My wife's 2013 died randomly while she was at work a few weeks back. the battery voltage had somehow dropped to 8v. (battery is about 2 years old, AGM energizer from Costco). I used a booster pack (on OVERRIDE) and no problems since. I had a gut feeling that it was going to do that, as she had only been driving short trips for 2 weeks, not giving the battery any time to charge. Still quite annoying. I don't think it's the network gateway, as she doesn't have those options either.

You have very few miles on your GS... clearly it has never been driven enough to charge it properly. 27000 miles / 10 years = 2700 miles per year, /365 days = 7 miles per day. likely not enough to properly charge the battery (for this energy hungry vehicle). You might want to look into a trickle charger like people use on sports cars / boats.

 

I had this with a new marine alternator once. The regulator was not shutting down when the engine was turned off, and I measured a ~3amp draw from the alternator energizing the field coils.

 

Hey @bclexus remember my battery issues a few months back?

I had the Costco/Interstate battery that died due to car not being used. So, I went and got a battery from Lexus, production date 1/2025. Naturally, it died a few weeks later due to the same problem as above.

I bought a battery charger and let it charge overnight. Then, I plugged in my Costco battery to charge in the garage.

All is good for a while. A couple of weeks of constant driving then suddenly the car is struggling to start.

Took the Lexus battery out and put the Costco in. Two weeks and no issues.

Stopped by the Lexus dealer and after getting passed around from parts to service, the guy asks me where the battery is and that he needs to test it and all that. I told him it’s losing cranking power. Explained him the whole issue.

Last night, I put it back in the car when it was reading over 12.65v. Try to start it today and it struggles. Now I will need to stop by and show the guy while it’s in the car.

I would have had the battery replaced at Costco but Lexus dealer is giving me a hard time.

 

It sounds like you don't have a battery problem, but either a starter problem (with a hanging solenoid) or an alternator problem (with failed diode(s).

 

I'm taking a break from this until the weather clears up. Replacing the starter looks like quite a job. I still need to get to a parts place to test the battery/alernator, but my limited DIY testing shows no trouble with either. Fully charged the battery tests about 12.5, or 14.5 running. Left sitting overnight and it is down to 50+ percent. It always starts eventually but sounds terrible getting there. My 33 year old Buick is likely to become my driver once again as it never fails me.

 

You need a load start test. It can show 14v then on start pull down to 8.2v. That's why you need to have someone test and include a load start test.

 

Very possible since my alternator whines too, but a battery that is fully charged on Tuesday at 6pm shouldn’t struggle to start at 11am Wednesday. Just to test it, I re-installed the Costco battery that came out of the car on Tuesday this morning and no issues starting.Now I need to make the knuckleheads at the dealership to understand this battery is junk.

 

Repeat: - You need a load start test. It can show 14v then on start pull down to 8.2v. That's why you need to have someone test and include a load start test.

This will let you know exactly. Also have you looked at your Belt? The whine noise.

 

@SC300Es - An alternator doesn't whine (I'm not talking about belt or pulley or bearing noise) unless it has failed diode(s) which can most definitely backdrain (repeat: DRAIN) the battery.

The diodes in a bridge in an alternator act like one-way valves for electricity, allowing current to flow in only one direction, ensuring the electrical energy generated by the alternator is rectified from AC to DC and flows to the DC battery to charge it. HOWEVER, when one or more of the diodes fail in an alternator the current flow reverses! (See where this is going?) When diodes fail, they can become leaky or shorted, allowing current to flow in the wrong direction, from the battery back in to the alternator. This will drain a battery! And the drain can indeed happen with the car turned off.

Now you know more than you did before, so let's move forward in this scenario and and talk about why failed diodes make an alternator whine. Failed diodes in an alternator can cause a whine because it disrupts the smooth conversion of AC to DC. This disruption, due to a failed diode preventing proper rectification, introduces ripple voltage spikes in the output, which can be heard as a whine, especially when the alternator is under load.

 

I get both your points. My issue is the difference between two batteries. Costco(old) vs Lexus(4 mo old).

 

Take the Lexus battery to any auto parts store or NTB store and have it load tested. That load test will determine if it has a bad cell. Bad cells happen on relatively new batteries - it's not uncommon. Get the load test tape readout for proof if it fails so you can show the Lexus dealer the battery is bad...

 

I ended up taking my battery back to the dealer and talked to a service tech that ended up being a super fun guy to deal with. Once I explained to him my side of what happened, he gave me a new battery at no cost. He commented why I had to go through him to get this done that it should have never gone past the parts department. My observation over two visits was that every thing was getting punted to him constantly. He is the guy that gets sxxt done.

Here are the measurements of the "old" and new batteries with my tester

new

 

Glad you finally load tested that problematic 'old' battery (and found it to be bad and needed to be replaced), and were able to deal with someone at the dealership with common sense. Too bad it took so long to get it done...

 

That test would have made it simpler from the start. You can't just read volts to tell.

 

Yep! We just couldn't get that to sink in... All one has to do is look at the voltage in the image (see below) that says 'REPLACE' the battery - it's 12.57 Volts. The health of a battery is NOT determined by its voltage.