Frustrated with Maxxfan.

[twinster2]

June of 2019 I installed a Maxxfan 4000K vent fan. It seemed to be working for the first 3 months but after that it would randomly go into a green light lockup. Well I gave Maxxfan a call today and was told that this fan model is sensitive to high voltage issues. Essentially if the fan sees voltages above 13.4 volts it can go into this lockup. I told them that voltages put out by fully charged 12 volt Lead Acid batteries is <13.8 volts so why would you sell a rv fan that cannot run off a full charged 12 volt battery? He told me to put in a voltage regulator. Frustrating. For anyone thinking of buying one of these fans, don't do it.

[profdant139]

Good advice -- thanks!!

[twinster2]

I should have said a fully charged battery is greater than (i.e. >) 13.8 volts.

[JimboFunFinder]

Originally Posted by twinster2

I should have said a fully charged battery is greater than (i.e. >) 13.8 volts.

I am thinking that you could put a silicon diode in series with the motor and it would drop 0.6 to 0.7 Volts. We would need to know how much current the motor draws (in Amps or milliamps) to make sure the diode would not overheat. If they rate it in watts or VA that will also be enough information.
I think this might be a very simple and low cost solution. Can you find out the maximum current draw?

[JimboFunFinder]

Twinster,
I went to Amazon and read some of the reviews. There are several negative ones relating to the voltage sensitivity. I then found this one on the current consumption:
Q: Does anyone know the Wattage of this fan?
A: The instructions say a minimum of five amps for correct operation. In my experience so far the max draw has been 6.2 amps on high. I hope this helps. I'm not a salesman for this product, but this fan is the best addition made so far. Using this in Arizona heat and it works incredibly well. Moves huge amounts of air ef… see more
By G's Hookupz on April 28, 2018
Using his figure of 6.2 Amps and a max voltage drop of 0.8V for a silicon diode (just to be conservative) that means the VA or Watts would be 5W. This is a lot of heat in one small device. The diode would need to be a stud mount and fastened to a piece of metal with some surface area to dissipate the heat. Although this approach would work the heat generated makes me think there might be a better way.
Here is voltage regulator I found on Amazon which will provide an output of 12VDC regardless of the input at up to 6 Amps. The Maxxair spec was 5A so it should be enough. The cost is ~$25 using the coupon. I offer it for your consideration.

[twinster2]

Thanks for checking but I already ordered this regulator from Amazon.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[JimboFunFinder]

Originally Posted by twinster2

Thanks for checking but I already ordered this regulator from Amazon.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Unfortunately I doubt that will work because the spec states the output needs to be >2V lower than the input. A Buck or Step Down switcher means the output must be less than the input applied. I believe you need a combination Step Up/Down (aka Boost and Buck) function since the input will be only a volt or so above the desired output.

[twinster2]

Originally Posted by JimboFunFinder

Unfortunately I doubt that will work because the spec states the output needs to be >2V lower than the input. A Buck or Step Down switcher means the output must be less than the input applied. I believe you need a combination Step Up/Down (aka Boost and Buck) function since the input will be only a volt or so above the desired output.

You brought up a good point. I will send it back and get a boost/buck regulator.

[gator]

Where do you plan on mounting this unit? It most likely won't fit near the fan. If you mount it near the power source you only want to power that fan. Otherwise you may find that this unit isn't powerful enough for all you 12volt devices in the trailer.

[twinster2]

Originally Posted by gator

Where do you plan on mounting this unit? It most likely won't fit near the fan. If you mount it near the power source you only want to power that fan. Otherwise you may find that this unit isn't powerful enough for all you 12volt devices in the trailer.

I will mount it next to the fan. The one I got is not very big, only 2 inches by 1.5 inches. I will just dig out a spot in the foam insulation for it.

https://www.amazon.com/Stabilizer-DR...xpY2s9dHJ1ZQ==

[Eagle]

I took the advice of the selling dealer and opted for the Fantastic fan when ordering my unit. Have never had an issue with it ... so maybe a wise choice over the Maxxi fan.

[twinster2]

This Maxxfan issue never ends. So I installed the voltage regulator yesterday. Checked that the voltage going to the fan was now 12.2 volts. Turned the fan on medium and about 15 minutes later I get the green light of death. Called Maxxfan up today and told them I did everything they recommended and the fan still locks up. They now say the control board is bad and will send me a new one. I bet next summer I will be doing this same thing again.

[JimboFunFinder]

Originally Posted by twinster2

This Maxxfan issue never ends. So I installed the voltage regulator yesterday. Checked that the voltage going to the fan was now 12.2 volts. Turned the fan on medium and about 15 minutes later I get the green light of death. Called Maxxfan up today and told them I did everything they recommended and the fan still locks up. They now say the control board is bad and will send me a new one. I bet next summer I will be doing this same thing again.

The specs on the DROK all look reasonable but I note that they do not specify ripple. Ripple is the high frequency variation cause by the internal switching. If the new board behaves the same I would suggest that it might help to install a polarized capacitor across the 12V output lines. This will tend to reduce the ripple. A ceramic or tantalum capacitor would have the best high frequency response to dampen the ripple. An aluminum electrolytic would likely not be beneficial. They should be low cost at an electronics supply store or Digikey.

[Gerald Miller]

Electricity to me is like reading Chinese hieroglyphs! But this thread is timely since I’m ordering a new unt this week, and, I was going to specify Maxx fans. Now I’ll need to research it, or like Eagle was advised to go with th Fantastic fan.

[twinster2]

Do not buy a Maxxfan. They sent me a new control board and I hooked it up before I winterized. Five minutes after I turned it on, it quit on me. Too bad, because the fan seem to be well made, except for the electronics.

[Gerald Miller]

Thanks for the update.