I have to put my hood issue on hold at the moment, as funds are very very limited right now. I have greater issues... Ok, the car has power, but as I was about to drive it last night (and it started fine) i noticed that one of my headlights was working. The other flickered once, or would not come on, while one worked fine, until I flicked on the foglights, and then it would flicker. I parked the car, and now it won't start. There is no clicking noise at all, and the battery with the multimeter showed 10.29 on a red optima. There seems to be no dimming of lights, and I am wondering if it might be the starter.

10.3v is a DEAD battery. like a completely shorted cell.

a fully charged lead acid battery should be 12.6v.

11.7v is a 10% charge.



try cleaning up the terminals first, just in case

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Oh ok, I thought it was anything under 9.29v. I guess I will see what's up with this warranty then. Thanks man.

I think the 9v number is the lowest acceptable voltage during cranking.

my optima red top could actually still start the car at 10v, but it is an optima. but your numbers are a bit low really. im confident it is your battery low right now, but it doesnt hurt to check your alternator if it is the culprit.

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i had a yellowtop that would never charge to over 10ish volts. it would consistently start the car still, just slowly

Well they are charging it at the shop, but still though. I heard the clicking of the solenoid once trying to start it. Then nothing. Just this hum sound as the car tried to start. Well at first it was like the engine was trying to turn. But now nothing. Had power, windows, sound system, all that worked. I guess the battery could be low, and my negative terminal could be replaced... Which I am going to do once the battery charges (picking it up tomorrow, if it charges, it is still under warranty). Then when I install it, I am going to run a test on it with the alternator, which is I guess checking the volts with it running, and then with a load applied. Right?

It sounds like the alternator is on it's last stage of life, you might want to check it out. With the engine running, the battery should have more voltage since the alternator is essentially charging it. If the alternator is failing (usually they will work intermittently before not working at all) then the voltage will slowly go down instead of stay at 12.6 or whatever they should to be on our cars.

One way you can check if its your alternator, is when you get your battery back charged, hook it up, start the car, then detach your negative cable on your battery....if your car still runs, its your battery thats shot, if it dies....your alternator is shot....
( this method is not usually reconmended ) however, i have used it many of times, throughout the life of my vehicles Celica GT included, and never had an issue

do not disconnect the alternator from a running car, if the alt isn't already bad that can kill it and even damage other electronics in the car. It sounds more like you have a bad or very weak ground somewhere.

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Do NOT do this! That is not a solid way of finding out the status of your ALT. It can also destroy the alt by sending a voltage spike. You can also fry the ECU that way.

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What he said!

Take it to a shop with a tester like AAA has. You can't measure a battery solely on the volts. You have to know what the cranking amps are at. Your battery can be 12v and 100 CCA and not start the car. Also, just because your electronics work doesn't mean the battery can start the car. The electronics take much less power than the starter motor to do anything and they'll show full usage up until the battery is down to 0CCA and 9V.

What I would say to do is to get the battery fully charged on a trickle charger (Spiral cell batteries don't like 40A fast charges... trust me), re-install it and have a shop with a real tester, test the system. Or take the alt out and the starter out and have them bench tested. It's super easy to do. The alt has 3 bolts, a plug and a nut. 14MM, 10MM and you've got it out. The alt is 12MM two bolts and a nut and solenoid plug. I've changed both in a parking lot in 20 mins before. Easiest charging system to deal with.

Just my .02

id do like rabid ted said pull the starter an alt off an get them tested
autozone advanceautoparts almost any parts store can test them
its the only safe an sure way to get an awnser

i've done the alt check with the car running and pulling the POS, not the negative....if car dies, then it's the alt.

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DO NOT DISCONNECT THE BATTERY WHILE THE CAR IS RUNNING.

reason not to disconnect the battery while the engine is running:
1) Batteries build up gasses inside the cells. When you disconnect the battery it can cause a spark causing the battery to explode sending acid, sharp plastic, and pieces of lead flying.
2) Your car battery acts as a voltage stabilizer. When the engine is running it keeps the voltage at a reasonable 12.6 to 14 volts. If you have a bad voltage regulator it can shoot the voltage up to 18 volts instantly frying your ecu.
3) There are free, more accurate, safer tests available.

Disconnecting the battery method of testing the charging system is only 100% accurate on cars without fuel injection. Newer cars have clutches on alternators, ecu controlled voltage regulators, and more sensitive electronics. This disconnect battery method is a thing of the past. Please stop recommending this method as its becoming obsolete.

There is no such thing as lowest acceptable voltage while cranking. It all depends on the engine compression, age of starter, and oil weight. I have seen cars start with 6 volts of power, i have also seen cars struggle to start with brand new batteries. If your engine has high compression, use thick oil(20w-50), and the battery is cold, along with an aged starter your car would have a hard time starting. On the other hand if your battery is 70 degree and has a thin 0w30 oil with a brand new starter you would have no trouble starting.