1998 V70 - My battery has been tested and is good, but if the car is left parked for a few days, the battery goes dead. I can recharge and it works as long as I drive regularly. there are no lights on. Any idea how to trace this issue?

You say your battery is good, I would remove a battery, fully charge it, leave out of car overnight and only then if it passes a digital check in the morning would I presume it good.

If the battery is good then you need to get a multimeter and check for current draw. Anything above 30-40ma after the car is locked and went to sleep is excessive. To fault trace then remove fuses one by one till current draw drops below 30-40ma (typically 10ma normal), whatever fuse you pull that drops the amp draw is the circuit with the fault.

Im presuming you know how to use a multimeter, if you dont then you may need to get help to sort this.

I cured a similar problem with my 96 850 by gluing a penny on the glove box door to turn off the light. You might try that. An alternative move might be to remove the lamp. I was never able to measure any high current but the glove box door must warp a little which changes the pressure on the switch. I think cabin temperature has something to do with it.

Good luck.
Tom