Maxxfan 7000K voltage regulator

[Sherri L]

Originally Posted by tdf-texas

Parts List:
LTC3780 14A High Power Auto Step Up Down Voltage Regulator 5-32V to 2-24V DC Adjustable Converter Transformer
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

VELCRO 2-Pack 3-in White Fastener
https://www.lowes.com/pd/VELCRO-2-Pa...stener/3043265

Procedure:
1. Turn off battery disconnect switch.
2. Rotate screen tabs 180 deg and remove screen.
3. Remove screws as marked and lower bottom housing.
4. Disconnect trailer wires from Maxxfan power wires, connect trailer wires to LTC3780 as shown, turn on battery disconnect switch, and adjust the potentiometer for an output voltage of 12.0 volts
NOTE: do not attach wiring to Maxxfan until voltage has been adjusted - the LTC3780 can output up to 24VDC which will make the Maxxfan control board very unhappy.
5. After verifying that the LTC3780 is set for 12.0 volts, turn off battery disconnect switch and connect Maxxfan power wires to output of LTC3780.
6. Attach velcro to back of LTC3780. It will need to be trimmed a little to make it flush with the edges.
7. Attach LTC3780 in the corner of the upper housing as shown.
8. Put everything back together the reverse of how you took it apart.
9. Turn battery disconnect switch on and test fan.

Congratulations, your Maxxfan can now operate with supply voltages from 5-32v.

Thank you for these detailed instructions! I went through 2 circuit boards before adding the 12v regulator. Works like a charm now. I hope MaxxAir Fan fixes this issue in the future. Converted Vans are a huge market for them and most are powered by Solar. MaxxAir Fan told me when Solar is used to charge lithium batteries the voltages can go up to 14V. Mine was showing 13.85V so burned up my circuit board twice!

[tdf-texas]

Originally Posted by Sherri L

Thank you for these detailed instructions! I went through 2 circuit boards before adding the 12v regulator. Works like a charm now. I hope MaxxAir Fan fixes this issue in the future. Converted Vans are a huge market for them and most are powered by Solar. MaxxAir Fan told me when Solar is used to charge lithium batteries the voltages can go up to 14V. Mine was showing 13.85V so burned up my circuit board twice!

You're welcome! The Maxxfan control boards have gone through several revisions trying to improve the reliability but - they still fail if they see the recommended charge voltages that the battery manufacturers put out.

I have voltage regulators on my Maxxfan 7000, Suburban SW6DEL hot water heater control board, and the Atwood AFSAD12 furnace control board. I also installed voltage regulator chips on all my lighting as they don't like anything over 12v!

It's amazing that the RV industry doesn't make their stuff to be able to handle normal RV voltages but a lot of them don't!

ps. Just curious - since you don't own an Escape trailer, how did you find the information about this?

[Sherri L]

Originally Posted by tdf-texas

You're welcome! The Maxxfan control boards have gone through several revisions trying to improve the reliability but - they still fail if they see the recommended charge voltages that the battery manufacturers put out.

I have voltage regulators on my Maxxfan 7000, Suburban SW6DEL hot water heater control board, and the Atwood AFSAD12 furnace control board. I also installed voltage regulator chips on all my lighting as they don't like anything over 12v!

It's amazing that the RV industry doesn't make their stuff to be able to handle normal RV voltages but a lot of them don't!

ps. Just curious - since you don't own an Escape trailer, how did you find the information about this?

No I don't have an Escape trailer. I have a converted Ford Transit 250. I just googled MaxxAir fan not working and this forum came up. Really appreciate the information.

[Great Eggstrications]

Originally Posted by Sherri L

Really appreciate the information.

I too really appreciate all the information that everyone has provided, and in particular thank tdf-texas for getting this thread started - over 2 long years ago. I have finally gotten around to worrying about the 2 long-suffering-but-so-far-ok MaxxFans in my E19 with respect to the over-voltage issue, and have plodded my way through this thread - along with some side-trips to other related postings - and me thinks I really need to protect the boards in my MaxxFans, furnace, water heater, and maybe (antique 8551) refrigerator sooner rather than later.

It looks like the choice is between:

The "DROK 200144 24V 12V to 5V 5A Converter, Waterproof Voltage Regulator Module 9-35V to 5 V DC to DC Buck Converter" on Amazon ($20.25) and other identical-looking items on eBay ($less than Amazon)

https://www.amazon.com/DROK-Regulato...ct_top?ie=UTF8

and the "DC DC Buck Boost Converter Adjustable CC CV Step Up Down Power Supply Module" profusely offered on eBay ($15-$20)

https://www.ebay.com/c/1277386264

The former, at least a couple of years ago, was reported to have some bad corrosion issues, which may have been resolved by now. The latter has a fan and a delightfully tech-ie looking display screen, nice stuff but more to go wrong.

So now for a few questions...

