Hi! Comments about poor battery replacement history (at bottom) and my “novice” guesses would be appreciated! Thanks!
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My dad passed away recently. I never really talked to him about his 2000 LS400. After reviewing service records, the car has a bad history of battery replacement (10 batteries in 16 years). The car only has 46k on it, so it wasn’t driven a lot. The Lexus dealer replaced 6 of them and Pep Boys replaced 4 of them. No sign of them flagging any parasitic drain problem in the records.

Guess #1: Sitting in the garage without being driven a lot, with the constant battery drain of the electronics, with the occasional drain due to starting and not completely recharging, caused the batteries to “deep cycle” and fail.

Guess #2: The Lojack parasitic drain, that was never detected by the Lexus dealer or Pep Boys, caused the batteries to "deep cycle" and fail.

In going through the service history, there was no evidence of my dad getting the Lojack serviced. In the Lojack manual it says “To comply with the terms of your warranty, an inspection is required in any of the following instances: 1) …accident… 2)..install other equipment…..3) …….non-operation for more than a month…..4) You experience battery or electrical system problems with your vehicle.

With a multimeter, I noticed something curious. The parasitic drain in just disconnecting and reconnecting the battery (after sufficient settle down time) was 30 mA (dealer says 30 mA is standard). If I ran the car and then let it settle down, without disconnecting the battery, the drain would “jump” between 40 and 50 mA.

I found and took out the Lojack and ran the same tests. The reading was now a solid 30mA.

I don’t have a track record with the Lojack disconnected, so don’t have any more to go on.

 

Here in AZ the batteries in cars don't last due to the heat. My last battery that I got since I bought the car died within a year. It was under warranty so I got it replaced for free. Looking at your profile looks like you are in AZ also. Only harm cars get in AZ are batteries going, seals and hoses drying up and cracking, and paint fading from the sun.

 

Thanks Winter4w! I do live in AZ. Batteries do go quickly here! I forgot to say, my dad lived in Southern California and that is where the car has been since purchase.

 

Have you checked the alternator? Since you have a multimeter, check the voltage for your next step. A good alternator generates 13.0V or more @idle and a bit higher than 14V @1000rpm. But the voltage should never exceed 14.6V.

 

Thanks Yamae! I have enjoyed reading your past posts and learning from them!

I don't have the car with me right now, but in the past I did measure the voltage at the battery with the car running. I cannot find my notes, but I think I remember a reading of 13.5 volts at idle.

In October 2016, the Lexus dealer report said the alternator was putting out 13.9 volts. In May 2006 the Lexus dealer report said the alternator was "within factory." Each time the car was taken to Pep Boys the receipt said "Prostart Starting/Charging System Test." There was no mention of alternator voltage output but there was no mention of alternator problems either.

 

I'm in Scottsdale, AZ also and the battery that came with my car from Batteries Plus, a Duracell standard one, only survived a little over a year as well. The car was a daily driver for the entire year with 40 mile drives to and from work each day on the highway, so it didn't sit for a prolonged period of time.

It is parked outside 24 hrs a day, half that under a carport overnight when I returned home from work. Good news is I got it replaced for free as it had a bad cell and wouldn't register any click when the key was turned.

 

Thanks Losiracer2! I think the "bad cell battery" situation probably happened a few times in the replacement history. I didn't talk to my dad about it, but I think he switched to Pep Boys because they had a better battery plan and price than the Lexus dealer.

 

Feedback would be appreciated!

OK, so I kept thinking about Yamae's suggestion of checking the voltage while the car was running. I had done that and it was 13.5 V. The dealer had documented "good" alternator test voltages on previous service reports. Multiple Pep Boys diagnostics flagged nop problems.

Decided to do an "under load" test following one of the Youtube videos. See results below.

I expected the voltage to stay at a minimum of 13.1 V at idle with the lights, fan, and radio on but at idle, it stayed steady at 12.84 V after "stressing" with repeatedly rolling the windows up and down. The "stressing" seemed to change the voltage output performance.

 

At idle the alternator cannot support much load. Better test would be driving or holding the RPM's above 1200rpm or so. But with nothing on, you shouldn't be seeing < 13 volts at idle...