Maxxfan 7000K voltage regulator

[Great Eggstrications]

Originally Posted by dstreight

Jeez, what a PITA. ...what equates to a 2-bit ventilation fan...

Yeah - except that it's a $300 2-bit ventilation fan. Of course, maybe it's got an 8-bit controller in there somewhere?

Originally Posted by cpaharley2008

"Necessity, the mother of invention"..........

Yeah - but in this convoluted case it's sort of a Frank Zappa version.

Originally Posted by Centex

One might wonder why the folks that make RV DC charging / distribution equipment don't regulate the DC 'house-distribution output' separate from the DC 'battery charging output'?
Until then ...

Yeah - one DOES wonder! Would have gladly paid for such a thing.

[Great Eggstrications]

The saga continues...

For those of you still following this (mis)adventure, the eBay/noname unit showed up - weeks ahead of schedule! And in this case, the eBay/noname device definitively beat the Amazon/DROK device.

While the eBay/noname unit is better than the Amazon/DROK unit, things still aren't quite right - the over-sized heat sink is still way too friendly with the SMD devices, so those forward-thinking eBay guys decided to stick a nice layer of baby blue (hopefully) insulating and (hopefully) thermal conducting sticky foam between the surfaces. But alas, a couple of the BA9U3D MOS-FET's oozed their way through the foam, and even worse, part of the foam got torn apart, allowing one of the SMD capacitors to short across the heat sink. Happily, the heat sink isn't epoxied on, and can be removed and with a bit of surgery it can be trimmed to allow plenty of clearance. Meanwhile, I just left off the offending heat sink, introduced the input lugs to a good 0-30V 0-10A variable power supply, and was happy to see that it takes a wide range of input voltages - both below and above the requested output - and spits out a nice steady 12 volts as called for.

NB: It appears that the previously-posted Amazon link in this thread now takes you to a constant 5V output device, not to the variable one that used to live at that URL.

Also, note that buck down converters seem to typically require that the specified output voltage be at least 1.5-2.0 BELOW the input voltage, so if e.g. you're only giving it V-in of 13.2, then it can do V-out of only 11.2 or less - it can't V-out the 12 V that you're asking for. Hence it's perhaps best to go with a combination buck down AND boost up device.

Meanwhile, the nice potted aluminum units shown in a previous post will arrive in a few days from Amazon. They have a 2.92" square footprint and a height of 1.25" so should fit nicely up inside the MaxxFan enclosure under the rain cover, and shouldn't be adversely affected by humidity or whatnot. We shall see.

As a side note, I contacted our friends at MaxxFan asking about the maximum current draw on a 7500K fan, pointing out that their installation document specifies 5 amps while the E-Trailer web site talks about a 9 amp draw at start-up and 4.5 amps at constant fan speed. The MaxxFan Technical Assistance Coordinator responded by saying, in a remarkably non-committal and non-definitive way:

"I would agree with the amp draws that you state in the email."

OK thanks, but that really doesn't pin it down very well, does it? So which is it?

Sticking a DMM in series with the +12v side, here's what I was seeing:

Switched off and back on, maximum current drawn to both spin up the fan and raise the rain cover:

min speed - .4 A
mid speed - 1.3 A
max speed - 3.4 A

Running at constant speed, current drawn to just maintain fan speed:

min speed - .12 A
mid speed - .9 A
max speed - 2.66 A


I never got a response back from the MaxxFan folks when I asked in an admittedly perhaps somewhat antagonistic fashion:

"I am planning to buy and install buck down / boost up DC-to-DC converters on both of my fans before the control boards are damaged. When doing solar Equalization charging I see 15.1 volts, and in Bulk mode 14.4 volts, Absorption 13.6 volts, and Float 13.2 volts. I understand that at some point the fans were upgraded to a version of the controller board that could handle higher voltages, but I believe that my fans pre-date this, being manufactured in 2015, and in any case my Equalization and Bulk voltages would still exceed the higher limit.

Why is it that these higher-voltage-intolerant products were released to market in the first place, given that you specifically address the RV market which typically involves the higher voltages?

Please clarify."

[medora]

Hey there, I had the dreaded beeping MaxxFan so just tried this install and - FAIL. I’m posting a video - can anyone advise on what I’m doing wrong? I have another voltage regulator on order.

https://vimeo.com/576292737/aced4582bf

To be specific, regardless of how I turned the blue bit the voltage stayed constant at 12.9 - and I finally broke it off after futzing with it too much.

