Method of charging a battery and a system having a dental light irradiation device and a battery charging device

1. A method of charging a battery of a dental light irradiation device, comprising the steps of:

(a) powering the battery at a first charging current I 1 and simultaneously at least temporarily measuring a first terminal voltage U 1 of the battery;

(b) powering the battery at a different second charging current I 2 and simultaneously at least temporarily measuring a second terminal voltage U 2 of the battery;

(c) calculating a battery source voltage U BAT based on the formula:

U

B

⁢

A

⁢

T

=

U

1

·

I

2

-

U

2

·

I

1

I

2

-

I

1

 and

(d) repeating steps (a) to (c) while the battery source voltage U BAT is below a predetermined threshold voltage, and powering off the battery as soon as the battery source voltage U BAT reaches or exceeds the threshold voltage.

2. The method of claim 1 , wherein the steps (a) and (b) are performed alternately.

3. The method of claim 1 , wherein the steps (a) and (b) are performed for a duration of at least 1 second.

4. The method of claim 1 , wherein the steps (a) and (b) comprise limiting the first charging current I 1 to a maximum first charging current I 1max and limiting the second charging current I 2 to a different maximum second charging current I 2max .

5. The method of claim 4 , wherein the battery is based on one Lithium-ion cell with the maximum first and second charging current I 1max , I 2max being each within a range of 500 mA to 2000 mA.

6. The method of claim 5 , wherein the battery is based on one Lithium-ion cell and wherein the threshold voltage is within a range of 4.15 V and 4.25 V.

7. A system comprising a battery charging device being configured for performing the method of claim 1 , and a dental light irradiation device, the system comprising a battery for powering the dental light irradiation device, wherein the dental light irradiation device comprises a polymerization light source for emitting visible blue light.

8. The system of claim 7 , wherein the battery charging device comprises a constant current source for powering the battery at a first charging current I 1 or, alternatively, at a different second charging current I 2 .

9. The system of claim 8 , wherein the constant current source is electrically switchable between the first charging current I 1 and the second charging current I 2 .

10. The system of claim 7 , further comprising a voltage measurement circuit for measuring a terminal voltage of the battery.

11. The system of claim 7 , wherein the battery charging device is integrated within the dental light irradiation device.