Battery drain

[commanderrostom]

Hi
Have a 1998 C5........battery drains. Anyone had similar....no lights radio etc left on. Alarm?? Its a pain!!

 

[Jack Cooper]

I haven't owned a C5, but if you leave the vehicle parked for a while (a week or more) then the various 'memory' functions - which are never idle - will
gradually run down the battery. We're talking a constant current of a few milliamps, I think, tho' I've never put an ammeter on my C6 to read the actual current. Anyway - long story short - if you aren't using the vehicle regularly, put a float charger on the battery to keep it fully charged.
This subject has been covered extensively on the CCCUK forums in the past; no doubt other guys will offer their views.
Hope your '98 serves you well! (Good machines, if they're looked after properly).
J.C. (1911)

 

[commanderrostom]

I haven't owned a C5, but if you leave the vehicle parked for a while (a week or more) then the various 'memory' functions - which are never idle - will
gradually run down the battery. We're talking a constant current of a few milliamps, I think, tho' I've never put an ammeter on my C6 to read the actual current. Anyway - long story short - if you aren't using the vehicle regularly, put a float charger on the battery to keep it fully charged.
This subject has been covered extensively on the CCCUK forums in the past; no doubt other guys will offer their views.
Hope your '98 serves you well! (Good machines, if they're looked after properly).
J.C. (1911)

Thanks. Yes, appreciate that. It happens in 2 or three days...have a new battery as well to see if old one was weak!

 

[teamzr1]

As mentioned C5 and never vehicles have many controllers that stored settings and draw amperage when vehicle is OFF
depending on the weather the draw can be even higher
The first battery on my 1999 Corvette only lasted about 4 years and then one cell got weak so battery never fully would charge up
Since then I began using a battery tender that only when in charge mode put outs about 1 amp so battery cannot get cooked.
The second battery is still been good all these years

You may want to check that the little relays used and there is several of them is not stuck in a on state by moving the functions
like seat, outside mirrors, HVAC, headlights, etc would cause forcing relays to change state.

If you do not have one, maybe a auto parts store would let you use their battery load tester tool to assure all cells are OK.

You do not want the battery to get too low as that would cause not just settings but also the adjustments the controllers for
engine, tranny, ETBCM, etc to erase all stored settings.

In my case I ran wiring from battery to outside the car and can simply pull tender in without having to open, door, hood, etc

 

[commanderrostom]

Hi
Have a 1998 C5........battery drains. Anyone had similar....no lights radio etc left on. Alarm?? Its a pain!!

As mentioned C5 and never vehicles have many controllers that stored settings and draw amperage when vehicle is OFF
depending on the weather the draw can be even higher
The first battery on my 1999 Corvette only lasted about 4 years and then one cell got weak so battery never fully would charge up
Since then I began using a battery tender that only when in charge mode put outs about 1 amp so battery cannot get cooked.
The second battery is still been good all these years

You may want to check that the little relays used and there is several of them is not stuck in a on state by moving the functions
like seat, outside mirrors, HVAC, headlights, etc would cause forcing relays to change state.

If you do not have one, maybe a auto parts store would let you use their battery load tester tool to assure all cells are OK.

You do not want the battery to get too low as that would cause not just settings but also the adjustments the controllers for
engine, tranny, ETBCM, etc to erase all stored settings.

In my case I ran wiring from battery to outside the car and can simply pull tender in without having to open, door, hood, etc

Thanks I’ll check it that way...... funnily enough thecseat height adjust stopped working so it might be that! I use an optimiser battery maintainer if left for a week or more ! It’s draining in 2 or 3 days so your idea good! Thanks all! PS fab car ..... want a C6 now!!

 

[teamzr1]

IF battery stays good with tender left on but low after just a few days without tender then either battery has a bad cell
or a relay is stuck on causing the voltage drain.
Also check that the battery cable terminals to battery posts are clean and tight.

The relays GM used are very small and quite easy over time to get weak and get stuck in one position
Sometimes trying several times (like seat adjustments) forces relay to flip state
I keep a extra supply of spare relays to change in controllers when needed

Corvette gets no credit, I have owned 10 of them since 1975, raced all of them hard, bounce the rev limiter all the time,
beat the hell out of them and very seldom have failures !

My 1999 C5 is custom built, has gone over 235 MPH at a race event and still on highway the car can get 30 MPG

 

[commanderrostom]

Thanks , it seems it could be a faulty seat adjustment relay?? Beyond my electrical ability which extends to wiring a plug but I know a man......I’ll let everyone know . All posts really appreciate. Tom

 

[Autocolor]

You may want to see how much current the car is draining after shutdown, make sure everything is switched off, then remove the battery terminal (I use the positive) then put a multi meter in line between battery and clamp, set multi meter to 10 Amp as the car will draw a lot of current initially as it goes through the shutdown process, then after a few minutes you will see the meter drop in stages, ideal draw would be 35-50 milliamps . See what you get as it may give you an idea of where it may be draining, mine was the alarm horn on the aftermarket alarm fitted during import for the UK market (Scorpion) horn usually located just under the rear of the off side (passenger) wing, there should also be a fuse for the alarm beneath the main dash so you can pull that to see if its that.
Good Luck
Mike.

 

[z06_tim]

I would do the test Mike has suggested. Then if you pull the fuse for the circuit you think may be faulty, and if you find the current drain changes significantly, then this is likely your faulty circuit. You can of course go through the different circuits pulling fuses to determine which is the likely cause.

 

[teamzr1]

Since disconnecting the battery will cause all the controllers that save settings to be erased another way to do the Amp testing
is
After car is turned off, close doors and wait about 15 minutes for all controllers to go to sleep mode.
Doing below prevents controllers waking up and causing a huge amp spike

Before disconnecting the positive cable from battery is tie a wire from positive post of battery to the 12 volts junction found on outside of
fuse panel (under a small cover).
Now the positive cable can be taken off the battery post and via that wire car still has 12 volts
Now can add in series the Amp meter to battery cable and battery post

With Amp meter ON then can cut the wire that was added and now flow is through meter
When done and before taking out Amp meter is splice together the cut wire ends and connect battery cable back to battery post.

 

[oelarse]

I have bought this good ( but cheap) amp clamp pocket meter UNI-T UT210E . With this amp clamp meter I can measure the current in one wire without disconnecting any wire .

It works on AC and DC . If you press the the blue Select button then you can alter between AC and DC .
I measure approx . 27mA on my 2000 mod. after 15 min

Here is a test of this instrument UT210E

 

[teamzr1]

Not sure how that can be done with wires hidden under the wire loom and hidden under the fuse boxes of the
PCM and BCM (under hatch of passenger floor) ?

 

[oelarse]

If it was my car I would put a meter on the negative terminal as shown in this thread ( or a amp clamp around the same wire) and follow Bill Curlee´s advice in this thread .
Bill Curlee mentions several typical current consumers like seatmodules , Bose amplifier...
Sometimes a interior light stays on due to a faulty relay.
Removal of fuses of these consumers one by one and observe the change in current draw on the amp meter can be a good way of isolating the main source of the current drain

 

[oelarse]

It is probably one of these Hot at all times circuits causing the current drain .
First have a check in a low light place and see if you can observe a interior light that never goes off after 15 min with closed doors
Then try first to measure the leak current from battery after the Retained Accessory Power has been switched of by the BodyControlModule (15 min as mentioned above)
After the drain current value is noticed , then remove fuses from then Inner Panel electrical center located in the passenger footwell , wait 15 min and observe any change in the leak current from the battery .
I

Note that each door modules have two seperate powersupply fuses .
I hope this will help you in locating current draining circuit