Li-ion Battery. Memory or not.

[NicholasG]

I just replaced my old Seiko kinetic capacitor with the  new Li-ion type. Some say “use it or lose it” because of memory issues. Others say the Li-ion has no memory, you can let the watch’s capacitor completely run down with no ill effects, when restarted the capacitor will still have the ability to retain a full charge. What’s the real story. 

[canthus]

Just been messing about with Li-ion batteries in mobile phones, which may be relevant to the seiko battery.  I have concluded that it is advised not to let them run down to zero as they can stop working and need a kick start to get going again (doesn't always work). Some say a long trickle charge will also do the job (again doesn't always work).  I gather there is a minimum voltage they can go down to before this happens.  It also appears that they do not have memory but need to be 'conditioned' when newly fitted, by going through 4 or 5 charge cycles from different discharged levels (ie 20%, 15%, 10% &, 50%).  The number of charging cycles does not seem to matter as much as with NiCad etc.  Once conditioned I gather it is best to recharge from 20-40% levels. 

Not sure how this pans out with a watch, but it may be best to wear (or put on winding machine) regularly.  I know it takes a lot of winding for a seiko Li-ion cell to charge (may times longer than the old capacitor).  Maybe this could be considered as a long trickle charge when being worn etc.

[JohnR725]

13 hours ago, NicholasG said:

Others say the Li-ion has no memory, you can let the watch’s capacitor completely run down with no ill effects, when restarted the capacitor will still have the ability to retain a full charge.

I'd like that that would imply the battery will last forever? Then you do have to be careful in that the original was a capacitor and the new is a battery. Even though everywhere you go they'll still use the word capacitor.

 I'm attaching the technical sheet for one of the more common batteries used in the watches. Unfortunately doesn't really say what happens if you drop the voltage to zero as to whether it's going to recover not but you'll notice in all their curves they don't actually take at the zero either.

 

TC920S_DataSheet_16e watch battery.pdf

[NicholasG]

5 minutes ago, JohnR725 said:

I'm attaching the technical sheet for one of the more common batteries used in the watches. Unfortunately doesn't really say what happens if you drop the voltage to zero as to whether it's going to recover not but you'll notice in all their curves they don't actually take at the zero either.

Thanks so much.