Wiring 24 volt vent fan to midniggt clasic 150

jallen

Recently upgraded to better system and am wondering how to wire a a 24v vent fan to the aux ports as they only put out 12 volts according to the manual. Fan calls for a 5 amp fuse so is this the way to go?

boB

You may need to add a relay to switch the 24V vent fan from the 12V Auxiliary output.  Is your battery bank 24V DC ?  That would be nice because the fan could simply run from that battery through the relay contact.  You can get relays a lot of places.  Make sure that the relay contacts are rated for the current draw of your 24V fan of course and that the coil of the relay is not much more than 100 milli-amps...  The maximum Classic Aux output current is 200 milli-amps but usually these relays can be around 100 mA or less at 12V.  You could also use a DC solid state relay (SSR) but contact type is probably just as good.  I'd try www.digikey.com  or mouser.com or something like that.  Could also find  a relay in something you could rip apart (used).
boB

jallen

Thanks. Yes, the whole system is 24vdc. It's a Shame I could re wire an entire house and pv system but can't figue this out. So would you run your fan hot lead to battery and negative to aux port 1? Does the ground on classic 150 shut down with settings (high,low,etc)

vtmaps

jallen said:

So would you run your fan hot lead to battery and negative to aux port 1?

No.  You connect the aux port output to the coil of a 12 volt relay (as boB explained).  The contacts on the relay are the switch for the fan (which is powered by the battery).   Don't forget to put a fuse or circuit breaker between the battery and the relay contacts.

--vtMaps

Raj174

Hi jallen,

The Classics aux port 1 acts like a switch turning the fan on and off as the batteries reach the specified voltage setting in the classic aux port program.  The relay you choose needs a 12 volt coil that draws less than 200 milliamps as boB said. The contact side of the relay needs to be able to carry the amperage draw of the vent fan at 24 volts.

In the wiring diagram below substitute the classic 150 aux port 1 connection in place of switch SW1.

 

jallen

Thanks. I'll pick up a relay ang give her a try.

jallen

Would negative running off relay go to battery bank because running off aux port, relay isn't kicking on

SolarMusher

No, this negative on relay is to be connected to the 12V aux1 neg into your classic.
Vent fan negative is to be connected directly to the battery negative post or bus.
A+
Erik

boB

On  Aux 1, you have to make sure that those 2 jumpers are in the correct position.  One position, Aux 1 is a small current dry contact.  The other position allows the terminals to put out 12V or 0 volts.  Actually it's more  like 14 volts.  Anyway, if those two jumpers are in the wrong position, your external relay won't pull in  or click

jallen

Got it, finally. The classics jumpers were in wrong. We'll see in the morning how it works. Wired it just like you guys said. Didn't work till i switched the jumpers around. Input on a good voltage to kick fan on at. I have her at 26.2vdc as the banks holding pretty steady overnight at 25.4. Should I be higher or less?

SolarMusher

26.2/26.4V is ok for start and stop.
Sorry boB, I missed the jumper New FW soon?
A+
Erik