• Upgrade to XenForo 2.2.15 has completed

Ratbag

Administrator
Joined
Jan 1, 2012
Messages
7,417
Location
Bayside, Melbourne, Vic
Car Year
MY06, MY10
Car Model
Forester SG & SH
Transmission
5MT/DR & 4EAT Sports
Gidday All

Roo2 (2006) developed a strange misbehaviour relating to the key activated central locking about 6 months or so ago.

Periodically, it would require a second press on the key button to lock/unlock the car. Sometimes (rarely) would not work at all. This got progressively worse, and more annoying, over that time until about 2 weeks ago, when my key stopped working most of the time. Had to lock/unlock the car using the physical key/lock and the internal car lock/unlock button.

[EDIT] Interestingly, it almost always worked fine in the afternoons, just not first thing in the morning, progressively worsening. I realise now that this was due to the battery becoming slightly warmer, and therefore having a slightly higher nominal voltage ... [end edit]

Visions of a new central locking unit and $$$ ... :(

Pinched my wife's key, and all was good again. Worked perfectly!

Pulled both keys apart, and measured the battery voltages. My key was 2.997V; wife's was 3.064V. Both no load voltage, so less than 0.1V difference between them.

Bought a couple of new 1620 batteries. Measured them. No load voltage is 3.315V for each new cell.

Changed both batteries (as ten y.o.) and all is sweet again :biggrin: :cool:.

What really surprised me is the extremely fine operate/not operate tolerance between the two exhausted batteries.
 
Last edited:
You bet - a common problem! Further discussion here: https://www.offroadsubarus.com/showthread.php?t=5493

I've found the Panasonic batteries are good


Also long story short: I couldn't open my doors after skiing at Perisher a few years ago; had to use the door key and set the alarm off. Had a flashing alarm light all the way down into Jindabyne where, once warmed up, the car gave a couple of beeps accompanied by light flashes and all reset to normal.
 
Thanks, Kevin. I've tagged the older thread with all the same tags as this one.

The replacement batteries I bought are Maxell, with an expiry date of 2020.

I just measured some dry cell batteries that had an expiry date of 2000. One was leaking; both were over nominal voltage still! Not bad going ...
 
Lithium cell open-circuit voltages don't tend to drop much (as you've measured) as they discharge.

It probably drooped a whole more when you pressed the button and drew some current.
 
For certain, Duncan.

Same with all batteries IME. A fairly dead car battery that measures a no load voltage of 12.3V may well drop through the floor when trying to start the car!
 
Back
Top