I have had one for a year now and it's working fine.  I have not had an
occasion to let the battery carry it for an extended time--for several
reasons-- 1 of which, some batteries are damaged by total discharge. I
have rolled airplane on several occasions and it has never tumbled nor
given an erroneous indication.  I think it's a better security blanket
than the handle in the overhead which deploys a chute.