Victron has a new Battery Monitor called SmartShunt and it seems to do everything that the normal Victron 712 Smart does, but at a much lower cost, but also with a much reduced bluetooth signal strength. Both send data via BT to smartphones for display with the Victron app, but the 712 Smart has a BT range of perhaps 30 feet while the SmartShunt, based on reviews, seems to be limited to perhaps 6 feet, perhaps less if the signal has to pass through a metal enclosure.
When I mentioned this in a thread on another forum someone made the suggestion of using a bluetooth extender so I checked on Amazon, but questions I posted about some of the less expensive extenders got responses that the extenders were designed for headphones, TV audio and speakers and so only worked for voice signals. Of course there were more expensive ones available on Amazon which might work (I don't know) but that raised the question about the wisdom of spending $100 or more for an extender in order to save $75 with the SmartShunt.
Given all of this I thought it was a good idea to ask on this forum, which is concerned with electronics, the basic question - are there any BT extenders which are designed to amplify data (as compared to voice) signals and, if so, which ones are they? Or are all BT extenders blind to the type of signal they are amplifying? The inexpensive ones I have seen for sale use an audio connection to deliver the signal and of course that would not work with data for a smartphone.