Charger with nanocrystalline ferrite choke

1. A battery pack charging system comprising:

a battery pack interface configured to receive a battery pack;

a charging circuit coupled to the battery pack interface and configured to provide charging current to the battery pack interface;

a controller coupled to the charging circuit and configured to control supply of charge current to the battery pack interface;

a power supply circuit coupled to the charging circuit;

a charger housing that houses the charging circuit, the controller, and the power supply circuit;

a filter circuit coupled to the power supply circuit and including a nanocrystalline ferrite common mode choke;

a filter block housing that houses the nanocrystalline ferrite common mode choke;

a power cable that connects the charger housing and the filter block housing; and

an alternating current plug configured to connect the filter circuit to an alternating current power source.

2. The battery pack charging system of claim 1 , further comprising a second nanocrystalline ferrite common mode choke in series with the nanocrystalline ferrite common mode choke.

3. The battery pack charging system of claim 2 , wherein the nanocrystalline ferrite common mode choke is outside a charger housing, and the second nanocrystalline ferrite common mode choke is inside the charger housing.

4. The battery pack charging system of claim 1 , wherein the nanocrystalline ferrite common mode choke is of a toroidal shape.

5. The battery pack charging system of claim 1 , further comprising a housing that houses the charging circuit, the controller, the power supply circuit, and the nanocrystalline ferrite common mode choke.

6. The battery pack charging system of claim 1 , further comprising a differential mode choke pair including a first differential mode choke and a second differential mode choke, wherein the differential mode choke pair is part of the filter circuit.

7. A battery pack charging system comprising:

a battery pack interface configured to receive a battery pack;

a charging circuit coupled to the battery pack interface and configured to provide a charging current to the battery pack interface;

a controller coupled to the charging circuit and configured to control supply of charge current to the battery pack interface;

a power supply circuit coupled to the charging circuit;

a charger housing that houses the charging circuit, the controller, and the power supply circuit;

an alternating current plug configured to connect to an alternating current source;

a filter circuit external to the charger housing and including a nanocrystalline ferrite filter element, the filter circuit configured to connect the power supply circuit to the alternating current plug to provide alternating current power to the power supply circuit;

a filter block housing that houses the filter circuit;

a first power cable that connects the charger housing and the filter block housing; and

a second power cable that connects the filter block housing to the alternating current plug.

8. The battery pack charging system of claim 7 , further comprising a second nanocrystalline ferrite filter element within the charger housing.

9. The battery pack charging system of claim 8 , wherein the second nanocrystalline ferrite filter element is in series with the nanocrystalline ferrite filter element.

10. The battery pack charging system of claim 7 , wherein the nanocrystalline ferrite filter element has a toroidal shape.

11. The battery pack charging system of claim 7 , further including a differential mode choke pair including a first differential mode choke and a second differential mode choke, wherein the differential mode choke pair is part of the filter circuit.

12. A method for charging a battery pack, the method comprising:

receiving, by a battery pack interface of a battery pack charger, a battery pack;

receiving, via a power cable, alternating current power at a power supply of the battery pack charger;

converting, by the power supply, the alternating current power to a direct current power;

controlling, by an electronic controller, a supply of charge current to the battery pack interface to charge the battery pack;

receiving extraneous signals on the power cable;

filtering, by a nanocrystalline ferrite toroidal choke, the extraneous signals on the power cable; and

housing, within a filter block housing separate from a charger housing, the nanocrystalline ferrite toroidal choke and the at least one differential mode choke.

13. The method of claim 12 , wherein the nanocrystalline ferrite toroidal choke is a common mode choke.

14. The method of claim 12 , further comprising:

filtering, by at least one differential mode choke, the extraneous signals on the power cable.

15. The method of claim 12 , wherein filtering the extraneous signals on the power cable includes:

filtering, via a first nanocrystalline ferrite toroidal choke configured to filter signals at a first frequency, the extraneous signals on the power cable, and

filtering, via a second nanocrystalline toroidal choke configured to filter signals at a second frequency, the extraneous signals on the power cable.

16. The method of claim 12 , wherein receiving alternating current power at the power supply of the battery charger includes:

receiving the alternating current power at an alternating current plug; and

providing the alternating current power from the alternating current plug to the power supply via the nanocrystalline ferrite toroidal choke and at least one differential mode choke.