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ajriding

st clair

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Joined: 12/28/2004

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Posted: 08/28/21 10:05am Link  |  Quote  |  Print  |  Notify Moderator

FWC wrote:

From my Victron BMV-712.

The FF does have brushes, but not user serviceable. Quite frankly the Fantastic Fans, like most RV appliances, are total junk designed in the 1980s.


Agree, it is amazing how little air the ten blades actually move for such a large motor and fast fan speed... I often wonder if the FF was originally designed as a blender instead of a fan.

Was your 0,9A reading on a speed equal to the Low setting? Im interested what it is on the speed where the fan barely has enough power to turn, it has to be much lower than 0.9..
3A on high, 2.3A on medium and 1.9A on low.
PWM 3A, ,,,1.6 and ,,,,,,,,,,,,,,,,,,,, 0.9A

I also realized that my electric fridge only pulls 3-4 amps, and it only runs some of the time, so the fan on high would be the biggest drawdown on batts. wow. Even with the fan pulling 1 amp it will still be the biggest draw since it runs all the time vs fridge running a fraction.

* This post was edited 08/29/21 09:59am by ajriding *

FWC

The Wilderness

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Posted: 08/28/21 10:33am Link  |  Quote  |  Print  |  Notify Moderator

My ~0.9A reading was at a speed kind of equivalent to the prior low speed. The current doesn't actually drop that much more when you go even slower, there is a certain amount of energy to overcome friction and that is lost in the motor windings, so the current isn't linear with speed. I don't remember what the minimum current is though.

Gdetrailer

PA

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Posted: 08/28/21 11:10am Link  |  Quote  |  Print  |  Notify Moderator

ajriding wrote:

FWC wrote:

From my Victron BMV-712.

The FF does have brushes, but not user serviceable. Quite frankly the Fantastic Fans, like most RV appliances, are total junk designed in the 1980s.


Agree, it is amazing how little air the ten blades actually move for such a large motor and fast fan speed... I often wonder if the FF was originally designed as a blender instead of a fan.

Was your 0,9A reading on a speed equal to the Low setting? Im interested what it is on the speed where the fan barely has enough power to turn, it has to be much lower than 0.9..
3A on high, 2.3A on medium and 1.9A on low.
PWM 3A, 1.6 and 0.9A


Which is why I am saying you are going down a rabbit hole.

You have two different "efficiencies" at work here.

1 is current draw of the inefficient brush can motor.

2 is lack of air movement of the fan blade design.

This is why I mentioned trying a computer case type of fan, the motors are high efficiency brushless PWM controlled motor and well designed fan blades that make the most of getting max air flow for the RPMs.

If you dig around you can find a 4" computer case fan that draws less than 1A and gets well over 100 CFM of airflow which is more than twice the airflow at 1/3 the amperage of what you now have. Get the right one that runs at a lower RPM and they tend to be very quiet also as a bonus.

HERE is just one example. That example is rated roughly 70 CFM at a noise level of 25 DB which is very quiet and runs at 1700 RPM max at 1.08W of power. 1.08W at 12V=.09A!!

Yes, you read that correctly one watt of power an yet get 70 CFM of air flow.

Full specs can be found HERE

The only downside to computer case fans it they are not designed to be reversible, but buy two for one each direction and switch between them.

I have converted my trailer fans over to computer fans yrs ago, much less noise with a lot more air movement with a bonus of less current draw.

TurnThePage

North ID

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Posted: 08/28/21 02:36pm Link  |  Quote  |  Print  |  Notify Moderator

I have several fans controlled by PWM. One of them is a Surflo product (similar to the FF) that is no longer manufactured. It has brushes but has run flawlessly for years and move tons of air. I installed the original version of the Heng's Vortex in the bathroom, then added a PWM to it. It really moves a lot of air, but can get noisy (wind noise) at top speed. I also have a fan that is intended for the windshield area of a motorhome, but I use it for the bed area. I added a 12.5 khz PWM controller to it that works excellently with no noise that I can hear. The Surflo fan has the highest draw at 2.1 amps on full speed. I'm a firm believer in this technology. It's worked great for me. It's awesome to be able to select virtually any speed you want.


