Maxxair Fan repair - system voltage correction

[EL34xyz]

My MaxxFan 5100k fan has the auto temperature circuit
That circuit died and the fan no longer would come on at a certain temp setting
According to the techs at Maxxair, the fan board should not see any more than 13.9 volts DC.
The guys at MaxxAir sent me a replacement board, no charge
They also said they order these boards by the shipload, so it's not an uncommon event.

Anyone who monitors voltages from their starter battery circuit or a separate cabin AGM battery circuit, probably already knows that voltages can exceed 14 volts DC easily when charging is taking place

Watch my Youtube video for more info about what I did to keep the fan voltage at 12 volts DC
There's a link in the video description to the Buck converter I am using
Here's the youtube video link

 

[tx2sturgis]

That board should be able to tolerate a higher voltage, 13.9 is just barely above 13.8 which is standard charging voltage, not counting spikes and surges, and of course, higher levels from solar charge controllers.

The Fantastic Fan I installed on my van was the simple 3 speed using a nichrome wire resistor network for speed control. 

Simple, and tolerant of voltages above normal, but of course, a bit less efficient.

 

[EL34xyz]

That board should be able to tolerate a higher voltage, 13.9 is just barely above 13.8 which is standard charging voltage, not counting spikes and surges, and of course, higher levels from solar charge controllers.
The Fantastic Fan I installed on my van was the simple 3 speed using a nichrome wire resistor network for speed control. 
Simple, and tolerant of voltages above normal, but of course, a bit less efficient.
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Charging systems go way higher than 13.8
My starter battery system runs at 14.2 volts just driving down the road
My AGM battery system can be charged two ways
By my 7 stage smart charger on shore power
Or by my 200 watts of solar via the solar charge controller

I have seen high 14+ volts on both systems as the chargers analyze the AGM system and then start charging 

 

[John61CT]

Could someone willing to sit through the video please post a summary?

I currently plan to put a DCDC buck converter / voltage stabilizer on a circuit for such (stoopidly) sensitive devices. Not expensive for low currents.

Many high quality House banks these days want 14.7V or higher.

Also note while equalizing (always manual, never automatic) to isolate the batts from all loads.

 

[tx2sturgis]

Charging systems go way higher than 13.8

Yes, exactly my point.

The 13.8v I mention is a normal, 'running down the road' voltage when the battery is fully charged and the alternator has cut things back.

If the fan controller board can get fried at above 13.9, that seems to be a flawed design.

 

[EL34xyz]

Yep, that's what I told the technician at Maxxair
They probably enjoy selling $42 replacement boards

Anywho, I hopefully have solved the issue in my van for now.

 

[EL34xyz]

Yes, exactly my point.

The 13.8v I mention is a normal, 'running down the road' voltage when the battery is fully charged and the alternator has cut things back.

If the fan controller board can get fried at above 13.9, that seems to be a flawed design.

The technician at Maxxair said this to me on the phone

"The Boards can get kinda wonky at higher voltages"

Not that the boards will automatically just blow up above 13.9 vdc, just that that can get wonky
Defining what "Wonky" means is anybody's guess

 

[highdesertranger]

yes several of the new RV electronic boards can get damaged from over voltage. but 13.8 seems a little low most can take 15v. highdesertranger

 

[EL34xyz]

yes several of the new RV electronic boards can get damaged from over voltage.  but 13.8 seems a little low most can take 15v.  highdesertranger

I agree
15 volts would make a good ceiling cap
Better yet 16 volts for a safety margin

 

[DannyB1954]

I installed some LED puck lights made for under a kitchen counter. They definitely did not like charging voltage. All of them burnt up.
Maybe this regulator would work well on lighting circuits.

 

[B and C]

I just make sure to get LED's that are dimmable or have a voltage range between 10-30VDC. All of mine are still working fine two+ years later.

 

[EL34xyz]

The LED's you see in my video are all 12 volt LED tape lights
No problems so far in the van

The ones I use come in a 16 foot spool and have a clear silicone waterproof coating
$9.99 on amazon

Here's the link on Amazon
https://www.amazon.com/dp/B005EHHLD8

 

[John61CT]

Or put in well-regulated circuit(s) for your load consumers that are voltage sensitive.

Even well designed, seemingly robust electronics on expensive devices like compressor fridges can last much longer that way.