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Suddenly losing electrical power, but after jump start, test the battery and alternator, they seem fine!!?
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shrewdy
Novice
Dec 9, 2015, 1:05 AM
Post #1 of 14
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Suddenly losing electrical power, but after jump start, test the battery and alternator, they seem fine!!?
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OK so first time it happened i was driving and i suddenly lost power (electrics / everything else) it just kind of putters a little and then that's it.
I called roadside assist and we jumped her and tested everything. and the numbers looked good. figured it was a buildup under the battery terminal possibly causing the problem, we gave that a good clean.
a couple of days later i was paranoid so i got the multimeter out just to check again while it was in the driveway, 12.8v without the engine turning over and 14.1V with the engine on. seemed nominal.
well today it just happened again, roadside assist looked at it and everything seemed fine again. perhaps it's something to do with the heat? (summer here atm) both times i had the AC running with the fans on. I'm a little stumped, perhaps the alternator is failing but only after warming up...
i just drove it about an hour home after the breakdown. it seems fine.
(This post was edited by shrewdy on Dec 9, 2015, 1:06 AM)
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Tom Greenleaf
Ultimate Carjunky
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Dec 9, 2015, 2:27 AM
Post #2 of 14
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Re: Suddenly losing electrical power, but after jump start, test the battery and alternator, they seem fine!!?
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What is this thing?
Volt readings are fine but inconclusive as I'd like to see what they read while starter is engaged both at post and again at u-bolt or if side post battery at the bolt then the just the cable's eyelet end should be the same. You saw troubles there once so both cables and at both ends are suspect areas to clean up and grease.
So if you get low to almost NO volts when testing cables and OK at the posts that's the likely problem. Below 9V while cranking in normal weather/temps isn't a good sign for a battery with enough amps able or too high a draw starter or engine too tight for some reason. Also when running and normal idle speed turn high amp use items like full speed blower, rear window defroster/defogger if equipped, headlights and watch volts again. It may drop but not below 13V and raising idle back up higher like 13.5 to close to 14V if charging system is well,
T
(This post was edited by Tom Greenleaf on Dec 9, 2015, 2:47 AM)
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shrewdy
Novice
Dec 9, 2015, 3:14 AM
Post #3 of 14
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Re: Suddenly losing electrical power, but after jump start, test the battery and alternator, they seem fine!!?
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I have to admit i'm not a car person (software engineer) so i had trouble following along with some of that jargon / idioms.
i think i got the gist, i might do some more tests (while i'm cranking the starter motor) but i could use an "explain it like i'm 5"
car is a 1999 toyota carolla hatchback
(This post was edited by shrewdy on Dec 9, 2015, 3:15 AM)
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Dec 9, 2015, 4:03 AM
Post #4 of 14
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Re: Suddenly losing electrical power, but after jump start, test the battery and alternator, they seem fine!!?
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That's pretty straight forward English now and if a second language to you have someone read it to you but I'll try at anything you didn't get. Just a suggestion as you spelled Corolla incorrectly which I would think you would know or a typo and I make many myself.
Battery connections on a Toyota are what at least I call "U-Bolts" meaning you put like a horseshoe over a round battery post and tighten it with a nut and bolt which is the connection to the car.
The post is exactly the battery and the U-Bolt of these goes on to cables, one positive one negative. Positive ends up at starter motor and negative ends up at engine's block of metal. Any loss is only as good as the weakest link so since messing at the battery did something the problems are probably still there if you need either one or both new cables or quality cable end splices.
If this isn't your thing that's fine let some qualified tech/mechanic take care of it for you just like they might at what you do if needed.
Understand that now a 1999 isn't new or close anymore. It takes relentless care for silly things like battery cables cared for on a schedule as by even 1999 they stunk being made of inferior metal as lead (PB - the metal) isn't used then or some time before that which lasted ages longer and more fixable than what you have as lead is a poisonous metal so as little as possible is used in a car.
Your observations of volts are fine but when and where observed matters.
Think of "VOLTS" as how much push electricity is and "AMPS" as the power and volume. Like stepping on a garden hose while running a sprinkler and it slows down or stops working if that's a close enough analogy. Yes if the hose had lots more power and push stepping on it wouldn't stop it.
Know that a battery's power is how many AMPS it can deliver most of which is needed to start a car as starter is a hog on power. Other things much less. So if too much of available power "AMPS" is being used the volts would drop as well strongly suggesting battery just doesn't have the power anymore or can't deliver it so asked you where to test.
