[Wetlens]

Went through diagnostics to find battery drain. Disconnected battery (-) and measured amp draw. After turning key on/off and waiting for things to quiet down, had a rather steady 145 mA. Tested several times - same result each time.

Reconnected battery and began going through each fuse. Found the culprit at fuse #12 - "Switches strip, on-board diagnostics socket, turn signal lamps, transmission control unit, exterior lamp switch".

Only problem is that I had to have door open in order to test. Any idea if this can be influencing the test?

When I put the leads on the fuse connection, the car chirps, there are a few hums and sits around 150 mA. After a few seconds, it drops to 100 mA, then drops to 93.5 and holds constant (as long as I can maintain contact, which is hard in that position).

And ideas? Dread taking it to the dealer as my experience to this point has not been po$itive.

 

[jimvw57]

There is a bit of a drain to keep the memory for the radio, clock, and the alarm system. If you have the door open, the internal light will be on for awhile too.

 

[Wetlens]

Other posts suggested a drain of about 25 mA to be normal. Internal light is off. I've played around with auto wipers and did find some draw (~0.1 mA - fuse 2) when this is left on, but I have it off right now. That draw did not affect reading across fuse #12.

Fuse R4 (not listed in my manual) had a draw of 5.05 mA; fuse R9 had a 0.01 draw (repeated several times as this did not seam logical). Fuse 28 had 0.01 as well.

Fuses 1 - 12, 28 - 31, R3, R4, and R9 have been checked - all zero unless otherwise noted above. Stopped at 12 when I found this large draw.

 

[JPaul]

R4 seems to be a spare:
Evilution - Smart Car Encyclopaedia

 

[a2jack]

Wetlens. Don't take it to the dealer, they will only throw expansive parts at the problem until it fixes it's self long enough to to get the car back out the shop door.

First find out what the normal current draw should be. I read somewhere it was around 20 mils, but check it out. 100 mils is not sustainable if the car is not driven every day.

Please keep us posted on your findings. A2Jack

BTW. Have you cleaned and checked all your grounds ?

 

[Brabus007]

Mine is a dead draw of 2.4 volts when the the key is turned off with the factory alarm(sonar)... Your car is always dragging juice waiting for your key fob to call and unlock the car...

 

[BB Benz]

If you turn off the overhead interior lamp, does that affect the reading with the door open?
The dome lamp as it used to be called is a filament lamp, that does draw significant current, but can be turned off with the dome light switch so that it doesn't operate when the doors are opened. The doors open will also be detected by the sam but that should not be a very large current draw. (You will get a low volume beeping if in gear, engine on with a door open.)
Just make sure your dome light is not your false positive with the door open.

 

[jimvw57]

Is there a problem? battery going dead overnight??

 

[larryw4csc]

One leaking electrolytic capacitor in any electronics, used to smooth the dc noise, will easily drain it like this. Unplug the "boxes", one at a time, while monitoring the current at the fuse in question is about all you can do as the boxes are pretty much unobtanium access to feel which cap gets warm....why the shop just swaps boxes until it stops.

They leave lots of stuff connected all the time that normally draws no current because it's cheap. Power filters is one of them. The high current power amps in any stereo are another as it draws little idle current and switching off the low current rest of it makes it idle.....until something starts leaking so bad the battery can't keep up parked/off.

 

[a2jack]

Is there a problem? battery going dead overnight??

WoW! That's what I assumed. I should have asked in front . OP never said.
My old flight instructor was right.

 

[Rustedwrench]

Most modern vehicles will draw from 20ma to 50ma after all the control modules go to sleep. That can take anywhere from five to forty-five minutes, depending on the vehicle and installed equipment. You can not test with the door open unless you use a screwdriver or similar to fully close the latch on the door while the door is open. The switches that tell the SAM the door is open are in the door latch. Just remember to pull the handle to release the latch when you are done before you attempt to close the door. If you do not, the first sound you hear will be a clank of the door's closed latch bouncing off the striker. The second sound will be your hand slapping your forehead.

Here is what I would do. You need a accurate digital volt-ohm-amp meter. Test leads for the meter with alligator clips. Or crocodile clips, depending on where you live. You also need a jumper wire with alligator clips.

Make sure the rear hatch/window are fully closed. Open the passenger door and trip the latch to fully closed position. Disconnect the battery ground cable from the body attachment, not the battery. Isolate the cable from touching anything on the car. Connect the jumper wire from the body to the ground cable. Then connect the meter leads in parallel to the body and the ground cable. Make sure nothing is turned on and the key is out of the ignition switch. You can also open the driver's door as well, just remember to trip the latch.

Now have a cold beverage, take a whiz, watch porn, whatever. After everything has timed out make sure the meter is set up for amps measurement and turn the meter on. Now disconnect the jumper wire while not disturbing the meter leads and you should have your draw measurement in milli-amps.

If the draw seems excessive you can then isolate it as before with the fuses except by disconnecting the components on the fuse that has the draw.

 

[Wetlens]

Battery drains over a couple of days. Worst case is when I drive out to the beach (~3 hours), park overnight (~10 hrs), then drive 2 miles to the aquarium. I spend ~6 hrs in the aquarium and come out to a dead battery. Starts up fine in the morning, but have needed a jump the last two times I've made this trip (every other week trip). Changed the battery between the two trips.

larryw4csc: What do you mean by "boxes?"

Overhead lamp is turned off. I have checked primary ground points and they are all clean and tight. Having trouble seeing what that would have to do with excess draw, but checked anyway.

 

[SmartDigger]

I would check the altanator. I had one go bad on another car in a way that it charged the battery on the highway. In town after a few small trips battery was low. turned out the alt. was not charging below a specific rpm

 

[Stan-MK-UK]

Smart 453 high battery drain. I have a bigger problem. Everything off, car looked, drain is 1.3A (1300mA). Any Ideas? About to disconnect the separate wires that go to the commoning block on the +ve battery connector and measure each current separately. Any better ideas?
Found it very difficult to get to the fuses on my RHD car, can the whole fuse assembly be removed?