battery (parasitic?) draw.
Thread Starter
Advanced
Joined: Oct 2016
Posts: 95
Likes: 6
From: San Francisco CA
battery (parasitic?) draw.
Hello all,
Wondered if anyone knows what is drawing down the battery on my ( or any of them) c5 when not used for a couple weeks. 29 k mile vehicle that runs perfectly. no after Market electronics. Previous owner told me if you don't intend to drive it for a few weeks you must use maintainer or battery will get weak. Something inherent in the vehicles? Brand new battery when i bought it but notice it has drawn down between maintainer use. Not a problem as long as I use maintainer but wonder about it. it does have "security" alarm from factory. Culprit?
Thanks!
Wondered if anyone knows what is drawing down the battery on my ( or any of them) c5 when not used for a couple weeks. 29 k mile vehicle that runs perfectly. no after Market electronics. Previous owner told me if you don't intend to drive it for a few weeks you must use maintainer or battery will get weak. Something inherent in the vehicles? Brand new battery when i bought it but notice it has drawn down between maintainer use. Not a problem as long as I use maintainer but wonder about it. it does have "security" alarm from factory. Culprit?
Thanks!
Safety Car
Joined: Jan 2015
Posts: 3,830
Likes: 394
From: Rocky Mountains
Hook up a multimeter in series with the battery. I think the spec is around 50-75ma. If it's higher, then you have to go one by one and start pulling fuses until you isolate the draw.
If it last for a few weeks before dying, I wouldn't worry about. I think it's a fairly common issue on the C5. Mine went complete dead once when it was only parked for like 5 days. But I usually drive it everyday, so it hasn't happened again since.
If it last for a few weeks before dying, I wouldn't worry about. I think it's a fairly common issue on the C5. Mine went complete dead once when it was only parked for like 5 days. But I usually drive it everyday, so it hasn't happened again since.
Burning Brakes
Joined: Jul 2014
Posts: 979
Likes: 532
From: Charlotte NC
The correct draw when the BCM is in sleep mode is somewhere around 25 ma.
Here is a cut and paste from a post by Bill Curlee, the Forums resident electrical wizard:
The correct BCM current draw should be 30 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
And here is a link to a thread, also by Bill Curlee, about how to test/isolate a current draw:
http://forums.corvetteforum.com/1567522286-post590.html
The batteries Reserve Time rating is a key to having the car last more than a few weeks without being on a battery tender. The higher the reserve rating the longer it will last undriven.
Here is a cut and paste from a post by Bill Curlee, the Forums resident electrical wizard:
The correct BCM current draw should be 30 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
And here is a link to a thread, also by Bill Curlee, about how to test/isolate a current draw:
http://forums.corvetteforum.com/1567522286-post590.html
The batteries Reserve Time rating is a key to having the car last more than a few weeks without being on a battery tender. The higher the reserve rating the longer it will last undriven.