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FWC

The Wilderness

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Posted: 08/28/21 04:15pm Link  |  Quote  |  Print  |  Notify Moderator

Gdetrailer wrote:



Which is why I am saying you are going down a rabbit hole.

You have two different "efficiencies" at work here.

1 is current draw of the inefficient brush can motor.

2 is lack of air movement of the fan blade design.

This is why I mentioned trying a computer case type of fan, the motors are high efficiency brushless PWM controlled motor and well designed fan blades that make the most of getting max air flow for the RPMs.

If you dig around you can find a 4" computer case fan that draws less than 1A and gets well over 100 CFM of airflow which is more than twice the airflow at 1/3 the amperage of what you now have. Get the right one that runs at a lower RPM and they tend to be very quiet also as a bonus.

HERE is just one example. That example is rated roughly 70 CFM at a noise level of 25 DB which is very quiet and runs at 1700 RPM max at 1.08W of power. 1.08W at 12V=.09A!!

Yes, you read that correctly one watt of power an yet get 70 CFM of air flow.

Full specs can be found HERE

The only downside to computer case fans it they are not designed to be reversible, but buy two for one each direction and switch between them.

I have converted my trailer fans over to computer fans yrs ago, much less noise with a lot more air movement with a bonus of less current draw.


This is all true about brushless motors and better fan designs being much more efficient. However it is also true that a simple and cheap PWM controller can significantly increase the efficiency of the existing fan on all but the 'max' setting. Re-engineering your fantastic fan to use a PC fan is a pretty major undertaking, adding a PWM controller in line with it is fairly easy.

ajriding

st clair

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Posted: 08/29/21 10:06am Link  |  Quote  |  Print  |  Notify Moderator

yea, the computer fans are great, but not for replacing the way more powerful FF motor. Maybe using one to blow air in from a window would help move air out the roof vent and that could be a compromise solution.

I have a second vent that is not FF but also not covered bc the solar panels are right there and I cannot shade the panels and cannot really leave the vent open all day and be gone due to the constant haarp rains all the time getting inside.

I ordered that controller in the link and will drill out some vent holes to help cool it. Hopefully the ringing of this one is out of my hearing range too

Gdetrailer

PA

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Posted: 08/29/21 10:32am Link  |  Quote  |  Print  |  Notify Moderator

ajriding wrote:

yea, the computer fans are great, but not for replacing the way more powerful FF motor. Maybe using one to blow air in from a window would help move air out the roof vent and that could be a compromise solution.



You haven't met some of the computer fans I have worked with..

Have used some computer fans that will push loose papers right off your desk at 15 feet away from them.

Go ahead and fiddle with junk, junk in = inefficient junk out.

FWC

The Wilderness

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Posted: 08/29/21 10:39am Link  |  Quote  |  Print  |  Notify Moderator

Could you suggest a specific brushless fan for replacing the standard fantastic fan and the hardware you would need to make this replacement?

Grit dog

Black Diamond, WA

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Posted: 08/29/21 10:55am Link  |  Quote  |  Print  |  Notify Moderator

What is amazing is the levels some will go to, to work on the “efficiency” of a fart fan….
While we’re on that, new camper doesn’t have a FF (which I’ve IE learned in the last4 pages is apparently horrible inefficient junk, lol, despite all the great press it receives here).

Camper has 3 basic fart fans, but the center one in the kitchen I’m considering replacing with something better/variable speed and directional.

Since FFs are ****, what do the experts recommend?


2016 Ram 2500, MotorOps.ca EFIlive tuned, 5” turbo back, 6" lift on 37s
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ajriding

st clair

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Posted: 08/29/21 12:11pm Link  |  Quote  |  Print  |  Notify Moderator

no gdtrailer, I havent found a computer fan like that. I see plenty of 70 cfm fans that are 1/15th of the FF's ability. Where do I find such a powerful comp fan?
Im not going to put a 70cfm fan in place of a 1200 one.

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