[Rossue]

These fans are used on a LOT of campers. I have one now on my Transit van and am curious as to whether this really a serious issue.

Mine went south after 7 years and ordered another board after calling Airxell. Am pretty sure I accidentally got the board wet while washing the roof and having a brain fart with the lid open and spraying water in the opened lid direction. They didnt have one so ordered one from a place in TN.

It didnt work so I called Airxell back and they offered to send me a new board and a motor and a keypad for free as my problem was "mis-diagnosed". Goodwill gesture. Had to wait 6 weeks for all the backordered items to arrive. They wanted them all installed at the same time. It now works.

My question is: do we really need a regulator? Am not installing one as we never had an issue until my stupid mistake.

[medora]

And besides the obvious question above, my thought is — if it IS necessary, as it seems to be in my case, why can’t manufacturers integrate it into the fan itself? It’s insane that I’m trying to figure this out (and failing) after I paid $200 plus for a new fan.

[dstreight]

@medora: Same exact thought! The 7 year old MaxxAir fan that came OEM with our 15A works fine. Well, other than the motor shaft nut rubs on the bug screen and makes noise...just another "re-engineering project" for me to take care of one of these days...argh.

Sold the A/C unit that came with the 15A as we don't go where plug-in is available. Bought another brand new MaxxAir fan to fill the hole from the A/C unit...and same problem as others here have experienced: No worky. They sent me a replacement unit...worked for a short while and it went dead. The only culprit, if you will, I can figure out is the over DC voltage. But why has the old MaxxAir fan worked just fine from the same voltage?

I suspect...China.

[medora]

I hear you. If we bought any other $250 appliance and it did this - and the “solution” was to install an obscure electrical part that comes with no instructions - we’d all be crying BS and heading to the store for a competitor’s model. Is it just that there’s not enough competition in these markets? And if so, isn’t there an enterprising Escapee that wants to fill the void?

PS I STILL HAVE NO IDEA WHAT I DID WRONG INSTALLING THE VOLTAGE REGULATOR …. Sigh

[RangerMan]

Originally Posted by medora

I hear you. If we bought any other $250 appliance and it did this - and the “solution” was to install an obscure electrical part that comes with no instructions - we’d all be crying BS and heading to the store for a competitor’s model. Is it just that there’s not enough competition in these markets? And if so, isn’t there an enterprising Escapee that wants to fill the void?

PS I STILL HAVE NO IDEA WHAT I DID WRONG INSTALLING THE VOLTAGE REGULATOR …. Sigh

Did you adjust the pot to 12v before attaching fan wires to the regulator?
tdx-tx posted a detailed description here on the VR install. Very useful. I can't remember the thread.

[RangerMan]

I don't recall ever seeing a voltage regulator of the size we are talking about with instructions. The Vin and Vout posts are usually marked on both the front and back of the board.

I've not seen the one that most here have installed but the Vin and Vout wires are usually attached with set screws on the board. Easy to attach the input wires and then your meter probes to the output terminals. As it will probably be just hanging there, put the meter probes in the Vout terminals and tighten the set screws down. Then you can adjust the pot.

Edit: Observer polarity with Vin and Vout and turn batt switch off when attaching/unattaching wires.

I don't know what the output is capable of but you don't want anymore than 12v output!

[medora]

Ok - adjust the “pot” - can you help me out a bit? I’m turning the blue box? How much? And what if turning makes no change in the voltage reading?

[Centex]

Originally Posted by medora

Ok - adjust the “pot” .... I’m turning the blue box? ....

Ooops, unfortunately that statement and your Vimeo video confirm you've broken the module, sorry.

Yes, reparable with the correct component and PCB soldering skills, but probably not worth the hassle for you given the low price of the module (buy another and try again if you want to pursue this mod).

(click the thumbnail to enlarge and read the text notes)

[medora]

Thanks so much, I have a new module here and will try tomorrow.

[tdf-texas]

Originally Posted by RangerMan

Did you adjust the pot to 12v before attaching fan wires to the regulator?
tdx-tx posted a detailed description here on the VR install. Very useful. I can't remember the thread.

