The pacemaker is powered by a battery with the lifetime of about 8 yrs, for that usually used lithium batteries, to several dozen yrs to the nuclear batteries. Since the pacemaker is usually a disposable and implantable gadget, the conserving of battery Power is crucial for that lifetime extension. The https://tedomarket.com/product/computers-and-network/power-bank/battery-capacity/9001-10000mah/blitzwolf-bw-p3-original-universal-10000mah-18w-qc3-0-quick-phone-charger-3-0-dual-usb-port-power-bank-external-battery/