Smart Keys!

[MrGrumpy]

Latest events in my ongoing hassle with my smart key...
Went to a local dealer today. They tested the current battery I have in the key, the original one I had in until December, and the first brand new replacement I put in. They declared that they were all below par. They were close to or just on the nominal 3V, but they said, that they should really measure something like 3.4V. So they've supplied yet another battery - and brand brand new battery, best before 2034, so we shall see what happens after a day or so!

[Andym]

Interesting.

Sorry if you've mentioned it above, but what's the battery size? CR232 or something?

What brand did they supply? I assume they tested with a multimeter on a battery out of the fob including the new one?

I'm still thinking knock-offs and/or supermarket supply chains not being the best, but am also wondering if they let the R&D department set warning light parameters. Imagine if the charging light in your car flashed everytime the starter battery wasn't between 12.51 and 13.21 Volts, reality being it'll stand a lot between 11.9 and 14.9.

Andy

[MrGrumpy]

The battery is a CR2025 - very similar to the more common CR2032 (possibly slightly thinner). They did test the previous batteries with a multimeter out of the fob.
They buy their batteries from a shop next door, so they bought one and put it in (didn't test it AFAIK). Not sure what brand it was - they seem to buy all their batteries from this particular shop (a car spares shop).

The previous batteries I was using were from a pack of Energizers, probably bought in Tesco, 'Best Before Mar 2030'. Whilst I also have another pack (as yet unopened) which are BB 2034 - as is the one the shop put in.
I will see in a couple of days if this new battery actually solves the problem - it may not!

It wasn't as if the previous batteries were way down - there were all very close to 3V, which is their nominal voltage. There again, it seems that scoots are (over?) sensitive - I did try a Duracell one at some point, and it didn't wake the scoot at all!

[Andym]

Energizer give a nominal closed circuit voltage new as 3V



An open circuit voltage (multimeter) might be 7% higher, so 3.2V

Not much leeway even in their own numbers?

3V on the bench is roughly 2.86V plugged in, so like battery after 700 test hours and about to drop off the cliff.

Andy

[MrGrumpy]

Well, the good news from this saga is that the new new battery in the smart key sold to me by the local dealer is continuing to work fine, and the Tmax hasn't complained that the key battery is flat for nearly a week now! This is progress! It would appear that shelf life of even Energizer batteries is critical - and that ones that are BBE 2030 aren't good enough! Its all a bit odd - I never had this trouble with any previous batteries!

[roadster]

Energizer give a nominal closed circuit voltage new as 3V



An open circuit voltage (multimeter) might be 7% higher, so 3.2V

Not much leeway even in their own numbers?

3V on the bench is roughly 2.86V plugged in, so like battery after 700 test hours and about to drop off the cliff.

Andy

These batteries work at such low current drain ( 0.193 mA on the interesting graph in your post) that testing them with a typical voltmeter is almost impossible unless it is done in the working circuit. Also given that cheap multimeters are not necessarily that accurate its only possible to use a relative reading to compare batteries both when new and after problems crop up. It is also important to always measure at the same temperature because the ( Lithium ion?) chemistry is temperature sensitive.

[Urbanfireblade]

Duracell have a bitterant coating to stop kids eating them like they're sweets or something. Likely this coating prevented the contacts from making a connection. Just use some isopropyl cleaner to remove it and the duracell battery should work. Apple air tags are another electronic item that don't like the Duracell bitterant coating, well discussed on the apple forum that one!