This thread has run so long that the first post seems to have been forgotten.
https://www.escapeforum.org/forums/f...tml#post278183

Adjusting the blue pot for 12v is mandatory before connecting to the Maxxfan control board - an unadjusted LTC3780 could put out up to 24v which will fry the electronics in the fan.

ps. I've been running the LTC3780 voltage regulators on most of my electronics in my trailer now for about 2 1/2 years with no failures - they really do help.

Also, don't forget to coat the board with a conformal coating and to seal that hole that the motor leads come through the fan frame to stop condensation from dripping onto the board.

[medora]

Ok friends, I still need help. I installed the new voltage regulator (and to be clear I did carefully review the initial instructions, it just wasn’t clear that the adjustment required turning a SCREW and not the blue component itself - electrical novice here). I carefully adjusted to 12 V on the dot and hooked everything up, but the fan is now not starting. Prior to starting this I was getting a fan start for about 30 seconds, then beeping and fan stop. I did NOT hook the power back up to the fan prior to checking I was getting 12v, so I don’t see how I could have fried the board. I have checked connections and am getting 12v into the fan wires. What could possibly be happening at this point?

[Rossue]

Bet the board is bad. As previously mentioned- with no voltage regulator a new board from an RV parts supplier didn't work. Called Airxell back; had consulted with Perry Knitig (pfk@airxcel.com) yet at that time they were back ordered so I bought from 3rd party. LSS Perry decided to send me a new board, along with a keypad and new motor at no charge and instructed me to install them all together. It took about six weeks to get all three in at various times. This was for a 7 year old trailer!

I would call them- can't hurt. Personally I wouldn't mention the voltage regulator being installed as that might make them think that installation somehow could have damaged the board. Good luck.

[tdf-texas]

Originally Posted by medora

Ok friends, I still need help. I installed the new voltage regulator (and to be clear I did carefully review the initial instructions, it just wasn’t clear that the adjustment required turning a SCREW and not the blue component itself - electrical novice here). I carefully adjusted to 12 V on the dot and hooked everything up, but the fan is now not starting. Prior to starting this I was getting a fan start for about 30 seconds, then beeping and fan stop. I did NOT hook the power back up to the fan prior to checking I was getting 12v, so I don’t see how I could have fried the board. I have checked connections and am getting 12v into the fan wires. What could possibly be happening at this point?

You have the output wires connected to the wrong terminals. On the Maxxfan control board voltage input, the black wire is positive and the white wire is negative.

Switch the wires going to the Maxxfan control board from the voltage regulator so that the black wire is on VO+ and the white wire is on GND.

Hopefully, the Maxxfan control board is reverse voltage protected. If it isn't, you may have fried another board.

[medora]

Geez — rookie error. Thanks for the tip, but here’s the best part - the fan now turns on, but I’m getting the very same works for 5 seconds then BEEP BEEP OFF. What now? I have called Aircel and they never called back (I was supposed to be in the customer service queue, so much for that). Yes, I have verified that I’m getting 12v out of the regulator and into the fan.

[rubicon327]

Originally Posted by medora

Geez — rookie error. Thanks for the tip, but here’s the best part - the fan now turns on, but I’m getting the very same works for 5 seconds then BEEP BEEP OFF. What now? I have called Aircel and they never called back (I was supposed to be in the customer service queue, so much for that). Yes, I have verified that I’m getting 12v out of the regulator and into the fan.

Is there any chance you're mistakenly in AUTO mode and the fan is reacting to a cabin temperature that is lower than the set point? Is the green light on next to the auto button? This has been known to catch some MaxxFan owners by surprise.

[dstreight]

I don't think the Maxx Fans are reverse polarity protected; at least the one I wired using black as ground .

In the automotive world of 12v DC I've never seen black color sheath as + with white as ground...on a 2 wire system.

[Rossue]

Originally Posted by medora

Geez — rookie error. Thanks for the tip, but here’s the best part - the fan now turns on, but I’m getting the very same works for 5 seconds then BEEP BEEP OFF. What now? I have called Aircel and they never called back (I was supposed to be in the customer service queue, so much for that). Yes, I have verified that I’m getting 12v out of the regulator and into the fan.

Had the same experience with call back option. Call them at 8 AM EST if you want to narrow the wait time. Or email Perry and ask him to call you.