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Discussion Starter #1
As most of you know I purchased a new battery on Jan 20, 2007. Car has been sitting in the garage with a trickle charger hooked up to the battery. The last time the car was driven was on Super Bowl day. The light on the trickle charger indicates green the whole time.

When I tried to start the car today, the battery does not has enough juice to crank the starter over. What gives? Do you all think there is something draining the battery? Or there is something more serious? I am at a total lost.

Any help and suggestions are much appreciated.
 

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00 SL500 SOLD, 05 SL600 Sport, 09 Silverado 4x4 LTZ,SOLD '15Silverado LTZ 6.2 8Speed John Deere 318
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If you have left a trickle charger on it all winter, and the battery is nearly dead, you have two choices, A bad battery or a bad starter,or a draw on the system that is greater than the charger can overcome.{YEH,YEH, I know thats THREE!!! Do the headlights come on BRIGHT ?{without the engine running} do they DIM or GO OUT when you try to crank it over? Do you have a VOLT METER? Should be 11.8-12.6 across the battery terminals without car running.
 

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1993 Mercedes Benz 500SL
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5 Posts
I went nuts for 3 yrs.. same symptoms and a battery per year.... Dealer insisted the car was not used enough.. Independent found a Kenwood SVLU, an after market Lo Jack type sending unit above the right front wheel well.... Emittted almost a zero trickle, so slight it was undetectable on the tester but over time caused the battery to die... Mystery is who installed it ?? Dealer says "Not I"
 

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1995 500SL
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I hope this reply doesn't upset anyone, I too store in Winter with a battery tender I connect thru the trunk. The first time I connected it I wanted to prop up the trunk lid to prevent crushing the wires and when I lowered the lid realized I needed to slide the trunk light switch - off. Could this have been left on all winter?
 

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Discussion Starter #5
Finally fixed it!!!!!!!!!!!

Now we will have to see if the fix is permanent.

Everyone, as all you may recall I have this no start problem for quite some time. Part is self inflicted, other part is outside factor. Called Roadside Assistance this morning to give me a jump. Drove it to the dealer and the car would not start after an hour driving. I told the Service Adviser what happened. He was very friendly & told me even it was booked solid, he would fit me in and had a mechanic worked on mine.

First they took a reading of the battery (9 volt left), then charged the battery for an hour. Car still would not start. Then took a reading on the draw and checked if there is something else was pulling on the battery with the car running. Then they put a new battery in. After an hour, the draw reading was normal. With the car unlocked, the draw was 17 amp. Same reading with the car locked. Then they took one fuse out of the box one at a time to check draw. Still within normal range.

Their diagnosis - bad battery.

So they gave me the new battery since the other one is still under warranty (bought it in January of this year).

The Service Adviser did tell me my car has not been driven enough. I only put 1,000 miles on it the last two years. He told me the R129 draws an average of 17 amp with the car sitting. The R230 only draws 5 amp. He said he has many R129 owners coming in the shop with the same problem and he advised me to use the car more often. So I better listen to his advise.

After leaving the dealer, I went straight to Sears and bought a brand new battery charger/maintainer for $65. I think my Trickle Charge was not doing its job. I am going to ship it back to the manufacturer and have it rebuilt (according to their instructions).

Car drives like a champ, and she purred all day without missing a bit. Too bad the sun sets so soon or I would have been still on the open road with that Cheshire Cat's look on my face.

To end this episode in a sweet note. The Adviser did not charge me for any labor. Not a penny. The dealer is Mercedes Benz of Annapolis. Sad part is, he is probably one of the best Advisers I have ever worked with and next week is his last week. He is moving back to Chicago so he can be closer to his family. So the R129 owners in the Chicago area will gain one great Service Adviser. His name is Toby Jamieson. He is a Brit and used to work for Rolls Royce in Cambridge, England. His philosophy is there is "no" in customer service. And he shows it. Sad to lose him in this area.
 

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2003 SL500, 2003 SL55, and four R129s
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elau said:
He told me the R129 draws an average of 17 amp with the car sitting.
The actual current draw is only about .03 amps! Hopefully the new battery isn't delivering 17 amps at rest, because even on a trickle charger it would be flat in no time.
 

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Black SL 500 1994
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Thanks for posting Elau! :)

Do you have any non-factory add-on electrical items on your car? Such as an extra alarm?

I have an additional Clifford alarm and immobilizer on my 1994 500 and I've noticed that if I don't drive it for a week, the cranking is definitely less powerful than if driven regularly. After about 2 weeks the car may not start, not crank at all, depending on the temperature, cold (Scandinavian winter) is obviously worse than summer). 3 weeks and the battery is completely dead (I don't let this happen).
So if I don't use the car I use my automatic battery charger to fill her up every two weeks. The battery is now 2 years old an in excellent condition. I can't say if the additional alarm / immobilizer makes the situation any different: I only activate the Clifford one when I lock the car, not the MB original.

PS I suggest members never use plain chargers with the battery connected - I have a friend who apparently fried the instrument cluster (possibly something else too, still under investigation) on a 1991 500SL by using a plain charger (without automatic safety features). In any case I would always recommend against charging the battery when connected. Although I've been doing this with my fully automatic charger (Halford's) please don't do as I do...

Check this Varta site for useful info:

VARTA Online - All about batteries - VARTA Automotive, VARTA Consumer Batteries, VARTA Microbatteries, VARTA AG
 

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Discussion Starter #8
I don't have any aftermarket add on. I thought battery charger with automatic operation is safe to leave on cars for extended period of time. Is it not the purpose of a Battery Tender?

Please someone clears this up for us. I don't want to fry anything on my car!!!!!

The one I purchased yesterday came with 3 settings: 2 amp, 10 amp, and 50 amp. According to the owner's manual, 2 amp is for motorcycle, lawn mower, etc. 10 amp is for car, RV, and boat, etc. 50 amp is used for actual jump start the vehicle. In addition to 3 settings, there are 2 other settings for different types of battery. One for maintenance free battery, and the other setting is for conventional battery. One nice feature of this battery charger is that it has a reading for you to see how much charging is needed.
 

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Discussion Starter #9
bobterry99 said:
The actual current draw is only about .03 amps! Hopefully the new battery isn't delivering 17 amps at rest, because even on a trickle charger it would be flat in no time.
That's what the Service Adviser told me. So maybe he is wrong. Maybe he meant 1.7 amps for the R129 and 0.5 amps for the R230.

I apologize if my information is incorrect. Not trying to mislead anybody. I just repeated what I was told.
 

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But even 1.7 amps is far too high. And the fact that they made a number of current measurements with different fuses removed after installing a new battery suggests that they recognized a problem of excessive current draw. If this is the case, the problem may be unsolved, as you did not mention them doing anything besides installing a new battery.

If I were you, I would connect a basic electronic multimeter in series with the (-) battery cable and the (-) battery terminal and measure the quiescent current draw for myself. If the ignition has been off for more than an hour, you should measure .025 to .035 amps. Otherwise the current can be around .35 to .40 amps, since the roll bar controller energizes the seat belt release solenoids for one hour after the ignition is switched-off.
 

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1997 SL320, 2003 SL500 (R230)
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Bob,

>>the roll bar controller energizes the seat belt release solenoids for one hour >>after the ignition is switched-off.

That's an interesting fact.... why does it do that?

IAN.
 

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2003 SL500, 2003 SL55, and four R129s
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The belt release solenoids draw a considerable amount of current. If they were energized at all times, then the car battery could go flat in a short period of time.
 
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