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Fan Wiring
#1
Hi All,

Just needed some advice on wiring of fans to cool the new Eddi i installed a week or two back.

Using a 4W, 12V solar Panel - jaycar.com.au/4-watt-12-volt-solar-panels-amorphous/p/ZM9026

Noctua NF B9 REDUX 92mm - noctua.at/en/nf-b9-redux-1600-pwm

Noctua NF R8 REDUX 80mm - noctua.at/en/nf-r8-redux-1800-pwm

My question is what is the best way to wire these fans to the solar panel?

I currently have them both tapping into the solar panel at the same spot (In parallel). If i power them on at the same time both fans spin. However if i let the sun slowly power them up e.g. from sunrise, Only the 80mm fan spins untill i cover the solar panel entirely, let the fans spin down and then power them up.

Should i wire them properly in parallel? or series?

If parallel which fan in the parallel chain first? (does it matter?)
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#2
So that solar panel has spec for voltage which are too high for the fans without a regulator.
The panels max power point (best volts/current to operate at) is 17.5V & 286mA (in perfect conditions when the panel is cold)
When the panel heats up in the sun after maybe 1/2 an hour it'll be a lot less output, maybe 70% of the above.

The fans are motorized devices that draw higher current to get them started & effectively "short out" the panel when the sun comes up gradually.
So the trick is to use a device/circuit called a maximizer that lets the panel get to about say 17V & gives the fans whatever current is available.
This will let the fans start much better.
Google this"solar maximizer circuit"
Eg here: https://www.ledsales.com.au/pdf/Maxi_max...ctions.pdf

But you also need 12V regulator in there because the fans are only rated 12V & 17V will blow them eventually.
A simple 12V regulator can be built with a transistor on a heatsink & a 12V zener & a resistor or two.
Eg here: http://www.learnabout-electronics.org/PSU/psu22.php
Running off solar, DIY & electronics fan :-)
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#3
(04-13-2019, 12:50 AM)Redpacket Wrote: Snip

So are you saying in the morning when the sun is slowly coming up that it is affecting the fans? 

I tried putting two fans of the exact same spec and they both wouldn't start as the sun slowly rose, however when i just turn them off/on they all started spinning.
Is there any way to fix this?

I just need a way to cause the circuit to reset which will triger them to both turn on.
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#4
Are you OK with simple electronics & soldering or prefer a modlue, eg ebay, jaycar, etc?
Running off solar, DIY & electronics fan :-)
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#5
(04-14-2019, 09:51 AM)Redpacket Wrote: Are you OK with simple electronics & soldering or prefer a modlue, eg ebay, jaycar, etc?

Would prefer to just buy something.
Pretty much if I have two different size fans, the smaller second one spins with sunrise. If you reset, then both work.

If I have two fans same size, then both don't spin with sunrise unless you reconnect them.

Also appreciate all the help
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#6
You need bigger solar panel or smaller fans or a controller that start Them when enough Sun exist.
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#7
One thing - can you measure the voltage when 1 fan is spinning and the second attached ?
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#8
(04-14-2019, 09:58 AM)daromer Wrote: You need bigger solar panel or smaller fans or a controller that start Them when enough Sun exist.

Tried that, I think it's something to do with the fans' control logic board that stops them after a while of having low voltage. 

Any recommendations on a controller that would do that?

(04-14-2019, 10:07 AM)Cherry67 Wrote: One thing - can you measure the voltage when 1 fan is spinning and the second attached ?

Wish i could, don't own a voltmeter unfortunately... 

But even when the sun is high and the panel is getting maximum solar, the same phenomenon happens. Either only one fan spins or both aren't spinning untill i disconnect and reconnect power.
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#9
After the inspiring comments of the others, i just assume the current of both fans to start required is more than the panel can deliver. There is a buck converter available which has an MPPT ( wich is an undervoltage shutof) in the Chinese market, i will add the link later. Perhaps this could work.
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4 kWh battery target
Ultra low cost
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#10
This module is what you want:
https://www.ebay.com.au/itm/Lithium-Batt...3945740995
You'll need to buy a cheap multimeter to set the voltages.
Connect the solat panel to the Vin input.
Connect a fan to the "bat" output.
Get the panel in full sun.
Use the blue adjustment pots to set the MPPT voltage to about 17V & the V-out to 12V.
Running off solar, DIY & electronics fan :-)
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