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Posted to sci.electronics.repair
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Ford car stereo F87F-18C815-BB drains car battery.
micky wrote:
On Thu, 14 Mar 2013 13:49:24 -0700, "David Farber"
wrote:
wrote:
David Farber wrote:
With the unit powered on and no load or signal, the draw was about
545ma.
About 6.5 watts... that seems reasonable.
In standby mode, the current draw was about 4.5ma.
This shouldn't kill a car battery in good condition. I have heard
various numbers for the acceptable "key off" draw on a car battery but
20 mA is usually somewhere in the ballpark. This is for everything in
the car - the radio station memory, a clock, anything the ECU needs,
security system, etc. 20 mA is 0.48 amp-hours a day, or 6.7 Ah in two
weeks. A car battery is very very roughly 50 Ah plus or minus [1];
with
6.7 Ah gone it will probably still start the car. ("Airport time" is
one name for this - you should be able to leave the car at the airport
for X amount of time and it should still start when you get back.)
I'm going to reinstall the radio tomorrow and see how these numbers
compare to the current drain from the car battery.
You might poke at the harness side of the connectors with a 12 V test
light before you reinstall the radio. Maybe it's not getting the
message that it could go into standby - short to battery power on the
"hot in run" line?
If this car has any aftermarket stereo equipment wired to the factory
head end, you can assume this was done incorrectly and be right about
half the time. Other sources of automotive electrical fun include
aftermarket trailer hookups and driving lights.
If the car has a trunk light or underhood light, look to see if it's
shutting off correctly when the trunk/hood is closed. This can be
a hard-to-catch source of battery drain.
Matt Roberds
[1] Yes, I know they are not rated by their manufacturer or sold this
way. If you use one like a deep-cycle battery instead of a
starting battery, you get roughly 50 Ah. Yes, it's not a good
idea to use a starting battery like a deep-cycle. The 50 Ah
number is just there as a reference for things like this.
This turned out to be quite the adventure. I got a little more information
from the owner. The problem started when the parking brake was pushed down.
(It uses a foot pedal for the parking brake)
That's actually a better design. If your hydraulic brakes fail, hold
the foot brake release handle so the brakes don't lock and then use
your foot to apply the "hand brake", "emergency brake". . You can
use it like the regular foot brake. I hate the hand brake between
the seats.
I always have problems with left push down brake. I never had problems with
right center pull handle system. One fault is left hand salt corrosion.
Sometimes they not release. Sometimes you got to pull up to turn lamp off.
I'm always afraid to use the push emergency brake. It's mostly a parking
hold brake, if it works.
. Somehow her foot dislodged the
connector going to something around the clutch pedal shaft. It has six
terminals and I'm guessing it's some sort of sensor that detects the
position of the clutch so you can start the car? I removed the plug and
checked for damage. It looked fine. I did take a reading of the battery
current before I put the radio back in with everything off before I started
troubleshooting. The reading was 0. Then when I was using my meter later on
I noticed that the DCV button was pressed in and not the DCAmps. At some
point I measured .22A from the battery. I put the radio fuse back in
(somebody had pulled it out so the radio wouldn't be draining the system)
On some cars there are 3 fuses for the radio. GM, for example. I
think you talked aobut this before. One for the clock, so it doesn't
stop when the car is turned off, one for the dash lights,, and one for
the radio itself.
and measured the current. I jumped two about 2 amps. I wasn't writing this
When you're miy age, you'll write it down. But I give you a lot of
credit for using a meter. It's hard to get anyone to use a meter.
(Anyone who doesn't read SER, at leat)
stuff down but I think that's what it was. Next I pulled the radio out again
and left the fuse in. It was still reading too high. Then I pulled the fuse
out and it was still reading too high. Huh?
I know that feeling. When I was 19, the first week I had my '50 olds,
the battery was dead every monring and I had to take my mothers car.
Short, Doconnect, Short Disconnect, Short, Disconnect, no short!!!
Reconnect last disconnected wire. No short, Reconnect wire before
that , No short, Reconnect wire before that. No short.
Up and down, up and down, 3 or 4 levels, 3 or 4 found tirps, and in
1950 there were no quick disconnects.
Finally found it. Glove box light. Every time I got close, I opened
the glove box to get something and if it was closed well before, I
closed it badly. If it was closed badly, I closed it well. That was
also what drained the battery.
:I proceeded to turn "off"
(though I can't specifically remember that it was even lighting up) the dome
light by moving the dome switch to one side. It's a three position switch so
I thought dome light, was a Pittsburgh thing.
It should be a hood light, Britain.
Greg
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