Trying to make this as basic as possible. Take a 9V household battery for example. Test it, it really is 9V but wouldn't start your car as it has no amps close to what it would need.
Seriously - if this or your understanding of battery in a car and connections to cables is too confusing for you send it out. This stuff is common to all vehicles with an engine for any tech or mechanic.
A car wouldn't run well if those connections or battery were not good up to not running at all and loss of anything electrical. This car the clock could reset and loss of anything programmed into a radio system or more plus memory in the car's computer would lose other info for some time as well.
I'm trying. I can convert to another language but use of automotive terms will confuse translator programs badly or translate the opposite of what was said by error.
If still confused I'll try again if point out a word that you don't understand. One used above is "AMPS" which is an acronym not idiom for AMPERAGE spelled out.
Hope that helped,
Tom
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shrewdy
Novice
Dec 9, 2015, 5:55 AM
Post #6 of 14
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Re: Suddenly losing electrical power, but after jump start, test the battery and alternator, they seem fine!!?
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Thanks guys for the advice. sorry i just had trouble with a few terms (like "eyelet ends" and "at the bolt" etc) otherwise i have a working understanding of batteries and how cars are supposed to work. at least roughly. I will run some more diagnostics and put it in for a service.
i'm just wondering what it could be? i assume the problem is either the battery or the alternator. perhaps the voltage regulator on the altenator when it gets warm? or maybe an internal short in the battery? (again just a guess) i considered perhaps a short in the AC fans but i assume that should blow a fuse.
(This post was edited by shrewdy on Dec 9, 2015, 5:56 AM)
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Tom Greenleaf
Ultimate Carjunky
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Dec 9, 2015, 6:41 AM
Post #7 of 14
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Re: Suddenly losing electrical power, but after jump start, test the battery and alternator, they seem fine!!?
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Shrewdy -as Discretesignals said and I mean is to catch BAD readings up to causing them so you know where this exact issue is not guessing which is totally annoying not knowing it's fixed and done with.
About the "eyelets" battery bolts on side posts - those are used on General Motors products not this so forget that detail for this car,
T
(This post was edited by Tom Greenleaf on Dec 25, 2015, 12:42 AM)
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shrewdy
Novice
Dec 9, 2015, 7:17 PM
Post #8 of 14
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Re: Suddenly losing electrical power, but after jump start, test the battery and alternator, they seem fine!!?
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OK
So i went for a drive with a multimeter in the lighter slot. good readings. battery was 12.6 at first but maintained around 14.1 while driving.
did a stress test (hazards on, fans max, rear defog on) and the voltage was reading 13.8 which to me seems good.
I'll just have to wait till it acts up again or get it more fully tested. perhaps it's a loose connection somewhere?
I wouldn't mind some guesses if anyone has any to offer.
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Tom Greenleaf
Ultimate Carjunky
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Dec 10, 2015, 12:35 AM
Post #9 of 14
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Re: Suddenly losing electrical power, but after jump start, test the battery and alternator, they seem fine!!?
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Those numbers are totally OK. If a problem still exists you would have to aggravate connections or wire and make an issue happen to catch it like intermittent problems if not active or obvious clues there isn't much to do except be ready anytime with any vehicle newer or older as to what you would do if a problem happened.
For my own I use constantly a power port voltmeter, LED and leave it on can be seen thru a window and while cranking and running digital accuracy and dirt cheap on line about $3 ea. They are exactly this............
Trouble with Toyota (some of them) power ports are not powered when key is off I don't think but still good info while underway something isn't right.
Just know a 12V automotive battery fully charged should read exactly 12.6V when nothing is draining it just sitting there fully charged. Once engine runs the alternator is running the electrical things after quickly recharging battery for what it used to start it then it can vary in the 13V to high 14V range depending and should. It's when you see it below when running or over 15V something is wrong to tend to. I do this for live info as I go for battery/electrical, carry oil and antifreeze as well in any if only to get a vehicle to a safe spot to stop for a fix or tow - any age can do something by surprise. Think, they put spare tires in vehicles knowing that's a common surprise,
T
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shrewdy
Novice
Dec 10, 2015, 12:44 AM
Post #10 of 14
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Re: Suddenly losing electrical power, but after jump start, test the battery and alternator, they seem fine!!?
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i will try aggravating the problem when i get the chance (i will get under the hood and try to shake the wires about while i monitor the voltage)
you are correct, while the key is in the off position the lighter receives no voltage, but just turning the key to pre ignition will check the battery (12.6v)
does anyone think maybe one of the diodes in the alternator has gone and it is leaking alternating current into the system? can i test that with a multimeter?
