About a month back I had my car (99 LX470) running for about 30 min (sitting idle) with the AC blasting at it's coldest, highest setting (front and back) trying to get some relief for my son who had just played a lacrosse game in 98 deg weather. When we left the car, all seemed fine. (nothing extra plugged it etc) I came back about an hour later to do more of the same...and found my car would not start.??? I had a friend jump the battery...and then drove around the parking lot and nearby roads for about 25 min to juice it up so I could keep my son in the AC prior to his next game.
Ever since that weekend, I have noticed at first start up, my car "sounds different" when trying to turn over. Sort of sluggish if you will. Although the battery registers within the OK range it is slightly on the low side prior to starting the car then adjusts to a higher reading after 5 min or so. I have also noticed my AC will fluctuate it's fan speed, as well as my headlights from full to slightly dimmer in output. My husband does not think it is my battery but is unsure...I am perplexed. I have this horrible feeling I am going to be left sitting somewhere before too long. Incidentally...when my friend jumped the car, he said my battery was registering OK...although being hooked up to his jumper is what got the car started. So I am perplexed as to what may be causing this to happen. I intend to take it to the shop to be looked at, but I would prefer to be semi informed as to what to expect as service is usually a sticker shock. I am hoping it is a simple battery issue. Any help is much appreciated. Thanks guys.

 

Probably battery,but make sure they check the alternator output. How many miles on your LX?

 

I've got about 160k, have done all of the major service recommendations as well as oil/filter changes. It sure seems like the battery, but puzzling as it is, the battery is still measuring "normal range" on the gauge (in dash). I'm going to have a garage measure the battery output tomorrow and see what they think. Thank you for your reply.

 

Time for a new battery.. Get your charging system checked out first though.

 

I would say it's the battery as well. Sounds like it has a bad cell, and the summer heat is torturing it as well. A bad cell could still register a "good" condition with a voltage tester; a better test would be a load test, most shops will have this equipment and should do it free of charge.

Like GS4 said, check the charging system just to be sure.

 

the gauge on the dash is not necessarily a great indication of the battery's health...

it is an indicator of the voltage coming from the alternator once the vehicle is running... it is only an indicator of battery voltage when the vehicle is not running...

batteries fail two ways - most commonly, they just wear out, get weak and can no longer supply the cranking amperage they used to - the other failure of batteries is that a cell shorts out, causing a dead cell, in which you will get no more than 10.5ish volts from the battery... most likely, your battery is just worn out - replace it and you are good to go...

 

The battery was registering low and we replaced it (with a Premium Bosch 27F from Pep Boys--$99) and that has solved the problem.
Thank you to all for your input. I appreciate your time and knowledge given on my behalf.