My apologies for a very late arrival which may have been mentioned:
My Beltone, and others I discovered during my search for a very thorny issue, offers backup-power rechargers.
That is, they’ll go several days’ worth of charging without mains connection. In the case of the Beltone unit, you can get 3 days’ recharges from a recharged base.
That doesn’t address masochists who have their aids in, with high power drains, for 20 hours a day, as to recharge would still involve putting the aids in the charger (30 minutes to fully charge in the case of the Beltones). But I’ve had, in my two years of my Beltone Imagine 17s, only a single instance of running out of juice on an extremely long day, and that was only one ear.
So, this is really about the concern for power failure at the mains. Another hack would be the 10-20kmAH portable batteries used with cell phones; my Beltone unit uses a USB-C input. I have (though I’ve not used it to that end) a 12000mAH brick which has both USB-A and -C ports. The -C is both charge or dispensary port; the -A is power-out only. But that’s just my particular brick. They all do about the same.
So, e.g., if you were away from the grid, that could be your backup - use the battery-powered recharger for a couple of days, and recharge it via your brick (typical US $20-25).
As for myself, for the rest of my life, I’ll never replace my aids with ones using disposable batteries, nor rechargeable replacements. BUT - that is a possibility for the OP; get a rechargeable set (well, two) and a recharger (and maybe a brick for the long-term-away-from-mains), and carry a recharged set with you (instead of packages of disposables)…
Hope that’s useful 
L8R
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