2011 Prius smart key (FOB) is not funational after replacing battery

I've replaced the battery on mine twice, and the second time it occurred to me how vulnerable the printed circuits appeared, when you're flexing the battery outa the retainer claws. Pricey item with a weak link. In your shoes, I'd just bring it in, see what they say. Maybe don't volunteer that you JUST changed the battery.

The OTHER possibility: the battery is a dud. Check, should be around 3.0 volt with digital multimeter.

 

That's a new question, very likely needing dealership intervention, unless you're a mini-VCI guru. Hopefully a gratis diagnosis/fix.

Simply replacing the battery shouldn't mess up the car/fob connection. Why did you replace battery, was the car warning of low battery? Our's did, last time I needed to replace battery.

Also, 2.4 volt is really low. Our bad battery read 2.9, and brand new read 3.0. After seeing that I put the OLD one back in, but a week later the car was again warning of low battery, so I caved and swapped them, warning went away.

 

is it just sks, or are the fob buttons not working as well? you're not putting the battery in backwards?

 

okay, so you're saying just the sks not functioning. do you have to hold the fob up to the power button to start it?my batteries last 4-6 years, so it might be a case of low voltage when new.also, you're 12 volt battery plays a part in this.

 

I would definitely try another battery. 2.4V is too low and could very well be your problem.

 

i think that's your problem. the battery that only lasted 1.5 months probably didn't start at 3volts either. maybe try a different source? also, if you do have a problem with short life, read up on where to not leave your keys.

 

Check the new battery package, if you still have it, for expiry date. If it's old that's ammo for getting another for free or refund.

 

whew, that was a long circuitous route to a 3v battery.

 

I remember reading something about taking care as to where you store your SmartKey fobs (on another thread here on PriusChat), away from metal objects (keys etc.) and other electronic devices and each other - it seems that the SmartKey fobs are continually trying to communicate with the system on your car, like a "heart-beat" and if you store two of them too close together they will both flatten their batteries quicker as they compete for the signal. I think there was also mention about other devices (TV remotes, mobile-phones, pagers) - Search is your friend! - Wil

 

Feb. 2015
We have had battery problems with both of our smart keys from our 2011 Prius. We need to replace the battery in BOTH 2011 smart keys every other month in BOTH for the past 14 months. The dealership has only generic replacement batteries and has checked the programming, synch with the car, the smart key buttons and only thing it has required is a new battery for the smart keys. We were told we cannot keep smart keys on a key chain with our 2007 Prius key. We received a print out of the "official" Toyota policy stating that all smart keys need to be 2 meters from anything metal or electronic.

I would think this could be possible EXCEPT that both smart keys have been on the same key chains with the 2007 Prius keys since 2011 and this problem only began 14 months ago Dec. 2013.

So the keys all lived together for 2 years successfully and suddenly this is no longer the case?? I read on some other Prius/Toyota discussion boards that Energizer replacement batteries may work better since that is the original battery in the keys and the original batteries lasted more than 2 years.

I got to thinking...what happened in Nov-Dec 2013 that could have changed our keys? We both got new iPhones (3G & 5). I believe the iPhones - magnetism or radio-waves or whatever? - are interfering with the generic replacement battery life span.

New plan for trying not to replace batteries every other month for the next 15 years while we own these cars. Well, we are keeping the 2011 smart keys in our bag and not on the key chain and looking into Energizer replacement batteries. Any other suggestions to help us? Please advise.

 

I've no brilliant suggestions, but will say the brand of battery shouldn't make much difference. No one brand of the same type and size cell is likely to contain significantly more energy than other brands in good condition, since that's limited by the chemistry and physical size.

Good luck with your "new plan"!