What is normal battery drain by a instrucmetn cluster in 1992 300SE?

Hi,

My battery on my 1992 300 SE (Chassis W140.032) died 2 times in 3 weeks recently, and the auto shop said the instrument cluster is using 0.11 amp when the car is parked. They said it is high and usually it should be

0.04-0.05. They told me to replace the instrument cluster which costs about US$1,000. Is the electrical current reading really too high? If it is, can I buy a second hand cluster and replace it? Any pointers to other online resources?

Thanks in advance for any advice.

Reply to
FatDaddy
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Parasitic load problems can often be difficult to find. I would recommend that you obtain a second opinion from a good auto electric shop.

Kindest regards,

BiLL......

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Reply to
Bill Darden

What is your alternator output? I suspect your alternator is not charging your battery enough... or that your battery is weak and old.

That draw is not enough to kill a battery overnight.

Reply to
Tiger

Check your battery voltage when the engine is running. It should be about

Reply to
Alec Hopley

Thanks for the suggestions. However, the shop has checked the alternator. Although I don't have the readings of the charging, the mechanic told me it is "strong and robust" and no problem. I just remember I have replaced a new alternator about 2 years ago.

First time the battery went dead, I replaced a new battery. Then the new battery went dead in 2 weeks, and I replaced it with another new battery. The new one also lasted only 2 week.

By the way, this car is not used during weekdays, so that's how the instrument cluster's drain can have 5-6 days to deplete the battery.

Any one know a normal draw from the instrument cluster? It has only a clock that draw power, I think?

Reply to
FatDaddy

Thanks for the suggestions. However, the shop has checked the alternator, and it's "strong and robust".

I have a more detail description of the problem in reply of previous post.

Reply to
FatDaddy

Instead of spending $1000 repair... you can buy a $30 battery disconnect switch or $70 Battery device that ensure that you have enough power to start the car by disconnecting the terminal automatically.

There is one other question I have... do you have any other aftermarket devices installed on your car?

Reply to
Tiger

Something doesn't sound right here. First, a typical auto battery has a reserve capacity of about 90 mins. This means it's able to supply a whopping 25 Amps for 90 mins before dropping to 10.5 volts. So, if you're drawing about 100Ma continuously from the dash, which is only

1.2Watts, the battery should last 250 times as long, or about 375 hrs which is about 2 weeks. And that assumes the car is not driven during that time to recharge it. Even a modest amount of use every day or two would recharge it.

Also, while starting batteries are not meant to be deep cycled, which will shorten their life, it's hard to imagine how draining it would cause a new battery to need to be replaced again in only 2 weeks. I would suspect something is either wrong with the charging system, cables/connections, etc. or else there is some other larger load draining it. The only way to find out is to do some investigating with a volt/amp meter.

Reply to
Chet Hayes

Thanks for the suggestion. I should go out and look for a switch, may be. :-)

No, I don't have any after market devices installed. Please see my reply in the other for more detailed description of how the auto shop found out the problem.

Thanks again

Reply to
FatDaddy

Thanks for the thoughts. Like I said, the car is only used during weekend, and the first time the new battery went dead, the shop just replaced a new battery without asking questions. Only when it went dead the second times in 2 weeks they asked me to go check what went wrong.

The auto shop actually did check the drain by the volt/amp meter, that how I got the 0.11 reading. When the mechanic took out the instrument cluster and unpluged it, the drain dropped to 0.01. So the drain is from the cluster for sure.

What I'm doing now is unplug the fuse for the Instrument cluster (fuse #17, if that matters), and hope the battery will stays full and fresh next weekend. I'm thinking of buying an used cluster, or like Tiger in another thread suggest, a battery switch.

Just hope someone could tell me the reading 0.11 is actually way too high, so I can go ahead and bite the bullet. :-)

Reply to
FatDaddy

Hi Again

0.11Amp drain should not flatten a battery in a week unless the battery is rubbish.

0.11*24*7=18.5 AH your battery will be at least 60AH

Do not waste money on an inst cluster yet.

Alec

Reply to
Alec

Reply to
mpb

My battery was drying up and doing the same thing. Check the fluid in your battery and top up as necessary with denaturalized H2O....

Reply to
jimbobeleeeeeoooooooooooeo

Also, when parked, that 40mA drain is the clock. Nothing else should be on. How do you know that your instrument cluster draws 0.11 amp? If you measure through the fuse, you might be measuring the wrong thing.

Reply to
jimbobeleeeeeoooooooooooeo

MB test for battery drain is FREE-BROADBAND

Reply to
lee.hewing

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