Insteon Door Sensor: Heartbeat Interval

I have some Insteon (Hidden) Door Sensor units installed, firmware versions 43 and 45.

Docs and scattered info online suggests these units should send a heartbeat every 24 hours, but somehow all of my units' hearts are beating every 60-61 minutes. The units already do low-battery reporting via a separate Insteon group command and I'm not really worried about comms-failures or anything, so I really only need a heartbeat once every day or two at most. My battery life on these units has been proven to be somewhat short, plus I have to disassemble and remove them to change batteries, so I'd like to try a longer interval in hopes of increasing battery life.

Anyone know whether it is possible to change the interval in software? I don't see any built-in Indigo menu commands for this, but I was sort hoping I could do a one-time fix with Interfaces>"Execute Raw Insteon Command... " or better still, the equivalent in script form - i.e., a script and do for each unit something like "indigo.insteon.sendRaw(<address>, <magic bytes>)" to set their intervals to longer values?

Anyone done this? The product user manuals don't seem to cover this kind of thing at all.... I assume you need "programmer's docs" or something to know the <magic bytes> part - hoping some other forum users might know the details.

Thanks in advance.