Solution's for a Seiko 9T82 that doesn't hold its charge.
The problem with these watches is that they are usually only worn for best, therefore the Cell (rechargeable battery) is only partly charged and may have deteriorated sufficiently that it will not hold its charge. These Cells must always be kept above 40% charged.
The original Cell is right in the centre of the watch, so the movement would have to be completely stripped down to replace it.
As it is a very complex movement with over 300 components and as Seiko will not supply any parts including the Cell, it has to go back to the factory in Japan to be repaired as no one else can repair it.
The cost in December 2018 was £429 for a service at Seiko
This is a copy of the Seiko Australia price list 1-4-2013 cost $909.55 Price List
Send it to Seiko who will forward it to Japan. When you receive it back keep it fully charged on a watch charging machine, otherwise it will deteriorate again in 6 years.
Solution 2 Just buy a Charging machine and keep your watch fully charged, so that the cell will not deteriorate any further.