This may not help, but here goes. The V525 was replaced a while back by the V550, and in the words of the manager of a local phone supplier, "it needed to be, as there were so many software issues"! The V550 was not a lot better, I had one for 12 months, before I forced the issue with Vodafone due to regular and repeated problems, and they replaced it with an E770V, and so far, that's not been a lot better.
Bluetooth is "tender" at the best of times.
A few questions. Did your V525 ever get updated software loaded in to it. There's no easy way to update without sending it in to a repair centre, if it's never been updated, then that may be an option that will help, but if it's out of warranty, the charge may be more than it's going to cost to get an upgrade to a newer phone.
From painful experience, the build and software quality of newer phones sucks. I've had more problems in the last 12 months with Motorola phones than I had in the previous 14 years using Sony, Ericcson and Nokia, and prior to this last 12 months, I've never had to get a phone repaired, let alone repaired or replaced 4 times while in warranty. That unfortunately should tell you something about the quality of the newer products, I fear that the newer phones are being designed to be throw away just after the warranty expires, that's certainly the impression I am getting having visited the local repair centre so much in recent months.
If the 525 is similar to the 550, and I am told it is, then there's no timer function as such on the bluetooth. One thought though, there is a power setting for the bluetooth module, and it needs to be set to on, it can be made to work if the connect is off, but that may allow the phone to power off the bluetooth again after a while.
Other than that, the plan you are using is good, test all the combinations with other devices until you've nailed which bit is not performing.
Last thought is that several people have said that to get the best bluetooth performance, it's helpful to have phone and bluetooth from the same manufacturer. It shouldn't make a difference, but experience suggests that it does.