My 2004 RX has had a weird electrical problem for the last few days. When I get in to start it there are signs that the battery is weak, dim dash lights, etc. When I turn the key there is a delay and then the starter just barely turns a little bit. So far it sounds just like a weak battery. Now the strange part. As I try to start it repeatedly it gets stronger and stronger. Eventually it starts, but will stall a couple of times before it will run without stalling. So that is the opposite of what I would expect with a weak battery. Also the MPG average is reset as though it lost memory. I've also set the clock for daylight savings repeatedly now as each time this happens it goes back to regular time. So it is losing some of the memory at least. Other than the problems at start-up, it runs otherwise perfectly. The battery was replaced in November.

Thought I would see if anyone had any ideas before I took it in to the shop. So far I've found that when there are problems on a Lexus they are more than likely not isolated and others have had them too.

 

All the symptoms of a bad battery. I'm sure they will check the charging system but definitely get a new battery!

 

Dave2K,
I would journey to your nearest parts house and have them test the battery. Some places can test your alternator, though the alternator test they do is a simple voltage test not a load test so be cautious of that. If it is a bad battery, Consumer reports did a eval on batteries recently and chose the Duralast Gold brand over every other brand except OPTIMA which is the top of the line but far more expensive than the Duralast Gold.
I would bet you have a battery issue. I would also have a full alternator test done (with load) to make sure the alternator is not causing the battery to burn a cell over time. My battery on my 04 went out about 6 months ago so its about time for yours. The factory battery can last 4 - 6 years usually depending on different factors.

 

He said the battery was replaced in November........
I would still have it tested.

 

first thing I would do is remove the battery cables and clean the posts and replace. Sounds like the connection is marginal and the draw from the starter causes the connection to vary as you start, thus the indication it gets stronger as you try to start.

 

i am sure i am not the only one to see a battery fail right out of the box, it happens. many places will test your battery for free, but like it was said previous, do some simple things like clean or at least inspect your battery terminals.

not knocking the other battery mentioned, but i have had good luck with costco batteries, down side, up here anyway, you have to install it yourself.

 

I will have the battery checked but this behavior is only like a battery initially. I've never seen a bad or weak battery get stronger with repeated cranking. The terminals were cleaning and treated a few months ago when the battery was replaced. It seems impossible that it could be so weak the memory is lost and then it actually starts the car.

 

Lexus bad battery behavior is legend. Make no attempt at rhyme or reason.

 

Well I went ahead and had the battery tested at the place of purchase and they replaced it. So far so good. No abnormal behavior. I'll consider the problem solved for now but I will have the charging system checked when the vehicle seen by the mechanic next time. This is my third battery in about 4 years so there might be another factor. However, the mechanic did say he thought they had a bad batch of batteries when he replaced mine. Thanks for the input.

 

You need resistance for the electricity to flow:

E=IR where voltage (E) is equal to current (I) multiplied by resistance (R)

If no resistance, open circuit for example, you have no voltage.

Perhaps you are building up some resistance in the battery by repeated cranking by putting a load on the battery itself or alternator adding something to the equation. As they replaced the battery they must have found a bad cell or something similar. What brand battery was it?

 

The wires were screwed up in my Lexus Rx. My door sills would not turn off and were draining my battery. It cost me over $465 to have the car re-wired. Check your door sills when the car and see if they stay on?

It is cheaper to go the dealership to find out what the problem is, because I took my Rx to my local mechanic first and he prematurely stated that is was the starter. I do have a new starter but did not need one.

 

The two failed batteries were Energizer batteries from Sam's Club. The first one may have been damaged when I let it run down in the summer in a hot garage. I've since read that high temps are very bad for a battery that is allowed to drain. I do believe the second one may have been a bad batch. The comment about resistance makes sense because the battery seemed to be practically dead a few times but eventually started the car each time until the last failure, which followed over a week of no use. I have checked for possible drains but I have found none, other than the current used to maintain the electronics when nothing is being used. In the summer the car may not be used for months so I plan to get a battery tender this year.