Allow charger voltage of 0

[kurthuwig]

Tesla Model 3 LR AWD reports a voltage if 0 when not plugged in, so it
is not an invalid value.

[lephisto]

I'm not sure if the reported charge value can ever be < 0, i doubt that, so that PR would not make much sense. I will dig into this later this week. Thanks for PR

[kurthuwig]

As the value is actually 0 with my Model 3, it really makes sense as without it, the software just does not work right. And as it is a validity check for voltage, values below 0V are invalid. Still it more looks like an example for a validator than a real check, so you might also remove the check completely.