Key battery

[Hpaul]

How long should the key fob Battery for a Prius normally last?

[Ancient Nerd]

You should be ok for around two years, or a bit more.

However, I always keep a spare in the glove box. They cost very little from Amazon or eBay, but much, much more from your friendly dealer.

[alan333]

The keyless entry keys use the Battery more since they're always 'looking for' something to connect to. Except they go into idle mode after a week or something. 

[RunningInPleasePass]

I think the Battery is replaced as part of the full dealer service, after 2 years or 20k miles.

[Joseph D]

22 minutes ago, RunningInPleasePass said:

I think the battery is replaced as part of the full dealer service, after 2 years or 20k miles.

Although it is on the schedule they don't often do it as it is a consumable, so they need your approval to do the Battery change. The price they charge is bit eye-watering, considering it is a user replaceable process and you can pick up good quality button batteries from many mainstream outlets for much cheaper. It only takes about 10-15 min to do the swap.

[Duffryn]

The car will detect and 'tell' you when the key Battery needs changing, so best to just make sure you alternate use of both fobs inside the car to ensure both are kept serviceable.

[Ancient Nerd]

57 minutes ago, Duffryn said:

The car will detect and 'tell' you when the key battery needs changing, so best to just make sure you alternate use of both fobs inside the car to ensure both are kept serviceable.

When you get the warning, change it quickly. I forgot once, and ended up changing the batteri in the car with the alarm going off. Embarrassing and extremely unpleasant.

IIRC, the Gen 3 key had a bigger Battery than the Gen 2. So the Battery life wasn't a lot shorter.

[PeteB]

Starting the Hybrid system will stop the alarm.

You can do this with a 'dead' key (before changing the battery) by holding the key close to the Start button while you press it.  A sensor reads the security chip directly without the key needing to be transmitting.

[kithmo]

13 hours ago, alan333 said:

The keyless entry keys use the battery more since they're always 'looking for' something to connect to. Except they go into idle mode after a week or something. 

I think you've got it the wrong way round there Alan, it's the car that looks for the key. Once the key loses the car signal, which is about 6 feet away, the key will be inactive.

Using the remote buttons on the fob uses the Battery up more, if you always use smart entry the key fob is good for two to three years.

[DMGbus]

The key fob Battery for my Plug In Prius needed replacing at 3 years 3 months old.  I don't recall seeing a Battery replacement showing on the dealer invoice for the second year service.    In my case the Battery was difficult to source locally so was bought from Amazon @ £2.35 for a pack of two Panasonic CR1632.

[Heidfirst]

4 hours ago, kithmo said:

I think you've got it the wrong way round there Alan, it's the car that looks for the key. Once the key loses the car signal, which is about 6 feet away, the key will be inactive.

Using the remote buttons on the fob uses the battery up more, if you always use smart entry the key fob is good for two to three years.

certainly not on my Avensis. Car was serviced at start of August 15 (at which time they replaced the fob Battery as had been dead for a while) & in the last few days the car is now telling me that the key Battery is getting low -  that is under 9 months & probably similar to the previous one before it had died.

[kithmo]

I was referring to the Prius, I changed my Gen 3 fob Battery at 2 years old as a matter of course, not because it told me to as at the time I didn't know it would and was under the impression they lasted two years. I left the Prius+ fob Battery in for three years before changing it, again before it told me to. Maybe it's different with the Avensis. 

[Heidfirst]

There is a big difference between the Battery life of a fob for a car without Touch to Start & keyless entry & one with (like my current). 

[kithmo]

20 hours ago, Heidfirst said:

There is a big difference between the battery life of a fob for a car without Touch to Start & keyless entry & one with (like my current). 

I agree, but would think a car without would not last as long because of the constant keyfob button pressing to open and close the car.

Both my Prius cars mentioned above had keyless entry and start.

[Heidfirst]

not in my experience of an Avensis without keyless entry/start & 1 with - the one without lasted ~2 years on average & the one with is currently averaging ~9 months. So I am with Alan333 (who also had several Avensis).

Because I live in a terraced house the car usually is parked under 30 feet from where the key is when not in use which I do believe is part of the issue.

[kithmo]

It's got to be an Avensis thing, my cars were parked on my drive, the key being no more than 20 feet away, I hardly ever use fob buttons. What make of Battery do you use?

I always buy Panasonic.

[Heidfirst]

Or alternatively , it's the Prius which works in a way other than the norm ...

Whatever the dealer fits. It doesn't bother me not having keyless start or touch to start - it's not something that I would specify, indeed I prefer a good old mechanical key. 

[kithmo]

Yeah, weird things these Priuses 

[posing]

What is the Battery type for Gen 4 Prius?

[ian rooke]

Hi the fob Battery is part of the 2 year service my dealer did the change at 2 years and 4 years (I mark the Battery to make sure it is changed )

[posing]

My dealer changed at 2 years but that Battery died a couple weeks later. I got that replaced with a suspicious look that it's a different key. Now 1.5 years later, Battery dead. Just got a pack of 8 batteries for £2. Hope I can open the key up myself.

[Catlover]

8 batteries for £2.  that is 25p each. That seems a cheap, too cheap.  What make were they? Remember the often proved right rule.... buy cheap, buy twice. If you said you bought 2 for £2, that would be more of a good buy.  

[TonyHSD]

Two years on average is normal lifetime, keyless remote uses a lot more energy than standard lock/unlock key. Best way is to have some spare Battery in the car. 

[posing]

My mistake. It was a pack of 6 Panasonic batteries for £2 from Home Bargains store. 

Fitted it after prising the key fob apart. Wasn't too hard, just needed some strength to open it.

[Catlover]

Ok, 6 batteries for £2..... however from my experience Panasonic are not the longest lasting batteries in the world.... so probably expect to change them more frequently. On that basis, best keep a spare in the car somewhere.