Smart Key not working

Next I would check voltage of the fob battery. 3.3v is fine, 3v is too low. Also use only fresh brand name batteries that are known not to be fake (everyready is commonly fake).

 

Just a thought... How far away from the car do you keep both key fobs? If either are less than 10 feet away, the car might always be "on," sort of. This scenario would drain both the fobs and the 12 volt. This happened to a someone at work with all the batteries always dying too soon. He bought the car used with only one fob. I told him about what would happen if the fobs were kept too close. The next day he found the other fob -- in the glove box! The car had always been in alert mode. For a year.

Oh, and the 12 volt should be north of 12 volts, when tested.

 

yeah, Energizers and Sony are frequently counterfeited. especially if you buy from amazon or ebay. because of that, i only buy Renata brand (Swiss made) lately.

 

No not dead.....yet.
Those numbers are not good.
They indicate a failing battery.
Might last another year but maybe only a few weeks too.
How old did you say the battery IS again please ?

 

disagree.
he tested it once, discharged it some, especially if driver door was opened first and brakes pressurized.
then the battery sat overnight without charging and was discharged some more during the second test, especially if driver door was opened again.
his numbers look reasonable for that scenario.
why don't you duplicate that routine and report back with your own numbers?

BTW, his battery age was stated before.

 

You can disagree all you want but the total drain from opening the door really isn't a lot and if the battery goes down to 12.4 and stays there, it indicates that the battery is a bit weak.......whether you believe it or not.

A totally healthy and fully charged battery should start out about 12.8 and a couple of door openings might take it down to 12.4 momentarily but it should bounce back to 12.6 or so. When you are using resting voltage as your ONLY measurement, those tenths of a volt can be important.
The older it gets, the more important the tenths become.

 

Where are your numbers to support your opinion?

 

A bit over 50 years as an Electronics Engineering Technician.
Where are your "numbers" ??
(No please don't. These pissing contests are just disruptive.)

 

OK so at the risk of catching flack because this was discussed earlier.........
I still think this could be a case of failing door lock actuators. Your is just about the right age when that starts to show up.
Have you actually watched/listened to the mechanism(s) operating ?? If not, you should.
The car I just traded in got so bad that when trying to unlock it would beep 3 or 4 times instead of just the normal once.

But......trying to separate the grain from the chaff.........That one reading of 8.4 volts is REALLY worrisome. It should NEVER be that low and if it stayed that low for very long the battery might have been damaged some.

 

And I have 120 years experience as a Dean of engineering.

You started the pissing contest.

 

perhaps something afoul in the sks system. have you tried testing the 12v everyday to see if something is draining it?

 

agreed. i guess that would be okay, but battery testing is more complex when it's constantly being charged and discharged.

 

I was going to suggest this as well. I had a similar issue with my car a few months ago where sometimes I could lock it or unlock it with the key fob, but not always. One of the door actuators was dying and when it wouldn't respond, the kep fob would not work (they car would not detect the car locking or unlocking). Actually, to begin with it would lock fine but have issues unlocking. It also gave me a hint in that the car wouldn't beep when I locked/unlocked it. Eventually the lock actuator died (two of them did, actually). Once I replaced them the issue obviously never returned. I will add that my problem began intermittantly so, like the OP, it worked some of the time and not others.

I would suggest that the next time it doesn't work, check all the doors to see if they're completely locking and unlocking.

 

The LV battery should hold it's voltage around 12.7 for at least a few weeks without being used.
You guys are correct in measuring the battery under load. I would try lights and aircon at the same time and test battery.
Also open up the fob any water ingress or cracked coper tracks on the circuit board.
We had a wet fob that was causing issues.