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Posting for my father, here...

The battery on his CLA (purchased in October) doesn't seem to hold a charge. He might occasionally let the car sit for a week, but I've never had issues with a car sitting for less than a month. I have to head over to his house today to put the battery tender on, but I told him to drive it to the dealer once it's charged and have them check it, or give him a new battery!

The guy he knows at the dealership says "well, there are lots of computers and gizmos on these new cars, and it does take a bit of juice to run them all!"

Bollocks.

Anyone else having any battery-not-hold-a-charge issues?
 

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Wow this is new to me, but I have never let my CLA sit for over a week, maybe a few days, but I have never experience that, did they did a battery test?

I don't think sitting a car for over a week would completely drain all the juice especially for a brand new battery.
 

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For the record, in the middle of Winter my car sat untouched for 3 weeks. It fired up smoothly with no issues.
 

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Definitely something causing an excessive constant draw on the battery, even though it is turned off. I got mine in December '13, and at one point my CLA sat for almost a month while I was away, and that was in the dead of winter. The car fired right up when I went to start it.
 

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my car has had tons of issues but not this... but what i can tell you is my service guy said he's only had 2 cla's in with problems mine and another with battery issues like what your having. he said it would die after a few days and sometimes overnight... i believe they ended up fixing the problem so i would imagine if you took it in they have a fix for it. not much help but just letting you know the dealer can fix it
 

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Discussion Starter #6
thanks, all.

yeah, I'll have him bring it to the dealer after we get it charged. I'll let him know about that other car with similar battery issues. (Is it a Columbus dealership? We're in the Twin Cities, but I can see if the dealerships ever talk to each other for problem-solving advice!)

I have a BMW 325i Touring that I don't drive in the winter, and that started right up after a month, too. (I did toss a battery tender on it for the remainder of the winter...)

But dying after a week, that's just crazy.
 

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Either a current draw or a compromised battery. Dealer should perform a battery test and a current draw test in that order in one visit to confirm. Batteries can go bad in relation to a current draw and subsequent recharging from dead state. If they just replace the battery and the issue remains (crossing fingers it doesn't) then you know you have a current draw issue... and that'll be a pain to fix.

Older Mercedes use to have a two position fuse for having accessory plugs stay on or auto off when ignition is off. Don't know if CLA's have this. If so, check that fuse and if he has something like a charger in the power port the whole time, arguably you can drain a battery. Although that'd take a long while if it was just the LED on a charger.
 

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Had the same issue with a new LR3. Dealer kept telling me that "neighbors with sophisticated garage opener are causing electronic systems to go on/off draining the battery" during the week that I'm away... Can you believe it?
Ended up being a faulty battery from the factory.
 

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Posting for my father, here...

The battery on his CLA (purchased in October) doesn't seem to hold a charge. He might occasionally let the car sit for a week, but I've never had issues with a car sitting for less than a month. I have to head over to his house today to put the battery tender on, but I told him to drive it to the dealer once it's charged and have them check it, or give him a new battery!

The guy he knows at the dealership says "well, there are lots of computers and gizmos on these new cars, and it does take a bit of juice to run them all!"

Bollocks.

Anyone else having any battery-not-hold-a-charge issues?
Went on vacation for 12 days and returned to a dead battery. I did not leave anything on before I left. It took several attempts to jump start it with my wife's 10 year old VW (which held it's charge for 12 days with no problem). When it started the driver's window went down on its own. I put it back up and as soon as I took my finger off the button it went back down. Repeated this 4 times and eventually had to raise the window and shut the ignition off while still holding the button up. The next morning the car was back to normal. Went to dealer a month later for Service A and told them about it. After checking they found no problem and said Mercedes would not replace the battery. I had not asked them to replace it, just to diagnose the problem.


-- John
 

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I apologize for bumping this thread but I am posting to report exactly the same issue.

I would leave for the weekend on perfectly normal temperatures and come back to a dead battery. I also had random problems when starting the car; power would go off, I would have to try and reinsert my key a few times and it would eventually work, until the day it no longer did.

That's when I found out the battery ground was not properly tightened and that's what caused all of my problems. I found out while inspecting my battery; I only moved the ground a little bit and I would see sparks flying around.

Now that I have tightened my battery ground , I don't experience battery drain or problems at ignition.

Hope this helps,

Cheers

Jeffz

Black CLA45
 

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I apologize for bumping this thread but I am posting to report exactly the same issue.

I would leave for the weekend on perfectly normal temperatures and come back to a dead battery. I also had random problems when starting the car; power would go off, I would have to try and reinsert my key a few times and it would eventually work, until the day it no longer did.

