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
Thanks in advance for any advice.
Parasitic load problems can often be difficult to find. I would
recommend that you obtain a second opinion from a good auto electric
On Sun, 04 Jul 2004 02:52:24 -0400, "FatDaddy"
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?
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?
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
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.
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. :-)
MB test for battery drain is <0.05 Amps.
The technician probably disconnected the cluster and found the battery drain
dropped to an acceptable level.
Try disconnecting your cluster and see if the problem goes away.
Also, when parked, that 40mA drain is the clock. Nothing else should
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.
On Mon, 25 Oct 2004 23:39:31 -0400, jimbobeleeeeeoooooooooooeo
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