Gen2 prius PHV spare key dead

[johalareewi]

Went to use the spare key for my gen2 plugin prius and it was dead. I tested the Battery and it was completely flat.  Fitted a new Battery but the key won't open the prius remotely.

It was working when i got the car.  Does the prius forget the key if it isn't used for some time?

 

[HSDish]

I had Battery problem with our 2018 phv keys but it seemed to bee bad connection between the small melat parts that hold the Battery.

I adjusted/ bendt the smal metalparts a bit and it helped

[johalareewi]

Tweaked the Battery clips but still no joy.

Key fob buttons do nothing.

The SKS system doesn't recognise the key.

But the Start button does recognise the fob when using the "dead fob battery" start method.

 

[Ancient Nerd]

It may be worth getting a new Battery from another source.

I have fitted two new batteries, one after the other, from the same batch, several years old, but well before the expiry date, with just those symptoms. I bought a new batch of batteries, and the key worked fine again.

[Joseph D]

I found that it is really imperative to check the new CR2032 batteries with a voltmeter.  Anything below 2.9 V will give problems and should not be used.  3.3 V - 3.4 V is what you should aim for.

[johalareewi]

The 'new' Battery was 3.1V (the pack is rather old but still in date) so i got another brand new Battery which was 3.3V and key fob is working fine.

Many thanks for the help.