That's when I found out the battery ground was not properly tightened and that's what caused all of my problems. I found out while inspecting my battery; I only moved the ground a little bit and I would see sparks flying around.

Now that I have tightened my battery ground , I don't experience battery drain or problems at ignition.

Hope this helps,

Cheers

Jeffz

Black CLA45
mine was dead in 4 hrs. the neg terminal was fine. She thinks she left it on
 

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FYI, there are a lot of computers running in the background which drain the battery. Ford has the same issue on some models. A mechanic told me that once the battery dies completely, even if you recharge it, it will never be as good again.
 

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I am curious just how effective the charging system is in the CLA 250. When you are driving in town my car will shift rapidly to a higher gear, usually in 6th gear by about 40+ mph. That is very, very, low rpms and may not effectively be allowing the alternator to turn sufficiently to charge the system. Then you have the eco system which will turn the engine off, and subsequently no charging, while sitting at a light but the headlights, air conditioning, radio, navigation, dash displays, brake lights, tail lights, turn signals, etc are all still on but the engine is not charging. I am curious if the engine turns enough rpms on a regular in town use to charge the battery fully.
 

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Recently happened to me at 30K miles. Yesterday, it would not start.
Called dealer service, they offered to dispatch roadside assistance, and discouraged me from jump starting the car, making it sound like
it required a trained techinician do this. They said something like "Well the cla 250 has a lot of electronics". I just jump started it anyway,
it works like any other car, no apparent deep dark mistery.
I guess to get me to buy into the service model of "You need to call an MB dealer pay to do anything on this car". I am still under warranty,
so this is just part of baiting the deer.
So took it down to AutoZone, had the battery tested. Battery is low but sound, but AZ claims my regulator is toast. (Alternator failures are usually regulator failures)
Come to think of it, something like this happened b4, MB replaced the battery and alternator once already.
So, off to the dealer tonite, see what they say.

Update: Dealer recharged battery, says nothing wrong with the alternator.
My usage pattern is: drive the car 80 miles Monday, drive a couple of short trips Tue-thurs, (2X3 miles daily)
then drive it another 80 miles Friday. Under the circumstances, a healthy battery and alternator should keep
the car working, (it did last winter and the winter b4), or am I delirious? Opinions?

I guess I could check the battery voltage every weekend and recharge as necessary.. : - (
It is just not my idea of a hassle free ownership experience. This car has been spectacularly troublesome
so far. If the number and expense of repairs so far is a predictor of the future, I am really worried about owning
this car when out of warranty.
 

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so my battery is doing the same simply wont homd a charge, but its literally because rats have done their number on the car already, i live in ny and rats and constantly messing with the wiring, i got a rat repellent engine wash, and idk if it been helping but rats pee and poop in your engine bay, all these things hurt your car.
 

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Recently happened to me at 30K miles. Yesterday, it would not start.
Called dealer service, they offered to dispatch roadside assistance, and discouraged me from jump starting the car, making it sound like
it required a trained techinician do this. They said something like "Well the cla 250 has a lot of electronics". I just jump started it anyway,
it works like any other car, no apparent deep dark mistery.
I guess to get me to buy into the service model of "You need to call an MB dealer pay to do anything on this car". I am still under warranty,
so this is just part of baiting the deer.
So took it down to AutoZone, had the battery tested. Battery is low but sound, but AZ claims my regulator is toast. (Alternator failures are usually regulator failures)
Come to think of it, something like this happened b4, MB replaced the battery and alternator once already.
So, off to the dealer tonite, see what they say.

Update: Dealer recharged battery, says nothing wrong with the alternator.
My usage pattern is: drive the car 80 miles Monday, drive a couple of short trips Tue-thurs, (2X3 miles daily)
then drive it another 80 miles Friday. Under the circumstances, a healthy battery and alternator should keep
the car working, (it did last winter and the winter b4), or am I delirious? Opinions?

I guess I could check the battery voltage every weekend and recharge as necessary.. : - (
It is just not my idea of a hassle free ownership experience. This car has been spectacularly troublesome
so far. If the number and expense of repairs so far is a predictor of the future, I am really worried about owning
this car when out of warranty.
[/QUOT

sounds like your problem is like mine, rats, rats have been tearing my engine bay apart, and they just seem to be everywhere here in ny, its causing my battery and alternator to act stupid the car keeps throwing error codes at me that have to start issues, mechanic told me everything good it’s literally just the rats, not sure where u live but animals are a problem.
 

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awww man
dryer sheets
ultrasonic megaphone
fancy oils
sometimes those work
sometime those dont

sounds like that damn choco bar ad ...
 
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