Is my logic correct?

[pappaecho]

I had 2 solar panels on the boat. A large one which connects to the battery banks via a charge controller.

I had a small 15 watt second panel which was used in the winter to drive 3 x 12 volt fans for ventilating the cabins. That second panel got trashed in the winter gales.

The second system had no controller, and worked if there was enough solar gain to drive the fans.

If I was to connect these fans to the big panel, between the panel and the charge controller, then when there is a solar gain the fans will work, but I assume that the blocking diode in the charge controller will stop the batteries driving the fans in darkness?

Is this logic correct?

 

[lpdsn]

What voltage do the panels output?

Can the fans take it?

Do you rely on the solar panel to charge batteries? In other words is there a problem if the fans take the output?

 

[CaptainBob]

If you connect the fans across the solar panel outputs they're potentially going to see high teens, possibly 20s of volts at times, and potentially oodles of power available.

You could wire up a simple relay to turn on the fan circuit when there's voltage/current from the panel. Would cost pennies from Maplin. And then the fans would always have ~12V sent to them, only when the panels are producing.

 

[Hadenough]

Why not power them off the battery banks direct???

 

[macnorton]

Why not power them off the battery banks direct???

Via a caravan charge relay, then they would be secondary to the batteries.