[SolarCharger] Wrong data type for battery_voltage and battery_charger_current.

[DaveDavenport]

Describe the bug

I am getting weird very high Currents back when the battery charging number becomes negative.

To Reproduce

Connect to a smartsolar, make sure load is higher then solar input.

Expected behavior

A negative battery charging current

Screenshots

Integrating it in a mqtt bridge. no screenshot.

Desktop (please complete the following information):

• OS: linux popos 22.04
• a5144f7

In solar_charger.py change Int16ul to Int16sl for battery_voltage and battery_charging_current to fix it.

[DaveDavenport]

Confirmed using documentation provided in #17

[DaveDavenport]

Thanks!