Battery and radio Codes

I replaced the battery in my CR-V before disconnecting the battery I pluged
a 9 volt adapter into the cigarette lighter socket so not to loose the
pre-sets, or have to mess with the security code.

Radio and ignition switch off ( not on accessories).

After the replacement, the radio still had to be coded to operate, the 9 v
battery was new.

On my other CR-V that has a non OEM radio I lost the pre-sets but the clock
was ok.

I thought the 9 volt battery was supose to keep everything in check.

Tom

 

I think if you check the owners manual, you will find that it is called a
power jack. I also think that it is turned off with the key off like my
2000. Next time try leaving the key on.

R.

 

Unless the stereo and the power jack are both connected to the "ACC"
output of the ignition switch (which they are on my '94 Civic), in which
case it should work with the ignition off.

 

Did you perhaps reverse polarity when you hooked up the 9V battery?

 

Not reversed as far as the 9 v is concerned, center pole on the plug ..+..
the outer slide (ground) area of the plug ..-. Checked wireing with volt ohm
meter continuity.

Tom

 

I made an alligator clip arrangement and clipped the 9V battery leads to the
car battery cables before I disconnected them. Works every time.

Bearman

 

Surprising you didn't burst the 9V battery;a 12 V car battery can source a
LOT of current.

 

Well, I can tell you that my 2000 turns off the socket with the key off
because to run and charge my phone the key has to be on.

R.

 

I understand your point, but if the stereo and the power jack are both
connected to the ACC circuit, a battery connected to the power jack will
supply voltage to the stereo even with the key off. With the key off,
the power jack and stereo are still connected to each other, they just
don't have a connection to the car battery.

However, if the power jack is connected to a relay, there can be
problems. On the '97 CR-V, the front power jack was connected to the
same circuit as the stereo, but the rear power jack was connected to the
battery through a relay. (Relay closed whenever key is in ACC or ON).
Thus if one were to connect a 9V battery to the rear power jack, the
relay coil would not be energized with the switch off, and thus the 9V
battery would not supply power to the stereo.

 

You didn't say what year your CR-V is. The circuit diagram for the '97
shows the rear power jack being powered from the battery through a relay
which coil is energized when the key is in "ACC" or "RUN". The front
power jack is shown connected directly to the ignition switch "ACC"
without the use of a relay. The stereo is shown connected to the same
point on the ignition switch.

So, if yours is like the '97 and you used the rear power jack, it would
explain why you still lost your stereo presets etc.

When doing this sort of thing. it would pe prudent to use a diode in
series with the 9V battery to avoid 12V being applied to the 9V battery.
Anode to + on the 9V battery, cathode to + in the cigarette lighter
socket (or wherever you connect to the car electrical system). A simple
1N4148 would work, a 1N4004 would be more robust. Both are available at
Radio Shack.

 

Radios have TWO power leads. The one that is connected to the ignition
switch's ACC terminal does *not* provide power to the memory circuit.
If it did, the radio would require code reactivation every time you
switched off the ignition.

A *second* lead feeds the memory circuit, and it is to that one that you
must connect your backup battery.

Although 9V may (or may not) be enough to maintain memory, it is *not*
enough to activate the ignition switch's ACC-terminal relay (if there is
one), so turning the key to "ACC" will not always solve that problem.
Also, the relay could reduce the backup battery's voltage to less than
9V.

I recommend that you use a small 12V battery aligator-clipped to the
car's battery terminals.

 

The difference in potential is three volts.

Bearman

 

Actually,nominal voltage for a fully charged lead acid is 13.8V,not 12V.

 

I'm wondering why anyone would be changing a battery that can be fully
charged. Even so, the difference in potential is not great enough for the
12V--I mean 13.8V--to source a LOT of current into the 9V battery.

Bearman