I have owned my TCH for approximately 3 months. Every single time the vehicle has sat unused for more than 3 days, I end up with a dead starting battery. It starts immediately when jumped, but this is becoming more than a bit annoying. The dealer at first insisted that the $350 starting battery was defective and has replaced it 3 times. They are now convinced that something is intermittently draining the battery, but after having the car for a week on one occasion and almost a week currently, they have no clue what is going on. I had thought it was probably the smart keys “communicating” but on the most recent dead battery occasion both keys were 1300 miles from the car. I am beyond careful to be certain that everything is off and lock the car every time it is left. Any ideas or similar experiences??

obrienklm

 

You definitely have a power drain somewhere. I've left my TCH sitting for 24 days and had no problem starting it.

Try looking over the car at night. See if any lights are on. The map light (not the dome light) will not shut off automatically and will kill your battery. Try folding down the rear passenger seat and see if the trunk light is staying on.

If you don't see any lights, then I would call the owner of the dealership detailing your problem and that it needs to be fixed. If that doesn't get any action, call and write the regional office. There is a Regional Customer Relations Manager whose job it is to stay on top of dealers that are receiving poor customer satisfaction scores. Those scores for both service and sales are quite a big hammer that the Region uses to keep it's dealerships in line. Request through both the 800# AND the dealership's customer relations manager that you speak with the Regional CRM and/or the District Service Manager.

 

obrienklm — Weren't there Diagnostic Trouble Codes (DTCs) stored by the TCH, which the dealer would have read to determine the nature of the problem? The TCH has so much self-monitoring capability that it's difficult to conceive that there was no such information available to guide the service technicians. Without such information there are just too many possibilities to hazard a guess as to the cause of your problem.

Stan

 

Thanks for your thoughts… a few more details. The dealer has actually had the car in on 4 separate occasions and other than replacing the battery has not been able to find anything. This last time, they had it for a week, during which they talked to Toyota engineers from the US and Japan. They even had the car “camp out” in my garage overnight and came back the following day to be certain that there is no mysterious electrical interference in the vicinity. They have never been able to measure more that a 22 milliamp draw, just enough to run the clock, presets, etc. At this point, they have given up… and I guess I’m on my own until it happens again. This our 8th new Toyota vehicle over the last 12 years and the first I have had any problems with. It has been a rude awakening to learn quickly the dealer is willing to write off a significant problem. Live and learn.

obrienklm

 

obrienklm — Have a look at the thread "Disconnecting the 12 v Battery" for quite a lot of information on the current drain from the 12-V battery when the car is "off." It's very low indeed. I assume that you didn't inadvertently leave your car in ACCessory mode by mistake. It's easy to do! If the radio is "off" the only indications that it's in ACC mode are, I think, the fact that the clock display is still "on," and the Start switch still glows amber. It draws quite a high current in this mode (~5 A as I recall), but even this mode powers down after an hour or so (I don't remember the precise time-out offhand). The 12-V battery is a 48 Ah unit, so to run flat in 3 days requires a current drain of ~0.67 A.

Stan

P.S. The 12-V battery does not start the car! This is one of the functions of the high-voltage (NiMH) battery. The 12-V battery powers all the control electronics, lights, gauges, etc. You can't start the car if the 12-V battery is flat because the control electronics don't work. [You also can't start the car if the NiMH battery is too low to crank the engine (via motor-generator #1), even though the 12-V battery is fine.]

 

Thanks so much for your comments!

I had read the Disconnecting 12 Volt thread. All I have lost during all the 12 volt drains and battery changes are the radio presets. I'm not really sure if the dealer did the re-initialization, but I'm not experiencing any changes in mileage or idle speed.

Interesting that the high-voltage (NiMH) battery actually starts the ICE. That explains why it starts instantly when it's jumped - just needs enough power to get the electronics going and the high voltage power kicks in. The NiMH battery has always been at near full charge on these occasions as I have a big downhill run to end my commute home. I guess this also indicates how dead the 12 volt battery has been; literally not enough to unlock the doors or power the ignition switch.

I am absolutely positive that I have had the car powered down correctly. I've experienced all of the various issues powering down... wife's key in car, left in accessory 1 or 2 mode, etc. I never leave the car with any of the alarms beeping and/or the doors unlocked. I’ve been paranoid about the discharging battery and am very careful. Unfortunately, I travel for business and cannot even leave this car at the airport. With security et al, it costs over $100 bucks to get a jump in the airport ramps.

Do you think it could possibly be in the charging system... voltage regulator, alternator, somehow not charging the 12 volt system? I've had no indications of that, but I'm out of ideas.

obrienklm

 

Sorry for the dumb question re the charging system for the 12 volt battery. Just read the post on "jump starting" that explains the charging regime through the high voltage system. Still leads back to a 12 volt drain somehow.

obrienklm

 

obrienklm — Yes, it certainly looks that way, unfortunately!

Stan

 

Interesting, a couple Highlander Hybrid owners are having the same problem. Car sits for a few days and the 12 volt battery is completely dead.

https://www.greenhybrid.com/discuss/...ad.php?t=11694

 

If the problem can't be reproduced by the dealer at all, but happens to you quite frequently, then is really has to be something you are doing as part of your normal drives (not necessarily your fault, but might point to other faults that are user triggered). Just throwing out a bunch of things that might fit into this category:

• Malfunction when headlights left in auto mode
• garage door opener button stuck in
• flaky or poorly adjusted light switches
• seat belt buckle stuck in door preventing full close
• brake light switch on pedal not well adjusted, brake lights left on sometimes (I had this happen on 2 separate cars I had)

Try things that you might turn on or off, but that should normally turn off when the car is off yet might not be for some reason or another.