Short battery life and hybrid braking system?
05-08-14, 07:37 AM
#1
Driver School Candidate
Thread Starter
Short battery life and hybrid braking system?
I am new to Lexus and new to the forum so please don't flame me if this has been covered. From what I've read, some owners are experiencing short battery life when the car sits for a few days.
I was watching a YouTube video entitled "How to replace brake pads on a hybrid vehicle, Lexus RX 400h" by a guy who calls himself spelunkerd. He says that hybrid systems will pressurize the brake system even when the key is off if the fob is close by. To be safe, he takes the key into the house to get it away from the car before he begins working on the brakes.
That got me thinking. If you keep your keys near the garage (or wherever you park), will the system be active and drawing enough current to drain the battery prematurely?
I was watching a YouTube video entitled "How to replace brake pads on a hybrid vehicle, Lexus RX 400h" by a guy who calls himself spelunkerd. He says that hybrid systems will pressurize the brake system even when the key is off if the fob is close by. To be safe, he takes the key into the house to get it away from the car before he begins working on the brakes.
That got me thinking. If you keep your keys near the garage (or wherever you park), will the system be active and drawing enough current to drain the battery prematurely?
05-10-14, 12:24 AM
#2
Welcome to Club Lexus, mamerica.
As no one has jumped in yet, I will try to help out. Hopefully, some hybrid owners will jump in here with further details as necessary.
The 12V battery is smaller in the RX400h than a standard non-hybrid application. Not needed to start the vehicle, its main job is to run all the accessory systems. Other hybrid owners here at CL have noted problems in the past with the battery going dead after sitting for what would normally seem to be short intervals of time. In these cases it usually turned out to be the need for a new 12V battery. Do you know how old the battery is in your RX400h? If more than 3 years old it may be time for a replacement and definitely at least to be checked to make sure it does not have any bad cells.
If you are a member of Costco, that would be one place to go for a replacement.
The search features here at CL are your friend. Many questions like this have been asked previous. You can also go to Google and simply add "clublexus.com" to your list of search terms to help narrow your search to CL items. What turns up are threads such as:
https://www.clublexus.com/forums/hyb...e-12-volt.html
https://www.clublexus.com/forums/rx-...-business.html
There are plenty more on the topic.
Finally, do not think key fob placement will affect the battery life and the brake system should not be a continual draw. If for some reason you do find the need to keep a charge on the 12V battery, there are a number of battery tenders on the market, such as those from Schumacher, which are inexpensive and easy to use. These are different than battery chargers which can be used to help jump start a vehicle and for charging a dead battery. Battery tenders are designed for a slow, low charge -- just to keep the battery topped off. I keep one on the battery, out of the vehicle, of my Chevelle as it does not see the light but a few times each year.
As no one has jumped in yet, I will try to help out. Hopefully, some hybrid owners will jump in here with further details as necessary.
The 12V battery is smaller in the RX400h than a standard non-hybrid application. Not needed to start the vehicle, its main job is to run all the accessory systems. Other hybrid owners here at CL have noted problems in the past with the battery going dead after sitting for what would normally seem to be short intervals of time. In these cases it usually turned out to be the need for a new 12V battery. Do you know how old the battery is in your RX400h? If more than 3 years old it may be time for a replacement and definitely at least to be checked to make sure it does not have any bad cells.
If you are a member of Costco, that would be one place to go for a replacement.
The search features here at CL are your friend. Many questions like this have been asked previous. You can also go to Google and simply add "clublexus.com" to your list of search terms to help narrow your search to CL items. What turns up are threads such as:
https://www.clublexus.com/forums/hyb...e-12-volt.html
https://www.clublexus.com/forums/rx-...-business.html
There are plenty more on the topic.
Finally, do not think key fob placement will affect the battery life and the brake system should not be a continual draw. If for some reason you do find the need to keep a charge on the 12V battery, there are a number of battery tenders on the market, such as those from Schumacher, which are inexpensive and easy to use. These are different than battery chargers which can be used to help jump start a vehicle and for charging a dead battery. Battery tenders are designed for a slow, low charge -- just to keep the battery topped off. I keep one on the battery, out of the vehicle, of my Chevelle as it does not see the light but a few times each year.
05-10-14, 07:24 AM
#4
My one year old 12 volt battery would not start the car after sitting for 2 weeks in my garage. I keep my keys on a hook inside the house about 10' away. I think the theory of keys being close is a long shot but I may do a test if timing works out 
.
.
05-10-14, 08:00 AM
#5
Driver School Candidate
Thread Starter
It would be easy enough to test. If someone has an ameter, they could connect in series with the battery and compare the current between key present and key absent.
05-10-14, 12:32 PM
#6
Since the 400h does not have the "smart" key that communicates to the door locks when you approach the car, I highly doubt this theory.
Even with a new battery, when mine sits for 2 weeks without running, it will drain to the point of not starting, especially in cold weather. I keep a battery charger around for these situations.
Even with a new battery, when mine sits for 2 weeks without running, it will drain to the point of not starting, especially in cold weather. I keep a battery charger around for these situations.
05-13-14, 03:14 PM
#7
The location of the key wouldn't matter since the second generation doesn't have smart key (unless you leave the key in the ignition). Also, even with smart key, the car recognizes when the key has been left near the car and eventually will disable the smart key function after a period of time.
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07-02-14, 11:09 AM
#8
Driver School Candidate
I did the rear brakes before and had the keys near the garage and didn't have any issues.
I did have my dash light up like a x-mas tree afterwards, apparently if you push the caliper back there's a brake sensor that senses a reverse flow of brake fluid which triggers this. As a result, I had no regerative braking until the dealer reset the lights for me.
They said to try pushing the caliper back very slowly to avoid triggering this sensor.
I did have my dash light up like a x-mas tree afterwards, apparently if you push the caliper back there's a brake sensor that senses a reverse flow of brake fluid which triggers this. As a result, I had no regerative braking until the dealer reset the lights for me.
They said to try pushing the caliper back very slowly to avoid triggering this sensor.
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