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Tom Greenleaf
Ultimate Carjunky
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Dec 10, 2015, 1:07 AM
Post #11 of 14
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Re: Suddenly losing electrical power, but after jump start, test the battery and alternator, they seem fine!!?
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NO! 12.6V is with nothing on only. Just turning key things take some power and 12.6V would read lower and still be fine.
Diodes. They are inside alternators to convert AC voltage to DC voltage for cars. If some fail it's usually not intermittent and volts would stay substandard range or alternator not work at all. THAT'S NOT THE PROBLEM - I'M NEAR CERTAIN.
There can be issues that just are not going to show themselves or warn you. No different than guessing when a table lamp's bulb will blow type thing. We live with that. Same as that if that table lamp blew a bulb every other day you check what's wrong with the lamp. If nothing found and another lamp did the same it could be the outlet in the wall not the lamp at all type issue and when things get that tricky and test fine you may not get a clear answer as to why.
Basics: Test when something is wrong or what can make it wrong. If nothing you deal with it until it's a problem simple as that,
T
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shrewdy
Novice
Dec 24, 2015, 11:41 PM
Post #12 of 14
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Re: Suddenly losing electrical power, but after jump start, test the battery and alternator, they seem fine!!?
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ok so i replaced the battery, and with a new battery in the car while i was driving initially i read 13.9 volts at the lighter with a multimeter
but shortly after for a while it droped to 12.3 which prompted me to go home, in the driveway though it went back to 13.9
does anyone know if perhaps the charging system is realising the battery is full and just disengaging the alternator for that time? or does this indicate i have a definite issue with the alternator?
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Tom Greenleaf
Ultimate Carjunky
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Dec 25, 2015, 1:11 AM
Post #13 of 14
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Re: Suddenly losing electrical power, but after jump start, test the battery and alternator, they seem fine!!?
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OK - You need to know some things to work on your own car and said so up top.
New batteries are not fully charged on the shelf unless the place the sells them did it! Just from filling they are enough to start a car and then some % but not "full" rather call it charged up or low charge.
Would be nice to know if the old one could test out OK if charged off car and behave but if over 4ish years old a new battery is OK with me. You charge them first - nobody does!
13.9V suggests it was charging hard to fully charge up new battery or was in fact all happy and wonderful.
It would take a load on it for it suddenly to drop to 12.3 while running exceeding what the alternator can put out for AMPS for any reason - connections, wires, loads excessive or plain alternator not working if just a short time.
A warning or two: If you are putting test probes into a power port be super careful not to touch probes to side wall of the port with and center of the bottom of them is battery positive and will blow a fuse or should.
When if you are doing this touching the battery to remove or clean any connection or replace a part involved do always disconnect negative post first and positive post second. When done positive back on first then negative back on last.
You think you saw 12.3V while engine was running I take it? If using probes held by hand that's iffy for good info and may have just done a better job when parked again? Can't know that.
Even if you are not going to do the work you could help the tech/person who is. Spray some Power Blaster penetrating oil on all non battery cable ends and fasteners to alternator - adjuster included on threads as this may have a non self adjusting belt to alternator or two belts? If those things break it's hard to fix up to a nightmare.
What do you want to do? Play swaptronics till you hit on something or just send this out to a qualified shop to find and fix this? You said to treat you like a 5 year old mostly language wise I take that but think you need real pro help or get lucky with part swapping.
Since it's capable of working by your observations then suddenly not the guess of the day is belt too loose, alternator itself or wiring connections already discussed.
If you want me to guess I'll blame the alternator for you with no other better info they can be intermittent. If you check those on or off cars when working it isn't going to be conclusive which is why you rule out the other things already listed,
T
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Discretesignals
Ultimate Carjunky
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Dec 25, 2015, 6:53 AM
Post #14 of 14
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Re: Suddenly losing electrical power, but after jump start, test the battery and alternator, they seem fine!!?
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The alternator voltage output should never go below battery voltage when the vehicle is running unless there is an issue. The alternator becomes the power source for the electrical system when the vehicle is running and the battery acts as a buffer to suppress voltage surge.
As Tom stated, it could be an intermittent connection problem, but you could also have an internal problem in the alternator itself. Now you have to test the circuits at the alternator plug to be sure they are not dropping out causing the alternator to quit. If those things are not dropping out at the alternator plug, the alternator is your culprit.
What is the year, make, model, and engine size?
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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