# Join the Car Talk Community!

Discussion Rules

#### Welcome to the Car Talk Community!

Want to ask a question or join the discussion? Great! Join now.

# Lexus RX350 Battery Drain Problems

2»

• Tester,
Fine, Just trying to give ideas to an OP who has to burn 260Miles of gas in alaska (higher than 4\$ a gallon I bet) to get back to the DEALER, who likely caused the issue to begin with. You are right up to a point but then I have nothing more to say as it will not change anything.
• edited June 2012
Not for nothing but could one see power dissipation across a fuse with a thermal scanner if the current is just - say - 40 mA?

I'm assuming some normal batter so somewhere around 40 AH and let's assume that drains over four days to being dead as a door nail. That's 40/4 = 10AH per one day. That's 10/24 = 42 mA.
LEt's assume the fuse is a horrible fuse and has an internal resistance of 0.1 Ohm.
That means that the actual power dissipation of that fuse is 0.42 * 0.42 *0.1 = 0.2 mW and I'm being generous with the numbers, rounding them before calculating.

You can't see 0.2mW on a wire.
There won't be any appreciable amount of heat dissipated by the wire. The fuse is in an outside area (in cold Alaska no less!) and it wants to be at ambient temperature.
You'd have to drain a lot more current than just 40mA. If the dealer can't find where some parasitic drain is going, they have no business repairing cars, let alone putting remote starters on.

There's no way that car shouldn't last for weeks if left alone. Sure, Alaska is cold but your summer is probably still warmer than our CT winters. We leave our cars in long term parking all the time at the airport for weeks on end without any issues.

I agree with the other suggestion of disconnecting the remote start fuse first. Actually bring it to the dealer and make some noise. They clearly are morons.
• Thanks for all the comments. The RX 350 is an SUV, so it has a hatch not a trunk. Checking for the light has been easy, and that has not been the issue.

The car lives in a heated garage most of the time and that is usually where it had the dead battery until we got the trickle charger.

We've read some posts on the "Club Lexus" web site that suggests disabling the "Smart Key" when the car is not going to be used for a long period of time (like when she is out of town for a week or longer). It appears this has happened with other Lexus models (also BMW's and other electronically tripped out cars from what we have seen on the discussion boards). However, her manual does not discuss this or the location of the switch. Any thoughts?

And yes, gas is \$4.47/gallon in her home town, \$4.20 in Anchorage currently.
• Tiny levels, though.
4.5mV on single ended wire into a high impedance (ie open wire because the circuit is off) could easily be construed as noise. A regular half way decent multimeter measures about that much if you just leave the leads dangle.

Also, if specialized equipment is involved it no longer is a home mechanic approach.
• @ddieckgraeff,
It would be nice to know how bad the current drain is on this. The Lexus shop should be able to fix this problem. There are other shops in Anchorage that could look at the issue also. I live in Anchorage and if you would like me to check it out let me know.
• I agree with Cougar that it would be nice to know what kind (amount) of parasitic loss is involved.

While I'm not familiar with the vehicle in question as to what's normal or not I might add this in relation to what Tester stated. Both of my Lincolns and my youngest son's Lincoln Aviator have comparatively large parasitic drains until things settle down and go to sleep. We're talking 700 milliamperes for about an hour and that type of draw can run down an iffy battery in that length of time.
Assuming a new battery for the sake of discussion, a draw that large can run a new battery down if things don't go to sleep pretty quickly.

Maybe this large draw the dealer referred to was an initial current draw without waiting for things to go to sleep. I also don't see a mechanic driving a car into the shop and allowing it to tie up rack space for an hour while waiting for it to doze off.......... :-(

On a side note, if this remote unit was not installed in the service department and was done by an outside vendor then one runs into the sticky issue of exactly who is going to pay the mechanic for sorting this out.
Warranty will not cover it, the dealer will not cover it out of pocket, etc. and a mechanic who is coerced into doing something for free is not going to give a darn.
• Wow, OK4450. I am surprised to hear that high of current numbers for that long of time period.
• The OP said "The dealer installed a remote starter at the time of purchase (we live in Alaska)." I just wanted to say.
This discussion has been closed.