In the Product Description, the former is stated to have "Continuous Output Current: 12A, maximum 14A (input 14V, output 12V)" which I would guess is plenty for our purposes, while the latter states in a magnificently cryptic manner "Output power: 50w - Output current: 4A - Current resolution: 0.001A. This can only delay our service." Hmmmm.... Would this be able to provide enough current for the fan? I have been unable to determine what maximum current the MaxxFan 7500K draws. Although the AIRXCEL web site has a section devoted to "MaxxAir Service/Support, Document Library", I could not find the information there, and they have not replied to my inquiry.

I don't sense a clear-cut winner in the longevity and/or reliability department, so to those of you who have experience with these two devices, are there any strong opinions regarding such things?

Is one a better/easier fit up inside the fan enclosure? It's about 6.3 cu in vs. about 7.0 cu in, but the shapes are quite different, the latter being more cubical.

There has been some discussion regarding "potting" the converter and/or fan controller board using a conformal coating to mitigate problems with humidity. Does anyone have ideas on that?

The former appears to have a pot with which to adjust the output voltage, while the latter has a "Set" button and an "ON/OFF" button, along with pots for "CC" = Constant Current and "CV" = Constant Voltage. Why no CC/CV on the former and no Up/Down / Increase/Decrease pot on the latter? What kind of rabbit hole have I fallen into here?

Because there are fewer questions and uncertainties involved, I'm tempted to just go with the DROK / DROK-look-alike and call it decided, but really would like to base the decision on something more solid. Any opinions / cautions / discussions would be most welcome and appreciated.

[fudge_brownie]

Have the Maxx Fans from your era of Escape suffered failure? It is hard to tell from the discussions just what manufacturing date is involved but it seems to have been more common in newer models. Have you suffered a failure?

[Greg A]

2015 19. Whatever Maxx fan was included as base. No issues in 5.5 years.
Solar, twin 6V, and run the equalization on controller every month.

[Great Eggstrications]

Have you suffered a failure?

Nope, no failure, at least not yet. Just wanting to be proactive - before a failure happens.

Two 6 volt batteries with solar; 15.1 volts of solar equalization charging for 3 hours every 4-6 weeks (per Interstate's instructions), plus presumably the occasional 14.4 volt bulk charge and certainly plenty of absorption charging at 13.6 volts from the WFCO.

Don't want to be like a guy I used to work with. He went out and bought a nice used car, and decided that since it was running just fine, he really didn't need to change the oil. Wonder how that went for him long term

[dfandrews]

2015 Escape 17A: MaxxFan has worked as advertised; no problems.

[tdf-texas]

Originally Posted by Great Eggstrications

The "DROK 200144 24V 12V to 5V 5A Converter, Waterproof Voltage Regulator Module 9-35V to 5 V DC to DC Buck Converter" on Amazon ($20.25) and other identical-looking items on eBay ($less than Amazon)

This is the vendor I have bought several LTC3780 modules from and they have all worked well.

https://www.ebay.com/itm/DC-DC-Conve....c101198.m1985

From the Maxxfan installation manual: The MAXXFAN requires a minimum 12 Volt DC, 5 amp service.
https://www.airxcel.com/docs/default...-b-01-2016.pdf

From Etrailer: "While running the MaxxAir MaxxFan Deluxe # MA00-06401K requires about 4-1/2 amps. For startup it will pull around 9 amps. "
https://www.etrailer.com/question-212291.html

The 7500K should be about the same current draw as the motor is most of the load.

The regulator you use needs to be able to handle at least 9 amps as the fan will start/stop when controlling temp pulling the 9 amps each time it starts.

[Great Eggstrications]

Originally Posted by tdf-texas

This is the vendor I have bought several LTC3780 modules from and they have all worked well.

https://www.ebay.com/itm/DC-DC-Conve....c101198.m1985

From the Maxxfan installation manual: The MAXXFAN requires a minimum 12 Volt DC, 5 amp service.
https://www.airxcel.com/docs/default...-b-01-2016.pdf

From Etrailer: "While running the MaxxAir MaxxFan Deluxe # MA00-06401K requires about 4-1/2 amps. For startup it will pull around 9 amps. "
https://www.etrailer.com/question-212291.html

The 7500K should be about the same current draw as the motor is most of the load.

The regulator you use needs to be able to handle at least 9 amps as the fan will start/stop when controlling temp pulling the 9 amps each time it starts.

Seek and tdf-texas shall find! Thanks so much for jumping in with the additional info - just what I needed. I looked right past it in the MaxxFan document, and didn't think to look at e-trailer.

I was a bit concerned since when first turned on, it not only starts the fan but also raises the plastic cover, which should draw a good bit of current.

[Rossue]

Looking at the ebay item that tdf-texas posted I see it estimates 3-5 weeks for delivery. Anyone else buy another one on Amazon recently with good results?

