Car Key causing battery discharge??
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From: Florida
Car Key causing battery discharge??
I am having some repair work done at my local Chevy Dealer. One of my concerns was a battery drain overtime when the car is turned off requiring me to either leave on charger or charge frequently. To my surprise, the dealer stated if I left my keys in (not in the ignition) or near the car that would cause a battery drain. All of the service advisors chimed in stating the same thing as a fact. As my Vette is kept in my locked garage I frequently leave the keys in the car (not in the ignition) I will obviously stop this practice. Has anyone else heard of this issue?? I own a 2001 C5 Convertible purchased new and now has 81,000 miles.
Last edited by ezzrider; Feb 3, 2022 at 01:53 PM.
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I could certainly see this being the case with an older C5 due to the passive keyless entry feature. This feature was not included in the newer C5s. If you have a newer car without PKE, then this should not be an issue. There are a number of things that can cause a power loss in these cars.
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I do not see keeping the fob in the car as a drain on the battery. The C5 has plenty of other ways for a battery drain to happen, especially if you do not drive the car regularly.
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I only know what the dealer's service department told me concerning the key issue. Sounds a bit far-fetched to me also. One item is my Vette stayed at the dealer for well over a month awaiting parts. During that, the battery apparently did not discharge. When I left the keys in the car it only took days to a week to completely discharge if not on a charger. During that time period, the car was not being driven. I will see what happens now. We have had continued issues over the years with the BCM Body Control Module going on our 3rd one now. Hence there were time periods the Vette was not being driven.
Last edited by ezzrider; Feb 3, 2022 at 09:47 PM.
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I wanted to come back and post that after keeping my car keys out of my Vette I have no longer experienced car battery draining or dead battery and I do not leave my Vette on a charger. I realize this sounds crazy but I can attest the keys left in the car will cause battery drainage. I hope this helps someone else.
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The following might help...What kind of shape is your battery in???
Have you had it load tested? Have you measured the voltage across the battery posts using a digital multi meter? What is the reading?
Don't bother with the readings on the dash gauges. They do NOT indicate the state of health of the battery. Rather they indicate the state of health of the CHARGING system.
A good battery at full charge will measure 12.7 to 12.9 volts or more measured across the battery posts with the neg battery cable disconnected. While the car will start with a reading of 12.2 or less the electronics in the car will NOT be happy if the reading is 12.5 or less.
Originally Posted by johnfin
Is there a common cause of battery drains? I unlocked the car in the garage a week ago and heard something running like a motor. It stopped after a few minutes. What about the hood light..how does that turn off?
Hood light is turned off by the BCM via relay #37 in the IPC fuse box after about 15 minutes. Same for several other lights inside the car like the glove box light, rear view mirror lights and vanity mirror lights ......
Here is a cut and paste from a Bill Curlee post from some time back about common parasitic drains in the C5:
The correct BCM current draw should be 20 Milliamps or less. Most C5 run around 25ma
but I have see some as low as 15 ma.
Leave the engine compartment fuse box for last and start with the passengers compartment
box first. Pull the power seat breakers FIRST! The power seats have a tendancy stay on
and cause this issue.
Also pull the fuses for the Bose system amp.
Examine the car in the dark for lights staying ON.
Once you prove the interior circuits good,,, check the headlight circuits, and then test
the current draw of the alternator.
Look at my electrical stickey. I think I cover this in detail in that post.
There are several COMMON things that cause excessive current draw
-Seat multifunction switch & Lumbar Switch
- Bose Amp relay stuck on
- Alternator didoes bad and drawing current
- Headlight control module bad
- Interior light on (check in the dark)
- Added aftermarket accessory not shutting off
If you still cannot isolate the cause of the drain here is a link to Bill's procedure for finding the cause:
http://forums.corvetteforum.com/1567522286-post590.html
Last edited by 8VETTE7; Yesterday at 11:32 AM
8VETTE7
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Quote:
You are aware that there is a second fuse box in the passenger footwell.
I'd start by checking the electric seat. The motor on these things have a habit of getting stuck in the on position and draining the battery. If that doesn't pan out go to the Electrical Information stickey at the top of the Tech page. Bill C. did an outstanding job on this and as I recall there is a procedure for finding current drains. Been a while since I read the section but it should allow you to find the problem yourself. Put away the vasaline and DO NOT take the car to the stealer. If after reading the stickey and trying Bill's procedure you cannot find the drain PM Bill and ask his help. I'm sure he can get you to the bottom of the problem without the rear end job from the stealer.
