Remote Battery getting exhausted

Probably not a good test. The car will complain if it can't "hear" a FOB close by.

 

but it will keep running.

 

Trying to think this thru, but you could keep key fob away from car or turn off SKS system to see if batt drain is just something happening to your Fob even when it is "OFF"

The analogy to my iphone is I tried to turn it off to see if batt was draining when off. Only to find out I could not turn it off permanently, it just came back on later. This finally allowed me to Google the issue was short due to lint or malfunction in the charging port. Opps Gen3 I don't think SKS has off setting?

 

maybe in the menu.

 

The drain I experienced was a parasitic drain, but just on one fob.
The other fob didn't exhibit the drain.

 

wouldn't hurt to test the 12 volt, not sure i'd just change it out without testing.

 

I am just sayin anything conductive that bridges the black line in below pic will short out battery. If I am making a homemade button battery holder, sometimes I will place some electric tape over the gaps to prevent short.

 

great, but it makes no sense, since you tested the battery out of the fob.

 

Conductive pocket lint.

Bill the Engineer

 

Ahh, yes CPL. I think that is a real thing... isn't ? lol

 

The Gen II operate at 315 Mhz
Some decoding info here:
Prius Key Fob Study

 

Hmm, interesting. That is also the frequency that most garage door openers operate at. But it sounds like a good cleaning was all that it needed.

 

thanks for the tip on the cleaning part. i have a smart key with shrinking battery life. the first battery lasted 4 years, second 9 months, and third is failing after 3 months already.

 

update, the "old" battery was 3V. too low for it to work. New is over 3.3V. the inside of the fob was clean, but i wiped it with alcohol. i noticed that the new battery has instructions to "wipe" the cell before installation. i did that with alcohol too and tried to avoid touching it with fingers while putting it in. will report back how long it lasts this time.

 

update 2: not even a month later, problems again. sometimes the fob is completely dead but works when i wiggle/twist the plastic body.
next step: i'll check for dry/cracked solder. anything else to check for?

 

When I had problems with my fob the Toyota service rep said they often have to bend the contacts to put more tension on the battery edge. Did you check the voltage on the recently replaced battery? As noted in my earlier post I ended up getting a new fob since mine was consistently draining batteries quickly.

 

it's in my post: the "old" battery was 3V.

update 3:
i couldn't find any dry joint, but it's difficult to see anything in those SMD. i bent the battery contacts slightly and greased them with dielectric grease. so far, dielectric grease fixed all kinds of bad connection issues for me. maybe it will work this time.

i also practiced the mechanical key. the door closing action is fine, but opening is a bit hard and not smooth. i greased the blade but no help. i guess it's not meant to use often.

 

I will agree that cold solder joints are difficult to detect. You have to get up close and personal. Would recommend a 2X/3X magnifying head visor. Radio Shack has a good one. Since you can't take the SMD out of the circuit easily, just use a small pick to flex the joint while carefully observing. The usual spot for a break will be between the solder bead and the printed circuit trace or sometimes a lead and the solder bead. If I can't find it this way and the problem persists, then I will carefully re-melt each junction with a 14W grounded soldering iron.