I have 2 85 watt panels and a wind generator. Solar positive goes to an on~off switch and then joins the positive wire of the wind generator. These wires go to one side of an ammeter and then onwards.

The panels are putting out 17~20 volts measured at the in side of the switch. When I turn on the switch and test voltage at the in side of the ammeter it reads 13.25 which is the present battery charge

Not sure what is going on. The 13.25 reads all the way back to the solar panels.
Rather than display ignorance I'd appreciate any explanations.