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Discussion Starter #1
Hey guys, had a (supposed) battery problem that I couldn't explain. Here's a thread I started on one of my other forums, but this thread is about my '02 IS. I hope you guys don't mind me asking; can you read along and see if you have any further inputs??

Starting from post #21...got the car started and took it to get the alternator tested. Guy said 12.2V and ~30 amps. Bought a new alt but haven't put it in yet. When I hook a voltmeter up to the batt with the car running, I'm getting 14+ VDC. IDK...I'm no convinced it's the alt, but don't know for sure. Car's running just great right now, but in about a month the batt will randomly die again. Any other thoughts outside what's been covered here? I sent you to this link cause there's some good info posts in here.


Random, Unexplainable Dead Battery? - F150online Forums
 

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First, to a comment that was made in that thread about Optima's, these batteries are excellent batteries and been using them in all my cars for over 6+ years with little problems. Optimas can go bad if the car does a lot of sitting as I've found out and afted many conversations with their techs. Optimas need to be used and often for them to work right, the parasitic(car off) drain is what can kill these and really any battery, so you need to find out your parasitic draw outlined in my thread below. Make sure ALL lights are off, doors/trunk closed and wait 5 minutes...it should be less than 50mA or 0.050A(mine is stock and 32mA). Any new battery can go bad from the very start if it was manufacturer defect, usually a bad cell. New batteries can also be low on the shelves but know that a free load test should always be done to know for sure. From the sounds of it, you have a digital volt-ohm meter with hopefully 10A DC capability(even the $5 meter at Harbor Freight does). Something as simple as engine grounding or a connection can cause these issues or high drain as mentioned. This can be easily found and fixed.

Usually an alternator bench test is the best check method and is correct because it places a heavier load on the alt verses sitting in park idling(as well as checks AC ripple and possibly diode leakage), but i don't always trust the store employees tests so if it said it was ok/bad i get a second opinion or test. When testing an alt with a DVOM you want to test what you can and what the bench test mainly does(except for load testing) such as high AC ripple, diode leak(causing battery to die while off), and poor connections that cause high resistance. A DC clamp inductance meter can help as written in the link. Just an fyi, if it turns out to be a brush or regulator issue you can obtain them seperatly. Got brushes for my Denso that's still in the car for $10 off ebay.

Anyways, If your battery symbol didn't come on your cluster it is possible the alt is good. That symbol does not always nessesarily mean the battery is dead either, it means charging/running voltage is too low(below 13.2vdv). Usually at that point it is the alt if it's illuminated. Which by then if it was a bad battery it would take out the alt by then. Most people don't realize a healthy battery is needed to buffer the voltage spikes from an alt and is what it regulates, otherwise it can easily damage the $600 alt.
There's a chance your alt was good but finally got taken out by low voltage(bad battery), so i would get a second opinion if you can at NAPA if they're around ya, they seem to have the better testers.

You will want to do these tests if you have a DVOM. These tests will show you what's wrong so you don't waste more money, that's why i wrote it up.
Http://my.is/forums/f221/diy-charging-system-full-diagnostic-alternator-battery-426000/

Post back your parasitic draw and other values and I'm sure we can figure this out for sure. Sorry for the book, just wanted to make sure i covered everything discussed.
 

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it sounds like the battery has, either, a dead plate, or the post is broken inside, and occasionally not making contact.
 

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One thing about Optima batteries i have learned is that completely discharging it continuously will cause sulfication and the battery's ability to charge back to 100% will drop. It can happen rather fast with these batteries when they sit with a partial load on them as well.

I had an Optima that went bad because my car sat a lot. It was partially my fault not to keep an eye on it, but after awhile it would only charge to 12.2vdc max(which is no good). What happens is the gel inside between the plates start to turn to sulfer and you lose good conductivity between the plates.

Jay could very well be right and making sure the battery has a good charge is the first step, otherwise your charging voltage will be low as well. Has this Optima been load tested? That's the first thing to rule out, car off voltage should be 12.6vdc or higher for a fully charged battery. I thought you had replaced the battery already and are on your second but still having problems.
 

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If you leave the Optima sitting, disconnected, overnight, what is the morning voltage? If it is under 10.5 get a new battery...it can't be saved.

If it's over 10.5 you can try a load dump. Charge it at 16v for 20-30 minutes. You'll hear it boiling and sounding like it's going to explode....it might, so be careful. As soon as it's done on the charge put it in the car and start the car 5-10 times in a row. Then put it on a 4-5 day trickle charge. This will break up any crystallization between the plates. It's a last ditch effort to save the battery.
 

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Discussion Starter #6
So I'm still chasing this ghost parasitic drain! It's random, and thus making it literally impossible to find. Just killed another battery this week in less than a year. Got a new battery fully charged in excellent shape. Got it in the car last night, did all the test...pulling 30 mA (with reader setting on 10A, showing .03). That is not bad. So how in the world do you catch a random ghost?
 

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So I'm still chasing this ghost parasitic drain! It's random, and thus making it literally impossible to find. Just killed another battery this week in less than a year. Got a new battery fully charged in excellent shape. Got it in the car last night, did all the test...pulling 30 mA (with reader setting on 10A, showing .03). That is not bad. So how in the world do you catch a random ghost?
Have you check your alternator? Also is the car stock as far as electrical system. No sound system or stuff.
 

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Discussion Starter #8
Measure 14+ volts at the battery with the car running. Car is bone stock. Zero electrical mods.
 
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