Hey all,

So I am having a really strange thing that’s been happening lately on my 07. Just 2 days ago, my car was perfectly fine, no starting or battery issues whatsoever, then the very next day, the battery was completely dead. The door locks barely functioned. I had to jumpstart the car and what got really scary was while on the freeway, the dash flickered and the nav screen kept restarting itself. I lost power for second or 2 and on the front display it said something about it operating in low power mode or something to that effect. As if there wasn’t enough current for all the systems to function properly. Well I drove the car at least 12-13 miles to hopefully get the battery charged up somewhat which helped, but when I parked the car and tried restarting it, the battery was dead again. I jumped the car a second time and drove it at least 15 miles this time around, went to Autozone for battery and charging test, and the reading said that my battery was good, and the charging system was good. So I’m dumbfounded on what’s going on. The alternator is recharging the battery, but could it not be putting out full voltage anymore thus not fully recharging the battery? I did check the voltage while the car was running and the volt meter read 13.72 volts.

Is it common to have a parasitic drain on these cars? I know i didn’t leave any lights on because I always make sure that the lights turn (exterior & interior)off anytime I walk away from the car.

This same exact problem happened a couple of weeks ago. Car sits for like 2-3 days, then completely dead.

The issue doesn’t happen every day, it just happened to happen a couple of days ago. And 2 week to 3 weeks before.

Thanks.

 

How old is the battery? Anything over 3 years old, replace. Then, if issue still persists, continue diagnosis. Resting (overnight) voltage on a charged battery should be around 12.6v

 

Battery is a AGM and is not even a full 2 years old. I’ll check the resting voltage like you said and see what it reads.

 

Get one of these: intAct Battery-Guard Extremely handy to monitor what's going on.

 

Nice thanks for that link. I might have to get one.

BTW, the battery voltage after the car has been sitting for a few hours is 12.36 volts. That’s a bit below normal .Does anyone think it could be a bad voltage regulator in the alternator? The car does have almost 170k miles on it and I believe the alternator is original.

 

How often do you drive your car and how long time wise are your drives? How many aH is your battery? How many cca?

also with the test each door close switch the rubber covered switch on the body of the car that is depressed when you close the door. You want to depress it see if the door light goes off, you want to jiggle it etc and see if all 4 of them work correctly.

you might want to make sure all inside lights are set to auto(mine are always off I hate bright lights) I also make sure there’s nothing plugged into the outlets when I leave the car as a precaution.

if you have access to a garage get a noco genius 10 , hardwire the connector and keep battery charged. If not check my reply I posted about how to set up without power outlet access.

 

I drive the car daily to work, so the car never has time to sit for long by periods of time. What was so strange is that I went to work last week, which is about 30 miles each way, when I went to leave work one day, the battery was completely dead. So I had to jump it which worked and it got me home but I was surprised how fast the battery drained in only 8 hrs.

But then over this past weekend, since I just relaxed and stayed home for Labor Day weekend, the car sat for almost 3 days, and it started right up tonight, no problems.

I did check the door switches and interior lights to see if they were staying on, and they weren’t. So I’m good there.

The battery has 750 CCA, not sure about the aH but the reserve capacity says 140 mins.

I don’t have access to a garage, but I plan on getting the car serviced soon and having a shop try to diagnose the parasitic drain or whatever is going on.

 

Everything you described indicates a failed voltage regulator. I read that in your first post (which I just read). That would be the top of the differential diagnosis given what has been presented. Be careful with this, you can damage electronics that get pricey this way, if you keep ignoring the problem. It COULD be something else, but this is the first suspicion.

Take a multimeter and look for AC voltage at the battery terminals. If you see any, that’s very indicative of a VR failure (definitive, actually). That can really do unpredictable damage so, if that’s the case, get the alternator rebuilt or replaced right away. Do NOT buy a replacement alternator from O’Reillys, Autozone, etc. They will fail again soon. Napa is OK, or get a legit unit elsewhere or the existing one rebuilt locally by a good shop. Check this soon and don’t keep ignoring it and hoping for it to heal itself. That does not work.

 

I forgot the site in the US thats great for Toyota/lexus parts someone else comment, they have 3rd party parts too

 

that is strange. If you drive everyday this is not normal. The guy above me commented check on that.

 

1. Disconnect the battery from the car.

2. Use a battery charger to fully charge the battery. “Fully-charged” is when the charging current drops to zero. Depending on the battery’s condition and the charging current it may take 24 hours or longer to fully charge it.

3. Measure the battery’s State-Of-Charge. If the fully charged SOC is less than 75% you will need a new battery. You can measure the SOC with a battery hydrometer. Battery hydrometers are inexpensive and available at auto parts stores. Or, you can use a voltmeter and lookup table to estimate the SOC. Lookup tables are available on the Internet.

 

I would have the battery retested at a different parts house. Make sure they're load testing the battery and not simply checking voltage.

 

What you really want to know about the battery is its Amp Hour capacity. You get that from the “fully charged SOC.”

 

Hey guys, so I found out that cause for the battery drain/non start, is that the positive side battery terminal was ever so slightly loose, like I’m talking like barely, and because of that, this was causing issues that I’ve been having.

I found this out tonight when I went outside earlier to start the car, the doors unlocked, but once I tried to start it, because the terminal was a little loose, it didn’t allow the car to fully start. I found out after looking at the terminal and by accident I wiggled on them to see if they were loose, and sure enough the positive terminal had slight play and once I moved it slightly, it sparked and all the lights in the car, including the headlights lite up.

The car started up right away after that. The issue now though is that i tried tightening up the terminal but it’s no longer grasping securely on the battery terminal itself, so i just ordered a new positive terminal and hopefully once installed, my battery issues will be fixed for good. I’ll report back with an update after I install the new terminal.

 

Wow. This is eerily similar to what I’m also experiencing with my 2013 LS460. Car battery about 7 months old, no trouble starting it and then out of nowhere it suddenly starts acting up. Have to jump it to get it to start after turning off the engine for any length of time. Drive it where I’m going, no issues there, but as soon as I turn car off and then come back to go somewhere else, back to having to jump it again. Voltage on battery at rest is 12.5+ V every time I check with multimeter. Took it to AutoZone a bit ago and they hooked up their gadget and told me it’s the starter that’s bad. Not the battery, not the alternator. But I personally think it’s an issue with connection at the terminal. Just like you, I’ve tightened em down as much as I can but the terminal looks as though it’s misshapen so it’s not hugging the post as fully as it could be. And aside from not being able to start it each time I need to go somewhere (without the help of a jump) I am having a weird issue with one of the door locks. I have a recent post about that, but basically the door in question will lock and unlock perfectly fine when the engine is running and also when the car is in Ignition mode, but won’t work at all when the car is in accessory mode or fully off. Haven’t had any luck figuring out what’s causing that and I’ve tried the obvious fixes to no avail. Makes me suspect that it’s part of a larger electrical issue I’m having that’s now manifesting with the trouble I’m suddenly having getting car to start.