Chuck S. AKA 8VETTE7
Have you had it load tested? Have you measured the voltage across the battery posts using a digital multi meter? What is the reading?
Don't bother with the readings on the dash gauges. They do NOT indicate the state of health of the battery. Rather they indicate the state of health of the CHARGING system.
A good battery at full charge will measure 12.7 to 12.9 volts or more measured across the battery posts with the neg battery cable disconnected. While the car will start with a reading of 12.2 or less the electronics in the car will NOT be happy if the reading is 12.5 or less.
Originally Posted by johnfin
Is there a common cause of battery drains? I unlocked the car in the garage a week ago and heard something running like a motor. It stopped after a few minutes. What about the hood light..how does that turn off?
Hood light is turned off by the BCM via relay #37 in the IPC fuse box after about 15 minutes. Same for several other lights inside the car like the glove box light, rear view mirror lights and vanity mirror lights ......
Here is a cut and paste from a Bill Curlee post from some time back about common parasitic drains in the C5:
The correct BCM current draw should be 20 Milliamps or less. Most C5 run around 25ma
but I have see some as low as 15 ma.
Leave the engine compartment fuse box for last and start with the passengers compartment
box first. Pull the power seat breakers FIRST! The power seats have a tendancy stay on
and cause this issue.
Also pull the fuses for the Bose system amp.
Examine the car in the dark for lights staying ON.
Once you prove the interior circuits good,,, check the headlight circuits, and then test
the current draw of the alternator.
Look at my electrical stickey. I think I cover this in detail in that post.
There are several COMMON things that cause excessive current draw
-Seat multifunction switch & Lumbar Switch
- Bose Amp relay stuck on
- Alternator didoes bad and drawing current
- Headlight control module bad
- Interior light on (check in the dark)
- Added aftermarket accessory not shutting off
If you still cannot isolate the cause of the drain here is a link to Bill's procedure for finding the cause:
http://forums.corvetteforum.com/1567522286-post590.html
Last edited by 8VETTE7; Yesterday at 11:32 AM
8VETTE7
CF Senior Member
Member Since: Jul 2007
Posts: 17,148
Thanks: 40
Thanked 627 Times in554 Posts
Quote:
You are aware that there is a second fuse box in the passenger footwell.
I'd start by checking the electric seat. The motor on these things have a habit of getting stuck in the on position and draining the battery. If that doesn't pan out go to the Electrical Information stickey at the top of the Tech page. Bill C. did an outstanding job on this and as I recall there is a procedure for finding current drains. Been a while since I read the section but it should allow you to find the problem yourself. Put away the vasaline and DO NOT take the car to the stealer. If after reading the stickey and trying Bill's procedure you cannot find the drain PM Bill and ask his help. I'm sure he can get you to the bottom of the problem without the rear end job from the stealer.
Chuck S. AKA 8VETTE7
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Thread Starter
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From: Florida
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Thread Starter
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From: Florida
I can certainly understand your suspicion and skepticism on this. I had the same response at the Chevy Dealers Service Department when they told me this. I frankly thought they were full of crap. However, after taking the keys completely out of the Vette the battery no longer went dead after a couple of days. I replaced the battery and tried everything before this. The keys were kept in the cup holder when the battery would go dead. Now after no longer keeping the keys in the car cup the battery no longer goes dead even after several weeks of not starting or driving the car. Use this information as you wish or simply ignore it. I put this out as possible help to others.
Drifting
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From: Denver, NC
What other work was done - curiosity. I always try to keep an open mind, but I have left my keys in the car as you describe and never an issue. The C5 is not PKE, it's a manual pushbutton so I just can't see this as possible.
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From: Florida
I had the Body Control Module rebuilt as a new one was not available. I guess this could all be a coincidence with the keys in the car draining the battery but since removing them I have not had any issues and the service department was adamant about taking the keys out of the car. I also thought they were full of crap but if it works it works and I will continue to take them out of the car. Don't shoot the messenger.
Drifting
Joined: May 2008
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From: Denver, NC
I had the Body Control Module rebuilt as a new one was not available. I guess this could all be a coincidence with the keys in the car draining the battery but since removing them I have not had any issues and the service department was adamant about taking the keys out of the car. I also thought they were full of crap but if it works it works and I will continue to take them out of the car. Don't shoot the messenger.