Is this AC adapter correct for my DC fan?

nyoffgrid
nyoffgrid Registered Users, Users Awaiting Email Confirmation Posts: 18 ✭✭
in Solar Beginners Corner #1
I bought this cheap AC to 12V DC adapter to use with my fan in winter. Can someone confirm the adapter is properly sized? 

This is the adapter: https://www.amazon.com/dp/B0CKYRBRWM?psc=1&ref=ppx_yo2ov_dt_b_product_details

This is the fan: https://www.amazon.com/dp/B0955WB2KL?ref=ppx_yo2ov_dt_b_product_details&th=1

And another question: What size circuit breaker for my 100 watt solar panel? 

this is what I bought: https://www.amazon.com/gp/product/B0B55Q8KYQ/
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Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #2
    I did not find a lot about the fan with a quick search... It looks like a 12 VDC stable power supply should work fine (runs at "full RPM"). Quiet and reliable.

    "Down side" is it appears to be designed for "low back pressure" applications--If that is how you wish to use it, that fine. If you have a long duct, filter, etc. that increases back pressure, it will not move much air.

    For the solar panel... Its Isc (short circuit current) is ~5.9 Amps... I would multiply by 1.25x to prevent "false trips" of breakers/fuses (in North America, typical fuses and breakers are "guaranteed" to not trip below 80% Current, and trip >100% of rated Currenrt--could take minutes to hours to "never" at 100% current, not that accurate). 1/0.8 = 1.25 (value for derating):

    5.9 amps * 1.25 = 7.4 amps rounded up to ~10 amps.

    Did not find a detailed spec sheet--Which usually lists that "Series Protection Fuse" value... So the 10 amps is my "guess".

    Note you only need series fuses/breakers for solar panels when (typically) 3 or more panels/strings are connected in parallel (multiple strings array). Breaker/switch is nice when servicing the solar power system (always connect Vbatt to controller first, and solar panels 2nd--And disconnect/turn off solar panel power first, then 2nd disconnect battery bank).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • nyoffgrid
    nyoffgrid Registered Users, Users Awaiting Email Confirmation Posts: 18 ✭✭
    #3
    Thank you Bill. Current run for fan is 3ft but I will want to extend to 12ft... I will test to see how bad it is. I have a fan gauge to test CFM. 

    I know that I do not need a break for this panel - I want it to be able to "switch off" the panel in winter and not have it charge battery and destroy it. it is just the toilet fan battery. In winter I will have the fan run of ac power and let everything freeze when we are away = no smell. 

    If you think I am better off with a 12v DC on/off switch vs this break - then let me know and I will do that instead. 
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #4
    This fan draws around 0.1 amps... So just about any switch will work. Either switch or breaker will work fine...

    The solar panel is just under 6 amps or so... You want to make sure you have a DC rated switch for >6 amps. 12 VDC is not "that difficult" to switch, but DC in general "arcs" more than AC current so you need a DC rated switch.

    Sustained Arcing starts around 12 VDC... The panel runs around 17.5 VDC, so "need" DC rated 24 VDC (or greater) for the panel switch. 24 VDC makes a very nice arc welder (the quick and dirty arc welder is 2x 12 volt car batteries in series).

    Not that this really applies to your system (at this time), just a nice example of AC vs DC switching for higher voltages:

    https://www.youtube.com/watch?v=Zez2r1RPpWY

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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