[Great Eggstrications]

I ordered one from Amazon on March 9, and it's due for delivery tomorrow March 14 via USPS. Had previously ordered one from eBay on March 8, and delivery is estimated for the wide-open window of April 2 - April 20. The eBay seller was the one suggested by tdf-texas, and they only had one left so I figured I would order their last one as well as one from Amazon and see what happens. The're pretty inexpensive and I'll likely end up using several so may as well order a couple of 'em.

When the one from Amazon shows up I'll post whether it has the bad corrosion problem which has been reported in the past (both here and on Amazon reviews), albeit from a couple of years ago - hopefully it's no longer an issue.

[cpaharley2008]

I am finding that most deliveries are taking longer, even Amazon's one day is now 2-3 days....

[Rossue]

Thx Dave.

[Great Eggstrications]

Originally Posted by Rossue

Looking at the ebay item that tdf-texas posted I see it estimates 3-5 weeks for delivery. Anyone else buy another one on Amazon recently with good results?

Nope - not exactly good results - quite the contrary.

It appears that the corroded terminals have been traded in for shorted components. No signs of any corrosion - terminals or otherwise - but they seem to have decided to position the heat sink so it shorts out some of the SMD devices. Or maybe they're using a special non-conducting heat sink alloy of some sort?

The heat sink is mounted at a jaunty angle, and at first glance it looks like that can be addressed by loosening an M3-ish looking phillips screw that goes through from the back of the PCB and into the heat sink. Not too much of an issue - my wife claims that I have a serious case of OCD, but it's actually just a moderate case of ATDD - Attention To Detail Disorder. It turns out that the heat sink is epoxied to the underlying component(s), so it can't be rotated without prying it off. The edge of the inductor coil is hard up against the heat sink, but can easily be scooted away from the heat sink by gently bending the coil wires as shown. So far not too bad.

But what about the unmarked SMD capacitors (?) that can't be moved? The heat sink should do a splendid job of shorting between the pair peering out from the end of the heat sink, and one of the ones that peeks out from the side of the heat sink would be shorted across.


We'll see what (eventually) shows up from eBay...

[Rossue]

Hmm- well thanks for that; mine shipped today; won't bother opening. Isn't there anything else good out there without a 3 week or longer wait from China?

[Great Eggstrications]

Originally Posted by Rossue

Hmm- well thanks for that; mine shipped today; won't bother opening. Isn't there anything else good out there without a 3 week or longer wait from China?

Hmm - indeed! What to do, what to do, what to do?

How's about I stop messing around with the cheapo stuff and get this burly-looking 8-40 vdc-in to 12 vdc-out 10 amp fully potted and thermally dissipatoriatively proficient (yikes!) and waterproof device:

https://www.amazon.com/gp/product/B0...0?ie=UTF8&th=1

I got the last two available 10 amp versions for 29 bucks each, and it's buck-down / boost-up to boot! The 20 amp version is a good bit bigger and 50 bucks. Don't know where they're made, just hope it'll work ok. Would - as always - prefer "Made In USA", but I sure don't see any good candidates, and if it was from Tektronix it would retail for $300, so whatdayado?

I had just about decided to try one of the cute little guys with the LCD display screen showing the volts in/out and amps in/out and some trim pots and Constant Current / Constant Voltage and buttons and other fun stuff to play with, but my purchasing department manager claimed that I already have enough such stuff and said to quit messing around and shut up about it already and get something that'll just work and you don't need any more "interesting" gadgets.

Will be getting 7-day free delivery so we'll see what shows up next week.

And by the way, post #115 in this thread includes a link to a nice DIY video from a Fleetwood MoHo visitor in which he mentions a problematic spacer above his MaxxAir 6200K fan - seems it was difficult for him to get the spacer lined up correctly during reassembly. I found no spacer in the 7500K that I took apart today during my reconnaissance run, so it's well worth it to fully drop the inner fan-motor-and-control board assembly for better wiring access.

[dstreight]

Jeez, what a PITA. Hard to believe no one is offering a robust enough controller & electronics already integrated onto RV fans, out of the box.

So, even if I bought a million dollar luxury coach for example, I'm still getting what equates to a 2-bit ventilation fan that requires custom modifications to perform reliably with a LFP/solar set-up...

[cpaharley2008]

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

[Centex]

Originally Posted by dstreight

Jeez, what a PITA. Hard to believe no one is offering a robust enough controller & electronics already integrated onto RV fans, out of the box. ....

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'? IOW, a regulator integral to the power-center which limits the DC to ~13V before the +DC fuse buss (after the battery) - making that the max voltage for all fused circuits regardless of what's happening at the battery / charging side of things. The 'deluxe' implementation could offer both 'buck' and 'boost' to not only limit the max but maintain some minimum voltage (within limits of course).

Yeah, I know, complexity (packaging bulk, cooling, etc), co$t, lack of market demand (at least so-far it seems). The tech is certainly available, maybe someday someone will market that strategy as a value-added feature for RV power-centers and we'll see if it takes-off.

Until then ...