After my 2005 Crossfire convertible sits in the garage for about four days without being driven, the battery goes dead. Has anyone else had this problem, or can anyone tell me where to start looking for the battery drain? I wonder if it could be the convertible top pull down.

 

Have you checked to make sure it is a battery drain and not a bad battery?

 

Also, goto AutoZon, Advanced, or Pep Boys, they will check your Battery/Alternator for free.

Engine off should read +12.5 to 13 volts, engine running, look for +14 volts.

Also when running, turn on all lights/radio to place a load, and read Voltage.

Could also be a faulty Alternator, but the battery check above should narrow it down.

 

It is VERY likely that you simply have a bad battery, as 180 has already indicated. If it is over 3 years old, I'd simply replace it and go from there.

However....
The only reliable way to find current draw is to MEASURE THE DRAW and follow it to it's source. There is only one way to do this. Read on.



Take off one of the battery cables, it does not matter which one but I like to use the positive one.

Set a DVM or Multimeter to it's milliameter scale and make sure you put the probes in the right jacks on the meter.

Now, "clip lead" the DVM or multimeter in series with the battery and cable.

You will see some slight current draw, should be no more than 100 miilliamps. (1/10th of an amp)

If you see more than that (and if it really IS current drain and not a bad battery you will see 150 to 500 milliamps) then start pulling fuses from the box under the hood until the drain goes down to well under 100 or to zero. When you get to the fuse carrying the offending current, you will know it!

(I do not tell you to pull fuses from the box in the dash, as those fuses are fed by switched power from the key - all of them, I believe. If none of the underhood fuses stop the current flow, go ahead and pull the ones in the dash if you want to, but I am certain they are all switched by the key - but I've been wrong before, so try them if you need to.)

This won't FIX the problem, but it will tell you about where the problem is. The fault MUST be beyond that one fuse. Go download the service manual, or at least look in the owner's manual to find out what that particular fuse feeds. If you need help at that point, I'll be back on here later today.

If you cannot get the current to stop flowing with all of the fuses out, there are few options left but you probably have leaking diodes in the alternator (there is no fuse in this lead). Remove the heavy red wire from the alternator and keep it insulated from ground! If your current goes down, replace the alternator. If the current does not go down, there are few options left. But let's deal with that not-very-likely possibility only if we go that far.


Some notes:
If you allow the red lead to the alternator to touch ground, you will blow the fuse in the meter - or destroy the meter if it is a super-cheap unfused type.

My personal experience is that any battery with more than 30 to 45 milliamps of draw on it (.030 to .045 amp) will discharge in a week or two, less if the battery is old and weak. I have seen police cars with 100 milliamps of draw drain their battery in two days, but by putting a new battery in, the battery is good for a week or more.

Large storage batteries like in cars are designed to supply several hundred amps for a few seconds, but, oddly enough, they DO NOT like to provide 1/2 amp (500 milliamps) for even a few days. They simply are not designed for that. If you have an aftermarket audio amp or other item connected to battery, it COULD be operating normally but drawing too much standby current. Placing a relay in it's power lead that is keyed by the ignition would solve this problem.

Whatever the cause, by allowing the battery to be discharged like this a few times, will have degraded it's life considerably. Such batteries as in cars do NOT like to be fully discharged like this! When you get this fixed, it will probably be time for a new battery.

 

Pizzaguy, nice write-up on addressing cureent draw, and the symantics and design around Car batteries.

This is exactly the reason why I'm a fanantic about keeping my Battery Tender attached, whenever I garage my ride, and put it to sleep (even if only for a few days).

My brother-in-law thinks I'm strange, but I still have my original White battery, and it turns over real strong, and has never left me stranded. Mean while he's on his second battery in a little less than three (3) years...

 

Obvious question, how old is the battery? If you think it isn't the battery, then look to make sure the light switch is in the off position, because you can turn it too far, leaving the parking lights on, meaning the left or right parking lights which aren't on normal cars. Dome lights.... Can't think of anything else to put a drain on the battery.
Nice write up Mark...

 

I had a problem with the battery going dead on my 2004. In my case, the A/C & heater blower motor continued to run after the engine was turned off and the key was out of the ignition. It turns out that is was a faulty blower motor resistor, which is bolted on to the blower motor and accessible through a removable panel inside under the glove compartment. The crossfire part is expensive, but I was able to buy an equivalent replacement part for a Mercedes CLK320 for around $65 shipped.

 

Hi, just joined the forum (from UK) as I'm also having a battery drain problem that got worse when my heater fan also now stays on all the time.

The only way I can turn it off it to remove the fuse, otherwise it's on full blow all the time. The battery drain problem started a year ago (it's a 2004 Coupe/Auto) and I fitted a new battery but nothing changed - the car does however get left unused for a week or more.

Over winter we moved house and it was left outside unused for a few months. I noticed once that either the drain holes down the pillars had blocked or frozen, as the roof lining was full of water after heavy rain, and dripping inside from the light unit.

It has been garaged now for a while and it totally dry, however now I have the problem with the fan on all the time. I talked to a dealer and he said something like the 'SAM unit might need replacing/reprogramming', but my motor experience pre-dates modern 'can-bus' type systems and I don't have a clue on this one.

Someone else did talk about resistors, and I've just taken off the bottom of the fan unit having removed the glove box. There are a few old leaves in inside, and I guess it could have got very wet inside here during winter.

Any assistance with this issue would be great. Do I just need to buy another resistor?

Cheers, Martyn

 

I would definitely try replacing the blower motor resistor first, because it isn't that expensive and you can do it yourself with zero labor cost. When looking for the resistor also check for Mercedes Benz (I'm not sure if it's a SLK320 or a CLK320 that our Crossfire shares parts with but that part will also work) buy the cheapest part that will fit and go with that one.