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12v 0.2amp pc case fan on 12v 105ah battery?


Gabriël
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3 minutes ago, plonkster said:

I'm not sure what you're asking

pardon my vagueness... must've been the wee hours of morning...

i want to hook up a 12v .2amp pc case fan [image] to a maximus 12v 105ah battery [see pdf] by connecting the red and black wires of the fan [not yellow] to the correct battery terminals.

if possible, how many [years ;)] will it run on a full battery charge...

Maximus_105.pdf

pc case fan.jpg

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14 minutes ago, gabriel said:

pardon my vagueness... must've been the wee hours of morning...

i want to hook up a 12v .2amp pc case fan [image] to a maximus 12v 105ah battery [see pdf] by connecting the red and black wires of the fan [not yellow] to the correct battery terminals.

if possible, how many [years ;)] will it run on a full battery charge...

From full to totally discharged about 3 weeks. Remember to fuse the fan.(AC make sure there is a CB - DC make sure there is a fuse). This battery must not be part of a string of batteries unless you have an HA02 in which case you may get away with it but still not recommended.

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the yellow on old case fans was 12v+ but is now 7v+ and used for sensor, now the red is 12v+. ground or - has always been black.

i have gleaned the above from google...

there sometimes is a fourth wire used for leds.

i just want it to spin full throttle, no fancy schmancy controls etc. it is part of a box with bulbs in it, like these biltong driers, but i use it to dry powder - i'll post a photo if it doesn't look too shabby :)

 

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5 minutes ago, Chris Hobson said:

My understanding without a signal the fan runs full tilt. With a 3 wire fan the 3rd wire I think is the tacho. Since I don't fiddle with PCs anymore I might be wrong.

I think the yellow wire is used for fan speed sensing which the smarter PC's can then adjust by PWM on R+B. If 12v applied to R+B it will run full speed.

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1 hour ago, gabriel said:

if possible, how many [years ;)] will it run on a full battery charge...

You would want to limit it to 250 hours run time to maintain 50% DOD.

On the other hand if you got a small 12v/10w panel from one of the hundreds of Chinese product outlets for about R100, you could hook it directly to the fan and allow it to run all day while sun is up (no fan at night).

If it must run 24hr then if you did the same as above but with the 100Ah battery as well I reckon you could run the fan forever without requiring a charge controller, the panel should produce about 60Wh per day and the fan draw about 60Wh per day.

If you start with a fully charged battery you could check the voltage maybe once a month to make sure things aren't going pear shaped.

NOTE: if the fan packs up and stops drawing current then the panel will eventually cook the battery:( 

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14 minutes ago, pilotfish said:

On the other hand if you got a small 12v/10w panel

could i not just clip the fan to one of my 12v 250ah units in my bank - or would that cause undue strain on the ah200 or the other batteries?

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25 minutes ago, gabriel said:

could i not just clip the fan to one of my 12v 250ah units in my bank - or would that cause undue strain on the ah200 or the other batteries?

The slightest bit of extra draw on one battery, even just 50mA, will cause imbalance in the long term. That's why Chris said that if you have a balancer on there you might be okay: What the balancer will do is pass some current from the other batteries to compensate for it, so you get a kind of cheap buck converter (which technically is how the HA02 works, as I understand it it is a 1:1 DC/DC converter of sorts) that powers the fan from all 4 batteries. As long as the draw is lower than the current the HA02 can pass you can get away with it...

BUT... I still wouldn't do it. Hacks are hacks... do it properly.

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ok, what i'll do is use the 12v 105ah or any other dedicated power source [i've got an old ac/dc 12v adaptor lying around] for the fan and not hack my solar system for a little bit of power. in case i go for a battery like the aforementioned i'll just regularly check and top up the charge

thanks!

dis lekker bewolk hier by ons vandag!

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6 minutes ago, gabriel said:

dis lekker bewolk hier by ons vandag!

I noticed you guys have a very favourable forecast today. Hoping you get some rain. It should pass this way around noon, Looks like it will also hit the mountains towards the east where we get most of our run off. Holding thumbs and looking up today, in more than one way.

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