mph?
Most vehicles read battery voltage at the ECM on the hot wire from the battery. The voltage drop test tests the wiring and connections themselves. It's a quick, easy test that most people can accomplish with just a multimeter. Voltage doesn't charge the battery or power the system, however. It's amperage that does that. Any shop worth it's salt has the equipment to test this and they should perform the test when dealing with any charging system issues. There are several diode sets in the rectifier assembly inside the alternator. As they burn out, amp output is reduced. It can reach a point where the alternator can no longer keep up with the demand placed on it. The car will still run fine but it will start having issues such as needing frequent battery replacement, glitchy electronics, headlights that rapidly fluctuate in intensity, etc.
Even a battery tender whose light turns green merely measured voltage from what I remember. And again from hs v = ir, with r increasing as the battery ages. That's why a Battery Tender can sit on a battery, green, and said battery cannot start a car (depends on the battery). Also why a battery charger that can deliver 70-100 A costs well over $500, not the $39 that Costco gets for a 3A Battery Tender....if one does a lot of coding, maybe, but I'd build my own from one of thoes 12V RV power supplies as they can delivery 70A clean...
Again if one just wants to be practical, and doesn't want to go to too much trouble, buy a $85 battery and put it in. You've got a shot to say goodbye to the issue. If not, you know you've got a serious issue, you're out $85, but you do have a brand new battery with which you can level set. Because the term "new" battery seems to be based on how long one expects to get out of it--if 6 years, a 2 y.o. battery is new. But new to me, means it was purchased within the last 2-4 weeks.
edit p.s. I disagree with Lexus' advice # 3 to disconnect the battery if the car will be sitting longer than a week. If you live in a state that has emissions testing now you've introduced a new problem to deal with i.e. I/M readiness = yes. That's not a real solution...
Again if one just wants to be practical, and doesn't want to go to too much trouble, buy a $85 battery and put it in. You've got a shot to say goodbye to the issue. If not, you know you've got a serious issue, you're out $85, but you do have a brand new battery with which you can level set. Because the term "new" battery seems to be based on how long one expects to get out of it--if 6 years, a 2 y.o. battery is new. But new to me, means it was purchased within the last 2-4 weeks.
edit p.s. I disagree with Lexus' advice # 3 to disconnect the battery if the car will be sitting longer than a week. If you live in a state that has emissions testing now you've introduced a new problem to deal with i.e. I/M readiness = yes. That's not a real solution...
As I noted above, the battery had already been replaced. I don't know what the "I/M readiness - yes" means? What does emissions testing have to do with the battery having been disconnected and then presumably reconnected before the emissions test? Thank you.
(I would not use the disconnect method, as it is a pain in the neck to reset stuff when the battery has been disconnected to be replaced. I will get a battery tender or somesuch or figure out some not too time consuming way to keep the battery charged.)
My LS430 will not start if I park more than 2 weeks. I bought a 15amp battery charger to charge, it need charge 2 hours to start my car. I bought a battery tender junior, so I can plug-in to charge without open hood. It can keep battery in more than its 80% capacity. It is very convenient especially when you take long vacations.
I drove LS400 locally for less than 10 miles for few months. I need to jump start it a few times. Battery is more than 3 years old. I am not sure whether it need to replace, so I get a battery load tester. It shows battery need to replace, but it shows ok after battery full charge. I use battery load tester to monitor battery health. That was a year ago. LS400 starts every morning these days as I drive more than 30 miles highway daily. Battery load tester save me an early battery replacement.
My LS430 will not start if I park more than 2 weeks. I bought a 15amp battery charger to charge, it need charge 2 hours to start my car. I bought a battery tender junior, so I can plug-in to charge without open hood. It can keep battery in more than its 80% capacity. It is very convenient especially when you take long vacations.
I drove LS400 locally for less than 10 miles for few months. I need to jump start it a few times. Battery is more than 3 years old. I am not sure whether it need to replace, so I get a battery load tester. It shows battery need to replace, but it shows ok after battery full charge. I use battery load tester to monitor battery health. That was a year ago. LS400 starts every morning these days as I drive more than 30 miles highway daily. Battery load tester save me an early battery replacement.
Science is coming into play, v = ir. Battery tender focuses on V. When it's proper, light turns green. As the battery ages, r goes up. So i comes down. A battery that has the proper voltage, can in fact not have enough juice to start or rather turn over a vehicle.
In the past 10 years, I've had 2 batteries fail within one year. And when I hear basically only 2 companies make all the batteries no matter what brand (supposedly there is a 3rd tiny co), I tend not to think that it can't be the battery.
What I would find hard to believe, is a battery failing between the time it's picked up from the store, and brought home--that's far fetched. But failing in 8 mos? It happened to me, the replacement 11 mos? Yes. Are these considered "new?" Very subjective. there are times in real life, we think so hard, that we overlook the simple things. I could tell the story of a buddy who setup a call center of 400 agents, and none of the phones worked, how many hours upon hours of troubleshooting. Turned out to be faulty CAT5e cables included with every phone set. They never considered that could be the issue.
10-22-20, 04:39 AM
