A hybrid battery power source for implantable medical use provides relatively
stable
resistance during discharge and avoids the voltage delays that develop as a result
of variable resistance increase in Li/SVO cells. The hybrid battery power source
utilizes two batteries or cells, one being a primary battery of relatively high
energy density and the other being a rechargeable secondary battery of low relatively
stable internal resistance. The primary and secondary batteries are connected in
a parallel arrangement, preferably via an intermediate voltage boost circuit having
an inductor and a pulse generating control circuit therein. The energy storage
capacitors of the medical device in which the hybrid battery power source is situated
are driven in whole or substantial part by the secondary battery. The primary battery
is used to as an energy source for recharging the secondary battery. By arranging
the two batteries in parallel, with one serving as a primary battery and the other
as a rechargeable secondary battery, all the benefits of the defibrillatory impulse
will be obtained and the deficiencies arising from variable voltage delay found
in prior art implantable power sources will not be present.
