Seiko 5M42 Supercapacitor Issue

[S6PNJ]

I bought a second hand Seiko Kinetic SQ50 via FB Marketplace a number of months ago - about 6 from memory. It has a 5M42 mechanism fitted. It needed 'winding' when it was shown to me and the seller just said it hadn't been worn in a while. After getting it home and checking it over etc and 'winding' it for a good amount of time, it was still not showing anything more than 5s of movement when the button was pressed. Know the watch was not all that new, I just assumed it needed a replacement supercapacitor, which was duly bought from a good seller on eBay with lots of sales for the 30235MY supercapacitor.

All was good for about 3 months, though my mechanism only ever showed 20s of sweep for charge status and never the 30s I thought it should show. Then around the 3 month point, I noticed the charge indicator wouldn't go to 20s and only to 10s, then after another day or two, it would only go to 5s and wouldn't hold charge overnight. Thinking I had a dodgy supercapacitor, I tried getting a supercapacitor exchange via the eBay seller but even from the first message, it was obvious that he was having none of it and was doing everything to suggest it was due to a faulty fitment / not being fitted by a jeweller etc etc.

I then went to AliExpress and found a seller with, again, lots of sales of this supercapacitor and bought another one - claiming to be genuine Seiko and coming in the same packaging as the one I bought via eBay. This one, also has only lasted 3 months and has exactly the same symptoms as the first one I bought - no initial 30s charge indication, only 20s etc etc. I'm now (obviously) suspecting the watch rather than 2 dodgy supercapacitors - but what could be causing it? Or what , if anything can I do to try and sort it?

Before anyone suggests it, there is no chance of a refund / return to the FB Marketplace seller as it has been at least 6 months and possibly longer. Other than throwing the watch in the bin, is there anything else I can try? Getting it repaired / checked would probably cost more than something like a new Seiko 5 for example.

[Regbuser]

Have you googled SEIKO 5M42 SUPERCAPACITOR ISSUE ?
Several threads on other forums referring to problems with these.
It appears that if you replace the capacitor, it'll run until that cap is depleted; which could be a sign that the charging circuit/coil is faulty.

[S6PNJ]

I Googled similar if not that exact phrase but didn't see that info. I'll try again unless you have any links you can share?

Seems strange it lasts for 3 months each time, so the charge circuit must work in some way, mustn't it?

[Regbuser]

Links >
https://www.thewatchsite.com/threads/seiko-kinetic...
https://www.watchuseek.com/threads/old-seiko-kinet...
https://alt.horology.narkive.com/qGzONbYW/seiko-ki...

From what I read from the above, when you pop a new capacitor in, it has a charge, but this is depleted over a few months as the charging circuit isn't working properly / if at all.

[S6PNJ]

Fab! Many thanks, I shall have a good read. 👍