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.

. 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 figured one of the other choices was always off
and the other position would be always on. The light didn't come on
so I figured I made the right choice. Later on I found out that
those other two positions of the switch were for, always on left
lamp and always on right lamp. All these little details that you
don't think about beforehand.

So now both doors are closed to make sure the dome lamp won't come
on. The radio and Fuse 29 is removed. The current from the battery
is in the 1.8 amp range. Great. I've done nothing but inspect the
system and things are getting worse. Then I looked at the schematic
http://webpages.charter.net/mrfixite...ck_Fuse_29.mht
There were four other lines that distributed standby power to the
car. They were the cigarette lighter, flasher, instrument panel, and
generic electronic module / central timer module. I pulled those
fuses one at a time and went back and measured the current. After
pulling the lighter fuse, the current drop to about .8A.

Snmeone may have wired something to the cig lighter circuit. I use
that alot because I almost never use the lighter, so it doesn't
interfere with add-ons.

Pulling the flasher fuse had no effect. Pulling
the instrument panel fuse lowered it a bit more, and then pulling
the last fuse dropped it down to near nothing. I put on my
magnifying glasses and took a good look at the cigarette lighter.
There was some rust or corrosion in there. By the way, the
receptacle itself was not covered/protected so it made sense that it
was getting to look a bit rusty. I took a sharp ended pick tool and
started to scrape away at the corrosion. I put the fuse back in and
the current didn't spike up. In fact with all the fuses put back in,
the current leveled off at .22A. I didn't know if this was an
acceptable

If you have a decimal point, please put a zero in front of it. With
my monitor, it's about the only way I can tell it's there. Right now
it looks like 22 amps.

reading or not. One of my friends was visiting with me so I asked
him if I could remove the battery cable from his 2001 Honda and
check how much current was flowing from his battery in standby. It
was identical .22A. I'm still waiting to hear back from the owner if
the battery made it through the night or it had to be jump started.
That's usually good news when somebody doesn't call you back when
you ask them if your repair went well, isn't it?

I suppose so.

Thanks for your reply.

Excellent point about the leading zero when displaying numbers less than
zero. I will adopt that format.

I finally did get in touch with the owner and I was told that the battery is
holding up quite nicely. I probably should have mentioned that during the
initial inspection, there was a bit of corrosion on the positive battery
terminal post which was cleaned off. The connecting terminals to the battery
cables were also cleaned.

Thanks for your reply.
--
David Farber
Los Osos, CA