Multiple battery management

A card reader, comprising:

• a read head within a slot of the card reader, the slot to receive a financial transaction card during a financial transaction between a plurality of entities, the read head configured to read data that is stored on the financial transaction card and generate a signal indicative of the data that is stored on the financial transaction card;
• backup electronic circuitry other than the read head, the backup electronic circuitry configured to provide at least one backup operation;
• a first battery that is electrically coupled to a control line of an electronic switch, the first battery configured to provide power to at least one of the read head or the backup electronic circuitry when the electronic switch is in a first state, wherein a drop in voltage at the control line of the electronic switch from the first battery causes the electronic switch to change from the first state to a second state;
• a second battery configured to provide backup power to the backup electronic circuitry through the electronic switch when the electronic switch is in the second state;
• and
• the electronic switch, wherein the electronic switch is configured to:
• operate in the first state to electrically isolate the second battery from at least the backup electronic circuitry, wherein the first battery provides power to the read head and the backup electronic circuitry when the electronic switch is in the first state, and
• operate in the second state, wherein, the second battery provides power to the backup electronic circuitry through the electronic switch when the electronic switch is in the second state.

A method, comprising:

• activating a card reader, the card reader including a read head within a slot of the card reader, the slot to receive a financial transaction card during a financial transaction between a plurality of entities, the read head configured to read data that is stored on the financial transaction card and generate a signal indicative of the data that is stored on the financial transaction card;
• determining that a voltage of a first battery exceeds a predetermined threshold voltage, wherein the predetermined threshold voltage is greater than zero;
• operating an electronic switch in a first state, wherein operation of the electronic switch in the first state electrically isolates a second battery from at least the read head and backup electronic circuitry other than the read head;
• providing power to the read head and the backup electronic circuitry from the first battery while operating the electronic switch in the first state;
• determining that the voltage of the first battery no longer exceeds the predetermined threshold voltage;
• causing a non-linear drop in power provided from the first battery in response to determining that the voltage of the first battery no longer exceeds the predetermined threshold voltage;
• receiving the non-linear drop in power provided from the first battery at a control line of the electronic switch;
• and
• operating the electronic switch in a second state in response to receipt of the non-linear drop in power provided from the first battery at the control line of the electronic switch, wherein operation of the electronic switch in the second state causes the second battery to provide backup power to the backup electronic circuitry through the electronic switch.